Arctic Sea Ice : Forum

Cryosphere => Arctic sea ice => Topic started by: Neven on January 04, 2018, 04:50:55 PM

Title: 2018 sea ice area and extent data
Post by: Neven on January 04, 2018, 04:50:55 PM
Here's a new thread to replace the 2017 version (https://forum.arctic-sea-ice.net/index.php/topic,1837.msg137857.html#msg137857).

Have at it, spread the data.

(https://lerarenontwikkelfonds.onderwijscooperatie.nl/wp-content/uploads/Meten-is-weten.jpg)
Title: Re: 2018 sea ice area and extent data
Post by: Frosty on January 05, 2018, 09:30:11 AM
Obviously too early to draw any conclusions regarding what will happen this year.

That said, let us all take a moment to hope and pray for the best.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 05, 2018, 03:50:32 PM
JAXA still not showing the graphs and the data for 2018, so I had a look at the NSIDC daily data spreadsheet.

This says extent on 4 Jan still 300 k km2 less than 4 Jan 2017, BUT extent stalled last year for a good few days from now.
Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on January 05, 2018, 07:43:07 PM
Welcome to the posting world, Frosty.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 06, 2018, 07:55:07 PM
JAXA still not showing the graphs and the data for 2018, so I had a look at the NSIDC daily data spreadsheet.

As at 5 Jan extent still lowest, but now by only about 150 k.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on January 07, 2018, 02:27:37 PM
NSIDC extent dropped quite a bit, pretty much removing yesterday's upward spike.

(https://image.prntscr.com/image/b0HsIGKjRL6q4KQBh8S4Zw.png)

2017 extent barely grew over the second week of January, but shot upwards nearly a million km2 in the second half of the month. IOW, we can expect 2018 to fall into second place over the next day or two, and remain there until at least the 18th or so.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 07, 2018, 02:50:01 PM
NSIDC extent dropped quite a bit, pretty much removing yesterday's upward spike.

2017 extent barely grew over the second week of January, but shot upwards nearly a million km2 in the second half of the month. IOW, we can expect 2018 to fall into second place over the next day or two, and remain there until at least the 18th or so.

From "aperson" on the freezing thread:-

Quote
Both GEFS and EPS ensembles are mostly in agreement on a synoptic setup that supports warm anomalies driven from subtropical advection on both the Atlantic and Pacific sides in the 5 day to 2 week mid range.

On the Pacific, a return of strong -EPO conditions starting around 5 days out will support another round of anomalies on the Pacific side. In the Atlantic, a strong pressure gradient along the NAO will transport subtropical moisture over the Greenland and Barents seas.

The 5 day cci-reanalyzer forecast also has both ends warming up.

So the question is - will this warmth slow down extent gain as in 2017, allowing 2018 to keep in first place to mid-month and later in the month to become ridiculously lower than 2017 ?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 07, 2018, 03:10:52 PM
JAXA 2018 data and extent graphs still not available., so I sent a polite e-mail to the Japanese National Institute of Polar Research to ask when it may appear.

Will they answer?
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on January 07, 2018, 10:25:08 PM
JAXA 2018 data and extent graphs still not available., so I sent a polite e-mail to the Japanese National Institute of Polar Research to ask when it may appear.

Will they answer?

Not sure. But I follow their Twitter feed, and they're normally pretty good about keeping up-to-date in regard to outages. But there's been no such tweet lately, so I assume they're just on break, maybe?
Title: Re: 2018 sea ice area and extent data
Post by: A-Team on January 08, 2018, 10:40:19 AM
Quote
JAXA 2018 data and extent graphs still not available
Ditto NOAA's RASM-ESRL: it is still frozen on 26 Dec 17 with no advisory 13 days later about when or if it will resume. [[Update: forecasts to resume 14 Feb 18]]

The attached image, adapted form @zlabe, wraps up 2017 extent for the Chukchi. The definition of that sea is elusive, with boundary definitions varying widely by source. The inset shows a common choice that may be what NSIDC used for the data.

Researchers at NSIDC often do not use this boundary in their journal articles, more often taking a contour line such as -150 m as the northern extent, which makes more oceanographic sense than a latitude line oblivious to bathymetric shelves and basins. It is also common to see no definition, simply Chukchi text floating conceptually north of the Bering Strait.

The scale has been changed to percent of maximal possible extent as this is more to the point of seasonally ice-free. By pixel counts, 63% of maximal extent was realized over the year but only 44% over May-Dec and similarly over the insolation season. So we are about halfway there to 'seasonally ice extent-free' for the Chukchi and many of the consequences will have set in already.

On the admin oddities front, it appears that "viewed n times" is not working today.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 08, 2018, 12:55:49 PM
JAXA 2018 data and extent graphs still not available., so I sent a polite e-mail to the Japanese National Institute of Polar Research to ask when it may appear.

Will they answer?

Not sure. But I follow their Twitter feed, and they're normally pretty good about keeping up-to-date in regard to outages. But there's been no such tweet lately, so I assume they're just on break, maybe?
Japan does well for National Holidays. Perhaps tomorrow may see some scientists and technicians stagger into work.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on January 08, 2018, 02:07:03 PM
NSIDC extent down yet again:

Click for up-to-date, full-size image:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_nsidc_six_week_detail.png&hash=daed5fdc1da70674f1a8b83169859375) (http://iwantsomeproof.com/extimg/sie_nsidc_six_week_detail.png)

Of course, record low winter extent doesn't mean record low summer extent (see: 2017).
Title: Re: 2018 sea ice area and extent data
Post by: Gray-Wolf on January 08, 2018, 02:22:18 PM
NSIDC extent down yet again:

Of course, record low winter extent doesn't mean record low summer extent (see: 2017).

Hi Jim!

Yes I think that we are seeing more of our degradation of the pack over the winter now with changes to the summer weather over the pack meaning the type of 07'/2012' summers are no longer there
In some ways this is far worse as a 'perfect melt storm' leading to a blue ocean event would see some recovery the following year
(if that pattern of weather does not repeat the following summer?)
Our pathway now will mean that a poor summer for melt/export will still lead to the blue ocean event and then it will probably repeat thereafter with only exceptional years retaining the 'over the million' in ice cover all summer?

That said I do see this as an ongoing change to summer weather over the basin as more heat/moisture becomes available so who knows what comes next?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 08, 2018, 03:26:20 PM
Last year at about this time, due to the slow 2017 extent gain in the Arctic,  there was discussion about the relative importance of sea ice loss in summer and winter, especially given that the September extent minimum has been going down at about 12.5 % per decade while the March maximum only at about 2.5 % per decade.

The question is - are we seeing an acceleration of winter extent loss ? If so, that leads to the question as to the relative importance of the oceans and the atmosphere, and then to what does this mean for summer ice.

Trouble is, I haven't the faintest idea of how to answer any of these questions.
Title: Re: 2018 sea ice area and extent data
Post by: RikW on January 09, 2018, 09:10:22 AM
I still think in March extent will be low, and I guess we have a good (or bad...) chance it will be a record again, but I think the polar night will be so cold for decades to come, and the ocean not warm enough, that the top layer will still freeze, but it will lack thickness. But it is just a gut feeling/ based on simple logic without thorough understanding of all mechanics.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on January 09, 2018, 12:45:11 PM
I had received an e-mail stating that something had been changed in the JAXA SIE data sheet, but now the ADS NIPR site can't be reached. Has anyone seen whether data had been updated? I know it's winter/hibernation time, but 10 days of no data is too much!  ;)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 09, 2018, 01:25:50 PM
I had received an e-mail stating that something had been changed in the JAXA SIE data sheet, but now the ADS NIPR site can't be reached. Has anyone seen whether data had been updated? I know it's winter/hibernation time, but 10 days of no data is too much!  ;)
I am encouraged that the site is now down - perhaps that means they are trying to fix the problem.

Meanwhile, my spreadsheets are dying from data malnutrition.
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on January 09, 2018, 01:36:03 PM
Hey-ho, we may still book passenger flights crossing arctic to get data :P .  Remember tuesday updates on windows-machines may be a bit more tricky this time around. For sure, some of JAXA stuff runs on Linux, but will the updates talk to each other?
Title: Re: 2018 sea ice area and extent data
Post by: A-Team on January 09, 2018, 04:27:00 PM
Quote
10 days of no data is too much!
RASM_ESRL to resume its forecasts on 14 Feb 18. After a 50 day hiatus! No word on whether they will infill missing data days nor if algorithm is changing (and backwards-comparable). Possibly a good window to get in comments, feature requests and bug reports. Email contacts on web page.

https://www.esrl.noaa.gov/psd/forecasts/seaice/
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 09, 2018, 09:20:01 PM
Quote
10 days of no data is too much!
RASM_ESRL to resume its forecasts on 14 Feb 18. After a 50 day hiatus! No word on whether they will infill missing data days nor if algorithm is changing (and backwards-comparable). Possibly a good window to get in comments, feature requests and bug reports. Email contacts on web page.

https://www.esrl.noaa.gov/psd/forecasts/seaice/
Life must be very difficult at NOAA at the moment - they still do not know how much they will be clobbered when the 2018 Federal Budget is decided. I understand that at the moment they are on 2017 pro-rata budget levels. Something might be decided at overall level in the next 10 days.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on January 09, 2018, 11:01:52 PM
Hey-ho, we may still book passenger flights crossing arctic to get data :P .  Remember tuesday updates on windows-machines may be a bit more tricky this time around. For sure, some of JAXA stuff runs on Linux, but will the updates talk to each other?

Recently flew Tokyo to London and noticed that the plane did not cross into the Arctic despite it being the shortest route. so don’t go booking Arctic flights without checking if the plane goes there. is avoiding the Arctic normal practice for commercial jets?
Title: Re: 2018 sea ice area and extent data
Post by: Neven on January 09, 2018, 11:30:39 PM
I had another look at what numbers had changed in the JAXA SIE data file, so here's a provisional graph:
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on January 10, 2018, 02:28:11 AM
Hey-ho, we may still book passenger flights crossing arctic to get data :P .  Remember tuesday updates on windows-machines may be a bit more tricky this time around. For sure, some of JAXA stuff runs on Linux, but will the updates talk to each other?

Recently flew Tokyo to London and noticed that the plane did not cross into the Arctic despite it being the shortest route. so don’t go booking Arctic flights without checking if the plane goes there. is avoiding the Arctic normal practice for commercial jets?

Not in summer at least, i don't know of winters... Could of course be a matter of jet streams, the airlines like to use'em to save in fuel. Flying counterclockwise this might be more of an issue.
Title: Re: 2018 sea ice area and extent data
Post by: Phil. on January 10, 2018, 04:34:25 AM
Definitely if you can get in the jet stream uses a lot less fuel and saves time, similarly if flying from London to NY you'd want to avoid it.
Title: Re: 2018 sea ice area and extent data
Post by: binntho on January 10, 2018, 08:00:08 AM
Well Jaxa is up and running again.
Title: Re: 2018 sea ice area and extent data
Post by: A-Team on January 10, 2018, 11:18:08 AM
Quote
Jim Petit wrote back in #637 of 2017:  I spend a few daysof the new year tweaking all my graphs and charts. I've read the suggestions for changing the baselines and so on; any changes incorporating those suggestions will be made public in early January.
@zlabe linked to the definitive meteorological article used to justify climate baseline definitions, anomaly charts, and what to do during periods of rapidly changing baselines, first article below. It has been cited 131 times; I chased through those to find the best five, all free full text.

The Definition of the Standard MO Climate Normal
The Key to Deriving Alternative Climate Normals
by A Arguez and RS Vose
http://journals.ametsoc.org/doi/pdf/10.1175/2010BAMS2955.1
131 cites since 2011

NOAA's 1981–2010 US Climate normals: an overview
A Arguez et al
http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-11-00197.1

Projecting “Normals” in a Nonstationary Climate
DS Wilks
http://journals.ametsoc.org/doi/pdf/10.1175/JAMC-D-11-0267.1
Discussion of "hinge" functions to represent changing normals

Performance of Alternative Normals for Tracking Climate Changes, Using
Homogenized and Nonhomogenized Seasonal U.S. Surface Temperatures
DS Wilk RE Livezey
Considers eleven alternatives to the annually updated 30-yr average for specifying climate normals

How well must climate models agree with observations?
D. Notz 2015
http://rsta.royalsocietypublishing.org/content/373/2052/20140164
Arctic sea ice-free timing used to illustrate ideas

Public Perception of Climate Change and the New Climate Dice
J Hansen M Sato R Ruedy
https://arxiv.org/pdf/1204.1286.pdf
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 10, 2018, 02:31:24 PM
JAXA DATA AS AT 9 JAN 2018.   Hoorah..

                        Whoops !
Although extent loss   gain on average is 85% done, there is on average 66 days to go to maximum. Extent is still just lowest in the satellite record.

Historical data suggests a low or record low maximum, but over the last 10 years maximum has been reached any time from the 2nd to 31st March.

cci-reanalyzer forecasts high temp anomalies in the Arctic for the next five days, especially at both ends (Pacific and Atlantic) , weather-forecast.com shows a big push of wind from the South into the far north Atlantic this week and continuing stormy weather in the Bering Sea.  Slow or zero extent gain over the next few days ?
Title: Re: 2018 sea ice area and extent data
Post by: gregcharles on January 13, 2018, 04:52:01 AM
I'm trying to post my first image! It's the count of days for each year with the lowest JAXA (or NIPR or VISHOP) extent number for its date. 2018 has 11 first places finishes in 11 days. It looks like it will probably move to second for the next couple of days, then maybe get first place back.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 13, 2018, 11:51:06 AM
JAXA DATA AS AT 12 JAN 2018.   Hoorah..

Extent gain on average is 86% done, there is on average 62 days to go to maximum. Extent is still just lowest in the satellite record, and as commented above, is likely to be second on the 13th for a couple of days, and then possibly to be lowest again.

Historical data still strongly suggests a low or record low maximum. We will see.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on January 13, 2018, 02:28:44 PM
JAXA DATA AS AT 12 JAN 2018.   Hoorah..

Extent gain on average is 86% done, there is on average 62 days to go to maximum. Extent is still just lowest in the satellite record, and as commented above, is likely to be second on the 13th for a couple of days, and then possibly to be lowest again.

Historical data still strongly suggests a low or record low maximum. We will see.

At the moment, a record low maximum is likely, though not a certainty:

Click for most recent full-size image:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_projections_from_current_date.png&hash=631dd70911503be6e82f233c9d454f7c) (http://iwantsomeproof.com/extimg/sie_projections_from_current_date.png)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 15, 2018, 01:38:44 PM
JAXA extent at 14 Jan now 90K km2 greater than 2017. This could easily change over the next week, as the graph indicates. A record low remains on the cards.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on January 16, 2018, 08:12:46 AM
The third biggest January increase in the JAXA record has 2018 leaping by over 151K putting it well behind 2017 for the moment but still comfortably in second place. 

2006 is now the big challenger as it takes over as lowest on record on the 19th for 8 days.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 18, 2018, 08:27:07 PM
JAXA DATA as at 17 Jan

150k increase immediately followed by 34 kn and 11k. Result ? No real change.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 21, 2018, 12:37:01 PM
JAXA DATA AS AT 20 JAN

2018 is lowest again by nearly 170 k km2, representing about 4 days average extent gain at this time. The average remaining extent gain is about 1.1 million km2, ranging from 0.7 to 1.5 mllion km2 in the previous 10 years.

The historical data points more strongly to a record low maximum.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on January 22, 2018, 07:59:23 AM
Another small decline on the 21st puts 2018 almost  120K km^2 below 2006.  2006 jumped 200K in the next 2 days not quite catching 2017 and is  the lowest on record for the next 5 days.  2018 will need significant increases over the next  five days if it  is to lose first  place anytime soon.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 23, 2018, 10:47:30 AM
JAXA DATA - Extent at 22 January 2018

Just a 4K extent increase, meaning 2018 now 317 K km2 less than 2017 (circa 8 days average extent gain). If remaining extent gain was average, the maximum would be 13.72 million km2, some 160 k less than the record low of 2017.  However, on average about 50 days and 1 million km2 extent gain to go, so.. who knows.

The image shows extent for all years since 1979, the colours reflect the passage of time from top to bottom.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on January 24, 2018, 06:28:14 AM
JAXA had a daily increase of only 36.5K km2. To match 2006, it has to increase 232K km2 in 2 days. I do not think it will happen.

After the 25th, the year 2006 had important extent increases. So 2018 will stay being the lowest on record. After the 25th, the competition will be with 2016 and 2017.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 25, 2018, 03:45:13 PM
JAXA DATA - Extent at 24 January 2018
JAXA says an An 80 k extent increase on the 24th and a 37k increase on the 23rd , while NSIDC says a similar 80 k increase on the 24th but a 150 k increase on the 23rd . 

The next 50 days will tell us if a record low will happen.But 2018 has already written a line on the graph below any previous year.


Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on January 25, 2018, 05:21:28 PM
I find it curious that the Pettit JAXA Arctic Extent projection available on the ASI Graphs (https://sites.google.com/site/arcticseaicegraphs/) page (reproduced below) is not obviously available on Jim Pettit's linked website (https://sites.google.com/view/pettitclimategraphs). 

I note that based on previous year's actual increases from this date (actually, yesterday), a new record low ASI maximum will likely be attained (but not by following 2012's increase).  Also, not only 2012-styled sea ice net loss but also 2016 mimicking net loss will cause a record or near-record September minimum.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on January 25, 2018, 09:40:57 PM
<snippage>
I note that based on previous year's actual increases from this date (actually, yesterday), a new record low ASI maximum will likely be attained (but not by following 2012's increase).  Also, not only 2012-styled sea ice net loss but also 2016 mimicking net loss will cause a record or near-record September minimum.
I find myself increasingly leaning towards using running 5 year averages for net losses/gains when making these comparisons.  My hunch is they will better reflect the more recent trend.

In this case, the longer trend incorporates larger increases and losses than have been typical the last few years, and I think weigh the averages in ways that aren't really reflective of the changing conditions.

I'm for me to dust off my spreadsheets, download some SIE/SIA data and crunch numbers again.
Title: Re: 2018 sea ice area and extent data
Post by: oren on January 25, 2018, 11:10:42 PM
I note that based on previous year's actual increases from this date (actually, yesterday), a new record low ASI maximum will likely be attained (but not by following 2012's increase).  Also, not only 2012-styled sea ice net loss but also 2016 mimicking net loss will cause a record or near-record September minimum.
We will quite likely get a near-record or a record, but I'd like to point out that a major reason for the record low extent in the fall and early winter comes from delayed refreeze, rather than avoided refreeze. This can easily be seen in the Chukchi where the ice-free season is longer by about 2 months compared to even a few years ago, but extent still reaches the maximum possible in the dead of winter. Some peripheral seas do have areas that may avoid refreeze (especially Bering and Barents, also Baffin and the mostly irrelevant but volatile Okhotsk), and that is where the record is decided.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on January 26, 2018, 01:05:42 AM
I find it curious that the Pettit JAXA Arctic Extent projection available on the ASI Graphs (https://sites.google.com/site/arcticseaicegraphs/) page (reproduced below) is not obviously available on Jim Pettit's linked website (https://sites.google.com/view/pettitclimategraphs). 

You may be viewing a cached version of the site; such caching would show a version with old thumbnails. In truth, that visualization, along with all the others, has been in the same place for many, many months. http://iwantsomeproof.com/extimg/sie_projections_from_current_date.png (http://iwantsomeproof.com/extimg/sie_projections_from_current_date.png)
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on January 26, 2018, 01:10:50 AM
<snippage>
I note that based on previous year's actual increases from this date (actually, yesterday), a new record low ASI maximum will likely be attained (but not by following 2012's increase).  Also, not only 2012-styled sea ice net loss but also 2016 mimicking net loss will cause a record or near-record September minimum.
I find myself increasingly leaning towards using running 5 year averages for net losses/gains when making these comparisons.  My hunch is they will better reflect the more recent trend.

In this case, the longer trend incorporates larger increases and losses than have been typical the last few years, and I think weigh the averages in ways that aren't really reflective of the changing conditions.

I'm for me to dust off my spreadsheets, download some SIE/SIA data and crunch numbers again.

For an early version of this graph I actually used discrete five-year averages at first, then five-year moving averages. In my mind, they were both a little messy and not as helpful as I was aiming for, so I chose instead to color-code the annual lines by decade. In case you're wondering. ;-)
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on January 26, 2018, 02:52:30 AM
<snippage>
I note that based on previous year's actual increases from this date (actually, yesterday), a new record low ASI maximum will likely be attained (but not by following 2012's increase).  Also, not only 2012-styled sea ice net loss but also 2016 mimicking net loss will cause a record or near-record September minimum.
I find myself increasingly leaning towards using running 5 year averages for net losses/gains when making these comparisons.  My hunch is they will better reflect the more recent trend.

In this case, the longer trend incorporates larger increases and losses than have been typical the last few years, and I think weigh the averages in ways that aren't really reflective of the changing conditions.

I'm for me to dust off my spreadsheets, download some SIE/SIA data and crunch numbers again.

For an early version of this graph I actually used discrete five-year averages at first, then five-year moving averages. In my mind, they were both a little messy and not as helpful as I was aiming for, so I chose instead to color-code the annual lines by decade. In case you're wondering. ;-)
What I am finding interesting in the estimate of the increase to maximum is the way that the linear trend line over the past fortnight  has moved from showing almost no change since 2003 to  showing a significant decline of about 250,000 km^2 currently.  Each of the past three years have been impacted by the El Nino, producing warmer Pacific water and have very low increases from yesterday to the max. Meanwhile 2012 may have been impacted by the 2010-12 La Nina, and cooler water,  causing greater than normal increases. Pacific waters are again warmer this year and I  am not expecting a lot of sea ice to form in that area.
Title: Re: 2018 sea ice area and extent data
Post by: harpy on January 26, 2018, 03:30:39 AM
What I find to be interesting is that much of the sea ice extent is seasonal ice, so much of the gain's that we've seen this year will disappear shortly into the warming season. 

i'd be more interested in knowing the thickness of the perennial sea ice that remains at the end of the summer.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on January 26, 2018, 04:19:50 AM
What I find to be interesting is that much of the sea ice extent is seasonal ice, so much of the gain's that we've seen this year will disappear shortly into the warming season. 

i'd be more interested in knowing the thickness of the perennial sea ice that remains at the end of the summer.
You'll find a graph  here that shows you that.
https://sites.google.com/site/arcticseaicegraphs/
By mid summer the remaining ice is around 1m thick obviously  by  ow it wil have thickened up to  2-3 m, but that is an average. Some will be thicker than that.
Title: Re: 2018 sea ice area and extent data
Post by: harpy on January 26, 2018, 06:12:58 AM
Are those graphs updated automatically if I just refresh that website every month or so?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 26, 2018, 10:39:25 AM

I'm for me to dust off my spreadsheets, download some SIE/SIA data and crunch numbers again.


Good-o, Mr Pettit, I bookmarked you some time ago.

https://sites.google.com/view/pettitclimategraphs

Meanwhile:

JAXA ARCTIC DATA at 25 January.

Extent up a modest 13k km2, Extent is  12,813,943 km2, some 400k below 2017 and 140k below 2006. 2018 continues to plough its lonely furrow across the graph.

I also had a look at annual averages for recent years - just to see the decline over time.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on January 26, 2018, 01:33:36 PM
Are those graphs updated automatically if I just refresh that website every month or so?
Many of the graphs are linked to the source data and most are updated regularly.  They are definitely  a good source of information.
Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on January 26, 2018, 02:50:14 PM
I wish the L. Hamilton contributions on the Long-term Graphs (https://sites.google.com/site/arcticseaicegraphs/longterm) page would get updated.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on January 26, 2018, 03:30:37 PM
I wish the L. Hamilton contributions on the Long-term Graphs (https://sites.google.com/site/arcticseaicegraphs/longterm) page would get updated.

I'll update that page before the melting season starts, Tor.  :)
Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on January 27, 2018, 05:52:31 AM
"before the melting season starts"
The Long-term Graphs (https://sites.google.com/site/arcticseaicegraphs/longterm) page has updated L. Hamilton graphs already.

Were you afraid the melting season would start this month? ::) :P ;D

Gratitude to L.H. for providing the graphs.

With the 'Minimum Daily ASI Extent' bar graph starting at zero, the amazingness of the 2012 season is exposed.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 27, 2018, 12:26:06 PM
JAXA DATA as at 26 Jan

About 4 weeks and 9% of extent gain to go. Extent today down by 1k km2.Each update points a bit more firmly to a record low maximum.  Even if there is a largish extent gain from now, that ice will be very thin.

Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on January 27, 2018, 12:52:58 PM
Is there any possibility of a flatline for a month?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 27, 2018, 01:13:44 PM
Is there any possibility of a flatline for a month?
It would have to be the first time it happened at this time of year (might happen very close to before and after maximum?)
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on January 27, 2018, 02:56:40 PM
JAXA DATA as at 26 Jan

About 4 weeks and 9% of extent gain to go. Extent today down by 1k km2.Each update points a bit more firmly to a record low maximum.  Even if there is a largish extent gain from now, that ice will be very thin.

What is the date, on average, that maximum extent is reached? Is the extent maximum or melt onset occurring earlier in the year?
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on January 27, 2018, 04:12:11 PM
JAXA DATA as at 26 Jan

About 4 weeks and 9% of extent gain to go. Extent today down by 1k km2.Each update points a bit more firmly to a record low maximum.  Even if there is a largish extent gain from now, that ice will be very thin.

What is the date, on average, that maximum extent is reached? Is the extent maximum or melt onset occurring earlier in the year?

No definite trend on this what I remember, the reason why I asked about the flatline month is that I've got no idea what North Pacific and North Atlantic are doing just now.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on January 27, 2018, 04:15:21 PM
JAXA DATA as at 26 Jan

About 4 weeks and 9% of extent gain to go. Extent today down by 1k km2.Each update points a bit more firmly to a record low maximum.  Even if there is a largish extent gain from now, that ice will be very thin.

What is the date, on average, that maximum extent is reached? Is the extent maximum or melt onset occurring earlier in the year?

No definite trend on this what I remember, the reason why I asked about the flatline month is that I've got no idea what North Pacific and North Atlantic are doing just now.

The Arctic melt season is lengthening. Is that because freeze onset is occurring later in the Fall?
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on January 27, 2018, 04:20:54 PM
Onset would have a trend but varies with currents, I believe... General thinning of arctic ice is one prediction that's long been included.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 27, 2018, 04:37:50 PM
JAXA DATA as at 26 Jan

About 4 weeks and 9% of extent gain to go. Extent today down by 1k km2.Each update points a bit more firmly to a record low maximum.  Even if there is a largish extent gain from now, that ice will be very thin.

What is the date, on average, that maximum extent is reached? Is the extent maximum or melt onset occurring earlier in the year?

No definite trend on this what I remember, the reason why I asked about the flatline month is that I've got no idea what North Pacific and North Atlantic are doing just now.

The Arctic melt season is lengthening. Is that because freeze onset is occurring later in the Fall?

The Arctic melt season measured by time elapsed from date of maximum to date of minimum is NOT lengthening. What is happening is that there are places that used to have sea ice that now usually never have it, i.e. no freezing season and no melt season. Other places are now ice-free for a longer time (e.g. Hudson's Bay). (One day per year average?)

So in Hudson's bay you would see a shorter melt season if you measured time elapsed from date of maximum (100% ice) to date of minimum(zero-ice), and a longer melt season if you measured time from date of maximum sea ice to date of ice starting to reform.

The confusion is looking at the Arctic as a whole versus places on the periphery.  It is quite confusing.

The fact remains that at 26 Jan 2018 there is 2.1 million km2 less Arctic sea ice than the 1980's average.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on January 27, 2018, 06:36:42 PM
NSIDC Arctic extent took a big dive yesterday; that metric now has 2017 2018 in first place by a fairly hefty 341k:

Click for current full-size image:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_nsidc_six_week_detail.png&hash=daed5fdc1da70674f1a8b83169859375) (http://iwantsomeproof.com/extimg/sie_nsidc_six_week_detail.png)

Is there any possibility of a flatline for a month?

March or September, perhaps, but not this month, not January. Month-to-date, NSIDC extent has grown by just under 900k. That's on the lower end of things, but it's nowhere near a record. In fact, both 2012 and 2015 saw smaller month-to-date increases.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on January 27, 2018, 06:47:49 PM
The Arctic melt season measured by time elapsed from date of maximum to date of minimum is NOT lengthening. What is happening is that there are places that used to have sea ice that now usually never have it, i.e. no freezing season and no melt season. Other places are now ice-free for a longer time (e.g. Hudson's Bay). (One day per year average?)

It would make sense that the length of the cold (warm) season hasn't changed.  What might be a more interesting question is the temperature at the onset of the cold (warm) season.  I would expect the temperature at onset of the cold season to remain fairly low until there is not enough ice to keep the ocean cold during the warm season, and then a fairly rapid decline in the freezing season.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on January 27, 2018, 08:14:54 PM
JAXA DATA as at 26 Jan

About 4 weeks and 9% of extent gain to go. Extent today down by 1k km2.Each update points a bit more firmly to a record low maximum.  Even if there is a largish extent gain from now, that ice will be very thin.

I think it will be important to contrast this with last season.  We were extraordinarily warm to start, and cooled off significantly (relatively speaking...) from around this point onwards.

This season we started off cooler, but may be finishing warmer than last year.

I suspect we'd be better off if it were the other way around.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on January 27, 2018, 10:03:57 PM
This season we started off cooler, but may be finishing warmer than last year.

I suspect we'd be better off if it were the other way around.

I'd agree.  Cold summers and warm winters are not happy happy joy joy for Humans.

(well...maybe they are if you are a real fan of Ren and Stimpy.)
Title: Re: 2018 sea ice area and extent data
Post by: oren on January 27, 2018, 10:31:57 PM
The Arctic melt season measured by time elapsed from date of maximum to date of minimum is NOT lengthening. What is happening is that there are places that used to have sea ice that now usually never have it, i.e. no freezing season and no melt season. Other places are now ice-free for a longer time (e.g. Hudson's Bay). (One day per year average?)

So in Hudson's bay you would see a shorter melt season if you measured time elapsed from date of maximum (100% ice) to date of minimum(zero-ice), and a longer melt season if you measured time from date of maximum sea ice to date of ice starting to reform.

The confusion is looking at the Arctic as a whole versus places on the periphery.  It is quite confusing.

The fact remains that at 26 Jan 2018 there is 2.1 million km2 less Arctic sea ice than the 1980's average.
I think the best measure is something that shows the lengthening of the ice-free period. Using Wipneus' AMSR2 regional extent chart, I made this crude animation showing my thinking. Define "Less than full ice cover" as <95% coverage, and "Nearly ice-free" as <10% coverage. Of course, these are arbitrary thresholds.
Comparing 2017 to 2012 for the Chukchi, the "less than full" period was longer by ~2 months, while the "nearly ice-free" period was longer by ~1.5 months.
"Melt onset" could be defined as the first date where it goes below 95% and doesn't rebound. "Refreeze onset" could be defined as the first date where it goes above 10% and doesn't rebound.
Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on January 27, 2018, 10:56:12 PM
I like where you're going, oren.  For the open-ended basins (Greenland Sea, Bering Sea, etc.) the 'full ice cover' area will be an arbitrary number (average max of 1979-2008 [30 yrs] prehaps?) (and will determine the 'refreeze onset' boundary.
Title: Re: 2018 sea ice area and extent data
Post by: oren on January 28, 2018, 09:54:44 AM
Another Chukchi animation along the same logic, but going back to 1979 using NSIDC data.
It can be seen that until 1990 the situation was mostly random variation on a stable theme. Since then, minima kept getting lower, melt onset kept coming earlier, and refreeze completion kept coming later.
Notable years pushing the envelope:
1991 (late refreeze)
1993 (new minimum)
1998 (new minimum)
2004 (new minimum)
2006 (late refreeze)
2007 (new minimum near zero, late refreeze)
2012 (earlier near zero)
2016 (late final refreeze, first into January)
2017 (early melt, late refreeze)

Notes: January of the following year is appended to each year. The actual date range is April 15th to January 20th.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on January 28, 2018, 01:55:42 PM
Not quite the bottom dropping out, but a nonetheless remarkable late-January departure:

Click for current full-size image:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_nsidc_six_week_detail.png&hash=daed5fdc1da70674f1a8b83169859375) (http://iwantsomeproof.com/extimg/sie_nsidc_six_week_detail.png)
Title: Re: 2018 sea ice area and extent data
Post by: Hyperion on January 28, 2018, 07:43:31 PM
Durn Jim. That looks a little disturbing. Until you take your advice and click for the up to date version (downsized copy attached).
The decadal averages seem to be accelerating downwards too. When I take note that the previous spread over 20 years on this date is about twice the gap with the previous 2006/2017 record presently, I feel a little prone to question the "not quite" part of your statement.

Reckon won't be long until feb 1 is time for Nevs to open the melt season thread. With 14C ssts off Svalbard, and +9C SSTAs off NFL and KMCH, the assaults on.


Not quite the bottom dropping out, but a nonetheless remarkable late-January departure:

Click for current full-size image:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_nsidc_six_week_detail.png&hash=daed5fdc1da70674f1a8b83169859375) (http://iwantsomeproof.com/extimg/sie_nsidc_six_week_detail.png)
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on January 28, 2018, 09:14:10 PM
A climate system in a chaotic state will behave chaotically. Perhaps our search for a new normal is misguided as abnormal variance now is the new normal.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on January 30, 2018, 01:06:44 PM
JAXA ARCTIC EXTENT DATA AS 29 JAN

On average about 45 days, just 0.83 million km2 and 8% of extent gain to go. Extent max date in the past has ranged from 32 days to to 61 days from Jan 29. Note that this does not correspond to min and max extent gain from now. So who knows the final result, though a record low is still on the cards.

In the last three days daily extent gain has increased to above the average for this time of year.

Title: Re: 2018 sea ice area and extent data
Post by: gregcharles on February 01, 2018, 07:33:02 PM
2018 set record lows in the NIPR Extent record almost every day in January, nearly wiping 2006 off the chart in the process. It's a little sobering to consider that the lows we're witnessing today with a mixture of odd excitement and plain terror will all be beaten within 10 to 12 years.

Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on February 01, 2018, 10:40:37 PM
It's a little sobering to consider that the lows we're witnessing today with a mixture of odd excitement and plain terror will all be beaten within 10 to 12 years.

Looking at the FDD I'm wondering if you didn't mean 1-2 years.

The less cold you have left the harder it is to keep things cold, and I don't know when there is no longer enough ice, but when there is no longer enough ice the last of it leaves pretty close to instantly.

Title: Re: 2018 sea ice area and extent data
Post by: oren on February 02, 2018, 12:22:44 AM
2018 set record lows in the NIPR Extent record almost every day in January, nearly wiping 2006 off the chart in the process. It's a little sobering to consider that the lows we're witnessing today with a mixture of odd excitement and plain terror will all be beaten within 10 to 12 years.
A. Thanks for the interesting table, and you're probably right with your reasoning. However,
B. It's a little heartening to think these records may hold for 10 to 12 years...  and not 1 to 3 years as my unsupported gut feeling suggests.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 03, 2018, 11:31:39 AM
JAXA DATA - Extent as 2 Feb is 13,251,377 km2
Extent gain continuing to accelerate, up another 96 k. Average extent gain in the these last 6 weeks remaining of 0.72 million would produce a maximum of  just under 14 million km2, whoops less greater than than last year's record low of 13.88 million km2..

Perhaps the extraordinary cyclone due to start roaring up into the Greenland Sea to over the North Pole will change things for a few days?
Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on February 03, 2018, 02:26:52 PM
Exciting times!  (and I'm speaking as an ASI-head)

['head', as in: a fan or devotee (usually used in combination): a Dead head; a chili head.]
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on February 03, 2018, 06:34:43 PM
JAXA DATA - Extent as 2 Feb is 13,251,377 km2
Extent gain continuing to accelerate, up another 96 k. Average extent gain in the these last 6 weeks remaining of 0.72 million would produce a maximum of  just under 14 million km2, whoops less greater than than last year's record low of 13.88 million km2..

Perhaps the extraordinary cyclone due to start roaring up into the Greenland Sea to over the North Pole will change things for a few days?
The coming cyclone may briefly *increase* extent while potentially reducing area.  It will stir things up no doubt.  Key question for me is whether the heat drug up from depth results in an early max.
Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on February 03, 2018, 06:59:53 PM
It's not just one cyclone. It's a vortex around Greenland that will bring repeated intense storms with huge waves. Watch for Jim Hunt to drop into Nazarre with his longboard. Seriously, the wave trains in the north Atlantic and the sub Arctic seas are going to be massive. Expect massive destruction of sea ice on the Atlantic side of the Arctic and sub-Arctic.

Title: Re: 2018 sea ice area and extent data
Post by: jdallen on February 03, 2018, 07:15:25 PM
It's not just one cyclone. It's a vortex around Greenland that will bring repeated intense storms with huge waves. Watch for Jim Hunt to drop into Nazarre with his longboard. Seriously, the wave trains in the north Atlantic and the sub Arctic seas are going to be massive. Expect massive destruction of sea ice on the Atlantic side of the Arctic and sub-Arctic.
I see that looking at nullschool.  Persistent 6-10M waves with 10-15 second periodicity, over a period of 72+ hours.  That will stir up the top 2-300 meters of the water column quite thoroughly.

You are right.  I think the Barentsz in particular is going to get clobbered, especially as there is already a lot of imported "warm" Atlantic water there at depth.
Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on February 03, 2018, 08:23:16 PM
Expect waves heights of about 20 feet (or 6m) at the edge of the ice pack. Wave heights of 50 feet (15m) or more will be generated in the Irminger sea. Nazare surf wave face heights could approach 100 feet in this series of storms. The Coastlines of Ireland, the U.K. and France will be battered by extreme waves. Swell wave periods of 20 seconds will be generated. The long persistent fetch of very high winds will produce extraordinary surf. Surges associated with wave sets will affect areas that are normally not affected by waves.

The sea ice will be slammed and driven back, but Europe will get the news coverage.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Hunt on February 03, 2018, 08:44:00 PM
Watch for Jim Hunt to drop into Nazarre with his longboard

No chance of that FooW! Did you see what happened to Cotty?

http://youtu.be/iCTApPTZ6PQ

Getting back to reality:

http://GreatWhiteCon.info/2018/02/facts-about-the-arctic-in-february-2018/

With apologies for the cross post:

Quote
Those maps shows 10 meter high, 15 second period waves heading straight for the ice edge north of Svalbard.
Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on February 04, 2018, 04:59:33 AM
Ouch. He faded right into taking that bomb on his head. He badly misread that wave and lost a lot of speed the way he faded back. He had nowhere to go once it started breaking. I hope the orhopods were able to put him back together.

The model run you showed might be more accurate on the details of the wave heights than what I showed.  That Navy model map shows the big picture well. It's going to be a huge swell that rocks western Europe and the ice edge.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on February 04, 2018, 05:29:55 AM
It's not just one cyclone. It's a vortex around Greenland that will bring repeated intense storms with huge waves. Watch for Jim Hunt to drop into Nazarre with his longboard. Seriously, the wave trains in the north Atlantic and the sub Arctic seas are going to be massive. Expect massive destruction of sea ice on the Atlantic side of the Arctic and sub-Arctic.
I see that looking at nullschool.  Persistent 6-10M waves with 10-15 second periodicity, over a period of 72+ hours.  That will stir up the top 2-300 meters of the water column quite thoroughly.

You are right.  I think the Barentsz in particular is going to get clobbered, especially as there is already a lot of imported "warm" Atlantic water there at depth.
It would be interesting to review the predictions from a week ago to see if the big increase in extent during the last week was indicated. Most of this increase occurred between Baffin and Barents.   If the current predictions are correct I would expect to see the extent increases of the last week largely reversed.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on February 04, 2018, 06:00:35 AM
<snippage>
It would be interesting to review the predictions from a week ago to see if the big increase in extent during the last week was indicated. Most of this increase occurred between Baffin and Barents.   If the current predictions are correct I would expect to see the extent increases of the last week largely reversed.
A possible max on Jan 31 or thereabouts?
Title: Re: 2018 sea ice area and extent data
Post by: Jim Hunt on February 04, 2018, 01:35:13 PM
Ouch. He faded right into taking that bomb on his head.

I think he was hoping to get barrelled. That's not quite how things worked out!

However perhaps we should keep the "wave" discussion going in the freezing season thread (https://forum.arctic-sea-ice.net/index.php/topic,2141.msg141007.html#msg141007) rather than here?
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on February 04, 2018, 07:53:06 PM
I hope the orthopods were able to put him back together.

i know it's just typo's (one i corrected for better understanding) but i find it funny since orthopods are probably indeed the future (robot surgeons) so perhaps you got it right by accidents because they're already in use for some hyper sensitive bodyparts like brain operations and the likes.

there remains the possibility that you wanted to write the word that way and not orthopedist as i assumed. just had to smile.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Hunt on February 04, 2018, 08:43:32 PM
I hope the orthopods were able to put him back together.

They're getting there: https://twitter.com/_physio_/status/956957784880353281

See also: https://www.medicinenet.com/script/main/art.asp?articlekey=4670
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 05, 2018, 10:40:57 AM
JAXA DATA - Extent as at 4 Feb is  13,303,213 km2, just 34 k less than extent in 2017 on that date.

Extent gain dropped to about 25k per day for the last 2 days. Average extent gain in the these last 39 days remaining of 0.66 million km2 ( 7 % ) would produce a maximum of  just under 14 million km2, less than last year's record low of 13.88 million km2.

The question is what effect the current drama unfolding in the Atlantic side (and perhaps extended into mid-Feb) will have on ice extent in the last 40 days or so of the freezing season. Extent could initially increase as ice is spread out, and then stall or even drop as warmer water brought up from depth attacks the ice.

If ice extent then became a record low maximum - would this be regarded as a genuine trend for accelerating loss of winter ice extent  or merely the result of a one-off event (the MJO record oscillation currently underway) ?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 05, 2018, 03:09:12 PM
Forgot to add the image from jaxa.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 05, 2018, 05:51:53 PM
The real professionals over on 2017-208 are producing some marvellous stuff. For someone like me, much more of an observer than a practitioner, it is more a case of finding images that I can put in front of ordinary people's faces to get the message across.

Weather-forecast.com is just the job sometimes. A picture (sometimes) is worth a thousand words.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 06, 2018, 02:33:00 PM
JAXA Arctic extent at 5 Feb 13,329,683 km2 is now 6 K km2 more than 2017, despite just an average daily increase of 26 K. This is liable to increase as 2017 goes through a very slow increase until the 11th Feb, but then large increases to about the 18th Feb occurred.

As yet, the data does not reflect the impact of the cyclone. There is still the possibility (as discussed on the 2017-18 freezing thread) that the cyclone has brought large quantities of relatively warm water up from depth that might attack the ice broken up by the cyclone and, with prospects of continued northward movement of relatively warm air up through the Greenland sea inhibiting further ice formation. We will see - interesting times?

ps The extent data might not show the effect of the cyclone, but the image below (JAXA sea ice drift 5 Feb) certainly does). Expect an up-tick in Fram Strait export?

Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on February 07, 2018, 01:31:57 AM
Last winter and this winter the Arctic ocean has been affected by persistent advection of heat and water vapor from both the Atlantic and Pacific oceans. This heat and precipitable water has been at low and mid levels of the atmosphere. This vortex splitting event is a "one off" but the storminess and warmth is not. We are watching the Arctic rapidly transition into a warmer and wetter climate.

Last summer's cool stormy weather has made everything look a little better than it is.
Title: Re: 2018 sea ice area and extent data
Post by: binntho on February 07, 2018, 06:56:27 AM
JAXA is back in lowest place February 6th after a 36.000 km2 daily drop. Latest value 13.293.000, 30.000 km2 less than 2017 for the same date.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 08, 2018, 01:03:59 PM
JAXA Arctic Extent as at 7 Feb 2018 13,250,852 km2 100k less than 2017 on that date.

The last two days have seen a 36 k (6 Feb) and 43 k (7 Feb) km2 extent loss, due to extent losses due to the cyclone. The cyclone is more or less over, but how long will its effect last? NO doubt a topic for the 2017-18 Freezing Season.

With 36 days (range 23 to 52), 0.59 million km2, and 7% of average extent gain to go, a new record low is still very possible.

ps The last table suggests ( think) that loss of winter sea ice is gradually accelerating, as does the NSIDC January graph? A little more work required, methinks.

ps: And the answer so far is - maybe a little bit faster
Title: Re: 2018 sea ice area and extent data
Post by: Lord M Vader on February 08, 2018, 01:40:57 PM
For the second day in a row, NSIDC reports a century break, down 114K(!) How many times have there been a century break in February and how many times have there been two consecutive days with a century break?

Meanwhile, Antarctica lost 58K so the global sea ice extent loss were a decent -172K. Is that lowest on record or is 2017 still in charge?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 08, 2018, 02:30:46 PM
For the second day in a row, NSIDC reports a century break, down 114K(!) How many times have there been a century break in February and how many times have there been two consecutive days with a century break?

Meanwhile, Antarctica lost 58K so the global sea ice extent loss were a decent -172K. Is that lowest on record or is 2017 still in charge?
NSIDC says 2018 is 134k < 2017,  JAXA says 2018 is 100k < 2017. So 2018 is in charge, at the moment....
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on February 08, 2018, 08:43:09 PM
For the second day in a row, NSIDC reports a century break, down 114K(!) How many times have there been a century break in February and how many times have there been two consecutive days with a century break?

There have only been five century+ decrease in NSIDC ASI extent over the past ten Februarys, and only ten total for the month since 2000; two of those have occurred over the past two days, so it's definitely a rare thing. There have been no back-to-back century+ decreases since 2000; in fact, only 2007 saw more than one for the entire month.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on February 09, 2018, 12:07:08 AM
For the second day in a row, NSIDC reports a century break, down 114K(!) How many times have there been a century break in February and how many times have there been two consecutive days with a century break?

There have only been five century+ decrease in NSIDC ASI extent over the past ten Februarys, and only ten total for the month since 2000; two of those have occurred over the past two days, so it's definitely a rare thing. There have been no back-to-back century+ decreases since 2000; in fact, only 2007 saw more than one for the entire month.

And we know how that year's melt season turned out.
Title: Re: 2018 sea ice area and extent data
Post by: harpy on February 09, 2018, 01:00:25 AM
....whoah, so we just had 2/10 of the only decreases on record this year in 2018?  AND we have the lowest sea ice extent in history?

....no no no, I must not think about climate change.  Look at the stock market, up ...oh ok it's down 10% in 4 days.  4th worst crash in history....b-b-but everything's going to be fine right?

I must keep going to work, keep paying my bills, keep consuming useless Chinese things - this is what I'm supposed to do while the arctic melts in February and the stock market crashes. 


  Hmm.
 
Title: Re: 2018 sea ice area and extent data
Post by: Tony Mcleod on February 09, 2018, 03:44:02 AM
A bit like road runner out over the gorge but hasn't realized it yet. :o
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 09, 2018, 10:17:33 AM
JAXA Arctic Extent as at 8 Feb 2018  13,241,477  km2, 116k less than 2017 on that date.

A small extent loss of 9k km2, but 2017 had a small increase of 6k, while the average increase is about 25k. The cyclone is more or less over, but how long will its effect last?

With 35 days (range 22 to 51), 0.55 million km2, and 7% of average extent gain to go, an average extent gain would result in a new record low of 13.80 million km2, 80k less than last year. But, cci-reanalyzer says a big warm-up over the next 10 days, there are unknown consequences of a possible big fat SSW, and the lingering effects of the cyclone are yet to come. Probably, average is going to be even more meaningless than usual. The 2017-18 freezing thread is going to be busy?



ps The last table suggests ( think) that loss of winter sea ice is gradually accelerating, as does the NSIDC January graph? A little more work required, methinks.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on February 10, 2018, 02:09:15 PM
NSIDC extent seems intent on staying in first:

CLICK FOR THE MOST RECENT FULL-SIZE IMAGE:
(https://image.prntscr.com/image/t4JEbKITQReevORWiywsZg.png) (http://iwantsomeproof.com/extimg/sie_nsidc_six_week_detail.png)
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on February 11, 2018, 12:14:45 AM
Since some have asked, based on statistics over the past ten years (2008-2017):

--IJIS extent is projected to reach of a maximum of 13.67M km2 on March 16, an additional increase of 424k over the next 36 days, or 11.78k per day.

--NSIDC extent is projected to reach of a maximum of 14.15M km2 on March 15, an additional increase of 407k over the next 34 days, or 11.97 per day.
Title: Re: 2018 sea ice area and extent data
Post by: Steven on February 11, 2018, 01:39:11 PM
based on statistics over the past ten years (2008-2017):

--IJIS extent is projected to reach of a maximum of 13.67M km2 on March 16, an additional increase of 424k over the next 36 days, or 11.78k per day.

I'm not sure what you are saying.  You are talking about the maximum, but in your calculation you only used the extent values for 16 March?  How about years with an earlier or later maximum?  The JAXA extent on 16 March is on average about 0.1 million km2 lower than the maximum.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on February 11, 2018, 08:08:48 PM
I'm not sure what you are saying.  You are talking about the maximum, but in your calculation you only used the extent values for 16 March?  How about years with an earlier or later maximum?  The JAXA extent on 16 March is on average about 0.1 million km2 lower than the maximum.

I wrote that my projections were "based on statistics over the past ten years (2008-2017)". That is, if SIE were to increase at the mean average rate measured over the past ten years, we'd see the maximums I mentioned. Also, if SIE were to behave in line with the mean average of those same ten years, this year's maximum would occur on those dates I mentioned. These visualizations might help:

Click for most recent full-size image:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_projections_from_current_date.png&hash=631dd70911503be6e82f233c9d454f7c) (http://iwantsomeproof.com/extimg/sie_projections_from_current_date.png)

Click for most recent full-size image:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_nsidc_projections_from_current_date.png&hash=80b9e93025f04cc597c2df3690280b18) (http://iwantsomeproof.com/extimg/sie_nsidc_projections_from_current_date.png)

The post was in response to comments I'd seen speculating whether the freeze could be over. I wanted to show why that, while theoretically possible, it was highly unlikely.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on February 12, 2018, 10:39:19 AM
IJIS is back after its long weekend with a modest  22K gain for the three days to 13,263,605.

With  2017 rising rapidly over the next week the next date where 2018 is likely to be challenged for lowest position is 7 days away on the 18th when 2016 drops to 13,547,054.  However the required rise of 284K would still be well above the long term average for that week which is 150K.


Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 12, 2018, 11:06:03 AM
JAXA Arctic Extent as at 11 Feb 2018 13,263,605 km2, down to just 87k less than 2017 on that date.

The last three days days have seen a net 22k gain, which is low. With 32 days (range 19 to 48), 0.52 million km2, and just 5% of average extent gain to go, average extent gain would end up with a new record low maximum of 13.78 million km2, just 100k less than 2017.

But with the lingering aftereffects of the cyclone, unknown as yet impacts from the SSW, and entering the wobbly month of transition, who knows ?
Title: Re: 2018 sea ice area and extent data
Post by: Steven on February 12, 2018, 07:32:53 PM
I wrote that my projections were "based on statistics over the past ten years (2008-2017)". That is, if SIE were to increase at the mean average rate measured over the past ten years, we'd see the maximums I mentioned. Also, if SIE were to behave in line with the mean average of those same ten years, this year's maximum would occur on those dates I mentioned. These visualizations might help:

Click for most recent full-size image:
(https://i.imgur.com/DTNIASq.png) (http://iwantsomeproof.com/extimg/sie_projections_from_current_date.png)

That method is biased low for estimating the maximum.  By taking the average trajectory over the past 10 years, you get an unrealistically smooth trajectory, which remains basically flat during mid-March.  In reality, the trajectories for individual years fluctuate much more.  You only need a brief upward fluctuation to increase the maximum for a given year. 

To get a corrected estimate for the 2018 JAXA extent maximum using that method, you would have to add about 0.1 million km2 to your calculated numbers.  For the NSIDC one-day extent maximum, the correction would be about 0.15 million km2.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on February 12, 2018, 08:37:58 PM
That method is biased low for estimating the maximum.  By taking the average trajectory over the past 10 years, you get an unrealistically smooth trajectory, which remains basically flat during mid-March.  In reality, the trajectories for individual years fluctuate much more.  You only need a brief upward fluctuation to increase the maximum for a given year. 

I think you need to have watched that particular graph for a few years.  It isn't artificially anything.  It this just a report.  A report I pay a lot of attention to.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on February 12, 2018, 08:54:49 PM
That method is biased low for estimating the maximum.  By taking the average trajectory over the past 10 years, you get an unrealistically smooth trajectory, which remains basically flat during mid-March.  In reality, the trajectories for individual years fluctuate much more.  You only need a brief upward fluctuation to increase the maximum for a given year. 

To get a corrected estimate for the 2018 JAXA extent maximum using that method, you would have to add about 0.1 million km2 to your calculated numbers.  For the NSIDC one-day extent maximum, the correction would be about 0.15 million km2.

Yes, multi-year averages tend to be smoother than any particular year comprising that average--sometimes even "unrealistically" so. It's almost a wonder scientists even use them, innit? ;-)

True, too, trajectory projections such as mine are not predictions. (Fact: that's why they're called projections, and not predictions.) The graphs merely show where extent is most likely to go given both current extent and historical behavior over the last ten years. Certainly 2018 could end up below or far above that projection, and it can max out far ahead of or far later than that projection. But that doesn't make the graph of any less use. YMMV...

As always, should you (or anyone else) care to create the same type of graphic and arbitrarily add 100k to the JAXA chart and 150k to the NSIDC one, I claim no ownership of the data, and I'm sure it would be of interest. Over the past couple of years, these projections have allowed me to be fairly accurate when projecting on maximum extent (though slightly less so on the minimum), so I'd like to see something else even more accurate.
Title: Re: 2018 sea ice area and extent data
Post by: oren on February 12, 2018, 09:58:56 PM
That method is biased low for estimating the maximum.  By taking the average trajectory over the past 10 years, you get an unrealistically smooth trajectory, which remains basically flat during mid-March.  In reality, the trajectories for individual years fluctuate much more.  You only need a brief upward fluctuation to increase the maximum for a given year. 
Good point. The chance of hitting a given maximum goes up with higher volatility, even when the average trajectory remains the same.
I do find Jim's graph quite useful in any case. You don't have to use the average, instead you could guesstimate the maximum using the spread of individual years.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 13, 2018, 10:38:36 AM
JAXA extent 12th Feb 13,268,427 km2, 129 k less than 2017, up by just 4.8K km2.

In 2018 extent has been less than 2017 36 days out of 43.

Also note the high temp anomalies at both ends of the CAB for the next few days. maybe one day we will get similar stuff on ssts and ocean heat transportation, since it is ocean heat that will in the end destroy the sea ice(?)


Title: Re: 2018 sea ice area and extent data
Post by: gregcharles on February 13, 2018, 11:55:47 PM
In 2018 extent has been less than 2017 36 days out of 43.

Even more, the 2018 JAXA extent is the lowest of any year for those 36 days. For many of them, but not all, 2017 is now in second place.

Here's an interesting statistical tidbit: today 2017 has 37 daily lowest extent records, and 2018 has 36. Tomorrow that will exactly reverse. 2018 will have 37 and 2017 will have 36.

I'm going out on a limb a bit making this prediction. JAXA extent could have a double century rise today and embarrass me. Still, to torture a metaphor, it's a limb of ironwood with a two foot diameter, and I'm a sugar ant. We'll see tomorrow, which I boldly predict will begin with the sun rising in the east.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 14, 2018, 12:04:04 AM
"The sun rises in the east". I was on a plane and saw the sun rise in the west. Weird.
Title: Re: 2018 sea ice area and extent data
Post by: gregcharles on February 14, 2018, 12:58:27 AM
Wait, what? Yes, OT, but how did that work? Were you flying faster than the sun? (OK, faster than the apparent speed of the sun. Damned physicists.) At the equator that would be 1000 mph or thereabouts, but at higher latitudes would be less, so feasible I guess. Or maybe you actually flew across the north pole, as some U.S. to Europe routes do?

(Disclaimer: my above prediction is intended for earthbound observers. For anyone traveling in a supersonic jet chasing the sun, YMMV.)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 14, 2018, 01:21:43 AM
Polar route flight at sunset /sunrise
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 14, 2018, 10:55:26 AM
JAXA Arctic Extent as at 13 Feb 2018 13,300,888 km2, now 136k less than 2017 on that date.

Extent gain on 13th of 32k, which is above average for that date. With 30 days (range 17 to 46), 0.47 million km2, and just 4.7% of average extent gain to go, average extent gain would end up with a new record low maximum of 13.77 million km2, just 110k less than 2017. 7 out of 10 of the previous 10 years say yes to a record low.

But with the lingering aftereffects of the cyclone, unknown as yet impacts from the SSW, and entering the wobbly month of transition, who knows ?
Title: Re: 2018 sea ice area and extent data
Post by: Peter Ellis on February 14, 2018, 06:38:20 PM
The simpler way to have a sunrise in the west involves a funicular railway, a sunset, and absolutely perfect timing.  Managed that one in Montecatini on honeymoon.  We had one sunset just as we got to the station at the bottom of the funicular,  then a sunrise on the way up, followed by another sunset after we got to the top.

Coming back down later that night was equally spectacular for different reasons. There's a point where the line goes through a deep cut with overhanging trees and you can't see much - then you emerge from the gloom, and FOOM... the whole of Tuscany appears, jewelled with lights.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 15, 2018, 09:16:51 PM
JAXA Arctic Extent as at 14 Feb 2018 13,342,060 km2, now 205k less than 2017 on that date despite a 41 k increase. With 29 days (range 16 to 45), 0.43 million km2, and just 4.3% of average extent gain to go, average extent gain would end up with a new record low maximum of 13.78 million km2, just 100k less than 2017. 7 out of 10 of the previous 10 years say yes to a record low.

In a few days and to the end of the month the 2017 large increases become low and even negative. However, at least until then 2018 should continue to plough its lonely furrow. (In 2018, 38 days out of 45 lower than 2017)

Extent gain on 13th of 32k, which is above average for that date.

Lingering after-effects of the cyclone, unknown as yet impacts from the SSW, and entering the wobbly month or two of transition, who knows ?
Title: Re: 2018 sea ice area and extent data
Post by: oren on February 15, 2018, 09:24:54 PM
Gerontocrat, thank you for your daily updates and analysis on this and other threads.
I want to add this chart from Wipneus' regional AMSR2 extent page, which explains a whole lot about the 2018 record low, and provides a lot to worry about for the coming melting season. Unprecedented is too easy a word for this.
Title: Re: 2018 sea ice area and extent data
Post by: romett1 on February 15, 2018, 09:51:43 PM
Gerontocrat, thank you for your daily updates and analysis on this and other threads.
I want to add this chart from Wipneus' regional AMSR2 extent page, which explains a whole lot about the 2018 record low, and provides a lot to worry about for the coming melting season. Unprecedented is too easy a word for this.
Unprecedented it is - I just add here Feb 14 vs Feb 6.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on February 15, 2018, 11:04:48 PM
A sense of foreboding about the coming melt season.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on February 16, 2018, 12:16:48 AM
When the Arctic Ice decides to go I don't think time of year is going to matter all that much.  We won't know until afterwards when it happens, but right now things taste bad.  Has 2018 decided to go its own way?

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 16, 2018, 12:31:22 AM

I want to add this chart from Wipneus' regional AMSR2 extent page, which explains a whole lot about the 2018 record low, and provides a lot to worry about for the coming melting season. Unprecedented is too easy a word for this.
Cor blimey. Stunning graph. Game changer ? Time to think aout what happens in the spring and summer?
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on February 16, 2018, 12:35:54 AM
GFS and EURO are both in agreement over a major heatwave and/or LP event for Greenland + Arctic D8-10.

(https://www.tropicaltidbits.com/analysis/models/gfs/2018021518/gfs_T2ma_nhem_36.png)

Relevant to most recent replies, models show a continued wave of 960-980mb LPS buffering the Bering with sustained southerly winds and waves. It seems the Bering front should continue to retreat following the losses from 2/6-14 as depicted above. Perhaps substantially so.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 16, 2018, 11:06:51 AM
GFS and EURO are both in agreement over a major heatwave and/or LP event for Greenland + Arctic D8-10.

cci-reanalyzer this morning has the maximum anomaly on 21 Feb, and by the 25th Arctic temperatures much closer to average.

Meanwhile,

JAXA Arctic Extent as at 15 Feb 2018 13,346,013 km2, just 4k up on the day, now 328k less than 2017 and 275k less than 2016  on that date.  Given average extent gain of about 15k per day from now to maximum, 2018 extent is about 2 weeks below 2017 extent.

28 days (range 15 to 44), 0.39 million km2, and just 3.9% of average extent gain to go., Average result a record low maximum of 13.74 million km2,  140k less than 2017. 7 out of 10 of the previous 10 years say yes to a record low.

For a few days until about 21-22 February Arctic temperature anomalies should be high, especially at the Bering and Atlantic ends of the CAB. Until then 2018 should continue to plough its lonely furrow. (In 2018, 39 days out of 46 lowest in the satellite record).

After the 22nd Feb, Arctic temperatures may drop like a stone, or maybe not. Entering the wobbly month or two of transition, who knows ?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 17, 2018, 12:18:07 PM
cci-reanalyzer this morning has the maximum anomaly on 21 Feb, and by the 27th Arctic temperatures much closer to average ( and the UK bloody cold)

Meanwhile,

JAXA Arctic Extent as at 16 Feb 2018 13,361,998 km2, an average 16k up on the day, now 347k less than 2017 and 305k less than 2016  on that date.  Given average extent gain of about 15k per day from now to maximum, 2018 extent is about 3 weeks below 2017 extent.

27 days (range 14*** to 43), 0.36 million km2, and just 3.6% of average extent gain to go., Average result a record low maximum of 13.72 million km2,  160k less than 2017. (maybe my guess in the Jan poll of 13.5 t5o 13.75 will be correct ?*!??). 7 out of 10 of the previous 10 years say yes to a record low.

*** In 2015 maximum was reached on 15th Feb, ridiculously early, and then for weeks there was almost no change in extent, i.e. significant melting did not start early.

For a few days until about 21-22 February Arctic temperature anomalies should be high, especially at the Bering and Atlantic ends of the CAB. (The last graph contrasts The Bering Sea, where temperatures have been high, with the Okhotsk Sea next door, which has been cold most of the time).

Until then 2018 should continue to plough its lonely furrow. (In 2018, 40 days (in the wilderness - Lent began on 14th February) out of 47 lowest in the satellite record).

After the 22nd Feb, Arctic temperatures may drop like a stone, or maybe not. Entering the wobbly month or two of transition, who knows ?
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on February 17, 2018, 04:19:16 PM
What really concerns me is how late the freeze occurred on the Pacific side. The Beaufort, Chukchi, Bering and ESS all struggled to freeze over. This meant these seas had far less time to thicken and, given the ridiculous warm anomalies on the Pacific side this winter, we have dangerously thin ice heading into this melt season.
Title: Re: 2018 sea ice area and extent data
Post by: liefde on February 17, 2018, 05:08:10 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fafluisterland.nl%2Fimg%2F6.7.png&hash=16cfeb5c434257c0b3acca6702ffd9d4)
^ This is certainly not going to help.
Title: Re: 2018 sea ice area and extent data
Post by: harpy on February 17, 2018, 05:53:48 PM
....  + 6.7 C in the arctic!!???? 


1.  How is it even possible to have ice in the arctic at the end of this coming melt season with anomalies like that during the refreeze period?

2.  What happens if these temperature anomalies keep up for the rest of the year?

3.  How much sea level rise are we going to see if we get 7C anomalies for the rest of the year? 
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on February 17, 2018, 07:57:02 PM
Sea level rise is a very slow process. Arctic temp anomalies for this freeze season have no impact.
Title: Re: 2018 sea ice area and extent data
Post by: harpy on February 17, 2018, 08:02:57 PM
Sea level rise is a very slow process. Arctic temp anomalies for this freeze season have no impact.

I'm sorry, but you're just 100% wrong.  No impact?  Where do people like you get your information?
Title: Re: 2018 sea ice area and extent data
Post by: Iceismylife on February 17, 2018, 08:10:01 PM
Sea level rise is a very slow process. Arctic temp anomalies for this freeze season have no impact.

I'm sorry, but you're just 100% wrong.  No impact?  Where do people like you get your information?
Impact yes, large no.  The loss of floating ice has no impact on sea level promptly. It has secondary impacts that feed back loops that will contribute.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on February 17, 2018, 08:22:35 PM
What really concerns me is how late the freeze occurred on the Pacific side. The Beaufort, Chukchi, Bering and ESS all struggled to freeze over. This meant these seas had far less time to thicken and, given the ridiculous warm anomalies on the Pacific side this winter, we have dangerously thin ice heading into this melt season.
Agree - it's not extent or area, its volume I'm worried about.

Extent is a secondary problem, and for all of our new min-maxes happening, the effect of that difference is trivial compared to the last 3 years.  The heat provided by open water will not be significantly greater.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 17, 2018, 08:52:42 PM
What really concerns me is how late the freeze occurred on the Pacific side. The Beaufort, Chukchi, Bering and ESS all struggled to freeze over. This meant these seas had far less time to thicken and, given the ridiculous warm anomalies on the Pacific side this winter, we have dangerously thin ice heading into this melt season.
Agree - it's not extent or area, its volume I'm worried about.

Extent is a secondary problem, and for all of our new min-maxes happening, the effect of that difference is trivial compared to the last 3 years.  The heat provided by open water will not be significantly greater.

I was given to understand that the negative feedback was all about additions to ocean heat during the insolation season, year after year after year. After all, there are about 2 million km2 of open water today on the fringes of the Arctic where in 1979 there was ice. If a simple average is used, say about 1 million sq kms that has been absorbing most radiation instead of reflecting most radiation for nearly 40 years.

Perhaps extent may not matter so much for an individual melting season, but surely it matters for long-term heating of the biosphere?
Title: Re: 2018 sea ice area and extent data
Post by: liefde on February 17, 2018, 09:55:20 PM
Impact yes, large no.  The loss of floating ice has no impact on sea level promptly. It has secondary impacts that feed back loops that will contribute.
Depends on the size of the floating ice, and where it floats to. If it's an Antarctic floater, a really big one, it can melt fast if it floats Northwards, and it will give a measurable SLR result worldwide.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on February 17, 2018, 10:19:39 PM
<snip>
Agree - it's not extent or area, its volume I'm worried about.

Extent is a secondary problem, and for all of our new min-maxes happening, the effect of that difference is trivial compared to the last 3 years.  The heat provided by open water will not be significantly greater.

I was given to understand that the negative feedback was all about additions to ocean heat during the insolation season, year after year after year. After all, there are about 2 million km2 of open water today on the fringes of the Arctic where in 1979 there was ice. If a simple average is used, say about 1 million sq kms that has been absorbing most radiation instead of reflecting most radiation for nearly 40 years.

Perhaps extent may not matter so much for an individual melting season, but surely it matters for long-term heating of the biosphere?
Yes, essentially correct.

However my point isn't about those feedbacks directly.  Rather it's about the difference in those feedbacks year over year.

The point I'm making is the current difference in additional open water this season vis-a-vis the last 5 doesn't significantly change that equation.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on February 17, 2018, 10:24:40 PM
Impact yes, large no.  The loss of floating ice has no impact on sea level promptly. It has secondary impacts that feed back loops that will contribute.
Depends on the size of the floating ice, and where it floats to. If it's an Antarctic floater, a really big one, it can melt fast if it floats Northwards, and it will give a measurable SLR result worldwide.
How do you get that? 

If the ice did not start off grounded, its displacement as ice will match its displacement as water.
Title: Re: 2018 sea ice area and extent data
Post by: oren on February 17, 2018, 10:35:12 PM
....  + 6.7 C in the arctic!!???? 


1.  How is it even possible to have ice in the arctic at the end of this coming melt season with anomalies like that during the refreeze period?

2.  What happens if these temperature anomalies keep up for the rest of the year?

3.  How much sea level rise are we going to see if we get 7C anomalies for the rest of the year?
It's best not to extrapolate from.extreme events to a whole year. Also if you take a look at the DMI "North of 80o" chart, spring/summer anomalies in recent years are much closer to zero, from around day 120 to day 220, regardless of winter anomalies.
And in general, such discussions belong in the freezing/melting season threads.
About SLR and wintertime arctic anomalies, it' s best to refer to the Greenland melt thread, but certainly the effect isn't very strong.

Sea level rise is a very slow process. Arctic temp anomalies for this freeze season have no impact.
I'm sorry, but you're just 100% wrong.  No impact?  Where do people like you get your information?
I also recommend using better decorum in forum posts.
Title: Re: 2018 sea ice area and extent data
Post by: Nix on February 17, 2018, 10:58:12 PM
As the ice cover is lost and the arctic warms most of the sea level rise will likely come from warmer ocean water and thermal expansion of the water... should it not be?
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on February 17, 2018, 11:05:48 PM
What really concerns me is how late the freeze occurred on the Pacific side. The Beaufort, Chukchi, Bering and ESS all struggled to freeze over. This meant these seas had far less time to thicken and, given the ridiculous warm anomalies on the Pacific side this winter, we have dangerously thin ice heading into this melt season.
Agree - it's not extent or area, its volume I'm worried about.

Extent is a secondary problem, and for all of our new min-maxes happening, the effect of that difference is trivial compared to the last 3 years.  The heat provided by open water will not be significantly greater.

I was given to understand that the negative feedback was all about additions to ocean heat during the insolation season, year after year after year. After all, there are about 2 million km2 of open water today on the fringes of the Arctic where in 1979 there was ice. If a simple average is used, say about 1 million sq kms that has been absorbing most radiation instead of reflecting most radiation for nearly 40 years.

Perhaps extent may not matter so much for an individual melting season, but surely it matters for long-term heating of the biosphere?

Of course insolation matters. Due to the very thin ice, the Pacific side of the Arctic is going to melt out very early allowing the sun to heat the water for a longer time. Let's hope for a cloudy summer.
Title: Re: 2018 sea ice area and extent data
Post by: harpy on February 17, 2018, 11:10:28 PM
This is going to be a long post, because I'm going to share my thoughts on the subject, so I'll break it into numbered sections for simplicity of responding.

1.  The main issue is that this temperature anomaly is going to worsen an already low ice thickness in the arctic.  It's not about extent, its about thickness.  The winter season helps to maintain thickness throughout the year so that in summer months thickness is maintained sufficiently that the ice which has been there for hundreds of thousands and millions of years (I believe the last time we had no ice in the arctic was several million years ago) of years is not lost.  This balance is in the process of being lost, and 7C temperature anomalies almost ensure that ice thickness will be record low this summer. 

2.  THE PROBLEM IS NOT JUST THIS ONE ANOMALY but that we've been consistently at least 2 -4C above baseline all winter (maybe someone can correct me I dont have the data in front of me)- I don't have the data in front of me, but I've been watching it often enough to notice that 2017-2018 has been impressive in the persistence of arctic temperature anomalies .


3.  we're currently at the lowest winter ice thickness and extent in thousands if not hundreds of thousands (perhaps multi millions) of years.   This means that there will be even lower ice extent in the summer and its possible that we will have a repeat of 2012, but this time with much thinner sea ice.  As a result, I would imagine it's likely to have almost no ice in the arctic this summer.

4.  As a result, and because the temperature anomalies are higher than they've been in hundreds of thousands if not millions of years, I would anticipate run away melting of the Greenland ice sheets. This is in addition to having almost no sea ice.  7C temperature anomaly is not just a "wow that's big" it's a "wow that's extinction material".  The current rate of temperature increase over the past 150-250 years is far faster than the Permian, which took thousands of years to reach something like 12C.

5.  Lower albedo effects in the summer months due to a lack of sea ice combined with methane release, CO2 release, and warmer sea temperatures will all feed back on each-other and produce remarkably warm conditions in the arctic this year, and EVERY SINGLE YEAR IN THE FUTURE.   This is not just a one time event, this is the new normal, and it's only going to get worse in an exponential fashion.  Unless of course something is done to lower arctic temperatures back to baseline levels immediately.

6.  This is going to be a very difficult year for the apes of planet earth, and I would imagine that the next 2-5 years, at this rate, will not be survivable for most of them.

7.  Already, temperatures in the northern hemisphere in many locations are 10-30 degrees above where they should be and its affecting agriculture.  I can only imagine what's going to happen if there's no ice in the arctic this summer (or within the next 5 years almost certainly) and positive feedback loops take over.

8.  The US only has a few months supply of grains to feed its population, and many countries has ZERO reserves.  Multiple billions do not have more than 7 days worth of edible food stored, the rest have less than 30 days, and only a very small fraction have more than 30 days worth of edible food stored.  Billions of apes rely upon agriculture to function almost perfectly each year, and if for any reason even 25-50% of that agriculture is unable to be harvested there will be famines of epic proportions that will activate positive feedback loops in the fragility of civilization that will cause even more deaths and more chaos.

9.  Once positive feedback loops in the climate combine with positive feedback loops in the fragility of civilization, the combined effect will be exponential and difficult to comprehend.  A good example of the positive feedback loops in the fragility of civilization is what happened in 2008 - one bank collapsed, which lead to more and more banks collapsing until everything collapsed - this is going to happen again, and this time it's going to happen at the same time that positive feedback loops in the arctic are ALSO taking place. 

10.  If societal situations spiral out of control and economic slowdown occurs, you trigger the removal of global dimming which increases worldwide temperatures by something like .5-3C within 1 month or so.  What this means is that GLOBAL DIMMING will be removed when civilization is unable to function and the economy begins to slow down - the slower the economy, the higher temperatures get as aerosols fall out from the atmosphere.  This will just make things exponentially worse because this process only takes a few months at most, as most of the aerosols are removed from rain events.  The loss of global dimming due to an economic slowdown would increase global average temperatures no less than .5C within a few months.  I've read figures as large as 3C within a few months. 


In short, positive feedback loops = extinction of large apes worldwide within a relatively short period of time of this message, IF nothing is done immediately to lower temperatures of the arctic. 


Title: Re: 2018 sea ice area and extent data
Post by: Rippleillusion on February 18, 2018, 12:59:30 AM
Every bit of the previous post is pretty dead on. Our near future is science fiction material without a happy ending.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 18, 2018, 02:09:58 AM
The temperature anomaly in the Arctic is impressive but not unusual and only for a few days.
Arctic temperatures this winter are in a very similar yo-yo pattern to previous years and are not spectacularly high
The signals are for a record low maximum extent but is not guaranteed.
Record low winter volume last winter and spring did not lead to record low summer extent or volume.
Summer extent and volume is on a downward trend but there are no indicators for Armageddon
The recession following the financial crisis of 2007-8 did not result in aerosols disappearing.

I am sure that as the next 10, 20 (?) years go by the rate of change will accelerate but my next post will be on 2018 sea ice area and extent data.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on February 18, 2018, 02:40:17 AM
Again, please move non ice related discussion to a Consequences thread.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on February 18, 2018, 02:59:27 AM
Again, please move non ice related discussion to a Consequences thread.

Thank you jd. Seconded.
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on February 18, 2018, 06:07:18 AM
Harpy, I will respectfully disagree.  First, we have no data that the current ice thickness is the lowest in thousands of years.  There is also significant debate as to whether today’s temperatures are the highest in this interglacial, not to mention most paleo data shows the last interglacial was warmer.  Your claim about the last time the Arctic was ice-free is also unsupported.  The summer albedo is determined by area, not thickness.  There is only a slight albedo difference with thick ice compared to thin, while the difference between thin ice and open water is quite large.  The other explanation for the lack of declining summer sea ice is the increased cloudiness.  This has a similar strong albedo effect.  Not sure where you are getting your astronomically huge temperature anomalies, but snow cover has not changed appreciably.  Your claims if agricultural collapse seem he contradicted by increasing crop yields.  World hunger has decreased appreciably over the previous decades.  Do you really believe that we will not survive the next five years? 
Title: Re: 2018 sea ice area and extent data
Post by: El Cid on February 18, 2018, 08:13:56 AM
Harpy, I will respectfully disagree.

I know its offtopic, so I just say that Daniel B is right, your presumptions about ice and agriculture are scientifically baseless
Title: Re: 2018 sea ice area and extent data
Post by: Neven on February 18, 2018, 11:16:17 AM
I can not move comments to appropriate threads with the click of a button, and even if I could, it would be time-consuming, so I'm going to ask you to stay on topic, or else I will remove comments.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 18, 2018, 03:39:39 PM
There has been a lot of excitement about an early end to the freezing season, but I could not see much correlation between the date of end of season and a low maximum.

As JAXA is on holiday today, I had a think and came up with two question:-
Is there a correlation between the number of days in a freezing season and the amount of extent gain in that year ?
Is there a correlation between the number of days in a melting season and the amount of extent loss in that year ?

After a bit of a tussle with Excel and a raid into one of the very old and rusty filing cabinets that pass for the memory in my brain,I came up with a result.

The answer is, not really. The correlation coefficients are really low. Graphs attached. So forget about the date of the maximum, it is the value of that maximum that matters.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on February 18, 2018, 04:13:13 PM
If this were a Democracy and I had a vote, I'd vote remove them.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on February 18, 2018, 05:10:24 PM
If you look at the behavior of ice extent growth in the latter part of the freeze season over the past 5 years, there is a pronounced, step wise trend downward. Likely the result of our rapidly warming Arctic winters?
Title: Re: 2018 sea ice area and extent data
Post by: harpy on February 18, 2018, 05:27:59 PM
If you look at the behavior of ice extent growth in the latter part of the freeze season over the past 5 years, there is a pronounced, step wise trend downward. Likely the result of our rapidly warming Arctic winters?

Looks exponential (relative to 1980s and 1990s levels). 
Title: Re: 2018 sea ice area and extent data
Post by: Sigmetnow on February 19, 2018, 07:04:25 PM
“So it goes - yet another anomalous winter in the #Arctic. Total sea ice extent remains at a record low (satellite era) and nearly 1.5 million km^2 below average [@NSIDC data] ”
https://twitter.com/ZLabe/status/965606352969072640
Image below.
Title: Re: 2018 sea ice area and extent data
Post by: Hautbois on February 19, 2018, 11:24:48 PM
A 2018 edition of the graph I put out a few times last year. The black dots are the maxima for previous years (timing and extent); the grey area is the extent range for each day. I'll update from time to time to the end of March.


(PS I've changed my pseudonym from deeenngee to Hautbois. A bit less cumbersome, if a bit more pretentious!)
Title: Re: 2018 sea ice area and extent data
Post by: Neven on February 19, 2018, 11:53:58 PM
I remember that graph! Thanks for posting it again, and welcome back.
Title: Re: 2018 sea ice area and extent data
Post by: harpy on February 20, 2018, 12:58:06 AM
“So it goes - yet another anomalous winter in the #Arctic. Total sea ice extent remains at a record low (satellite era) and nearly 1.5 million km^2 below average [@NSIDC data] ”
https://twitter.com/ZLabe/status/965606352969072640
Image below.

Honestly, this graph would be much more depressing if we had data from 1750-1850.  It looks bad compared to 1980-2010.  Compared to 1750-1850 - one can only use their imagination.
Title: Re: 2018 sea ice area and extent data
Post by: Phil. on February 20, 2018, 01:06:16 AM
A 2018 edition of the graph I put out a few times last year. The black dots are the maxima for previous years (timing and extent); the grey area is the extent range for each day. I'll update from time to time to the end of March.


(PS I've changed my pseudonym from deeenngee to Hautbois. A bit less cumbersome, if a bit more pretentious!)

Interesting is the range 2sd or something else?
I don't think using the name of a musical instrument is pretentious at all!
Title: Re: 2018 sea ice area and extent data
Post by: Ice Shieldz on February 20, 2018, 01:41:59 AM
Honestly, this graph would be much more depressing if we had data from 1750-1850.  It looks bad compared to 1980-2010.  Compared to 1750-1850 - one can only use their imagination.

It would probably look less bad compared to 1750-1850.

There are enough indicators of how poor arctic sea ice is doing. Extent is just one of them. The drop in the amount of multiyear ice is perhaps even more alarming than extent. The MYI graph below is Jan 1999 to Jan 2017. Given recent data shared by A-Team, the amount of MYI is probably now even less than 2017.
Title: Re: 2018 sea ice area and extent data
Post by: harpy on February 20, 2018, 02:05:27 AM
Honestly, this graph would be much more depressing if we had data from 1750-1850.  It looks bad compared to 1980-2010.  Compared to 1750-1850 - one can only use their imagination.

Actually it would probably look less bad compared to 1750-1850.

There are enough indicators of how poor arctic sea ice is doing. Extent is just one of them. The drop in the amount of multiyear ice is perhaps even more alarming than extent. The MYI graph below is Jan 1999 to Jan 2017. Given recent data shared by A-Team, the amount of MYI is probably now even less than 2017.

Interesting. 

It's difficult to comprehend that multi year ice has dropped by more than 50% in just 18 years.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on February 20, 2018, 02:21:58 AM
Honestly, this graph would be much more depressing if we had data from 1750-1850.  It looks bad compared to 1980-2010.  Compared to 1750-1850 - one can only use their imagination.

Actually it would probably look less bad compared to 1750-1850.

There are enough indicators of how poor arctic sea ice is doing. Extent is just one of them. The drop in the amount of multiyear ice is perhaps even more alarming than extent. The MYI graph below is Jan 1999 to Jan 2017. Given recent data shared by A-Team, the amount of MYI is probably now even less than 2017.

Interesting. 

It's difficult to comprehend that multi year ice has dropped by more than 50% in just 18 years.
3+ year old MYI has dropped by *90%*...
Title: Re: 2018 sea ice area and extent data
Post by: Hautbois on February 20, 2018, 09:18:06 AM
A 2018 edition of the graph I put out a few times last year. The black dots are the maxima for previous years (timing and extent); the grey area is the extent range for each day. I'll update from time to time to the end of March.


Interesting is the range 2sd or something else?

To clarify: it's simply the difference, for each day (not including 2018), between the lowest extent and the greatest extent.

Title: Re: 2018 sea ice area and extent data
Post by: Neven on February 20, 2018, 11:02:22 AM
I don't think using the name of a musical instrument is pretentious at all!

Well, in that case, I'm changing my name to Steinway!  ;)

Or Stradivarius.....
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 20, 2018, 11:19:01 AM
I don't think using the name of a musical instrument is pretentious at all!

Well, in that case, I'm changing my name to Steinway!  ;)

Or Stradivarius.....

or penny whistle

or triangle
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 20, 2018, 12:10:21 PM
JAXA back from holiday Arctic Extent as at 19 Feb 2018  13,439,935 km2, on average 26k up over the last three days, now 339k less than 2017 and just 138k less than 2016  on that date. 

24 days (range 11*** to 40), 0.33 million km2, and just 3.3% of average extent gain to go., Average result a record low maximum of 13.77 million km2,  just 110k less than 2017. 7 out of 10 of the previous 10 years still say yes to a record low.

*** In 2015 maximum was reached on 15th Feb, ridiculously early, and then 29 days later extent was down by a paltry 41K, i.e. significant melting did not start early.

One might wonder how the very warm weather at both ends of the CAB has not stopped extent rising. The Okhotsk Sea seems to be the villain of the piece (image below). That sea, next door to The Bering, has been cold just about all the time. With no direct impact on the Arctic Ocean, nevertheless in the freezing thread it has been pointed out that the cold and ice there has been assisting the channelling of warmth and wind into the Bering Strait, helping to cause the rapid decline of Bering Sea ice.

See the last graph below. ( I will be keeping an eye on the Chukchi Sea, showing a slight dip )
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on February 20, 2018, 01:35:11 PM
I don't think using the name of a musical instrument is pretentious at all!

Well, in that case, I'm changing my name to Steinway!  ;)

Or Stradivarius.....

those (Stradivarious & Steinway) are brands ;)
Oboe > Violin > Piano it would be then [Just Kidding]

Title: Re: 2018 sea ice area and extent data
Post by: Hautbois on February 20, 2018, 02:20:53 PM
I don't think using the name of a musical instrument is pretentious at all!

Well, in that case, I'm changing my name to Steinway!  ;)

Or Stradivarius.....

those (Stradivarious & Steinway) are brands ;)
Oboe > Violin > Piano it would be then [Just Kidding]

Ha! Glad to have caused such offtopic hilarity. My oboe was a bit more Skoda than Stradivarius, but it did the job. Anyway, that ice....
Title: Re: 2018 sea ice area and extent data
Post by: uniquorn on February 20, 2018, 03:02:11 PM
Banjo for me. Vega for the brand.

Okhotsk, Feb13-20.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 20, 2018, 03:37:17 PM
NSIDC DATA as at 19th Feb

Arctic extent up by 85k to 14.023 million km2. Was the villain of the piece the Okhotsk Sea - offsetting Bering Sea extent loss ? Partly, but not wholly. See table below (daily Extent data from NSIDC)
Title: Re: 2018 sea ice area and extent data
Post by: SteveMDFP on February 20, 2018, 03:40:43 PM
I don't think using the name of a musical instrument is pretentious at all!

Well, in that case, I'm changing my name to Steinway!  ;)

Or Stradivarius.....

or penny whistle

or triangle

I claim dibs on "spoons" !!!

Steve
Title: Re: 2018 sea ice area and extent data
Post by: Sigmetnow on February 20, 2018, 03:58:31 PM
I don't think using the name of a musical instrument is pretentious at all!

Well, in that case, I'm changing my name to Steinway!  ;)

Or Stradivarius.....

or penny whistle

or triangle

I claim dibs on "spoons" !!!

Steve

Cowbell!  ;D
Title: Re: 2018 sea ice area and extent data
Post by: Sigmetnow on February 20, 2018, 03:59:47 PM
Alaska's Bering Sea Lost a Third of Its Ice in Just 8 Days
Globally, sea ice is at record lows as the polar regions warm faster than the rest of the planet. Along the Alaska coast, it's affecting people's lives.
Quote
At a time when the sea ice should be growing toward its maximum extent for the year, it's shrinking instead—the area of the Bering Sea covered by ice is now 60 percent below its average from 1981-2010.

"[Bering sea ice] is in a league by itself at this point," said Richard Thoman, the climate science and services manager for the National Weather Service Alaska region. "And looking at the weather over the next week, this value isn't going to go up significantly. It's going to go down." ...
https://insideclimatenews.org/news/17022018/arctic-sea-ice-record-low-extent-alaska-bering-hunting-whales
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on February 20, 2018, 07:40:40 PM
NSIDC DATA as at 19th Feb

Arctic extent up by 85k to 14.023 million km2. Was the villain of the piece the Okhotsk Sea - offsetting Bering Sea extent loss ? Partly, but not wholly. See table below (daily Extent data from NSIDC)
I wonder if this is the first time in history that area in Okhotsk has been above both Bering and Chukchi in February? (or any month?)

The trend the past few years has been an outright average expansion of sea ice in Okhotsk, I believe this has to do with the increasing warmth in the peripheral seas which load the Arctic with heat -> result in Siberian snows -> allow colder airmasses to plunge/exist in Okhotsk for longer periods than before.

Now it seems that this development is directly influencing Pacific Warm Water's relationship with the Arctic proper as it combines with the general heat to devastate the Bering, where ice has traditionally been substantially more resilient.

This year, IMO, the contrast between Okhotsk vs. Bering + imminently Chukchi and Beaufort is likely to provoke substantial prolonged 500mb blocking episodes with negative height anomalies over NE Asia (Siberia/Okhotsk) and massive positive heights over the Bering & peripheral seas.

I would imagine this may be substantial enough to dominate the weather pattern well into the summer, with ATL melt relegated to general recurring massive storms, while the Pac front is driven quickly and rapidly into both Beaufort and Chukchi. As this occurs, it is, IMO, likely to result in the dislodging of a substantial freshwater dome/the Arctic halocline, and as Pac warm water advances farther and farther, it is probably going to make a substantial exit toward Labrador.

https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticictn_nowcast_anim30d.gif

Also, if HYCOM is correct, it seems a large proportion of the very thick ice north of Greenland has already been ejected through Nares into Baffin. And the next few days may see this worsen exponentially.

If this is the case, Baffin, Labrador, and Okhotsk are all likely to remain rather more resilient than most recent years. But that won't stop them from melting out entirely by July or August, and likely portends a very dramatic drop when the nearly mid-latitude "inflation" disappears under the summer sun.

I guess the best question to ask moving forward is that if ^ continues is it possible that within a decade or two we see a complete re-organization of Arctic sea ice (i.e. state change concurrent with first blue ocean CAB event) to the point where we end up with actual MYI in Okhotsk, Baffin, and Labrador that endures summer after summer? If general 500MB circulation collapses once the CAB goes and we end up with recurring weather patterns based on accumulations of oceanic heat, land biomes, and elevation, the "stickiness" of 500MB blocking could very be aided by whatever hell breaks loose from the melting Greenland ice sheet to yield a flip-flopping in traditional melt patterns.

Who knows...!

(https://ccin.ca/home/sites/default/files/snow/snow_tracker/plot_anom_sdep.png)

On a final note, technically, due to the extant Greenland ice sheet, we are still in an ice age.

Rolling the below animation, one can't help imagine wondering what the difference between the past 30 days and establishment of a new Canadian ice sheet would be. Would there actually be any difference? Is this in fact how they have been built in the past? Is the only difference between now and then the stability of MYI in the CAB which keeps weather rotating with vigor across the NHEM on a relatively stable basis, thereby resulting in enough sustained summertime warmth that snow does not accumulate year over year?

https://weather.gc.ca/saisons/animation_e.html?id=month&bc=sea

It seems both the Canadian and SE Siberian snowfall anomalies could also be partly to blame on the blazing oceanic SSTs to their SE. The Gulf Stream has shifted substantially north, and its waters now encroach directly onto southern Nova Scotia. The same seems to be happening in the NE Pacific, where there is a near 100% absence in Siberian-adjacent sea ice this year, despite the blues and purples of the snowfall anomaly map.

If accumulations of oceanic heat are all that's necessary for the current anomalous increase in snowcover and are seemingly sufficient to dwarf the impact of atmospheric CO2 to date, rolling the clock forward another 5-10 years could paint an image out of the Younger Dryas. Coincidentally, it is about the same time it took for that to happen as well.

I guess we will have to revisit this topic in 2025 :)

(https://ccin.ca/home/sites/default/files/snow/snow_tracker/nh_swe.png)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 20, 2018, 07:51:40 PM
Watching winter sea ice used to be a bit boring. I don't remember a February like this, not even last year - a record low but not all this movement, fracturing and general - whatever.
Title: Re: 2018 sea ice area and extent data
Post by: uniquorn on February 20, 2018, 08:04:05 PM
Quote
to the point where we end up with actual MYI in Okhotsk, Baffin, and Labrador

Interesting idea, but a lot of the Okhotsk ice looks very weak to me.
Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on February 20, 2018, 09:05:41 PM
I expect, gerontocrat, that A-Team's wonderful gifs (or movies or whatever they are [I feel like a Luddite after looking at an A-Team post]) show movement that has been happening in recent years.  Old Arctic HYCOM gifs showed movement (but it was 'all' model, and not nearly so 'real').
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 20, 2018, 09:34:42 PM
Very true,Sleepy,there is no doubt the new technology is adding a new dimension to observation and study of Arctic ice. But it is not just that to me.

I've been looking at Arctic Sea Ice since about 1991. Winter Sea Ice has always seemed to be the one that matters most, as that ice, when it is gone, is likely to be gone for the rest of my lifetime at least. And up until last year it was to watch a most gradual process.

I started to think back in October 16, that maybe something different was happening - when Antarctic ice started its most unusual decline. Since then we have seen records broken in the Arctic winter and the Antarctic summer on a regular basis. So perhaps something has changed (or perhaps not).

So me, I am waiting for next winter (until I get obsessed about the Arctic summer sometime next week).
Title: Re: 2018 sea ice area and extent data
Post by: Neven on February 20, 2018, 10:54:48 PM
lot of text, some graphs, very little on 2018 sea ice area and extent data

Your comment would fit better in the freezing thread, bbr2314!
Title: Re: 2018 sea ice area and extent data
Post by: harpy on February 21, 2018, 12:54:02 AM
Watching winter sea ice used to be a bit boring. I don't remember a February like this, not even last year - a record low but not all this movement, fracturing and general - whatever.

Certainly not boring anymore.  Watching the arctic sea ice extent has gone from boring to horrifying in just a few short years.
Title: Re: 2018 sea ice area and extent data
Post by: Paddy on February 21, 2018, 07:30:22 AM
I also had a look at annual averages for recent years - just to see the decline over time.

How's that simple average of previous 12 months graph looking now? I'm guessing it won't be great over the months ahead...
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 21, 2018, 12:59:33 PM
I also had a look at annual averages for recent years - just to see the decline over time.

How's that simple average of previous 12 months graph looking now? I'm guessing it won't be great over the months ahead...
Looking at the average of the previous 365 days means as a new day is added, the day a year ago is taken out. Then the total s divided by 365 for the new annual average. So if today's extent is 365,000 km2 less than the extent on that date one year ago, the average drops by just 1,000 (one thousand) km2.

It is the sort of graph that takes months for any real change to have a marked effect, and is looking back.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 21, 2018, 01:23:06 PM
JAXA DATA as at 20th Feb extent 13,479,711 km2, up 125k in three days, despite the Bering Sea retreat and general mayhem

Still 298k less than 2017 on that date, but just 124k less than 2016.

On average, about 3 weeks to go, and a mixture of very warm and very cold Arctic weather predicted. This p.m. will have another look at NSIDC regional data.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 21, 2018, 02:26:07 PM
NSIDC Arctic Total and some regions data as at 20th Feb

Arctic extent up by just 9k, with losses in Bering and Chukchi sea, and gains in Okhotsk and Baffin Seas. See table

There has been some talk about insolation already impacting these seas. It is Feb 21, one month before the equinox. The table below and graph attached suggests that meaningful insolation will not start for another month.
             Degrees North
Okhotsk        59
Bering Sea    57
Bering Strait  66
Chukchi         69   
Baffin Bay      75
Davis Strait    69 
Title: Re: 2018 sea ice area and extent data
Post by: oren on February 21, 2018, 02:51:20 PM
Thank you gerontocrat. An amazing stretch of 13 days of negative extent changes.
OT, eyeballing your chart, at Bering latitude insolation is now at about one third of its solstice peak. Not negligible IMO.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 22, 2018, 01:29:30 PM
JAXA DATA as at 21st Feb extent  13,556,973 km2, up 202k in three days (77k on 21st), despite the Bering Sea retreat and general mayhem

Still 228k less than 2017 on that date, but just 30k less than 2016.

On average, about 3 weeks to go, and a mixture of very warm and very cold Arctic weather predicted. This p.m. will have another look at NSIDC regional data.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 22, 2018, 03:11:47 PM
NSIDC daily extent at 21 Feb up 54k to  14.086 million km2. Still daily lowest but approaching 2016.

Regional data attached. Note Bering extent continues to fall, Chukchi starting to fall, while Okhotsk and Baffin continue up.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 22, 2018, 04:12:00 PM
And below are the images matching the above table from the ASI graphs link on the home page of ASIF.

Okhotsk - record highs,
Bering - record lows,
Chukchi - going down far too early.

This extreme contrast seems likely to continue at least to the end of the month.
Title: Re: 2018 sea ice area and extent data
Post by: uniquorn on February 22, 2018, 04:44:42 PM
Thanks gerontocrat.
Cyclone in Okhotsk today. I won't post the image as it clutters up the data thread. The link should open Worldview for those who are interested.

https://tinyurl.com/ybabo7qu
Title: Re: 2018 sea ice area and extent data
Post by: Nikita on February 23, 2018, 08:46:47 AM
About zero degrees Celsius at the North Pole
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 23, 2018, 10:08:10 AM
JAXA DATA as at 22nd Feb extent  13,596,151 km2, up 241k in five days (39 k on 22nd), despite the Bering Sea retreat, extreme temperature anomalies and general mayhem

Now only 216k less than 2017 on that date, and 3k greater than 2016.  No longer does 2018 Arctic Extent plough its lonely furrow for a few days).

On average, about 3 weeks to go, and a mixture of very warm and very cold Arctic weather predicted. This p.m. will have another look at NSIDC regional data.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 23, 2018, 02:03:42 PM
NSIDC Regional Daily Extent Data as at 22nd Feb (part)

It continues:-
Okhotsk - heading for a record high,
Bering - record lows,
Chukchi - going down far too early.

This extreme contrast seems likely to continue at least for a few more days (?).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 24, 2018, 11:25:07 AM
JAXA DATA as at 23rd Feb : Extent  13,662,634 km2, up 307 k in six days (66k on 23rd), despite the Bering Sea retreat and general mayhem

Just 136k less than 2017 on that date, but 33k greater than 2016.

On average, just 20 days (min 7, max 36), 0.28 million, 2.8% of extent gain to go. Average result is 13.94 million km2, 60,000 greater than the 2017 record low max.

Does this mean that 2018 ice is in better shape than 2017 for the melting season? I think not. The mayhem currently underway suggests that while extent may be greater, the ice is in a mess and already dispersed and fractured to a extreme degree. After the ridiculous warmth at the pole happening now and until Sunday, that warmth moves around. See last image (6 days ahead)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 24, 2018, 02:42:03 PM
NSIDC Regional Daily Extent Data as at 23rd Feb (part)

It continues:-
Okhotsk - heading for a record high,
Bering - record lows,
Chukchi - going down far too early.
Baffin -  expanding

This contrast seems likely to continue at least for a few more days (?).
Title: Re: 2018 sea ice area and extent data
Post by: Alexander555 on February 24, 2018, 05:22:04 PM
On Ventusky it looks like it's going to get a little colder the next week. That could maybe put some extra ice on Bering and Baffin. But probably it will stay thin, it's already pretty late . And with okhotsk further South, that's plenty of ice that could be gone fast.
Title: Re: 2018 sea ice area and extent data
Post by: oren on February 24, 2018, 11:57:41 PM
16 straight days of losses for Bering on NSIDC, down 55% from peak. In February. Will it stop?
Title: Re: 2018 sea ice area and extent data
Post by: Coffee Drinker on February 25, 2018, 02:59:00 AM
Is there a reason why the Baltic sea is not included in Arctic sea ice while Okhotsk is?
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on February 25, 2018, 03:22:07 AM
16 straight days of losses for Bering on NSIDC, down 55% from peak. In February. Will it stop?
According to Wipneus's figures it just did:
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-extent-regional.png
As did the rises in Okhotsk, Baffin, St Lawrence and Barents. Of course it may all just  be a temporary reversal.
Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on February 25, 2018, 03:47:08 AM
Baltic not included most likely because it is covered by relatively fresh water. See recent posts. (https://forum.arctic-sea-ice.net/index.php/topic,143.msg142244.html#msg142244)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on February 25, 2018, 05:57:23 AM
ADS JAXA: On Feb 24: 13.64M km2, a small but significant drop of 19.2K km2.  :o
2018 is breaking the record again.
2018 is 136.7K km2 under 2016 (second on record).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 25, 2018, 10:30:56 AM
16 straight days of losses for Bering on NSIDC, down 55% from peak. In February. Will it stop?
According to Wipneus's figures it just did:
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-extent-regional.png
As did the rises in Okhotsk, Baffin, St Lawrence and Barents. Of course it may all just  be a temporary reversal.
Daily extent data from NSIDC said it didn't while the graphs said it did. Perhaps the graphs come from the NSIDC 5-day average data ?
Time will tell.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 25, 2018, 10:34:32 AM
JAXA data for the 24th Fb. The average daily increases of 50 for the the five dys have switched to a decrease of 19k, and as pointed out already, means 2018 is in its lonely furrow again.
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on February 25, 2018, 12:47:49 PM
Wish the nullschool could incorporate the essential data to the graphs so I wouldn't have to cut and paste it so. It looks like north pole is almost 10 degrees warmer than home. It's of course happened once in a while before too, but it's anyway remarkable when it happens.

London's about the same as the pole, Paris a bit colder as is Split on the Mediterranean, Tokyo again almost the same, like is the tip of Antarctic Peninsula (this last one shouldn't surprise very much)
Title: Re: 2018 sea ice area and extent data
Post by: Ice Shieldz on February 25, 2018, 08:13:05 PM
The elephant in the room here is of course that extent is lowest in core arctic seas and high in peripheral seas. Is anyone cumulatively plotting that and comparing it with previous years?

Interesting to see this trend reflected in the CAB itself. Perhaps the lift off of ice from Greenland is beginning to show up in CAB extent. Short of more crazy weather, which it seems we'll be seeing a bit of a reprieve from, the recent losses in CAB extent should be recovered relatively quickly.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on February 25, 2018, 08:30:53 PM
...Short of more crazy weather...

It isn't crazy weather.  It is clearly WACCy (wacky) weather.

If there wasn't a clear pattern emerging it would be crazy, but the pattern is getting clearer every year.  The heat reservoir of the ocean is filling up even as the land mass quickly sheds heat every Winter.

Title: Re: 2018 sea ice area and extent data
Post by: Ice Shieldz on February 25, 2018, 08:38:35 PM
Hmm i don't understand how WACCy weather would lead to land masses shedding heat with the extra snow insulation impeding the escape of heat from the continents. Not sure it matters that much given how little heat the land stores relative to the oceans.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on February 25, 2018, 08:50:26 PM
Hmm i don't understand how WACCy weather would lead to land masses shedding heat with the extra snow insulation impeding the escape of heat from the continents. Not sure it matters that much given how little heat the land stores relative to the oceans.

Your last sentence answered your first.  Land doesn't retain heat very well when compared to water.  This leads to the ocean remaining warm in the dark of night while the land gets cold and snowy.

I think that the "Cold Continents" are only in comparison to the warm Arctic, and that they are warming up too -- just nowhere near as fast.
Title: Re: 2018 sea ice area and extent data
Post by: oren on February 25, 2018, 09:43:32 PM
The elephant in the room here is of course that extent is lowest in core arctic seas and high in peripheral seas. Is anyone cumulatively plotting that and comparing it with previous years?

Interesting to see this trend reflected in the CAB itself. Perhaps the lift off of ice from Greenland is beginning to show up in CAB extent. Short of more crazy weather, which it seems we'll be seeing a bit of a reprieve from, the recent losses in CAB extent should be recovered relatively quickly.
Bear in mind the CAB also includes that area north of Svalbard that is typically open water in February in recent yeara. On top of that you have the newly open water north of Greenland, which is surely reflected in the numbers, but will hopefully refreeze before season's end.
Title: Re: 2018 sea ice area and extent data
Post by: Hautbois on February 25, 2018, 10:15:19 PM
Updated maxima comparisons chart. I've picked out the daily trajectory of 2017 as well in this one.

Yesterday (day 55) was the max date for 2007. The statistical mode is day 65 (March 6th most years).

Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on February 26, 2018, 04:00:50 AM
I think that the "Cold Continents" are only in comparison to the warm Arctic, and that they are warming up too -- just nowhere near as fast.

Siberia is only in -30Cs so it's warm? In fact, no where on Northern hemisphere is currently -40C, coldest I could find was -38C in interior Greenland, couldn't survive that anymore for lack of proper insulated trousers. With doubled long johns you get by with -25C quite ok, but not with biting wind, the heat loss could get you serious frostbite after 2 hours. Not that I plan to be out for that long anyway.

So, the East Antarctic interior with ~-45C is the coldest place on earth also in 2018 late feb - NH winter.
Title: Re: 2018 sea ice area and extent data
Post by: kiwichick16 on February 26, 2018, 08:46:40 AM
its still , theoretically, summer down here.......although it has cooled off somewhat in the last couple of weeks

NZ had its hottest January on record this year
Title: Re: 2018 sea ice area and extent data
Post by: Neven on February 26, 2018, 08:47:44 AM
You guys are keeping it short, so that's good, but do try to stay on topic.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 26, 2018, 11:54:20 AM
On-topic:-

JAXA data for the 25th Feb. Extent 13,638,724 km2 The average daily increases of 50k for the the five days have switched to a 2 day decrease of 24k, and as pointed out already, this means 2018 is in its lonely furrow again. (2017 posted big extent losses in the next 3-4 days.)
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on February 26, 2018, 02:21:13 PM
NSIDC NT area makes a nosedive as it is sensitive to the near 0oC temperatures.

Attached are graphs of extent and area within the Arctic Basin.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 26, 2018, 05:18:08 PM
After those "Good Heavens" graphs from Wipneus, here is the NSIDC data for the 25th Feb on the seas around the CAB.

Bering Sea decline has changed to an 11k increase,
Okhotsk a small decline of 5k,
Chukchi a small increase of 3k,
Baffin daily increase down to 9k,
Greenland continues to decline (4k),
Barents increase continues but slowing down (6k).

Small beer compared with what is happening in the CAB, but definitely a switch. Too many lines on the table, put to one side until the next event.


Title: Re: 2018 sea ice area and extent data
Post by: Ice Shieldz on February 26, 2018, 06:32:23 PM
Big Beer  ;)

Thanks gerontocrat and Wipneus for all the excellent updates and charts!

https://sites.google.com/site/arcticseaicegraphs/regional (https://sites.google.com/site/arcticseaicegraphs/regional)
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on February 27, 2018, 03:59:09 PM
Area dives further.
Title: Re: 2018 sea ice area and extent data
Post by: Buddy on February 27, 2018, 05:02:21 PM
The CAB is pretty gobsmacking....

It looks from Wip's chart...for at least the years shown....that this would be the first "January max" (Assuming of course...that the Jan numbers hold).  Other maximum's in the CAB looked to have happened in Feb or March.

And of course....one of these years.....we're going to get a double whammy of (1) an early start like this year, and then (2) a bad middle/end of year melt season.  Just a matter of time... and the clock is ticking.

Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on February 27, 2018, 05:27:44 PM
The CAB is pretty gobsmacking....

It looks from Wip's chart...for at least the years shown....that this would be the first "January max" (Assuming of course...that the Jan numbers hold).  Other maximum's in the CAB looked to have happened in Feb or March.

And of course....one of these years.....we're going to get a double whammy of (1) an early start like this year, and then (2) a bad middle/end of year melt season.  Just a matter of time... and the clock is ticking.

I'd divide those graphs into three categories:  regions which always are full most of the year, regions that don't really matter because they always melt out, and the (2) regions that are open to other oceans.

The regions that are open to either the Atlantic or the Pacific are really scary this year.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on February 27, 2018, 06:31:39 PM
The CAB is pretty gobsmacking....

It looks from Wip's chart...for at least the years shown....that this would be the first "January max" (Assuming of course...that the Jan numbers hold).  Other maximum's in the CAB looked to have happened in Feb or March.

And of course....one of these years.....we're going to get a double whammy of (1) an early start like this year, and then (2) a bad middle/end of year melt season.  Just a matter of time... and the clock is ticking.

Also, unlike 2016/2017, the new ice forming now will not have 90 60 days of "cooler" weather like last year to thicken up.  The drop off last year started in the first week of February and continued through the rest of the season.  This year the heat is rocketing up starting about the same time, and there aren't a lot of indications to suggest the cold will be able to return and solidly establish itself.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 27, 2018, 07:46:15 PM
Wait Small !  (South Pacific Pidgin)

NSIDC Daily Extent Data as at 26th Feb up 60k to 14.203 million km2, now only 121k less than 2017.
Bering Sea up 24k etc (see table below).

cci-reanalyzer - Arctic Temp anomaly down to 4.8 degrees celsius now,
                     - Arctic Temp anomaly down to ZERO degrees celsius on 6th March.
                     - strong +ve anomaly only in Baffin over next few days.

JAXA shows extent gain mostly above average in last few days

Still at least two weeks to go in average freezing season.

It ain't over 'til its over.
The fat lady hasn't even found her sheet music yet.
Title: Re: 2018 sea ice area and extent data
Post by: AbruptSLR on February 27, 2018, 08:16:19 PM
Scribbler has a nice article related to this topic:

Title: "A Large Area of Open Water Forms in the Melting Sea Ice North of Greenland During February"

https://robertscribbler.com/2018/02/26/a-large-area-of-open-water-forms-in-the-melting-sea-ice-north-of-greenland-during-february/

Extract: "Only a month and a half of typical freeze season remains. But ten day forecasts indicate that Arctic region mean temperatures might return closer to normal ranges (0 to 1 C above average as opposed the 3-6 C above average) and could allow for some moderate recovery of the substantially reduced winter ice pack.

Overall, though, the tale so far has been one of highly unusual melt and warming. One that highlights the serious and worsening impacts of human-caused warming and related polar amplification."
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 27, 2018, 08:21:35 PM
I agree with
Quote
Overall, though, the tale so far has been one of highly unusual melt and warming. One that highlights the serious and worsening impacts of human-caused warming and related polar amplification.

If I didn't, I would not be on this forum.

But Armageddon is still postponed (at least for a while?)
Title: Re: 2018 sea ice area and extent data
Post by: Wherestheice on February 28, 2018, 06:31:34 AM
I agree with
Quote
Overall, though, the tale so far has been one of highly unusual melt and warming. One that highlights the serious and worsening impacts of human-caused warming and related polar amplification.

If I didn't, I would not be on this forum.

But Armageddon is still postponed (at least for a while?)

I think the real Armageddon (if it happens), would be in the summer. All we need is a bad summer to really destroy the ice. :(
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 28, 2018, 02:27:18 PM
NSIDC Daily Extent Data as at 27th Feb down 27k to 14.175  million km2, now only 109 k less than 2017.

Peripheral Seas data attached in table. All changing as warmth moves around the Arctic
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 28, 2018, 05:51:01 PM

I think the real Armageddon (if it happens), would be in the summer. All we need is a bad summer to really destroy the ice. :(

Probably not (yet ).
The two dramatic events in the last 15 years when looking at the extent minimum were in 2007 and 2012. In those years extent loss from max to min were 10 million and 11.1 million respectively. Assuming a 2018 maximum of about 13.8 million, resulting minimum would be 3.8 million and 2.7 million km2. Also remember that the 2012 maximum was well above average (by about 0.45 million).

So for 2018 to record the destruction of Arctic Sea Ice would require things to happen completely beyond what has happened before.
Yes, Arctic temperatures have risen,
Yes, Global Ocean Heat has risen,
but I believe so far on a slowly accelerating incremental basis.

Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on February 28, 2018, 07:02:13 PM
I think the real Armageddon (if it happens), would be in the summer. All we need is a bad summer to really destroy the ice. :(

All we need to really destroy the ice is for the Gulf Stream to decide to pass to the west of Greenland, and it won't matter what time of year.  It is very unclear what is going on in the North-west Atlantic, but it isn't normal.
Title: Re: 2018 sea ice area and extent data
Post by: Cid_Yama on February 28, 2018, 07:11:07 PM
Your calculation leaves out a couple very important variables.  The biggest one being the difference in sea ice volume.

Your assumption that what happened 11 years ago and 6 years ago has any bearing on what happens this year, when conditions this year are unprecedented, is simplistic and flawed.

Both weather patterns, and sea and air temperatures are vastly different.  Ocean currents have shifted.  The energy in the atmosphere has increased.

The Arctic is a very different place than it was.

 
How Abrupt is Abrupt? (https://www.youtube.com/watch?v=xT8bEz2Rp_k)

Jim White at the 2014 AGU.


 
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on February 28, 2018, 07:30:50 PM

Both weather patterns, and sea and air temperatures are vastly different. 


Different, yes. Changed, yes.
Vastly different  ? Where is the data to prove "vastly".

One amazing cyclone followed by an amazing SSW are events, not necessarily game changers. The Arctic is currently cooling down, maximum extent can now only be a fraction below 2017.
The 2012 melting season finished with the GAC-2012 cyclone. many thought that was it, the tipping point, but it was not.

Without data, "vastly" is mere speculation. History does tell us what has been the maximum deviation from the trend line. What has changed to make a larger deviation possible ?

ps: Volume Loss according to PIOMAS is still declining very much on the linear regression line. In a few days February will be published. Then we will see some more data.
Title: Re: 2018 sea ice area and extent data
Post by: Alexander555 on February 28, 2018, 07:36:14 PM
Maybe it's still possible. If extent goes up from this point. There are a few places where there is very little ice so far, like Bering. And it's gaining for the moment. And there are a few places where there is more ice than average , like Baffin and Ochotsk. If they hold on for a few weeks. And the same time i have seen many days of big anomolies on the Arctic itself. So that ice is probably not in a very good condition. So we have more ice that will be gone for sure, and plenty in a bad condition.
Title: Re: 2018 sea ice area and extent data
Post by: Hefaistos on February 28, 2018, 08:57:47 PM
I think the real Armageddon (if it happens), would be in the summer. All we need is a bad summer to really destroy the ice. :(

All we need to really destroy the ice is for the Gulf Stream to decide to pass to the west of Greenland, and it won't matter what time of year.  It is very unclear what is going on in the North-west Atlantic, but it isn't normal.

Not so easy! First need to answer how the Gulf stream might possibly overtake/reverse the Labrador current with its 5 sverdrups.
https://en.wikipedia.org/wiki/Labrador_Current
Title: Re: 2018 sea ice area and extent data
Post by: Iceismylife on February 28, 2018, 11:15:09 PM
I think the real Armageddon (if it happens), would be in the summer. All we need is a bad summer to really destroy the ice. :(

All we need to really destroy the ice is for the Gulf Stream to decide to pass to the west of Greenland, and it won't matter what time of year.  It is very unclear what is going on in the North-west Atlantic, but it isn't normal.

Not so easy! First need to answer how the Gulf stream might possibly overtake/reverse the Labrador current with its 5 sverdrups.
https://en.wikipedia.org/wiki/Labrador_Current
Open up a significant erea of hater inside of 80 north and you generate bottom water.  That pulls the surface water north.  Having the gulf stream go up the west side of Greenland is easy.
Title: Re: 2018 sea ice area and extent data
Post by: Archimid on February 28, 2018, 11:19:29 PM
Is 2sd "vastly different"? Because thats what we are dealing with in many key metrics.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on March 01, 2018, 12:59:19 AM
I think the real Armageddon (if it happens), would be in the summer. All we need is a bad summer to really destroy the ice. :(

All we need to really destroy the ice is for the Gulf Stream to decide to pass to the west of Greenland, and it won't matter what time of year.  It is very unclear what is going on in the North-west Atlantic, but it isn't normal.
Not so easy! First need to answer how the Gulf stream might possibly overtake/reverse the Labrador current with its 5 sverdrups.
https://en.wikipedia.org/wiki/Labrador_Current
Just watch what has been happening in the Gulf of Maine the last 5 years and ask the Lobstermen.
Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on March 01, 2018, 01:44:03 AM
You need to consider the vorticity (spin) of different water masses. Gulf Stream water drifts towards Europe both because it's driven that direction by the westerlies and because it turns right as it moves north because of the Coriolis effect (the effects of the spin from earth's rotation).

Please don't suggest non-physical things that violate the conservation of angular momentum.
Title: Re: 2018 sea ice area and extent data
Post by: Iceismylife on March 01, 2018, 02:44:46 AM
...
Please don't suggest non-physical things that violate the conservation of angular momentum.
But in a random chaotic system something as small as the flapping of a butterfly wing can turn into a hurricane... Or a GAC. Or two. 

As far as violating angular momentum that doesn't need to be crossed. Drop water into the bottom of the abyss at the north pole and it has to come from somewhere.
Title: Re: 2018 sea ice area and extent data
Post by: oren on March 01, 2018, 03:06:50 AM
This is becoming waaay off-topic here.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on March 01, 2018, 09:43:53 AM
But in a random chaotic system something as small as the flapping of a butterfly wing can turn into a hurricane... Or a GAC. Or two.

Solution: Kill all the butterflies.  ;D

I'm late to this party, so I'm not going to delete all those comments. But, please, people, stay on topic. Take each other's hand and go to the appropriate threads, or create them. It's a forum, not a chat room.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 01, 2018, 12:32:45 PM
Hullo Neven,

thanks for being gentle with the chide.

JAXA ARCTIC SEA ICE EXTENT DATA AS AT 28TH FEB 13,727,837 km2. Up again - by 46k, a big increase for this time of year. Extent is just 150k less than the 2017 maximum on 6th March. On average, 15 days, 1.8% and 0.18 million of extent gain to go, leading to a maximum of 13.90 million, i.e. to all intents and purposes the same as 2017.

Does this mean the ice is in as good condition as last year to meet the melting season? I think not. The spectacular images and animations on the freezing thread show the extent of damage to ice in the CAB. I suspect that much of the recent extent gains is due to this broken up ice being shoved in a generally southward direction into the Baffin and Greenland seas.

I wonder when our Guv'nor will feel the time is right to open the 2018 melting season threads. Can't be long.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on March 01, 2018, 01:06:05 PM
I wonder when our Guv'nor will feel the time is right to open the 2018 melting season threads. Can't be long.

Probably 7-14 days from now, given that the AO is projected to strongly negative.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 01, 2018, 01:52:40 PM
NSIDC Daily Extent Data as at 28th Feb UP 110k to 14.285  million km2, now only 20k less than 2017.

Peripheral Seas data attached in table. All continues to change as warmth moves around the Arctic, e.g. Baffin (warmer) Greenland (colder). Bering Sea up 70k in 3 days, while Okhotsk starts to fall.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on March 01, 2018, 08:11:36 PM
I wonder when our Guv'nor will feel the time is right to open the 2018 melting season threads. Can't be long.

Probably 7-14 days from now, given that the AO is projected to strongly negative.
I think 1 March should be declared the official opening day of the Melting Thread and 1 September the official opening day of the Freezing Thread.   In the NSIDC record several  years have already  passed their maximums.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on March 01, 2018, 08:39:00 PM
Let's not discuss that here. This thread (https://forum.arctic-sea-ice.net/index.php/topic,2265.0.html) would be a better place.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 02, 2018, 01:22:05 PM
JAXA ARCTIC SEA ICE EXTENT DATA AS AT 1st March 13,759,813  km2. Up again - by 32k, a greater than average increase for this time of year. Extent is just 120k less than the 2017 maximum on 6th March. On average, 14 days, 1.4% and 0.14 million of extent gain to go, leading to a maximum of 13.89 million, i.e. to all intents and purposes the same as 2017.

But 2018 extent still in its lonely furrow, 42k less than 2017, but likely to be second to 2015 for a bit very soon.

Look at 2012 - on Mar 1st 0.77 million greater extent than 2018, and about to go a lot higher (for about two weeks in April was above the 30 year average used by NSIDC). And yet produced the record low in 6 months.

Also attach a table of differences over the years. 1.8 million km2 less winter ice than in the 1980's. The decline in winter ice is still gradual.
Title: Re: 2018 sea ice area and extent data
Post by: RikW on March 02, 2018, 04:29:28 PM
Having above average changes isn't really surprising when we are so extremely low on extent. Because there is a lot of sea/ocean that is normally frozen that isn't frozen and it still is in most parts of the arctic below 0 degrees Celsius. And for area max it doesn't really matter if we have ice that is 10 cm thick or 2 meters thick. It still is covered with ice, until melting and/or wind/waves etc. starts
Title: Re: 2018 sea ice area and extent data
Post by: gregcharles on March 02, 2018, 05:45:49 PM
2018 set record lows in the NIPR Extent data almost every day in February, finally wiping 2006 off the chart in the process. The only pre-2010 year left with daily low extent records is 2007, with four days in October. Given that 2016 is about to dominate the early melt season and 2012 the late melt, I'm not sure how many more records 2018 will be logging for a while. There's no doubt it owns Q1 though -- well, at least until next year.  :(

(A small aside: the NIPR CSV data now blanks out Feb. 29 data for non-leap years. It used to fill in those gaps, I think with the value from March 1. I like it better this way, but have they said anything about why they changed?)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 02, 2018, 06:26:24 PM
(A small aside: the NIPR CSV data now blanks out Feb. 29 data for non-leap years. It used to fill in those gaps, I think with the value from March 1. I like it better this way, but have they said anything about why they changed?)

When making my spreadsheets Feb 29th was a real pain in the butt. I thought about it and realised that Feb 29th is at a time of year when extent gain (Arctic) and extent loss or gain (Antarctic) are minimal (transition season). But none of my stuff is going to appear in a peer-reviewed scientific publication). So I have to tell you that Feb 29 does not exist in my spreadsheets. SHAME ON ME.

No worries until 2020 ( I will take a day off on Feb 29).
Title: Re: 2018 sea ice area and extent data
Post by: oren on March 02, 2018, 11:06:35 PM
Gerontocrat, I do the same with the annoying 29th of Feb... unless dealing with PIOMAS, which has numbered days rather than dates.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 03, 2018, 11:15:25 AM
JAXA ARCTIC SEA ICE EXTENT DATA AS AT 2nd March 13,736,896 km2. Down  - by 23k, a which makes a change. Baffin and Bering regions still very warm ?

Extent is 140k less than the 2017 maximum on 6th March. On average, 13 days, 1.2% and 0.12 million of extent gain to go, leading to a maximum of 13.86 million, i.e. to all intents and purposes the same as 2017.

2018 extent still in its lonely furrow, 51k less than 2017, but still likely to be second to 2015 for a bit very soon. PIOMAS update - "Wherefore Art Thou, PIOMAS".
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 03, 2018, 02:32:35 PM
NSIDC Daily Extent Data as at 2nd March down 55k to 14.302 million km2, now 77k less than 2017.

Peripheral Seas data attached in table. All continues to change as warmth moves around the Arctic, e.g. Baffin (warmer) Greenland (colder and northerly winds pushing ice south).
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on March 03, 2018, 06:26:24 PM
Yeah, the leap day problem is a pesky one. To solve it for CT SIA, I had to convert all the dates to metric time. And still you get one line too many for complete uniform graphing for the data. I just split the difference over the whole year... But to be very accurate, technically, you'd need to start to number the datapoints of a year at six hour intervals on Metric time over the four year period. Thus you'd get staggered points of datevalues on graphs of several years. I figured that as I did not know the exact times of data acquisition, though the satellites orbit is very regular, this didn't matter. Anyway the fixed year+date/365 or date/366 made for prettier graphs at least with some illusion i knew what i was doing. And please don't ask me what to do about year 2100 which doesn't fit to the Julian calendar system.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 03, 2018, 07:31:42 PM
Yeah, the leap day problem is a pesky one. To solve it for CT SIA, I had to convert all the dates to metric time. And still you get one line too many for complete uniform graphing for the data. I just split the difference over the whole year... But to be very accurate, technically, you'd need to start to number the datapoints of a year at six hour intervals on Metric time over the four year period. Thus you'd get staggered points of datevalues on graphs of several years. I figured that as I did not know the exact times of data acquisition, though the satellites orbit is very regular, this didn't matter. Anyway the fixed year+date/365 or date/366 made for prettier graphs at least with some illusion i knew what i was doing. And please don't ask me what to do about year 2100 which doesn't fit to the Julian calendar system.
FAR TOO DIFFICULT for my Pooh-Bear Brain. Mind you, I got caught on March 1 when doing my semi-automatic transfer  from the NSIDC spreadsheets to my copies - NSIDC does, of course have the Feb 29 line in all their data.
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on March 03, 2018, 08:07:23 PM
FAR TOO DIFFICULT

(clip)

Yeah, I dropped the line too on some versions of the spreadsheet and worked it out as a puzzle to solve. The calendar system isn't too user friendly on science. Pmt on the evening of the day that ends at 12018.169863 (year.metric) of Holocene Era.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 03, 2018, 08:12:52 PM
FAR TOO DIFFICULT

(clip)

Yeah, I dropped the line too on some versions of the spreadsheet and worked it out as a puzzle to solve. The calendar system isn't too user friendly on science. Pmt on the evening of the day that ends at 12018.169863 (metric) of Holocene Era.

It could be worse - just think if we were changing from the Julian to the Gregorian Calendar.

Quote
The Julian Calendar in Modern Society. Although the Gregorian calendar has become the international civil calendar, the Julian calendar was still used by some countries into the early 1900s. Some Orthodox churches still use it today to calculate the dates of moveable feasts, such as the Orthodox Church in Russia.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on March 03, 2018, 09:54:46 PM
Seems to me if you wanted a rational dating scheme for the datatypes involved you'd want to tie it to the solar cycle (solstices, equinoxes, and the like) and completely ignore the Gregorian calendar -- but unfortunately, converting all the datasets to start on December 21 is beyond my pay grade.
 
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 03, 2018, 10:07:26 PM
Seems to me if you wanted a rational dating scheme for the datatypes involved you'd want to tie it to the solar cycle (solstices, equinoxes, and the like) and completely ignore the Gregorian calendar -- but unfortunately, converting all the datasets to start on December 21 is beyond my pay grade.
But the Equinox doesn't ALWAYS happen on December 21.

Better stop this, I feel the approach of Neven with his snipper.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on March 03, 2018, 11:14:55 PM
I wish I could snip February 29th once and for all.  ;D

But yes, a bit more on-topic, s'il vous plait.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 04, 2018, 10:46:31 AM
I wish I could snip February 29th once and for all.  ;D

But yes, a bit more on-topic, s'il vous plait.

Oui M'sieur, c'est on-topic

JAXA DATA as at 3rd March, extent 13,729,800 km2, down 7k.

Baffin (including Newfoundland) region still very warm ? cci-reanalyzer says so (but not for long), especially around Newfoundland, and above zero temperatures well up into the Barents Sea. NSIDC regional data may confirm.

Extent is 150k less than the 2017 maximum on 6th March, and 84k less than 2017 on the 3rd March. On average (last 10 years), 12 days, 1.1% and 0.11 million of extent gain to go, leading to a maximum of 13.84 million km2, 40k less than 2017's record low maximum.
BUT the strong NAO which even I can see is in play, may extend the freezing season as the Arctic becomes a lot colder.

2018 extent still in its lonely furrow, 84k less than 2017, but only 9k less than 2015 which lost extent over the next few days.So likely to be second to 2015 for a bit very soon - like today March 4th.

PIOMAS update - "Wherefore Art Thou, PIOMAS".
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 04, 2018, 02:46:36 PM
NSIDC Data as at 3rd March 2018.

Extent 14.227 million km2, down 74k, that's down 130k in 2 days
and 179k less than 2017 on that date
and 220k less than the 2017 maximum on 5th March

Regional Sea extent
Baffin down 25 k, Greenland up 23k, others not a lot of change, so where was the extent loss?
Title: Re: 2018 sea ice area and extent data
Post by: Steven on March 04, 2018, 03:29:10 PM
Regional Sea extent
Baffin down 25 k, Greenland up 23k, others not a lot of change, so where was the extent loss?

The regional numbers that you posted are based on 5-day running averages.

Wipneus has some regional data for the 1-day (unfiltered) NSIDC extent.  This shows that in the last two days there have been extent gains in the Central Arctic Basin and Greenland Sea,  and extent losses in the Baffin/Labrador, Okhotsk and Bering Sea.

(https://i.imgur.com/MZEAZKg.png)

Data: https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data/nsidc_arc_nt_detail.txt
Graph: https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/sea-ice-extent-area/grf/nsidc-nt-regional-extent-overview.png
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 04, 2018, 04:04:53 PM

The regional numbers that you posted are based on 5-day running averages.

MEA CULPA

I import the data from the NISIDc Sea Ice Tools page entitled:-
Daily sea ice extent, by region (Sea_Ice_Index_Regional_Daily_Data_G02135_v3.0.xlsx)

It said daily, so I assumed daily, as the overall data file has both daily and 5-day in it.

But now I have read the detailed documentation - oh dear. I was wrong. It's a pity as the Arctic is now in such a mobile state that 5-day trailing averages may mask abrupt change.

Ho hum. will have to add that proviso to the postings.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 05, 2018, 11:48:35 AM
JAXA DATA as at 4th March, extent  13,690,835 km2, down 39k.

Extent is down by just under 70k in the last three days. The possibility that March 1 was the maximum extent at 13,759,813 km2 cannot be discounted. BUT the strong NAO which even I can see is in play, may extend the freezing season.

2018 extent is now 2k greater than 2015, i.e. no longer is 2018 extent in its lonely furrow. Extent is 139k less than 2017 on the 4th March. On average (last 10 years), 11 days, 1.1% and 0.11 million of extent gain to go, leading to a maximum of 13.80 million km2, 80k less than 2017's record low maximum.

March is when Arctic ice extent dithers, so March 1 max? Extended freezing season? You pay yer money and you takes yer choice.

ps: This is the time of year when the table produces the odd impossible result.


URGENT : PIOMAS update - "Wherefore Art Thou, PIOMAS".
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 05, 2018, 03:00:56 PM
JAXA Regional Data (peripheral seas)
N.B. 5 day trailing average


Baffin extent loss 101k in 6 days.
Greenland Sea extent gain 95k in 6 days.

perfect switch round from previous days.
Title: Re: 2018 sea ice area and extent data
Post by: Gray-Wolf on March 05, 2018, 05:05:11 PM
When I see ice enter Greenland I always say 'Tara!'

The same is true for Baffin ( it ain't running back up Nares and into the basin!)

The ragging peripheral areas has been seeing must lead to an amount of 'collapse and spread' before that ice thins to less than 15% cover and blinks out.

There is also the mixing of the waters at the ice edge as swells and waves do their work feeding a constant supply of warmer, saltier water to work on the ice now liberated?

Okhotsk, Baffin,Greenland and Barentsz are all one way tickets to oblivion for the ice.

We may see cold air over the central basin and that may lead to some thickening of the ice there but the peripheral areas will still be plagued by LP systems and ever warmer background temps.

We may see a very slow start to melt season though as , over past years, it was peripheral areas that made up initial losses? This year we are low on peripheral ice ( apart from Baffin/Okhotsk) so losses will be slow until the main basin melt kicks in?
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on March 05, 2018, 08:31:42 PM
When I see ice enter Greenland I always say 'Tara!'

The same is true for Baffin ( it ain't running back up Nares and into the basin!)

The ragging peripheral areas has been seeing must lead to an amount of 'collapse and spread' before that ice thins to less than 15% cover and blinks out.

There is also the mixing of the waters at the ice edge as swells and waves do their work feeding a constant supply of warmer, saltier water to work on the ice now liberated?

Okhotsk, Baffin,Greenland and Barentsz are all one way tickets to oblivion for the ice.

We may see cold air over the central basin and that may lead to some thickening of the ice there but the peripheral areas will still be plagued by LP systems and ever warmer background temps.

We may see a very slow start to melt season though as , over past years, it was peripheral areas that made up initial losses? This year we are low on peripheral ice ( apart from Baffin/Okhotsk) so losses will be slow until the main basin melt kicks in?

about as you say which will result in an ever longer "quasi-plateau"  lasting from about now till ever later. if it were not for ice once could easily project what happens to an ever flattening curve with an ever longer plateau ;)
Title: Re: 2018 sea ice area and extent data
Post by: gregcharles on March 05, 2018, 10:55:40 PM
PIOMAS update - "Wherefore Art Thou, PIOMAS".

PIOMAS =  Pan-Arctic Ice Ocean Modeling and Assimilation System, so that's why (aka wherefore) PIOMAS, but, "What's in a name?" A rose by any other name would have the same total ice volume.   

Or did you mean "where"?  :)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 05, 2018, 11:26:59 PM
PIOMAS update - "Wherefore Art Thou, PIOMAS".

PIOMAS =  Pan-Arctic Ice Ocean Modeling and Assimilation System, so that's why (aka wherefore) PIOMAS, but, "What's in a name?" A rose by any other name would have the same total ice volume.   

Or did you mean "where"?  :)

I was being lazy, using it when knowing that it is a common misconception of the meaning. Unfair of you to pick me up on it, so "Lay off, MacDuff!"
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 06, 2018, 09:54:22 AM
JAXA DATA as at 5th March, extent   13,629,925 km2, down 61k.

Extent is down by 130 k in the last four days. The possibility that March 1 was the maximum extent at 13,759,813 km2 is moving from possibility to probability. One more day of extent drops would be it ? It is a classic transition, the CAB getting colder i.e. additional freezing, with peripheral seas warming and melting.

2018 extent is back down to 35k less than 2015, i.e. back in in its lonely furrow. Extent is 229k less than 2017 on the 5th March. It is difficult to see extent gain from now greater than that.

On average (last 10 years), 10 days, 1.0% and 0.10 million of extent gain to go, leading to 13.73 million km2, 30k less than the 2018 current maximum of 13.76 million km2 on March 1st..

ps: 2018 extent is currently just over 1 million km2 LESS than 2012, and yet 2012 ended up with the record lowest minimum extent to date.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on March 06, 2018, 12:52:35 PM
Nothing is off the cards for the next  few weeks. 2014 dropped 240K over the next few days then rose  440K to  set its winter maximum. Weather is a massive factor over the remainder of the month.We won't be sure of the maximum for a few weeks yet.

This year has been so unusual that anything  could happen. Having said that  2018  does seem determined to hang on to  first  place and definitely  not fall  below 2nd lowest.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 06, 2018, 05:07:53 PM
JAXA Regional Data (peripheral seas) as at 5th March
N.B. 5 day trailing average

Baffin extent loss 125k in 6 days.
Greenland Sea extent gain 1055k in 6 days.

perfect switch round from previous days continues. Bering and Okhotsk also going down

NISIDC Arctic daily extent  14.169 million km2, down 58k on the 5th and down 188k in the last four days.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 06, 2018, 05:17:02 PM
ESSENTIAL READING.

NSIDC HAS POSTED THE FEBRUARY ANALYSIS


https://nsidc.org/arcticseaicenews/
Title: Re: 2018 sea ice area and extent data
Post by: gregcharles on March 06, 2018, 06:45:31 PM
I was being lazy, using it when knowing that it is a common misconception of the meaning. Unfair of you to pick me up on it, so "Lay off, MacDuff!"

Yes, I guessed that already. ;)

"Just", Measure for Measure, II, 2
"giving", As You Like It, III, 5
"you", Comedy of Errors, I, 2
"a hard", Merchant of Venice, II, 2
"time.",  All's Well That Ends Well, I, 1

By the way, thanks for all you do in this thread. It's the first place I look every morning!
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 07, 2018, 05:21:52 AM
March 6th: JAXA drop of 17,592 km2.
Now 147,480 km2 lower than March 1st.
And 2018 is the lowest on record.   :-X
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 07, 2018, 09:40:41 AM
JAXA DATA AS AT 6TH MARCH Extent  13,612,333 km2

Extent is down by 147 k in the last five days. The possibility that March 1 was the maximum extent at 13,759,813 km2 has moved from possibility to probability.

2018 extent is now 48k less than 2015, i.e. staying in its lonely furrow. Extent is 266k less than 2017 on the 6th March, the day of the 2017 maximum. It is difficult to see extent gain from now greater than that, i.e. 2018 maximum will be a record low. The only question is by how much? 120k if March 1 was the minimum, less if extent increases by more than 147k from now.

On average (last 10 years), 9 days, 0.8% and just 73,000 km2 of extent gain to go, leading to 13.69 million km2, 70k less than the 2018 current maximum of 13.76 million km2 on March 1st..

The second table attached is a look forward to the 2018 minimum. Using the last 10 years data that minimum would range from 2.1 to 4.2 million km2, and with average melt 3.76 million, a clear 2nd lowest behind 2012. 2018 extent is currently 1.05 million km2 LESS than 2012, and yet 2012 ended up with the record lowest minimum extent to date.

Is the ice in good condition to meet the melting season compared with 2017? Extent says no, volume says yes. Damage to the ice especially during February says no. I expect an outpouring of hypotheses when Neven lets the genie out of the bottle by opening the 2018 melting thread.

Title: Re: 2018 sea ice area and extent data
Post by: oren on March 07, 2018, 10:51:47 AM
Gerontocrat, in calculating potential rises for the table, are you also looking at years that went up somewhat but have not reached a new maximum? I am specifically asking about the yellow line of 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 07, 2018, 11:57:11 AM
Gerontocrat, in calculating potential rises for the table, are you also looking at years that went up somewhat but have not reached a new maximum? I am specifically asking about the yellow line of 2015.

I have commented before on my postings that the spreadsheet can produce odd results when we are at the time when some years have reached maximum (or minimum) and some have not. The spreadsheet simply looks at the difference between extent on the day and extent at the maximum (minimum) to produce the additional extent gain (or loss) to come. No problem until the season is in transition .

If extent gain to maximum is +ve (i.e. max not reached yet), the spreadsheet uses that figure. If maximum has been reached, the spreadsheet says extent gain to come is zero. (The reverse for the minimum in September)

This has the effect of overestimating average gain as extent loss from years already beyond maximum is excluded. I was content with that, as it is a small error on the side of a conservative view. But the same methodology underestimates potential gain from an oddity like 2015 (maximum on 16th Feb and 29 days later extent loss just 41 k but a huge dip in the middle.

What to do about such oddities? Change the spreadsheet or admit the limitation. Methinks I should have highlighted 2015 as one of those years where standard operating procedures do not apply.
Title: Re: 2018 sea ice area and extent data
Post by: oren on March 07, 2018, 01:12:06 PM
Thanks for the clarification. 2015 was indeed peculiar in its behavior.
Looking at its numbers and assuming a repeat performance, this year could surpass its Mar 1 maximum, and even reach/surpass just about the 2017 maximum. We'll see, though I'd be very surprised if it actually happens.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 07, 2018, 03:09:32 PM
JAXA Regional Data (peripheral seas) as at 6th March
N.B. 5 day trailing average


The table below has changed a bit, and ordered by peripheral sea West to East, i.e. Okhotsk & Bering, Baffin and St. Lawrence, Greenland and Barents. Chukchi is out (CAB sea) and St. Lawrence in (peripheral sea). Will need a second table soon for the CAB seas.

(Sorry Sleepy, the Baltic didn't get an invite).

Bering down 52k in four days, Okhotsk down 32k also in four days.
Baffin extent loss 144k in 8 days plus St Lawrence 32k in 4 days.
Greenland Sea extent gain 112k in 8 days, Barents up 34k in 3 days.

perfect switch round from previous days continues.

NISIDC Arctic daily extent  14.152 million km2, down 17k on the 6th and down 205k in the last five days.
Title: Re: 2018 sea ice area and extent data
Post by: oren on March 07, 2018, 06:02:23 PM
I still can't get over the early and low max in the Bering.
Title: Re: 2018 sea ice area and extent data
Post by: charles_oil on March 07, 2018, 10:30:37 PM
Just looking at Chartic .. .2010, 12, 13, 14, 15, 16 I was surprised to see that all had "bounces" in area after a significant drop as we have seen in the last few days. 2011 & 17 were the only ones that didn't.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 08, 2018, 06:08:22 AM
JAXA March 7th:

Now ASI at 13,609,296 km2.
A small drop of -3,037 km2.
But another day has passed.
In my opinion, the recovery is not likely to happen now, so the maximum was on March 1st.
2018 continues to be the lowest on record.

Edit:

According to Hautbois analysis, it could still be possible...  ;)
March 7th = day 66, according to JAXA (Jan 1st=Day 0, February has 29 days)

Beware the false Max!!

Just for laughs ??? I thought I'd look over the last 10 years to see how often there was a 'cheeky peak' that might have got people thinking 'we've hit maximum', followed by a dip, and then followed by another peak that turned out to be the real maximum.

There were 5 that did that, and a sixth that nearly did, but not quite.

2008: 14.75m sq.km on day 62, lost 76k, then gained 100k.
2010: 14.651 on day 68, then lost 180k, then gained 217k
2011: 14.108 on day 67, then lost 181k, then gained 200k
2013: 14.513 on day 60 (March 1st, people), then lost 207k, then gained 217k.
2014: 14.255 on day 65, then lost 240k, then gained 433k as if to say 'haha just messin' with ya'

The 'not quite' year was 2012 - it dropped 199k, then gained 183k, so peak 2 wasn't quite the max in the end.

The 10 years before that were less tricksy. There were only three false max years; 1999 and 2003 stand out, overturning drops  of 307k and 258k respectively from an initial false max.



(Now, what was I meant to be doing....)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 08, 2018, 08:31:27 AM
As Juan C. García has noted above, JAXA extent on March 7th is 13,609,296 km2, a small drop of 3k. But it is still a drop, it is a day later in the year, reducing the chances of a late large extent increase.

But as Hautbois has pointed out, extent can go up and down and then up again by fairly large amounts at this time of year. I look at it more like waves - that happen all year, perhaps reflecting waves of weather flowing over the Arctic.

So is Arctic extent due to go up for a bit, and if so, by how much ?

And as I have noted before , once it is the time of year when in some years the maximum is done, but in other years not, the projections I post become somewhat meaningless. So I am  posting the projections for the September minimum instead, but without comment.


Meanwhile, extent at 7th March 2018 is 50k less than 2015, 249k less than 2016, and 257k less than 2017 extent on that date.


Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 08, 2018, 02:45:14 PM
WHOOPS !!! NSIDC Regional Data (peripheral seas) as at 7th March
N.B. 5 day trailing average


Bering down 61k in fivedays, Okhotsk going back up (4k).
Baffin extent loss 157k in 9 days plus St Lawrence down 52k in 5 days.
Greenland Sea extent gain 115k in 9 days, Barents up 48k in 4 days.

perfect switch round from previous days continues.

NISIDC Arctic daily extent  14.204 million km2, up 52k.  A second max starts to form?
Title: Re: 2018 sea ice area and extent data
Post by: Buddy on March 08, 2018, 03:11:57 PM
Quote
Bering down 61k in fivedays,

The condition of the Bering this year has to have a negative effect on the CAB.
Title: Re: 2018 sea ice area and extent data
Post by: oren on March 08, 2018, 03:18:21 PM
Gerontocrat, I am suddenly not sure... Is your regional data from JAXA, NSIDC, or a combination?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 08, 2018, 04:20:58 PM
Gerontocrat, I am suddenly not sure... Is your regional data from JAXA, NSIDC, or a combination?

Blast and damn. No sleep last night and brain wiring shorted. My rule is NEVER mix NSIDC and JAXA data in one post. It was NSIDC data. Post corrected.

Thanks for spotting it.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 09, 2018, 05:17:32 AM
JAXA March 8th:

After 6 consecutives drops on March, for the first time there is an increase in ASI, of 18,984 km2. JAXA SIE now at 13,628,280 km2.
2018 has to increase more than 131,533 km2, in order to have a new max.

2018 is still first of record, now 21,589 km2 below 2015. But 2015 had drops of -20,672 and -5,429 km2 on March 9th and 10th. So maybe 2018 will be second lowest on record tomorrow or the day after.


Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 09, 2018, 02:49:02 PM
NSIDC Regional Data (peripheral seas) as at 8th March
N.B. 5 day trailing average

Bering down 61k in five days, Okhotsk going back up (25k).
Baffin extent loss 166k in 10 days plus St Lawrence down 71k in 6 days.
Greenland Sea extent gain 113k in 9 days, Barents up 63k in 5 days.

perfect switch round from previous days continues.

NISIDC Arctic daily extent  14.289 million km2, up 86k (8 mar) + 51k (7 mar).  A second max starts to form?

Interesting times
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 09, 2018, 03:04:07 PM
JAXA extent on March 8th is  13,628,280 km2, an increase of 19k. But March 1 is still the current max, it is a day later in the year, reducing the chances of a late large extent increase.

But as Hautbois has pointed out, extent can go up and down and then up again by fairly large amounts at this time of year. We looked at 2015. I should have looked at March 2014 as well.

(Note:NSIDC daily extent up 137k in two days)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 10, 2018, 01:55:17 PM
NSIDC Regional Data (peripheral seas) as at 9th March
N.B. 5 day trailing average

Activity in extent in decline - and only exists in the peripheral seas. Net increase 21 k.

NISIDC Arctic daily extent  14.319 million km2, up 30 k (9 March), 86k (8 mar) + 51k (7 mar).  A second max starts to form or is the increase running out of steam?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 11, 2018, 03:38:27 PM
NSIDC Regional Data (peripheral seas) as at 10th March
N.B. 5 day trailing average

Activity in extent increases   (partly effect of using 5 day trailing average ?)- and only exists in the peripheral seas. (CAB continues to get colder).  Net increase in periphery 32 k, mainly in Bering and Okhotsk

NISIDC Arctic daily extent  14.303 million km2, down 16 k (10th March) after going up 30 k (9 March), 86k (8 mar) + 51k (7 mar).  Now 54 k less than its maximum to date on 5th March.

A second max starts to form or is the increase running out of steam? What a tease.

ps: Note the blob of warmth between NE Greenland and Svalbard on the map- that is a persistent feature.

(Jaxa continues its little holiday - back to tomorrow?)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 12, 2018, 09:43:31 AM
JAXA extent on March 11th is  13,780,135 km2, A new maximum for the year by 20 k. Typical that JAXA was off-line when a big change happens.
 
In the last three days extent increased by 32k ( 9 Mar ),  80k (10 March) and  40k (11th March), very high for this time of year. As a result 2018 extent is now 132 k greater than 2015 and only just below 2017 as at 11th March.

The table still shows a probability of a record low maximum (just). The average extent gain is totally distorted by just one year, 2014 where extent grew by 330k from 11th March to its maximum on 19th March. Given the current chilly outlook in the Arctic this is a real possibility. (see image for the equinox below)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 12, 2018, 01:34:17 PM
NSIDC Regional Data (peripheral seas) as at 11th March
N.B. 5 day trailing average

Activity in extent increases   (partly effect of using 5 day trailing average ?)- and only exists in the peripheral seas. (CAB continues to get colder).  Net increase in periphery 26 k, entirely due to Bering + 31k, and Okhotsk +8k. All other seas extent down.

NISIDC Arctic daily extent 14.289 million km2, down 14k, (11th March), down 16 k (10th March) after going up 30 k (9 March), 86k (8 mar) + 51k (7 mar). 

Now 68 k less than its maximum to date on 1st March. 
Very different from JAXA, but the poll was the date of the JAXA maximum.

A second max continues to form or is the increase running out of steam? What a tease.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 14, 2018, 09:37:15 AM
JAXA extent on March 13th is  13,837,866 km2, yet another  new maximum for the year . Typical that JAXA keeps going off-line when big changes happen.
 
In the last two days extent increased by 27k ( 12 Mar ),  and  31k (12th March),  high for this time of year. As a result 2018 extent is now 150 k greater than 2015 and greater than 2017 by 22k on this date.

The table now shows a probability of amaximum of 13.89k, not quite a record low. The average extent gain is totally distorted by just one year, 2014 where extent grew by 150k from 13th March to its maximum on 19th March. Given the current chilly outlook in the Arctic this is a real possibility. (see image for the equinox below)
On the other hand, as regards extent it is what will happen in the peripheral seas that matter at this time of year.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on March 14, 2018, 09:59:06 AM
What are the chances of JAXA SIE going over 14 million km2?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 14, 2018, 01:08:36 PM
What are the chances of JAXA SIE going over 14 million km2?

All about the peripheral seas - at the moment the Bering Sea.

NSIDC Regional Sea Data - 5 day trailing average
Data as at 13th March


Bering Sea extent up by  30,991 km2 (12th March) and 33,081  km2(13th March).
Total increase (all peripheral seas)  36,715 km2 (12th March) and 34,398 km2 (13th March).
 
Extent gain (all other seas) 2,235 km2

And tomorrow ??????????????
 
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 15, 2018, 10:06:00 AM
JAXA extent on March 14th is  13,853,284 km2, yet another  new maximum for the year . Extent is fourth lowest for the day, greater than 2015 by 167k, 2016 by16k , and 2017 by 18k.

Extent increased by 15k, less than half the previous 6 days average gain of  38k. Perhaps the tide is turning to extent reductions?

The table now shows a a maximum of 13.90k, not quite a record low. In 6 out of the last 10 years maximum had been reached, i.e. extent loss was now happening. In 4 years, significant extent gain was still to occur.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 15, 2018, 02:23:05 PM
NSIDC Regional Data (peripheral seas) as at 14th March
N.B. 5 day trailing average

Activity in extent increases  - and still only exists in the peripheral seas. .  Net increase in periphery 43 k, entirely due to Bering + 31k, and Barents + 18k. Bering Sea extent up by 149 k in just 5 days.

NISIDC Arctic daily extent  14,504,000 km2, up 51,000 jm2. (Up 215,000 km2 in just 3 days. Extent is now 57 k greater than the record low maximum in 2017 on the 5th March.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 16, 2018, 09:25:09 AM
JAXA extent on March 15th is  13,875,677 km2, yet another  new maximum for the year . Extent is fourth lowest for the day, greater than 2015 by 151k, 2016 by just 1k , and 2017 by 58k.

Extent increased by 22k, making 2017 extent just 2,610 km2 less than the record low maximum of 2017. The table now shows a a maximum of 13.91k, not quite a record low. In 6 out of the last 10 years maximum had been reached, i.e. extent loss was now happening. In 4 years, significant extent gain was still to occur.

The vagaries of the weather in the peripheral seas will determine the final result.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 16, 2018, 01:57:15 PM
JAXA extent on March 15th is  13,875,677 km2, yet another  new maximum for the year . Extent is fourth lowest for the day, greater than 2015 by 151k, 2016 by just 1k , and 2017 by 58k.

No that it is very important, but on March 15th, the year 2018 is the fifth lowest. 2006 is also below 2018.

                  March 15         vs. 2018
2018        13,875,677   
2006        13,874,040          -1,637
2015        13,724,438      -151,239
2016        13,874,820             -857
2017        13,818,067        -57,610

P.S. And there is still some anomaly cold weather on the following days...  ;)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 16, 2018, 02:16:53 PM
NSIDC Regional Data (peripheral seas) as at 15th March
N.B. 5 day trailing average


Activity in extent stays high  - and still only exists in the peripheral seas. .  Net increase in periphery 41 k, due to Bering + 16k, Okhotsk + 12k,  and Barents + 15k. Bering Sea extent up by 165 k in just 6 days. Extent gain in CAB seas a mind-boggling 132 km2 (which is, I suspect, not statistically significant.)

SNOW
It is being said by some commentators that loads of snow in N. America, especially Quebec Province, will slow down melt. It is obviously logical. However, the two peripheral seas with the most significant and persistent melt in March to date are The St. Lawrence, over half extent gone (down 131 k to just 97k) and Baffin (mainly southern end down 170 k or 12% ). Hudson Bay concentration does not look so good in parts as well.


NISIDC Arctic daily extent  14,502,000 km2, DOWN A WHOLE 2k. The contrast with regional data must be because regional data is  five-day-trailing average.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 16, 2018, 02:58:47 PM

No that it is very important, but on March 15th, the year 2018 is the fifth lowest. 2006 is also below 2018.

                  March 15         vs. 2018
2018        13,875,677   
2006        13,874,040          -1,637
2015        13,724,438      -151,239
2016        13,874,820             -857
2017        13,818,067        -57,610

P.S. And there is still some anomaly cold weather on the following days...  ;)

Well spotted JCG,

The longer the 2018 freezing season lasts, the more of the previous years were in melting season, and 2018 could slip further down the table. While the Arctic as a whole looks like staying obstinately cold, maybe at the periphery sufficient warmth and insolation will end the season by the equinox, or maybe not.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on March 16, 2018, 06:06:21 PM

No that it is very important, but on March 15th, the year 2018 is the fifth lowest. 2006 is also below 2018.

                  March 15         vs. 2018
2018        13,875,677   
2006        13,874,040          -1,637
2015        13,724,438      -151,239
2016        13,874,820             -857
2017        13,818,067        -57,610

P.S. And there is still some anomaly cold weather on the following days...  ;)

Well spotted JCG,

The longer the 2018 freezing season lasts, the more of the previous years were in melting season, and 2018 could slip further down the table. While the Arctic as a whole looks like staying obstinately cold, maybe at the periphery sufficient warmth and insolation will end the season by the equinox, or maybe not.
What I note actually is (1) how close all the numbers are and (2) the serious observed differences in ice quality and distribution.

I have doubts that snow such as in Quebec will significantly slow melt down other than locally.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 17, 2018, 01:05:20 PM
JAXA extent on March 16th is  13,874,375 km2, NOT yet another  new maximum for the year . Extent isnow  fourth lowest for the day, greater than 2015, 2017 and 2006. (Now less than 2016)

Extent decreased by 1,312 km2, making 2017 extent just 3,912 km2 less than the record low maximum of 2017. The table now shows a a maximum of 13.90k, not quite a record low. In 7 out of the last 10 years maximum had been reached, i.e. extent loss was now happening. In 4 years, significant extent gain was still to occur.

One might think that with no meaningful change in extent, things were quiet. How wrong can one be. Ice is moving around, cracking, new ice forming. This implies the ice has more room to move around. Does not this also imply that the more freedom of movement shown, the lower the volume? But how would one construct an index of mobility or freedom of movement so trends over time could be observed?

The vagaries of the weather in the peripheral seas will determine the timing of the final result as regards extent.  One waits a little bit for NSIDC data.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 17, 2018, 01:51:32 PM
NSIDC Regional Data (peripheral seas) as at 16th March
N.B. 5 day trailing average


Activity in extent a bit less  - and still only exists in the peripheral seas. .  Net increase in periphery 36 k, due to Bering + 11k, Okhotsk + 11k,  and Greenland + 7, Barents + 10k. Bering Sea extent up by 176 k in 7 days. Extent LOSS in CAB seas a mind-boggling 660  km2 in the Central Arctic Sea, (which is, I suspect, not statistically significant.)

SNOW
It is being said by some commentators that loads of snow in N. America, especially Quebec Province, will slow down melt. It is obviously logical. However, the two peripheral seas with the most significant and persistent melt in March to date are The St. Lawrence, over half extent gone (down 131 k to just 97k) and Baffin (mainly southern end down 170 k or 12% ). Hudson Bay concentration does not look so good in parts as well. (After writing this St Lawrence starts to gain extent.)


NISIDC Arctic daily extent  14,502,000 km2, DOWN 56k. The contrast with regional data must be because regional data is  five-day-trailing average. This largish extent reduction must feed through to regional 5 day data in the days to come.

Is that it for NSIDC extent? More days to wait.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 18, 2018, 01:48:08 PM
NSIDC Regional Data (peripheral seas) as at 16th March
N.B. 5 day trailing average

Whoops - table added

Activity in extent a bit less as expected from data re total daily extent- and still (mostly) only exists in the peripheral seas. Net increase in periphery 21 k, due to Bering + 15k, Okhotsk + 8k,  and Greenland + 6k, Barents + 6k.  baffin down 10k. Extent LOSS in CAB seas a further mind-boggling 2,637 km2 in addition to the 660  km2 on the 16th March in the Central Arctic Sea, (which is, I suspect, not statistically significant.)

SNOW
No more comments here. I am having a think about snow and permafrost. But if anything comes of it I will plonk it in the "Ice-free Arctic" thread (in "Consequences" section). Something did so I posted it.


NISIDC Arctic daily extent   14,467,000  km2, up 19k after the 56k reduction on the 16th. The NSIDC maximum this year is currently 14.504 million on the 14th March.

Is that it for NSIDC extent? Yet more days to wait.

(JAXA doing its annoying day off thing again.)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 19, 2018, 09:30:02 AM
As already reported by JCG elesewhere, JAXA extent on March 18th is  13,833,573  km2, which may very well mean that the max on 11th March of 13.891 million km2 was the 2018 maximum. This would mean 2018 comes in a t no #2 record low maximum.

Perhaps of more significance is that due to the late date of this maximum, extent on 18th March is 277k greater than 2017 extent on that date. But as pointed out elsewhere, although this means less early insolation, the date of maximum seems to have little correlation with eventual minimum extent.

Is this it ? Will Neven pull the lever and let the 2018 melt comments flood out?
Title: Re: 2018 sea ice area and extent data
Post by: Neven on March 19, 2018, 09:43:12 AM
Is this it ? Will Neven pull the lever and let the 2018 melt comments flood out?

Two more drops and I certainly will. Expect the 2018 melting season thread to open on Wednesday.  :)
Title: Re: 2018 sea ice area and extent data
Post by: Sleepy on March 19, 2018, 09:51:21 AM
As already reported by JCG elesewhere
...
Is this it ? Will Neven pull the lever and let the 2018 melt comments flood out?
Elsewhere would be here?
https://forum.arctic-sea-ice.net/index.php/topic,2265.100.html (https://forum.arctic-sea-ice.net/index.php/topic,2265.100.html)
When Neven opens the blue ocean season on Wednesday; duck and cover!  :)
Title: Re: 2018 sea ice area and extent data
Post by: be cause on March 19, 2018, 11:43:03 AM
meanwhile the dmi 80 temps almost touch the long term average for the date ..
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 19, 2018, 12:44:40 PM
Hi gerontocrat!

It is 17th, not 11th...
As already reported by JCG elesewhere, JAXA extent on March 18th is  13,833,573  km2, which may very well mean that the max on 11th 17th March of 13.891 million km2 was the 2018 maximum. This would mean 2018 comes in a t no #2 record low maximum.

Edit:
Hi!

On march 17th, JAXA 2018 register 13,891,190 km2, which is now the max for 2018.
Also, it is 12,903 km2 above the 2017 max, so 2018 is not the lowest on record anymore. But it is still under the 2015 and 2016 max, so 2018 is now the second lowest max on record.

On march 18th, JAXA 2018 register 13,833,573 km2, an important drop of 57,617 km2. In my opinion, it starts to be difficult to have a max above 2015 (13.94M km2), that now it is the third lowest on record.

Congrats Neven! Max on March 17th! And also on the range you voted!  ;)
We just have to wait some days, to confirm the max and open the melting season thread.

PS: At least 2 times on the year, I become addicted to JAXA! Please give me my daily dosis, JAXA!  ;D
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 19, 2018, 12:48:14 PM
meanwhile the dmi 80 temps almost touch the long term average for the date ..

Melting, when it occurs, will be confined to South of 80 for some time yet.
Also a big debate on relevance of 2m air temperatures vs. cloudiness (insolation effect), sst anomalies and ocean temps at greater depths and wind, waves, snow on depth on the arctic fringe ....... etc etc.

Nevertheless, the graph shows a huge drop from the early March extreme high and it is persistently low. Cannot find similar in recent years.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 19, 2018, 01:11:03 PM
Hi gerontocrat!

It is 17th, not 11th...
As already reported by JCG elesewhere, JAXA extent on March 18th is  13,833,573  km2, which may very well mean that the max on 11th 17th March of 13.891 million km2 was the 2018 maximum. This would mean 2018 comes in a t no #2 record low maximum.

Hi Juan - this getting to be an embarassingly regular occurrence. I am not checking me data properly. So thanks for the correction(s).

Meanwhile - NSIDC DATA at 18th March. Might encourage El Presidente Neven not to wait for a further two days of JAXA extent reduction?

NSIDC Daily Extent at 18th March = 14.349 million km2, down 117k on the day and down 155k on the maximum to date on the 14th March.

NSIDC Peripheral Seas Extent as at 18th march - 5 day trailing average

Total Extent gain of Peripheral Seas of 23k on 17th March turned round to small extent loss of 5k, mainly due to extent loss in Baffin (-8k) and Barents (-6k). Expect much greater extent changes as large drop in daily Arctic extent impacts 5 day totals.

Also to be noted is third day of extent loss in Central Arctic Ocean  (9k in total).
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 20, 2018, 02:13:19 AM
Hi Juan - this getting to be an embarassingly regular occurrence. I am not checking me data properly. So thanks for the correction(s).

Don't worry. Too much numbers and things going on. The true is that there is surely an emotional pressure when we follow the ASI events so closely. But well, at least talking about my feelings, hopefully we can relax a little, with the DMI temperature drop and because the ASI is not breaking daily records now.  :)

I'm not saying that there is a rebound. But it could be worst, if the JAXA max where on March 1st.
Title: Re: 2018 sea ice area and extent data
Post by: Lord M Vader on March 20, 2018, 08:05:01 AM
Another 70K down today according JAXA...
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 20, 2018, 08:11:58 AM
JAXA extent on March 19th is  13,761,282  km2,. This is a drop of 72k on top of the 58k the day before. Obviously this increases the likelihood that the maximum on 17th March of 13.891 million km2 was the 2018 maximum. This would mean 2018 comes in at no #2 record low maximum, just 13k above 2017 (well within the standard error of JAXA data?).

Extent is now third lowest behind 2017 and 2015, though it looks as though that will change to 2nd in the next day or two (2015 gained extent to 26th March)

Due to the late date of this maximum, extent on 19th March is still 201k greater than 2017 extent on that date.  On the other hand the 2018 March average is still more than 100k below 2017 and in 2017 there was a very low extent loss of 4k during the remainder of March.

I attach 2 tables below. The first looks at maximum. All previous years' data say the maximum has happened. The second table looks forward to the September minimum. Previous years' data give projections of the 2018 minimum ranging from a low of 2.25  to a high of 4.67 million km2 and an average of 3.94 million. My prediction is that the result will be none of those figures.

Meanwhile, NSIDC data will tell us where the extent loss is happening and maybe put even more pressure on the Guv'nor to open the floodgates of the melting season thread.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on March 20, 2018, 09:20:27 AM
Meanwhile, NSIDC data will tell us where the extent loss is happening and maybe put even more pressure on the Guv'nor to open the floodgates of the melting season thread.

Little Hansje Brinker shouts: Wednesday!  ;)

(https://www.aaenmaas.nl/binaries/twocolumn/content/gallery/am---website/common/informatie+op+maat/kinderen+0/kinderen/kids/hansjebrinker.jpg)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 20, 2018, 09:57:21 AM
Meanwhile, NSIDC data will tell us where the extent loss is happening and maybe put even more pressure on the Guv'nor to open the floodgates of the melting season thread.

Little Hansje Brinker shouts: Wednesday!  ;)

(https://www.aaenmaas.nl/binaries/twocolumn/content/gallery/am---website/common/informatie+op+maat/kinderen+0/kinderen/kids/hansjebrinker.jpg)

I was told Little Hansje Brinker was drowned in the flood, and his Mum said, " I kept on telling him to stop shoving his finger into that damn dyke, but he would not listen".
Title: Re: 2018 sea ice area and extent data
Post by: Neven on March 20, 2018, 10:06:11 AM
I was told Little Hansje Brinker was drowned in the flood, and his Mum said, " I kept on telling him to stop shoving his finger into that damn dyke, but he would not listen".

Fake news.  ;)

One more drop tomorrow and the thread will be opened.
Title: Re: 2018 sea ice area and extent data
Post by: echoughton on March 20, 2018, 11:30:08 AM
Simple...but not dumb...question: How can we be switching to melt mode when the temps up there are the frigidest of the season???

http://ocean.dmi.dk/arctic/plots/meanTarchive/meanT_2018.png
Title: Re: 2018 sea ice area and extent data
Post by: oren on March 20, 2018, 11:53:00 AM
Simple...but not dumb...question: How can we be switching to melt mode when the temps up there are the frigidest of the season???

http://ocean.dmi.dk/arctic/plots/meanTarchive/meanT_2018.png
Because the arctic is not a single location. The southern periphery is already melting while the inner areas continue freezing up until May.
Title: Re: 2018 sea ice area and extent data
Post by: El Cid on March 20, 2018, 12:03:28 PM
Simple...but not dumb...question: How can we be switching to melt mode when the temps up there are the frigidest of the season???

http://ocean.dmi.dk/arctic/plots/meanTarchive/meanT_2018.png

Because DMI calculates temperatures north of 80 and the melting is going on much further south
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 20, 2018, 01:15:48 PM
NSIDC Daily Extent at 19th March = 14.309 million km2, down 40k on the day and down 195k on the maximum to date on the 14th March 0f 14.504 million km2.

While this maximum is 57k greater than the 2017 record low maximum on 5th March and extent at 19th March is 114k greater than 2017 on that date , the March 2018 simple average to date is 112k less than the 2017 simple March average to the 19th March. It is therefore probable that NSIDC will record March 2018 as the lowest extent in the satellite record.

NSIDC Peripheral Seas Extent as at 19th march - 5 day trailing average

As expected the daily extent losses of the total Arctic are feeding into the five-day average extent losses in the peripheral seas. Peripheral Seas extent losses were 33k, up from 5k the day before.

Also to be noted is the fourth day of extent loss in Central Arctic Ocean (13k in total).

But nothing will persuade the Guv'nor to not wait til tomorrow to open the 2018 melting thread. (Anybody got a few hundred thousand bucks lying around doing nothing and needing a home?)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 21, 2018, 05:28:37 AM
JAXA extent on March 20th is 13,713,053 km². This is a drop of 178k in 3 days - 48k (20 Mar), 72k (19 Mar), 58k (18 Mar). Obviously this will convince even the Guv'nor that the maximum on 17th March of 13.891 million km2 was the 2018 maximum. 2018 comes in at no #2 record low maximum, just 13k above 2017 (well within the standard error of JAXA data?).

Extent is now third lowest behind 2017 (154k) and 2015 (7k) , though it looks as though that will probably change to 2nd on 21 March (2015 gained extent 21st to 26th March)

Due to the late date of this maximum, extent on 19th March is still 154k greater than 2017 extent on that date.  On the other hand the 2018 March simple average is still more than 100k below 2017 and in 2017 there was a very low extent loss during the remainder of March.

Previous years' data give projections of the 2018 minimum ranging from a low of 2.23 (2012 high melt) to a high of 4.67 million km2 (2017 low melt) and an average of 3.91 million. The 2.23 million result needs to be treated with caution. On 20th March 2012 extent was 0.95 million km2 greater than in 2018. It seems to me that a large part of the 2012 extremely high melt was simply catching up due to a late start to melting, (plus a late season fillip due to the late August central arctic cyclone)

My prediction is that the result will be none of those figures (bad joke). Meanwhile, NSIDC regional sea data will tell us where the current extent loss is happening.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 21, 2018, 01:38:00 PM
NSIDC Daily Extent at 20th March = 14.210 million km2, down 99 k on the day and down 294k on the maximum to date on the 14th March of 14.504 million km2.

Extent at 20th March is 7 k LESS than 2017 on that date , and the March 2018 simple average to date is 111k less than the 2017 simple March average to the 20th March. It is therefore very probable that NSIDC will record March 2018 as the lowest extent in the satellite record, especially given that in 2017 extent loss from 20th to 31st March was a measly 45 k.

NSIDC Peripheral Seas Extent as at 20th March - 5 day trailing average

As expected the daily extent losses of the total Arctic are continuing to feed into the five-day average extent losses in the peripheral seas. Peripheral Seas extent losses were 48k, up from 33k the day before.  Every peripheral sea had an extent loss.

Also to be noted is that it is the fifth day of extent loss in the Central Arctic Ocean (17k in total).

Just as well that today was an extent loss both in NSIDC and JAXA data. An extent gain could have provoked a palace revolution.
Title: Re: 2018 sea ice area and extent data
Post by: oren on March 21, 2018, 04:01:26 PM
It seems Bering has just almost made a new high, following Feb 7th which was at 411.5k, indeed a very strange year.
Title: Re: 2018 sea ice area and extent data
Post by: uniquorn on March 21, 2018, 06:58:31 PM
It seems Bering has just almost made a new high, following Feb 7th which was at 411.5k, indeed a very strange year.
extent+lower volume=stranger+stranger ;)
Title: Re: 2018 sea ice area and extent data
Post by: litesong on March 21, 2018, 08:52:20 PM
Average Arctic sea ice extent maximum for the 1980's was 15.6 million square kilometers. ALL the past 4 years (if 2018 has maxed out) have NOT reached 14 million square kilometers. All this while the solar TSI has been languid for half a century, & low for 11+ years(including a 3+ year period which set a 100 year record low).
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 22, 2018, 05:06:49 AM
JAXA March 21st: 13,721,567 km2. A small increase of 8,514 km2.
2018 is the second lowest on record. 2015 is above by 16.8K km2. 2017 is 180.7K km2 under 2018.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 22, 2018, 02:13:24 PM
NSIDC Daily Extent at 21st March = 14.268 million km2, up 58K in contrast with the extent loss of 99 k on the day before.

Extent at 20th March is therefore 51 k MORE than 2017 on that date , but the March 2018 simple average to date is still 108k less than the 2017 simple March average to the 21st March. It is therefore very probable that NSIDC will record March 2018 as the lowest extent in the satellite record, especially given that in 2017 extent loss from 20th to 31st March was a measly 70 k.

NSIDC Peripheral Seas Extent as at 21st March - 5 day trailing average

Despite the daily extent gain of the total Arctic of 58 k previous days losses are continuing to feed into the five-day average extent losses in the peripheral seas. Peripheral Seas extent losses were
 33k , compared with 48k  the day before.  Every peripheral sea had an extent loss, by far the greatest (-15k) in the Baffin.

Just as well that yesterday was an extent loss both in NSIDC and JAXA data as opposed to the extent gains that happened today . Palace revolution? Blood splattered all over the ASIF ?
Title: Re: 2018 sea ice area and extent data
Post by: litesong on March 22, 2018, 06:45:47 PM
.... the dmi 80 temps almost touch the long term average for the date ...
The existent Present High Arctic Berserker 8)(2), PHAB 8)(2) or FAB 8)(2) (continuous over-temperatures on the High Arctic) has died. FAB 8)(2) did exist for 215(+?) days, second only to FAB 8)(1) which existed for 231+ days from latter 2016 into 2017. Maximum days of continuous over-temperatures on the High Arctic in the latter 1950's & early 1960's lasted about 30 to 40 continuous days.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 23, 2018, 05:02:31 AM
JAXA March 21st: 13,721,567 km2. A small increase of 8,514 km2.
2018 is the second lowest on record. 2015 is above by 16.8K km2. 2017 is 180.7K km2 under 2018.

JAXA March 22nd: 13,711,450 km2. A drop of 10,117 km2.
Taking into account that yesterday had an increase of 8,514 km2, we can conclude that the change of March 20th to March 22nd is a little drop of 1.6K km2.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 23, 2018, 10:34:11 AM
JAXA March 21st: 13,721,567 km2. A small increase of 8,514 km2.
2018 is the second lowest on record. 2015 is above by 16.8K km2. 2017 is 180.7K km2 under 2018.

JAXA March 22nd: 13,711,450 km2. A drop of 10,117 km2.
Taking into account that yesterday had an increase of 8,514 km2, we can conclude that the change of March 20th to March 22nd is a little drop of 1.6K km2.
Just to add that JAXA extent could easily be third lowest, above 2017 and 2006 tomorrow.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 23, 2018, 01:11:48 PM
Just to add that JAXA extent could easily be third lowest, above 2017 and 2006 tomorrow.

The forecast on anomaly temperature has change from negative to positive on the following week. And the hottest place is going to be Bering and Chukchi seas. The Arctic can lose extent here, so my bet is that the JAXA extent is going to lose ice the same way or even more than 2006 on this week. Just a bet without to much study, but I think that 2018 could be the lowest on record the following week.

On April, the drop on 2016 was huge, so I hope that 2018 will not follow 2016.

Thanks for the graphs, gerontocrat. They look great and are a good complement on this thread!
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 23, 2018, 03:49:14 PM
NSIDC Daily Extent at 22nd March = 14.341 million km2, up 71k on top of the 60 K the day before, in contrast with the extent loss of 99 k on the day before.

Extent at 20th March is therefore 205k MORE than 2017 on that date (60k drop in 2017) , but the March 2018 simple average to date is still 106k less than the 2017 simple March average to the 22nd  March. It is therefore still very probable that NSIDC will record March 2018 as the lowest extent in the satellite record, especially given that in 2017 there was a small extent GAIN from 23rd to 31st March of 36 k.

NSIDC Peripheral Seas Extent as at 22 March - 5 day trailing average

Despite a second daily extent gain of the total Arctic of 71k on top of the previous 58 k previous days losses are continuing to feed into the five-day average extent losses in the peripheral seas. Peripheral Seas extent losses were 23k compared with 33k and 48k the 2 days before. By far the greatest loss this time (-19k) was in the Bering Sea, perhaps reflecting the current above zero temperatures reaching as far as into the Chukchi.

We are at the mercy of wind, waves, currents, and the northening of the sun (insolation). So these posts will mostly simply state what is, not what might be. (Especially as we now have a thread for speculation - Armageddon scenarios?)
Title: Re: 2018 sea ice area and extent data
Post by: litesong on March 23, 2018, 04:51:50 PM
The existent Present High Arctic Berserker 8)(2), PHAB 8)(2) or FAB 8)(2) (continuous over-temperatures on the High Arctic) has died. FAB 8)(2) did exist for 215(+?) days, second only to FAB 8)(1) which existed for 231+ days from latter 2016 into 2017. Maximum days of continuous over-temperatures on the High Arctic in the latter 1950's & early 1960's lasted about 30 to 40 continuous days.
Tho FAB 8)(2) has ended after existing for 215(+?) days, with present High Arctic temperatures dipping below the average temperature line, the dip appears to be brief. Already the average High Arctic temperatures have bottomed & are again above the average temperature line. It appears that southern heat from eastern siberia is heating its way into the High Arctic & even to the North Pole & may do so for at least the next 5 days.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 24, 2018, 05:25:22 AM
March 23th:
JAXA: 13,684,699 km2. A drop of -26,751 and second lowest on record.

2018  minus:
2017:   + 220,666
2006:       -  6,926
2016:   -  215,280
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 24, 2018, 02:17:12 PM
NSIDC Daily Extent at 23 March =  14,283,000 km2, down 58k to continue the yo-yo - up 71k Mar 22, up 60 K Mar21, and extent loss of 99 k on Mar20.

Extent at 23 March is 207k MORE than 2017 on that date (another 60k drop in 2017) , but the March 2018 simple average to date is still 101k less than the 2017 simple March average to 23  March. It is therefore still very probable that NSIDC will record March 2018 as the lowest extent in the satellite record, especially given that in 2017 there was an extent GAIN from 23 to 31 March of 96 k.

If NSIDC post a +100k record low March average, this would be (I think) a small acceleration in annual winter sea loss, and in my opinion, more significant than the daily extent max coming in at second lowest.

NSIDC Peripheral Seas Extent as at 23 March - 5 day trailing average

The ups and down of daily extent gains and losses are continuing to feed into the five-day average extent losses in the peripheral seas. Total Peripheral Seas extent losses were 17k compared with 23k and 33k the 2 days before. By far the greatest loss this time (-23k) was in the Bering Sea, perhaps reflecting the current above zero temperatures reaching as far as into the Chukchi. have a look in the melting season thread to see a great image of the havoc currently underway there. The Baffin is also losing ice steadily - 260,000 km2 so far this month.

We are at the mercy of wind, waves, currents, and the northward movement of the sun (insolation). So these posts will mostly simply state what is, not what might be. BUT, of course, can I resist a peek at cci-renalyser? No.
GFS say that a weather system stretching from the eastern Mexican Border to Baffin Bay will develop starting around 27-28 march, ending in loads of wind, above zero temperatures, snow and RAIN going far into the Baffin by April 2. Rain melts snow. Rain melts ice.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 24, 2018, 02:24:06 PM
JAXA Actual Outlook:

At the beginning of 2018 melting season, the year 2012 (the worst year on September) is still well above other years. It is interesting that 2012 is above 2000’s and 2010’s average. On the other hand, the lowest years on March have been 2006 the last ones:2015-2018.

2006 2017 is the lowest today, but 2016 is going to take the lead, at the end of March.

I expect that 2018 can take the lead of lowest on record for a few days, and hope that 2018 will not follow 2016 afterwards.

Future drops of 2016:

Date               Ext. (K km2)   Days   Daily drop
23-mar-16         13,900       
31-mar-16         13,496           8        -50.5
15-abr-16          13,158         15       -22.6
30-abr-16          12,293         15       -57.6
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 24, 2018, 02:52:27 PM
JAXA Actual Outlook:


2006 is the lowest today, but 2016 is going to take the lead, at the end of March.

I expect that 2018 can take the lead of lowest on record for a few days, and hope that 2018 will not follow 2016 afterwards.

Hullo Juan,

Having had my ego burnt, battered and bruised so many times by making definite statements without caveats that then turned out to be oh so wrong, I always try to remember to qualify a statement, for example,

but 2016 is going to take the lead becomes -

but previous years' data strongly suggest that 2016 is going to take the lead

especially as A-team and others in the melting thread suggest that the ice is in rotten shape this year and could easily come a cropper very soon.

ps: 2012 may have been the lowest extent by far, but the albedo warming potential of 2016 was much higher. To heat the Arctic Ocean best using insolation, a low maximum followed by early melt is the way to do it.


Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on March 24, 2018, 03:45:01 PM
Last year the ice was in rotten shape and there wasn't much of it. The cool stormy cloudy July saved the day. it may be that summers are getting stormier as open water increases in the Arctic. However, I wouldn't bet that this July will be as cool as last July.

I'm trying to understand how SSWs and ocean heat patterns might be used to predict summer weather. Wish me luck. So far, the models have shown limited predictive capabilities at seasonal time scales.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on March 24, 2018, 06:58:48 PM
Last year the ice was in rotten shape and there wasn't much of it. The cool stormy cloudy July saved the day. it may be that summers are getting stormier as open water increases in the Arctic. However, I wouldn't bet that this July will be as cool as last July.

I'm trying to understand how SSWs and ocean heat patterns might be used to predict summer weather. Wish me luck. So far, the models have shown limited predictive capabilities at seasonal time scales.

IMHO, the relatively cooler, cloudy summers we are seeing will become a persistent feature of the Arctic, due to reduced maximums, expansive open water and wobbly jet stream resulting in intrusions of moist air from the mid latitudes and locally generated cloud formation from evaporation. Difficult to say what the long term effects on summer melting seasons will be as the increased IR down welling caused by clouds and, likely, increased rainfall could counteract the reduced insolation.

At least during the melting season, the Arctic desert is disappearing.
Title: Re: 2018 sea ice area and extent data
Post by: litesong on March 25, 2018, 12:00:18 AM
The existent Present High Arctic Berserker 8)(2), PHAB 8)(2) or FAB 8)(2) (continuous over-temperatures on the High Arctic) has died. FAB 8)(2) did exist for 215(+?) days, second only to FAB 8)(1) which existed for 231+ days from latter 2016 into 2017. Maximum days of continuous over-temperatures on the High Arctic in the latter 1950's & early 1960's lasted about 30 to 40 continuous days.
Tho FAB 8)(2) has ended after existing for 215(+?) days, with present High Arctic temperatures dipping below the average temperature line, the dip appears to be brief. Already the average High Arctic temperatures have bottomed & are again above the average temperature line. It appears that southern heat from eastern siberia is heating its way into the High Arctic & even to the North Pole & may do so for at least the next 5 days.
Tho the rising present High Arctic temperatures stopped ascending at only a few degrees Celsius above the average temperature line, the excess AGW siberian heat still pours into the High Arctic & High Arctic temperatures should strongly rise above the average.   
Title: Re: 2018 sea ice area and extent data
Post by: Gray-Wolf on March 25, 2018, 12:01:30 AM
Last year the ice was in rotten shape and there wasn't much of it. The cool stormy cloudy July saved the day. it may be that summers are getting stormier as open water increases in the Arctic. However, I wouldn't bet that this July will be as cool as last July.

I'm trying to understand how SSWs and ocean heat patterns might be used to predict summer weather. Wish me luck. So far, the models have shown limited predictive capabilities at seasonal time scales.

IMHO, the relatively cooler, cloudy summers we are seeing will become a persistent feature of the Arctic, due to reduced maximums, expansive open water and wobbly jet stream resulting in intrusions of moist air from the mid latitudes and locally generated cloud formation from evaporation. Difficult to say what the long term effects on summer melting seasons will be as the increased IR down welling caused by clouds and, likely, increased rainfall could counteract the reduced insolation.

At least during the melting season, the Arctic desert is disappearing.
Have we all been lulled into a 'high solar activity' calm of cloudy cool summers only for 'low solar ' to shake us out of the lull?

It's been pretty clear around Svalbard since early March due to the northern high pressures the SSW helped keep in place. how long will this North Atlantic propensity toward High pressure persist/ will we slip again into cloudy/cool conditions as the sun rises or will whatever drives the propensity for northern blocking patterns transfer ever higher into the basin?

I hope it isn't going to pan out but this is the first of the proper 'low solar' years so the next two will probably be 'stronger' in their low solar forcing?

Any move toward high solar over the ice in early melt season will feed my fears that this is what can drive a 'perfect melt storm' synoptic with the last 3 seemingly at the low solar end of the forcings ( as opposed to 'high solar' activity)

We are not as secure with our ice as we were back in 07' so even a partial 'perfect melt storm' season would lead us into problems?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 25, 2018, 09:54:10 AM
JAXA EXTENT as at 24 Mar 13,668,115 km2 a drop of 17k, the third drop in a row. Extent is third lowest, greater than 2017 ( 204k) and 2006 ( 42k). 

So far extent loss from maximum is exactly average (0.22 million km2, 2.2% of average extent loss), giving a minimum of 3.93 million km2 but as it is so very early in the season not really helpful.  NSIDC data will give a better idea of what is happening in the peripheral seas.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on March 25, 2018, 09:59:18 AM
Have we all been lulled into a 'high solar activity' calm of cloudy cool summers only for 'low solar ' to shake us out of the lull?

It's been pretty clear around Svalbard since early March due to the northern high pressures the SSW helped keep in place. how long will this North Atlantic propensity toward High pressure persist/ will we slip again into cloudy/cool conditions as the sun rises or will whatever drives the propensity for northern blocking patterns transfer ever higher into the basin?

I hope it isn't going to pan out but this is the first of the proper 'low solar' years so the next two will probably be 'stronger' in their low solar forcing?

Any move toward high solar over the ice in early melt season will feed my fears that this is what can drive a 'perfect melt storm' synoptic with the last 3 seemingly at the low solar end of the forcings ( as opposed to 'high solar' activity)

We are not as secure with our ice as we were back in 07' so even a partial 'perfect melt storm' season would lead us into problems?

There are now two threads to discuss these things (the 'real-time' melting season thread, and the 'mid- to long-term' melting season thread). Let's keep this one focused on the data.
Title: Re: 2018 sea ice area and extent data
Post by: El Cid on March 25, 2018, 10:01:05 AM

Have we all been lulled into a 'high solar activity' calm of cloudy cool summers only for 'low solar ' to shake us out of the lull?

Can you point me towards research that confirms that solar cycles are responsible for changes between "cloudy" and "sunny" weather in the Arctic?
Title: Re: 2018 sea ice area and extent data
Post by: Neven on March 25, 2018, 11:00:20 AM
Quote
Can you point me towards research that confirms that solar cycles are responsible for changes between "cloudy" and "sunny" weather in the Arctic?

Do it somewhere else, please.
Title: Re: 2018 sea ice area and extent data
Post by: Gray-Wolf on March 25, 2018, 11:17:47 AM
Quote
Can you point me towards research that confirms that solar cycles are responsible for changes between "cloudy" and "sunny" weather in the Arctic?

Do it somewhere else, please.

over on the 'speculation thread' ta!
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 25, 2018, 02:36:30 PM
NSIDC Daily Extent at 24 March =  14,200,000 km2, down 83k

Extent at 24 March is 127k MORE than 2017 on that date (but down from 207k).  but the March 2018 simple average to date is still 99 k less than the 2017 simple March average to 24 March. It is therefore still very probable that NSIDC will record March 2018 as the lowest extent in the satellite record, especially given that in 2017 there was an extent GAIN from 24 to 31 March of 99 k.

If NSIDC post a +100k record low March average, this would be (I think) a small acceleration in annual winter sea loss, and in my opinion, more significant than the daily extent max coming in at second lowest.

ps: I missed that on 23 March, 2018 was 2nd lowest, 63k above 2006. On 24 March the difference is just 6k

NSIDC Peripheral Seas Extent as at 24 March - 5 day trailing average

The ups and down of daily extent gains and losses are continuing to feed into the five-day average extent losses in the peripheral seas. Total Peripheral Seas extent losses were 21k . By far the greatest loss again  (-28k) was in the Bering Sea, perhaps reflecting the current above zero temperatures reaching as far as into the Chukchi. have a look in the melting season thread to see a great image of the havoc currently underway there. The Baffin is also losing ice steadily - 263,000 km2 so far this month.

To see what seas might get hit or recover next the 2018 melting season thread is just over the road. My bet is on Baffin getting clobbered at the end of the month and into the first few days of April.
Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on March 25, 2018, 06:42:25 PM
Pressure gradients & winds will be almost ideal for blowing ice from the Pacific side of the Arctic to the Atlantic side and out the Fram strait. Remember that the Coriolis effect will tend to deflect ice movement to the right towards Greenland as it drifts southwards. Obviously, the ice already piled up against the coast of Greenland will limit the amount of deflection. We should see a burst of ice export for the next 10 days if the models verify.

There's also going to be much warmer than normal weather over the Chukchi sea. It looks like we will see a very early melt out in the Chukchi, which melted out very early last year. The early loss of ice will likely lead to a build up of ocean heat that will affect the whole melting season like it did last year.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 26, 2018, 06:25:14 AM
JAXA March 25th, 2018: 13,645,538 km2, a drop of 22,577 km2.
I still think that 2018 can become the lowest on record by the end on March.  8)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 26, 2018, 06:41:11 AM
In fact, I am concerned about the end of March forecast. (+3.5°C ?)  :(

Edit 1:
Sorry, I saw Antarctic. Arctic +2.0°C. Still, it looks strong to me.

Edit 2:
I was sure that I saw the 3.5°C on the Arctic.
It is until April 1st. Hope it change to a lower anomaly.
[See 2nd image]
Title: Re: 2018 sea ice area and extent data
Post by: litesong on March 26, 2018, 03:25:18 PM
In fact, I am concerned about the end of March forecast. (+3.5°C ?)  :(
Edit 2:
I was sure that I saw the 3.5°C on the Arctic.
It is until April 1st. Hope it change to a lower anomaly.
[See 2nd image]
Right now the entire High Arctic temperature has rebounded from a temporary sub-average temperature to its present 4degC above average. A relative small eastern Siberian region of heat is feeding into the High Arctic. However, a vast line of excess AGW heat from northern Africa to China may also be supporting the eastern Siberian heat flow to the High Arctic. It is this present Africa to China heat(which was positioned further north) that supported the continuous 215 days of High Arctic temperatures of the past winter, the Present High Arctic Berserker(2) or FAB 8)(2).
Of course, the sun has moved ~ 25arcdegs to the north since the beginning of winter & direct solar TSI heat is beginning to raise High Arctic heat. At some point direct solar TSI heat will overcome AGW heat to provide the most heat to the High Arctic. The import of this distinction is that present AGW heat is higher than past AGW heat, while direct solar TSI heat has been low for 11+ years(including a 3+ year period setting a 100 year record low). The low direct solar TSI appears to be affecting High Arctic summer temperatures & driving such temperatures to a sub-average High Arctic level..... as opposed to excess present AGW winter (darkness) heat in the High Arctic that supports winter (& longer) continuous over-temperatures. If the coming summer High Arctic temperatures(driven by low direct solar TSI) do dip below average temperatures, those temperatures do NOT off-set the ever increasing High Arctic winter continuous over-temperature anomalies, confirmed by FAB 8)(2),  FAB 8)(1) & other CONTINUOUSLY increasing days of CONTINUOUS High Arctic over-temperatures.   
Title: Re: 2018 sea ice area and extent data
Post by: oren on March 26, 2018, 06:07:06 PM
Litesong sorry but this belongs in a different thread (not sure which). This one is for area and extent data.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on March 26, 2018, 09:41:38 PM
NSIDC Daily Extent at 25 March =  14,192,000 km2, down a mere 8k.

Extent at 25 March is 119k MORE than 2017 on that date (downa trifle from 127k).  But the March 2018 simple average to date is still 95 k less than the 2017 simple March average to 25 March. It is therefore still very probable that NSIDC will record March 2018 as the lowest extent in the satellite record by about 75 to 100k, especially given that in 2017 there was an extent GAIN from 24 to 31 March of 99 k. Just 20+k loss from now to 31 March will make 2018 lowest again. 25 March, 2018 was again 2nd lowest, once gain lower than 2006 - by just 20k.

If NSIDC posts a +75-100k record low March average, this would be (I think) a small acceleration in annual winter sea loss, and in my opinion, more significant than the daily extent max coming in at second lowest. CAVEAT : Not sure how NSIDC is calculating average now.

NSIDC Peripheral Seas Extent as at 25 March - 5 day trailing average

The ups and down of daily extent gains and losses are continuing to feed into the five-day average extent losses in the peripheral seas. Total Peripheral Seas extent losses were just 5k . By far the greatest loss again  (-24k) was in the Bering Sea.

I attach the NSIDC image of NSIDC concentration. It shows where the ice is vulnerable - just about everywhere in the periphery, the south of Chukchi and the western edge of Hudson Bay.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 27, 2018, 06:18:45 AM
JAXA March 26: 13,663,549 km2. An increase of 18,011 km2.  :o

I guess that it is an increase in extent, not necessary on area.
But I am just guessing!  ;)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 28, 2018, 05:46:26 AM
JAXA March 27th: 13,700,128 km2. An increase for second consecutive day. Today it increased 36,579 km2.  8)
Title: Re: 2018 sea ice area and extent data
Post by: Lord M Vader on March 28, 2018, 02:18:37 PM
NSIDC also reports an uptick. Somewhat bigger though, up 49K... Might be due to Fram transport and the fact that the melting hasn't really started in Okhotsk. Once Okhotsk starts melting it will go down quickly..

The 5-day average is still moving down and is by a very slim margin still second lowest behind 2017.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 29, 2018, 05:56:06 AM
JAXA March 28th: 13,681,496 km2. A drop of -18,632 km2.
Title: Re: 2018 sea ice area and extent data
Post by: romett1 on March 29, 2018, 06:43:19 PM
Small update before storm - Bering Sea ice area (5-day trailing average) has dropped additional 4,000 km² (NSIDC). 2007 - 2017 average reached current level 56 days later on May 23.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on March 30, 2018, 06:02:05 AM
JAXA March 29th: 13,674,556 km2. A drop of -6,940 km2.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on March 30, 2018, 06:58:23 PM
Soon to be 4th lowest.
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on March 30, 2018, 10:09:22 PM
Soon to be 4th lowest.

and bit later to be lowest again, this is ice drift caused slow down of extent loss IMO, let's see
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 02, 2018, 06:03:48 AM
2018 started a clear downward trend, losing extent for five consecutive days:

Date                    SIE (km2)       Change
Mar 27, 2018     13,700,128      36,579
Mar 28, 2018     13,681,496     -18,632
Mar 29, 2018     13,674,556       -6,940
Mar 30, 2018     13,652,018     -22,538
Mar 31, 2018     13,625,158     -26,860
Apr 01, 2018     13,586,994      -38,164

2018 is now the third lowest on record:

Year         SIE (km2)      VS 2018
2015      13,638,921      51,927
2006      13,610,775      23,781
2018      13,586,994               0
2017      13,562,063     -24,931
2016      13,461,256   -125,738  (the lowest)

In order to be 2018 the lowest on record by April 15th, it will need to have an average daily drop of a little more than -33,420 km2.
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 02, 2018, 06:40:22 AM
Thank you for your early updates, JCG.
Title: Re: 2018 sea ice area and extent data
Post by: gregcharles on April 03, 2018, 12:53:38 AM
Not much change in the daily records since last month. 2018 picked up a few, and has nearly two thirds of the daily records for Q1. There's a small chance of more records in April, but then 2016 becomes dominant until summer, and hopefully 2018 won't challenge that.

Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 03, 2018, 06:50:50 AM
Thank you for your early updates, JCG.

You are welcome, Oren!

I am not sure that I will be able to do it all nights (for me  ;) ), so if someone can try to do it also, that will be good. I will check if someone did it, before I do it.
The important thing is to have it right away!

JAXA April 2nd, 2018: 13,555,616 km2. A drop of -31,378 km2.
2018 is now second lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on April 03, 2018, 12:50:00 PM
I am not sure that I will be able to do it all nights (for me  ;) ), so if someone can try to do it also, that will be good. I will check if someone did it, before I do it.
The important thing is to have it right away!

FWIW, I maintain a similar graph for both IJIS and NSIDC extent over at my climate graphs site (https://sites.google.com/view/pettitclimategraphs). If you ever need a day or two off, everyone feel free to see my versions:

IJIS (Click for larger image):
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_six_week_detail.png&hash=fe0acbe1355895129edf6fae57c065aa) (http://iwantsomeproof.com/extimg/sie_six_week_detail.png)

NSIDC (Click for larger image):
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_nsidc_six_week_detail.png&hash=daed5fdc1da70674f1a8b83169859375) (http://iwantsomeproof.com/extimg/sie_nsidc_six_week_detail.png)

Images are updated on the server every day around 1200 UTC.
Title: Re: 2018 sea ice area and extent data
Post by: litesong on April 04, 2018, 05:04:55 AM
I am not sure that I will be able to do it all nights (for me  ;) ), so if someone can try to do it also, that will be good. I will check if someone did it, before I do it.
The important thing is to have it right away!

FWIW, I maintain a similar graph for both IJIS and NSIDC extent over at my climate graphs site (https://sites.google.com/view/pettitclimategraphs). If you ever need a day or two off, everyone feel free to see my versions:

IJIS (Click for larger image):
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_six_week_detail.png&hash=fe0acbe1355895129edf6fae57c065aa) (http://iwantsomeproof.com/extimg/sie_six_week_detail.png)

NSIDC (Click for larger image):
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_nsidc_six_week_detail.png&hash=daed5fdc1da70674f1a8b83169859375) (http://iwantsomeproof.com/extimg/sie_nsidc_six_week_detail.png)

Images are updated on the server every day around 1200 UTC.
  Jim.... your graphs & details are spectacular. Your decade decreases in Arctic sea ice Volumes, even betters your spectaculars, tho.
http://iwantsomeproof.com/extimg/siv_annual_polar_graph.png
 At no point during the Earth's revolutions around the sun since the 1980's, do any of Arctic sea ice Volume decade losses cross other Arctic sea ice decade Volume losses. Its almost..... digital!!!! Even with the solar TSI being languid for half a century AND low for 11+ years (including a 3+ year period setting a 100 year record low), Arctic sea ice Volume losses.....remain losses.  There are zero decades of Arctic sea ice Volume increases, with the Arctic sea ice Volume losses of the "2010's" giving little hint that the "cold" sun will have much of any effect on continuing Arctic sea ice Volume losses.
Ditto for your decade extent losses, also:
http://iwantsomeproof.com/extimg/sie_annual_polar_graph.png
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 04, 2018, 06:26:54 AM
FWIW, I maintain a similar graph for both IJIS and NSIDC extent over at my climate graphs site (https://sites.google.com/view/pettitclimategraphs). If you ever need a day or two off, everyone feel free to see my versions:
...
Images are updated on the server every day around 1200 UTC.

Hi, Jim,

Your graph is great. Is there a way to update it when JAXA figures are published?
It will be great to put it on this thread, when the new data appears.

JAXA had a century drop today!  :o

April 3rd, 2018: 13,418,227 km2. A drop of -137,389 km2.
2018 is now the lowest on record!  :P
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 04, 2018, 07:52:55 AM
April 3rd, 2018: 13,418,227 km2. A drop of -137,389 km2.
2018 is now the lowest on record!  :P
Wow. That came out of the blue.
Title: Re: 2018 sea ice area and extent data
Post by: RikW on April 04, 2018, 09:00:14 AM
April 3rd, 2018: 13,418,227 km2. A drop of -137,389 km2.
2018 is now the lowest on record!  :P
Wow. That came out of the blue.

some more of these and it will be blue ;)

I'm really curious how soon Bering sea will reach zero/ how much earlier in the season that will happen
Title: Re: 2018 sea ice area and extent data
Post by: Wherestheice on April 04, 2018, 09:40:42 AM
Yikes!
Title: Re: 2018 sea ice area and extent data
Post by: Neven on April 04, 2018, 10:00:11 AM
Like Vyvyan from the Young Ones said: That's all right. It was an accident waiting to happen.

Wow... Curious to see which regions contributed most.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 04, 2018, 02:05:24 PM
Gerontocrat has been and is a poorly bunny, as is his computer.
Normal service may be resumed next week sometime.
But for an hour or two, Gerontocrat is functioning on a functioning (borrowed) computer. Messy but workable.

JAXA DATA AS AT 3RD APRIL

The recent extent losses means, to me, that once again albedo warming potential is high at the time of year and the latitudes (the periphery) where insolation is already high. See Arctic3 attached below. 1.7 million of open ocean where in the 1980's  there was ice must have some positive feedback (especially as this is year after year). It is even 0.5 million more than the 2010's average.

The recent extent losses also mean that using remaining melt in previous years always produces a minimum extent less than last year, while 10 year average remaining melt results in a minimum of 3.82 million, but that average is distorted by the extraordinary melt of 2012. (See Arctic1).
Title: Re: 2018 sea ice area and extent data
Post by: Neven on April 04, 2018, 02:15:52 PM
That drop that was reported today, was the largest March drop in the 2005-2018 period. I wonder if there will be a rebound tomorrow...
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 04, 2018, 02:46:52 PM
NSIDC Regional Sea Ice Extent Data (5 day trailing average)

Table below shows extent losses in Bering, Okhotsk, Baffin and St Lawrence  - and as yet do not show full effect of total Arctic daily extent losses of -27,000 (1 April) -68,000 (2 April) and
-138,000 (3 April).
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 04, 2018, 02:51:22 PM
That drop that was reported today, was the largest March drop in the 2005-2018 period. I wonder if there will be a rebound tomorrow...
Intetesting that NSIDC reports a similar daily drop.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on April 04, 2018, 05:37:23 PM
That should be 'largest April drop'.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on April 04, 2018, 07:16:59 PM
That drop that was reported today, was the largest March drop in the 2005-2018 period. I wonder if there will be a rebound tomorrow...
Intetesting that NSIDC reports a similar daily drop.
That would tend to argue against a rebound tomorrow....if I understand correctly that these are different data.
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on April 04, 2018, 08:21:16 PM
April 3rd, 2018: 13,418,227 km2. A drop of -137,389 km2.
2018 is now the lowest on record!  :P
Wow. That came out of the blue.

not really, i had some post in reply to SharedHumanity 7-8 days ago but still there is never a guarantee that things go the way we thought ;) it's just that okhotsk as well as some other regions were quite green and yellowish for quite a few days on the UniBremen maps. and so much south there must be some significant solar impact by now.

A "significant" rebound for above reasons is not probable while small moves are hardly predictable if anything. no cold spell in those regions and the now increased area of open water will certainly catch a fair share of sunlight, albedo is dropping
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 04, 2018, 08:24:44 PM
April 3rd, 2018: 13,418,227 km2. A drop of -137,389 km2.
2018 is now the lowest on record!  :P
Wow. That came out of the blue.

not really, i had some post in reply to SharedHumanity 7-8 days ago but still there is never a guarantee that things go the way we thought ;) it's just that okhotsk as well as some other regions were quite green and yellowish for quite a few days on the UniBremen maps. and so much south there must be some significant solar impact by now.

i rebound for above reasons is not probable, no cold spell in those regions and the now increased area of open water will certainly catch a fair share of sunlight, albedo is dropping
I agree. I think we will see massive continued sustained declines as the fake ice a la 2012 gives out even earlier than that year (with substantially more heat bubbling into Beaufort and Chukchi as we speak).
Title: Re: 2018 sea ice area and extent data
Post by: Wherestheice on April 04, 2018, 08:30:41 PM
the ice is definitely gonna be interesting this year
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on April 05, 2018, 10:39:57 AM
That drop that was reported today, was the largest March drop in the 2005-2018 period. I wonder if there will be a rebound tomorrow...
I have an IJIS  drop of 169382 on Mar 23 2014. Making this the second biggest drop to date.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on April 05, 2018, 10:44:11 AM
That should be 'largest April drop'.
And a drop of 154512 on April 10 2004 makes it the second biggest drop in April. It  does rate as the third biggest drop prior to June 1st.
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 05, 2018, 12:56:10 PM
Surprisingly, instead of a correction we have another small drop:
13,387,430, down 30,797 from yesterday's 13,418,227, and still at 1st place slightly below 2016.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 05, 2018, 02:01:11 PM
Surprisingly, instead of a correction we have another small drop:
13,387,430, down 30,797 from yesterday's 13,418,227, and still at 1st place slightly below 2016.

Even that 2017 is lower than 2016 on April 13th-16th, afterwards 2016 has a deep drop trend, being the lowest until June 27th.
So, in order to be 2018 the lowest on April 15th, it has to drop a daily average of 26k km2 for 11 days. But the real question is if 2018 will emulate 2016 afterwards and/or which will be its value at the end of June, when several years have similar extent.

Edit:
If 2018 follows 2016 on May, it will be a heart attack year for some of us, that follow-up the ASIE daily...
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 05, 2018, 03:01:54 PM
JAXA Data as at 4th April 2018

Nothing to add to Juan's comments except to say

- that since 2016 CO2 is up by over 4 ppm,
- CO2 emissions rose in 2017 and are expected to rise again in 2018,
- global ocean heat content is up substantially (record increase in 2017) and should rise strongly in 2018 while La Nina or ENSO neutral conditions prevail,
- global warming potential in the peripheral seas is already high due to current low sea ice extent,
- I understand ocean temperature anomalies (especially in the N. Pacific?) are very high,

so conditions favour melting and it would require a really lousy Arctic summer as in last year to prevent strong extent loss at least at the moment.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 06, 2018, 06:11:04 AM
JAXA April 5th, 2018: 13,371,769 km2. A drop of -15,661 km2.
2018 continues to be the lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 06, 2018, 04:37:45 PM
To add to Juan's analysis,

NSIDC Regional Extent Data ( 5 day trailing average) as at 5th April 2018

The strongest extent loss by far is in the Okhotsk Sea another 26 k on top of 21k and 14k the two days before. On the one hand this is irrelevant to what happens in the CAB, but on the other hand its another 60k of open water at around 60 o North so high insolation.

Regional sea ice extent loss in total was 46k, with no extent losses in the CAB (but Area?)

NSIDC Daily extent loss for the Arctic was 47k after a small gain of 12k the day before.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 07, 2018, 07:54:45 AM
JAXA April 6th, 2018: 13,376,062 km2. A slight increase of 4,293 km2.
Now, 2018 is second lowest on record, above 2016 by 23,970 km2.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on April 07, 2018, 02:21:55 PM
In the meantime, NSIDC is firmly in first place after a solid 93k drop:

CLICK FOR LARGER AND MOST-RECENT IMAGE]
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fiwantsomeproof.com%2Fextimg%2Fsie_nsidc_six_week_detail.png&hash=daed5fdc1da70674f1a8b83169859375) (http://iwantsomeproof.com/extimg/sie_nsidc_six_week_detail.png)

Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on April 07, 2018, 02:54:21 PM
Jim wrote "CLICK FOR LARGER AND MOST-RECENT IMAGE]".  When I don't click on the image, I definitely see an old image.
Title: Re: 2018 sea ice area and extent data
Post by: Alexander555 on April 07, 2018, 03:47:33 PM
How do you get that big difference in the the average 1980 and 1990 data ? Is it because they exclude/include some area's in the periferhy ?
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 07, 2018, 06:09:07 PM
How do you get that big difference in the the average 1980 and 1990 data ? Is it because they exclude/include some area's in the periferhy ?

There is not an important difference between NSIDC 1980's and 1990's average...
Or are you talking on JAXA figures? I don't know how they calculated...
Title: Re: 2018 sea ice area and extent data
Post by: charles_oil on April 07, 2018, 06:58:51 PM

Alex - Maybe you meant between 1990s and 2000s.  Best to go to NSIDC chartic (easy via ASI graphs) and you can see all the different lines & add / remove them as required as well as the std deviations etc. 


The 2010's line will be a step down again (probably...).

Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on April 07, 2018, 08:54:56 PM
Jim wrote "CLICK FOR LARGER AND MOST-RECENT IMAGE]".  When I don't click on the image, I definitely see an old image.

I imagine you're looking at a locally cached version of that image; I promise it links to the current one. :)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 08, 2018, 06:12:40 AM
JAXA April 7th,2018: 13,358,472 km2. A drop of -17,590 km2.
2018 is second lowest on record, above 2016 by 49,216 km2.

How do you get that big difference in the the average 1980 and 1990 data ? Is it because they exclude/include some area's in the periferhy ?

JAXA April 7th:
    80’s Average: 15,070,144 km2.
    90’s Average: 14,590,636 km2.
    Difference 80’s – 90’s: 479,508 km2.

I agree that the JAXA difference seems big.  :o
Maybe someone else on this Forum can give us an answer, because I don't know why...

Edit: Maybe as the satellite gets an equipment with better resolution, the sea ice extent gets a lower value. Kind of implicit when the definition is: "If sea ice on a grid is equal or more than 15%, then it becomes 100%". As the grid gets smaller, the rounding becomes smaller also.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 08, 2018, 07:19:03 AM
How do you get that big difference in the the average 1980 and 1990 data ? Is it because they exclude/include some area's in the periferhy ?

Edit: Maybe as the satellite gets an equipment with better resolution, the sea ice extent gets a lower value. Kind of implicit when the definition is: "If sea ice on a grid is equal or more than 15%, then it becomes 100%". As the grid gets smaller, the rounding becomes smaller also.

Explaining graphically what I mean:
Title: Re: 2018 sea ice area and extent data
Post by: Alexander555 on April 08, 2018, 07:50:44 AM
My question was about the diffrence between the JAXA end the NSIDC. But i explained myself pretty bad. With the JAXA you see a clear trend , the 1990 average is half a million below the 1980 average. And if you look at the NSIDC , at some days the 1990 average is above the 1980 average.
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on April 08, 2018, 10:10:19 AM
Éh, that question of different averages (noting the 80s to 90s difference isn't the only one present) is so old even I would need to check the answer from historical sources.   8) 8) 8) . Possibly it's a question of including/excluding Black Sea and Caspian (possibly also Great Lakes) to the Arctic numbers, which is somewhat silly, but JCGarcias explanation applies as well. I don't know the correct answer.
Title: Re: 2018 sea ice area and extent data
Post by: Steven on April 08, 2018, 11:54:48 AM
My question was about the diffrence between the JAXA end the NSIDC. But i explained myself pretty bad. With the JAXA you see a clear trend , the 1990 average is half a million below the 1980 average. And if you look at the NSIDC , at some days the 1990 average is above the 1980 average.

The 1980s average in Jim Pettit's graph (https://i.imgur.com/b2EObWT.png) for NSIDC extent is wrong.  In the official NSIDC Charctic (http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/) graph, the 1980s average is always higher than the 1990s average.
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 08, 2018, 01:05:28 PM
Maybe it's the pole hole?
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 08, 2018, 05:09:05 PM
The 1980s average in Jim Pettit's graph (https://i.imgur.com/b2EObWT.png) for NSIDC extent is wrong.  In the official NSIDC Charctic (http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/) graph, the 1980s average is always higher than the 1990s average.

The difference with Jim Pettit’s graph and NSIDC Charctic graph is that NSIDC includes 1979 and maybe Jim Pettit is also excluding 1980 (on the 80's average). So, there is a reason to have a different average.

Maybe it's the pole hole?

I don’t believe that it is the North Pole hole. The pole hole can make a difference on area, because in some cases the pole hole area is taken by ocean, no ice, and this hole has been shrinking. The normal status of the pole hole, and specially before 2000, is that it was ice. In extent it is taken as ice, so no problem there.

Edit:
Quote
maybe Jim Pettit is also excluding 1980
What I mean is that 80's average sometimes means 1980-89 and sometimes means 1981-90. So I am not sure what average is Jim making. On the other hand, the NSIDC 80's average has 12 years, because they explicit put it as 1979-1990 (it should included 79,80 and 90).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 08, 2018, 05:48:43 PM
I do check my spreadsheets and graphs before daring to post them on ASIF. But several times there have been errors. Perhaps there is an error in the extract of data for the graph in Jim's database ?

To err is human, to forgive divine. (Yesterday I found another error in one of my spreadsheets - fortunately not significant and fortunately no-one has spotted it yet).
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on April 08, 2018, 06:29:46 PM
Thanks, folks! The comments of several forum users led me to look into a small number of my graphs, and that in turn allowed me to hunt down and snuff out a data error that's gone undetected for several months.

For the record, it was indeed a legitimate screw-up on my part, a recently-introduced calculation error on a single range of cells on a spreadsheet that contains tens of thousands of them. More precisely, I'd previously been pulling older NSIDC extent data from one web-based source, but changed that last summer when I became aware of an easier-to-access, and more frequently-updated, source. In doing so, I inadvertently--and erroneously--neglected to update a formula in that range of cells that referenced the previous data; hence the incorrect 1980s average. Luckily, that cell was only reflected on a total of three graphs. And, luckily, that column and those graphs have now been updated. (And I've added +/-2 standard deviation shading to the graph in question.) (http://iwantsomeproof.com/extimg/sie_nsidc_six_week_detail.png)

I maintain dozens of graphs, each of them based on one or more spreadsheets, with each spreadsheet itself based on sometimes multiple data sources. Complicating matters, those data sources change: different baselines, enhanced algorithms, anti-biasing tweaks, and so on, and so forth. The result is that keeping on top of all those changes can be a frustrating task for graph creators--and that can lead to obvious frustration by those who use those graphs. So for that, I apologize. Mea maxima culpa. (That's Latin for "my bad".)

For what it's worth, in the future, a direct message or an email (my address is right on the graphs) will almost always get a quicker response, as I don't monitor this forum 24 hours a day. However, if you're the type of person who prefers jumping up, pointing your finger, and publicly shouting, "You're wrong!!!", by all means knock yourself out; I'll respond to those eventually, too. :)

Thanks again.
Title: Re: 2018 sea ice area and extent data
Post by: DoomInTheUK on April 08, 2018, 08:22:29 PM
Jim, Allow me to jump up and down, point a finger and shout "It's him, he does all the hard work so we don't have to".

Thanks for all your efforts. Spreadsheets are a breeding ground for bugs and you seem to be doing a great job of keeping the little buggers under control.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 08, 2018, 09:40:43 PM
For the record, it was indeed a legitimate screw-up on my part...

The one who does nothing, makes no mistakes, but he does nothing!
So, thank you Jim and others, for doing all that you are doing. The Forum is what it is, thanks to all your work!  ;)
Title: Re: 2018 sea ice area and extent data
Post by: Hautbois on April 08, 2018, 10:53:32 PM
Some first quarter of 2018 extent graphs, for what they're worth.

- 2018 compared to the daily range for each date (maxima now removed).

- 2018 compared to 5 year averages for each date. I quite like 5 year averages in climate-related graphs - especially effective for plotting surface temperature.

- For selected years, the accumulating number of days in the current bottom 3 for each respective day. I've left out any year that rack up only 1-20 days in their respective bottom 3 - and there are only three years in that group.

PS Many thanks Neven for putting my maxima graph in your blogpost - I was very gratified.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 09, 2018, 06:02:06 AM
JAXA April 8th, 2018: 13,343,374 km2. A drop of -15,098 km2.
2018 continues to be second lowest on record, 105,662 km2 above 2016.
Title: Re: 2018 sea ice area and extent data
Post by: Cid_Yama on April 09, 2018, 06:44:43 AM
Thanks, folks! The comments of several forum users led me to look into a small number of my graphs, and that in turn allowed me to hunt down and snuff out a data error that's gone undetected for several months.

For the record, it was indeed a legitimate screw-up on my part, a recently-introduced calculation error on a single range of cells on a spreadsheet that contains tens of thousands of them. More precisely, I'd previously been pulling older NSIDC extent data from one web-based source, but changed that last summer when I became aware of an easier-to-access, and more frequently-updated, source. In doing so, I inadvertently--and erroneously--neglected to update a formula in that range of cells that referenced the previous data; hence the incorrect 1980s average. Luckily, that cell was only reflected on a total of three graphs. And, luckily, that column and those graphs have now been updated. (And I've added +/-2 standard deviation shading to the graph in question.) (http://iwantsomeproof.com/extimg/sie_nsidc_six_week_detail.png)

I maintain dozens of graphs, each of them based on one or more spreadsheets, with each spreadsheet itself based on sometimes multiple data sources. Complicating matters, those data sources change: different baselines, enhanced algorithms, anti-biasing tweaks, and so on, and so forth. The result is that keeping on top of all those changes can be a frustrating task for graph creators--and that can lead to obvious frustration by those who use those graphs. So for that, I apologize. Mea maxima culpa. (That's Latin for "my bad".)

For what it's worth, in the future, a direct message or an email (my address is right on the graphs) will almost always get a quicker response, as I don't monitor this forum 24 hours a day. However, if you're the type of person who prefers jumping up, pointing your finger, and publicly shouting, "You're wrong!!!", by all means knock yourself out; I'll respond to those eventually, too. :)

Thanks again.

Hey, Jim.  Everything you do here, we all make mistakes.

 https://www.youtube.com/watch?v=JJvkmjK9fWc
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 09, 2018, 11:33:22 AM
Herewith some more JAXA data as at 8th April.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 09, 2018, 11:49:47 AM
And now for some NSIDC Data, but not the usual.

I thought it was time to have a look at area, and with NSIDC having produced the March Monthly Averages for 2018, I looked at that. I was somewhat surprised at what I found.

According to the NSIDC data, while extent has gone down by about 2 million km2 since 1979, area has only gone down by about 0.5 million km2.

So the answer must be
- I've got the data all wrong, OR
- the data on area is so unreliable as to be unusable, OR
- the positive feedback from ice turning into open ocean is far less than the extent loss indicates

or a mixture of the above
I've had a quick scan of June and September and it is sort of the same.

Title: Re: 2018 sea ice area and extent data
Post by: oren on April 09, 2018, 12:02:04 PM
I had the same problem with area recently and it turned out to be the pole hole. Make sure your data compensates for it.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 09, 2018, 12:19:56 PM
The pole hole is assumed 100% covered in ice (extent and area)? If so, it has no effect on that the data shows that extent is reducing far more than area? Especially as it is March averages in the table below.

The data is from the NSIDC spreadsheet - I will have to look at the documentation.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 09, 2018, 04:43:05 PM
The pole hole is assumed 100% covered in ice (extent and area)?
I have not follow area since Cryosphere Today stopped publishing. A shame, because I like area more than extent.

I recommend read all this subject:

Quote
4.2.3 Arctic Pole Hole
4.2.3.1 Relevance of the Arctic Pole Hole to Ice Extent and Ice Area Values
...
The holes are significant because, in calculating Northern Hemisphere ice extent, it is assumed that the entire region under the Arctic pole hole is covered by ice at greater than 15 percent concentration. In calculating Northern Hemisphere ice area, however, the region under the Arctic pole hole is not included.

http://nsidc.org/data/G02135 (http://nsidc.org/data/G02135)
[Page 37]

Wipneus knows a lot about area. I hope he can help us with that. Wipneus also follows one or more sources of area data. By example, download the following file:

https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data/nsidc_arc_nt_main.txt?attredirects=0 (https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data/nsidc_arc_nt_main.txt?attredirects=0)
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 09, 2018, 05:31:14 PM
So indeed the area and extent numbers in the NSIDC spreadsheet are not consistent. If you add the following values to the area numbers you should be fine:
http://nsidc.org/data/G02135?qt-data_set_tabs=2#qt-data_set_tabs (http://nsidc.org/data/G02135?qt-data_set_tabs=2#qt-data_set_tabs)
Page 37 in the user guide.
Quote
Table 8. Arctic Pole Hole Mask Sizes and Dates
Arctic pole hole Area (million km2)
SSMIS Arctic Pole Hole Mask, 0.029, January 2008 to present
SSM/I Arctic pole hole Mask, 0.31, July 1987 through December 2007
SMMR Arctic pole hole Mask, 1.19, November 1978 through June 1987
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on April 09, 2018, 08:10:36 PM
The pole hole is assumed 100% covered in ice (extent and area)?
I have not follow area since Cryosphere Today stopped publishing. A shame, because I like area more than extent.


I was asked to clarify.

Normal practice in calculating extent is assuming concentration within the pole hole is everywhere above the threshold (usually 15%), so counted as 100%.
I have looked into this and I find it a very reasonable assumption in the past, but the errors will get bigger when open water appears near the pole in the, perhaps near, future.

For area the calculations differ. NSIDC monthly area does not include the pole hole. It is causing "steps" with different instruments. That is not good for long term analysis.

Cryosphere Today's area used to estimate concentration inside the pole hole from the concentration in a ring around the hole. My own calculations are similar. For the reasons mentioned above, I hope that makes these data much better for climatic purposes.

Things are of course simpler in the Antarctic.

 
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 09, 2018, 09:56:17 PM
Thanks all for the info. No wonder amateurs like me fall into (polar) bear traps.

Methinks at the moment I will be looking at the perpheral seas and Hudson Bay. No pole holes to fall in for the unwary explorer.

But the Arctic no doubt has more surprises up its sleeve.

Cheers.
Title: Re: 2018 sea ice area and extent data
Post by: TerryM on April 10, 2018, 05:11:35 AM
Thanks to both Jim & Steve we now have access to the correct data. This is how it's supposed to work!


Congrats & thanks to both.
Terry
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 10, 2018, 05:57:40 AM
I was asked to clarify.
Thank you Wipneus!


JAXA April 9th, 2018: 13,321,482 km2, a drop of -21,892 km2.
2018 is 3rd lowest on record:
     169,803 km2 above 2016
         7,114 km2 above 2006
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 10, 2018, 01:38:14 PM
Hullo Oren, hullo Wipneus.

Sorry to nag but just one bit more of clarification, please, pretty please.

A quick look at NSIDC regional data and the map suggests the pole hole is entirely contained within the Central Arctic Ocean. Is that correct?

Interesting, if off-topic, that that is the only bit of the Arctic Ocean outside the 200 mile economic zone of any of the surrounding countries ? Though Russia is, I think still after extending its economic zone as far as the North Pole.
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 11, 2018, 04:28:27 AM
A quick look at NSIDC regional data and the map suggests the pole hole is entirely contained within the Central Arctic Ocean. Is that correct?
Yes.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 11, 2018, 05:59:55 AM
JAXA April 10th, 2018:   13,281,980 km2, a drop of -39,502 km2.
2018 is second lowest on record again:
     2018 is 175,869 km2 above 2016.
     2018 is   25,144 km2 below 2006.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 11, 2018, 12:57:32 PM
Herewith JAXA DATA AS AT 10 APRIL 2018. to add to Juan's post

2018 extent is also below 2017 by 36,924 km2.
Extent loss from maximum to date is just 20k more than average.

if remaining loss was average, the minimum would be just under 4 million km2.
But:-
- on average only 6 percent of the melting is done,
- excluding the 2012 outlier, remaining melt would result in a minimum of about 4.2 million km2.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 11, 2018, 10:04:34 PM
So indeed the area and extent numbers in the NSIDC spreadsheet are not consistent. If you add the following values to the area numbers you should be fine:

Quote
Table 8. Arctic Pole Hole Mask Sizes and Dates
Arctic pole hole Area (million km2)
SSMIS Arctic Pole Hole Mask, 0.029, January 2008 to present
SSM/I Arctic pole hole Mask, 0.31, July 1987 through December 2007
SMMR Arctic pole hole Mask, 1.19, November 1978 through June 1987

Thanks, so I did. Results below. For most purposes it would seem extent is a good proxy for area when looking at trends. I am sure purists will be howling in utter fury at such a remark.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 11, 2018, 10:39:17 PM
In the above post I should have said "For most purposes it would seem extent is a good proxy for area when looking at OVERALL trends".

Below are 2 tables from NSIDC Regional Sea data as at 10 April (peripheral seas)
The first is extent, the second is area. Differences, especially in percentage terms, are very large.


Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 12, 2018, 05:56:03 AM
JAXA, April 11th, 2018:  13,254,107 km2, a drop of -27,873 km2.
2018 is now the third lowest on record.

Interesting, on April 11th, the three lowest years are the last ones.
2018 is 135,226 km2 above 2016.
2018 is  3,623 km2 above 2017.

2018 could become the lowest on record on the following 5 days.
Afterwards, 2016 starts a deep downward trend.
Title: Re: 2018 sea ice area and extent data
Post by: Alexander555 on April 13, 2018, 07:35:21 PM
We are waiting.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 13, 2018, 10:29:55 PM
We are waiting.

ADS NIPR (JAXA) has not updated the data...  :-\

https://ads.nipr.ac.jp/vishop/#/extent (https://ads.nipr.ac.jp/vishop/#/extent)
Title: Re: 2018 sea ice area and extent data
Post by: Alexander555 on April 13, 2018, 10:38:07 PM
Gerontocrat's graph from NSIDC shows a drop of 91 000 km2 for the 12th. And on your last graph it looks like 2016 is moving up a little.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 14, 2018, 10:54:15 AM
JAXA DATA AS AT 13 APRIL 2018  13,255,427 km2

JAXA says extent has stalled in the last 2 days. (Somewhat different from NSIDC data) As a result extent is third lowest, 100k above 2017 and 76 k above 2016. With on average 7% of melting done, extent loss is 50k below average, leading to a minimum of 3.98 million km2.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on April 14, 2018, 08:54:09 PM
JAXA says extent has stalled in the last 2 days.

Are we about to see a century break in the next few days?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 14, 2018, 10:19:04 PM
JAXA says extent has stalled in the last 2 days.

Are we about to see a century break in the next few days?

Perhaps not but on the other hand warmth entering from the Bering sea (images below)

( Does this make me a doubting Thomas ? )
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on April 14, 2018, 11:05:54 PM
That is finally a more typical temperature pattern; although slightly colder in the central U.S., and warmer in eastern Europe.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 14, 2018, 11:51:03 PM
That is finally a more typical temperature pattern; although slightly colder in the central U.S., and warmer in eastern Europe.
Those are high temps across the US/Canada... this is not a typical pattern. We are still at record continental SWE and it is 4/13.

(https://ccin.ca/home/sites/default/files/snow/snow_tracker/na_swe.png)
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on April 15, 2018, 03:39:49 AM
I thought that was a time stamp plot with the current temperatures measured at the time posted.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 15, 2018, 03:41:06 AM
I thought that was a time stamp plot with the current temperatures measured at the time posted.
It is, but 18z is 2PM EST which is normally when the highs occur. I would also recommend avoiding the GFS for anything but short-range forecasts in parts of the Lower 48 removed from any sensible substantial snowcover.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 16, 2018, 09:36:01 AM
JAXA ARCTIC EXTENT 13,125,342 km2(April 15, 2018) down 72k and 58k over the last two days.

Extent is 6k above 2017 and 8k below 2016. Extent loss to date totally average.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on April 16, 2018, 10:56:40 AM
Not a century break, but more or less what I expected after the short lull.
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on April 16, 2018, 02:06:58 PM
Within the Arctic Basin the way down has not been started, yet.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 16, 2018, 04:55:38 PM
Hullo Wipneus,

By coincidence, I got around to looking at AREA in the seas that tend to melt later than the seas in the periphery. (Note:- not adjusted for the pole hole)

When looking at extent (1st table below) the answer is - no change, nothing happening.
When looking at area (2nd table below) the answer is - things are moving all over the place even if the net effect is very small.

Another indication of ice mobility? Worth posting every week or so?

Sorry about the size of the tables. When I reduce them to 700 pixels they become more or less unreadable. Click on them and they should display properly.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 17, 2018, 05:53:10 AM
JAXA April 16th, 2018:  13,052,208 km2. An interesting drop of -73,134 km2, after doing drops of -71,918 and -58,167 km2 the days immediately before.

So, 2018 is the lowest on record again.   :o

Tomorrow, 2016 starts to have important drops every day. (295K km2 in the following 5 days).
Will 2018 follow 2016? From my point of view, it is bad enough if 2018 stays as second lowest on record, for a couple of months…
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 17, 2018, 04:48:46 PM
NSIDC Regional Sea Ice Data (5 day trailing average) as at 16 April

Extent
The decline continues in the periphery - Decline in extent especially in the Okhotsk.
Extent loss in other seas minimal or zero.

Area
In the periphery following extent decline.
In other seas (e.g. Chukchi, Kara, Laptev) decline in area seems to have commenced.

NSIDC Arctic total  (one-day) as at 16 April
Lowest. Down 96k to 13.686 million km2, just 18k less than 2017 and just 36k less than 2007.



Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 18, 2018, 05:53:06 AM
JAXA April 17th, 2018: 12,985,833 km2. A drop of -66,375 km2.
2018 is the JAXA ASI extent lowest on record.

2016 [2nd lowest] is 73,303 km2 above 2018.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 18, 2018, 06:06:16 AM
JAXA April 17th, 2018: 12,985,833 km2. A drop of -66,375 km2.
2018 is the JAXA ASI extent lowest on record.

2016 [2nd lowest] is 73,303 km2 above 2018.
2018 is going to hemorrhage in Okhotsk, Baffin, Bering, Beaufort, and Chukchi over the next thirty days. I would not be surprised to see its lead expanded. 2016 had significantly more volume in the way of the Pacific -- 2018 is in very dire straits, especially ^.

The ATL side in Barentz may actually mask losses as melt is matched by import. But this will probably end by 6/1, at latest.

I do anticipate Hudson Bay will hold up phenomenally well this year, with some ice possibly even making it through summer. But that is still unlikely, and will probably lead to sustained drops in the very late season (late July/August instead of May/June).
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on April 18, 2018, 06:47:06 AM
JAXA April 17th, 2018: 12,985,833 km2. A drop of -66,375 km2.
2018 is the JAXA ASI extent lowest on record.

2016 [2nd lowest] is 73,303 km2 above 2018.
2018 is going to hemorrhage in Okhotsk, Baffin, Bering, Beaufort, and Chukchi over the next thirty days. I would not be surprised to see its lead expanded. 2016 had significantly more volume in the way of the Pacific -- 2018 is in very dire straits, especially ^.

The ATL side in Barentz may actually mask losses as melt is matched by import. But this will probably end by 6/1, at latest.

I do anticipate Hudson Bay will hold up phenomenally well this year, with some ice possibly even making it through summer. But that is still unlikely, and will probably lead to sustained drops in the very late season (late July/August instead of May/June).
I wouldn't bet too heavily on Hudson Bay.  Most of that ice is well under 2 meters, and what isn't is still going to be acutely vulnerable.  Late season cold won't be enough to strengthen it against the coming melt.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 18, 2018, 06:50:48 AM
JAXA April 17th, 2018: 12,985,833 km2. A drop of -66,375 km2.
2018 is the JAXA ASI extent lowest on record.

2016 [2nd lowest] is 73,303 km2 above 2018.
2018 is going to hemorrhage in Okhotsk, Baffin, Bering, Beaufort, and Chukchi over the next thirty days. I would not be surprised to see its lead expanded. 2016 had significantly more volume in the way of the Pacific -- 2018 is in very dire straits, especially ^.

The ATL side in Barentz may actually mask losses as melt is matched by import. But this will probably end by 6/1, at latest.

I do anticipate Hudson Bay will hold up phenomenally well this year, with some ice possibly even making it through summer. But that is still unlikely, and will probably lead to sustained drops in the very late season (late July/August instead of May/June).
I wouldn't bet too heavily on Hudson Bay.  Most of that ice is well under 2 meters, and what isn't is still going to be acutely vulnerable.  Late season cold won't be enough to strengthen it against the coming melt.

I think the extraordinary snow amounts across the Canadian Shield will serve to buffer HB against melt for the foreseeable future, as incoming heat loses potency/deposits as snow across either Quebec or Ontario. This will likely change by mid-May or early June at the latest, but I think it will be sufficient to postpone melt-out of HB by a similar duration of the postponement of Canadian snow melt (on the order of 1.5-2 months).
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 18, 2018, 09:37:33 AM
I think the extraordinary snow amounts across the Canadian Shield will serve to buffer HB against melt for the foreseeable future, as incoming heat loses potency/deposits as snow across either Quebec or Ontario. This will likely change by mid-May or early June at the latest, but I think it will be sufficient to postpone melt-out of HB by a similar duration of the postponement of Canadian snow melt (on the order of 1.5-2 months).
Your "sense of snow" is generating very strange predictions, but I like it that they are presented clearly. I feel bad about it but I will again take the other side of your bet. HB has been extremely predictable these last few years - most of the melt occurs between mid-June and mid-July, as shown on Wipneus' graph. There is simply no way that melt-out of HB will be postponed by 1.5-2 months, and I predict it will arrive like clockwork on the same schedule, give or take a couple of weeks.
Title: Re: 2018 sea ice area and extent data
Post by: Sailaway on April 18, 2018, 10:00:21 AM
Any chance of leaving one thread for data. It is getting a little to much marching through "snow drifts" on every thread. Thanks
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 18, 2018, 10:01:55 AM
Any chance of leaving one thread for data. It is getting a little to much marching through "snow drifts" on every thread. Thanks
Do you think ice melts without reason? I didn't post any maps. I posted analysis. If you find ignorance blissful I suggest putting me on ignore.
Title: Re: 2018 sea ice area and extent data
Post by: binntho on April 18, 2018, 10:10:53 AM
Any chance of leaving one thread for data. It is getting a little to much marching through "snow drifts" on every thread. Thanks
Do you think ice melts without reason? I didn't post any maps. I posted analysis. If you find ignorance blissful I suggest putting me on ignore.
This snow thing might be interesting but it's annoying having it drift into the wrong discussions. How about putting it all in Land snow cover effect on sea ice (https://forum.arctic-sea-ice.net/index.php/topic,292.0.html) where it belongs?
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 18, 2018, 10:14:47 AM
Any chance of leaving one thread for data. It is getting a little to much marching through "snow drifts" on every thread. Thanks
Do you think ice melts without reason? I didn't post any maps. I posted analysis. If you find ignorance blissful I suggest putting me on ignore.
This snow thing might be interesting but it's annoying having it drift into the wrong discussions. How about putting it all in Land snow cover effect on sea ice (https://forum.arctic-sea-ice.net/index.php/topic,292.0.html) where it belongs?

...so I am supposed to comment on sea ice area without mentioning the reasoning behind my predictions!?!?! What is it with you people

Sea ice and snowcover are a COUPLED SYSTEM and intrinsically linked, discussion of one without the other is why we are sitting in a spiraling AGW situation with no idea what is coming around the corner. Segmenting discourse and reason from one another is the opposite intent of this forum (IMO).

If you cannot discuss the merits of the arguments of course you attack the fact that the arguments are being made at all...
Title: Re: 2018 sea ice area and extent data
Post by: be cause on April 18, 2018, 10:40:34 AM
bbr .. 'you people' are your readership .. and abusing us is scarcely the way to bring us flocking to the Guru's feet . This thread is for data not arguments about what you think might happen (see title ! ). Some folks are even taking a holiday from posting as seeing every thread snowed on is no more beneficial than a forum filled with AGW deniers . Please review your methodology .. b.c.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 18, 2018, 10:42:41 AM
bbr .. 'you people' are your readership .. and abusing us is scarcely the way to bring us flocking to the Guru's feet . This thread is for data not arguments about what you think might happen (see title ! ). Some folks are even taking a holiday from posting as seeing every thread snowed on is no more beneficial than a forum filled with AGW deniers . Please review your methodology .. b.c.

2018 is going to hemorrhage in Okhotsk, Baffin, Bering, Beaufort, and Chukchi over the next thirty days. I would not be surprised to see its lead expanded. 2016 had significantly more volume in the way of the Pacific -- 2018 is in very dire straits, especially ^.

The ATL side in Barentz may actually mask losses as melt is matched by import. But this will probably end by 6/1, at latest.

I do anticipate Hudson Bay will hold up phenomenally well this year, with some ice possibly even making it through summer. But that is still unlikely, and will probably lead to sustained drops in the very late season (late July/August instead of May/June).


What is off-topic about the above?!?!?!

I am not a Guru and I do not care if you want to lick my feet or not. It is up to you to pursue your foot fetish.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on April 18, 2018, 10:47:17 AM
What is off-topic about the above?!?!?!

This thread is about discussing area and extent data as it comes in, not about what is going to happen the next 30 days and how snow plays a major role in it.

Keep it short in the Melting Season thread, and do whatever you like in the NH snow cover thread. Shut up about snow over here.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 18, 2018, 10:48:26 AM
What is off-topic about the above?!?!?!

This thread is about discussing area and extent data as it comes in, not about what is going to happen the next 30 days and how snow plays a major role in it.

Keep it short in the Melting Season thread, and do whatever you like in the NH snow cover thread. Shut up about snow over here.
Will do  8)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 18, 2018, 11:23:36 AM
JAXA DATA AS AT 17TH APRIL 2018 12,985,833 KM2

2018 extent below 13 million km2 4 days before 2017, and just one day before 2016. On average 8.4% of the extent loss done. A bit too early in the season to get hyperbolic about melting prospects.

Nevertheless, an impressive extent loss of 270,000 km2 in just 4 days and of fairly consistent amounts? Also one day closer to a minimum of below 4 million km2. Worth keeping an eye on.
Title: Re: 2018 sea ice area and extent data
Post by: Phil42 on April 18, 2018, 11:26:05 AM
Since we hit the 13 million km2 extent mark now, I decided to look at the dates when the extent hit this mark in previous years. I ordered them by the date it hit the mark and added the decade averages.

ASI Extent first time below 13 million km2 by year (JAXA):
2018: April 17
2016: April 19
2017: April 21
2004: April 22
2007: April 24
2006, 2014, 2015: April 26
2010's Average: April 28
2000's Average: May 4
1990's Average: May 13
1980's Average: May 21

edit: Looks like gerontocrat was faster than me, I'll leave the post up anyway.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 18, 2018, 01:47:57 PM

2010's Average: April 28
2000's Average: May 4
1990's Average: May 13
1980's Average: May 21

edit: Looks like gerontocrat was faster than me, I'll leave the post up anyway.

I am sure all who look at this thread agree that all data is welcome, especially data like that from you showing the more than one month difference between now (2016 to 2018) and then (1980's). A good measure of how far the melt has got.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 18, 2018, 02:19:21 PM
A LOOK AT AREA

NSIDC AREA - 5 day trailing average

When looking at extent the data says nothing is happening outside the peripheral seas (e.g. Bering, Okhotsk, St Lawrence). But the change has happened when one looks at area. Hudson Bay, .
Chukchi and Laptev have just started to lose measurable area.

Summary in table below.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 19, 2018, 05:50:15 AM
JAXA ASIE April 18th, 2018: 12,938,678 km2, a drop of -47,155 km2.
2018 is the lowest on record.
2018 is now 57,915 km2 under 2016.
 
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 19, 2018, 11:29:41 AM
JAXA EXTENT AT 18 APRIL

To add to Juan's post just
- that 2018 extent is also 105,817 km2 (3 days) below 2017,
- that for 63 days out of 108 2018 daily extent has been at a record low in the satellite record,
- extent loss has been 316,749 km2 in the last 5 days.

Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 20, 2018, 05:56:59 AM
JAXA ASI Extent.
April 19th, 2018: 12,888,393 km2, a drop of -50,285 km2.
2018 is the lowest on record.
2018 is now -39,724 km2 under 2016.
Title: Re: 2018 sea ice area and extent data
Post by: LRC1962 on April 20, 2018, 08:03:27 AM
JAXA ASI Extent.
April 19th, 2018: 12,888,393 km2, a drop of -50,285 km2.
2018 is the lowest on record.
2018 is now -39,724 km2 under 2016.
I 'Liked' this, Actually should for each one, but most times I come on it is more to see what is happening then quickly leave. Not very kind to the forum, but what value I can add is very bad from education standards. On the otherhand liking it leaves me with a very sick feeling, because the legacy my generation has left (over 55) the next many generations will be paying a very high price for their entire lifetimes.
Keep the data coming because you are recording history and there are very few sites that are doing a very good job of it, and right now governments seem to be doing more and more to erase it.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 20, 2018, 08:27:34 AM
JAXA EXTENT AT 19 APRIL

To add to Juan's post just
- that 2018 extent is also -145,302 km2 (3 days) below 2017,
- that for 64 days out of 109 2018 daily extent has been at a record low in the satellite record,
- that extent loss has been -367,034  km2 in the last 6 days, above average for the time of year, but not enormously so.

The low March maximum and early strong melt is very significant for the positive feedback of albedo warming potential. We are just entering the maximum insolation season of the next 4 months or so (last graph attached from https://sites.google.com/site/cryospherecomputing/awp ).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 20, 2018, 02:39:36 PM
NSIDC AREA DATA AS AT 19 APRIL

Being the 5 day average the data shows better the gradual acceleration of daily area loss from under 20,000 km2 per day one week ago to approaching 50,000 km2 per day now.

Of interest is that Hudson Bay is losing area quite strongly at the moment despite all that snow in that corner of N. America.
The Chukchi Sea is also starting to show significant melt (Bering Strait is pretty well open now?)

NSIDC Arctic Total Extent down 91k, but still second to 2016.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 20, 2018, 08:13:28 PM
JAXA Analysis:

On April 30th, the year 2016 is the lowest on record, with 12,293,447 km2. 2018 will have to drop a daily average of 54.1K km2, to continue been the lowest on record on April 30th.

2006 is the second lowest on record on April 30th, with 12,661,451 km2. That is, 368K km2 above 2016. So, 2018 will be second lowest on record, if the daily average drop is less than 54.1 km2 but greater than 20.6K km2.

It is possible that 2018 drops more than 54.1K km2 average on the next 11 days, so I do not discard that could continue been the lowest on record. But I see a big probability that the average drop will be more than 20.6K km2. So, I think that -at least- 2018 will be second lowest on record at the end of April.

While the average drop of 2016 was 57.7K km2 on April 19-30, the average drop of 2012 was 75.4K km2. So, 2012 is already falling faster than 2006 and 2015-17.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 21, 2018, 06:03:45 AM
JAXA ASI Extent.

April 20th, 2018: 12,854,880 km2, a drop of 33,513 km2.
2018 is the lowest on record.
2018 is now 23,075 km2 under 2016.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 21, 2018, 11:00:12 AM
JAXA EXTENT AT 20 APRIL

To add to Juan's post simply that
- 2018 extent is again 145k km2 (3 days) below 2017,
- for 65 days out of 110 2018 daily extent has been at a record low in the satellite record,
- a 33k drop is pretty well average for this time of year.

Attachments show no real change from 19th April
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 21, 2018, 03:27:34 PM
NSIDC AREA ANALYSIS (5 day trailing average data) as at 20 April 2018

It is the Pacific side that is showing the most area losses - the Okhotsk, the Bering and now the Chukchi seas. This is likely to continue for at least a few days more. There is real day-time warmth up there now (see map attached)

On the Atlantic side, zilch area loss on the 20th after a few days of modest losses in the Kara and Laptev for a few days before.

Despite all that snow, Hudson Bay is losing area, though it is a bit late this year. (A post said that Churchill was at 12 celsius and sunny yesterday).

Area loss is at well over 40,000 km2 per day.
Title: Re: 2018 sea ice area and extent data
Post by: mitch on April 21, 2018, 06:42:09 PM
The Chukchi Sea region is still cold enough to resurface itself with ice when big open ocean areas form.  This will stop soon, so I expect to see major drops in ice extent soon.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 21, 2018, 09:33:24 PM
The Chukchi Sea region is still cold enough to resurface itself with ice when big open ocean areas form.  This will stop soon, so I expect to see major drops in ice extent soon.
The Chukchi and Beaufort are going to begin opening wide and clear within the next 10 days. It is going to be a sight to see! More like a zipper instead of a gradual march.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on April 22, 2018, 12:15:57 AM
On the Atlantic side, zilch area loss on the 20th after a few days of modest losses in the Kara and Laptev for a few days before.

Is there any way for us to get some estimate of export into this section?  How much is melting that is hidden in the lack of change in the extent?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 22, 2018, 01:26:29 AM

Is there any way for us to get some estimate of export into this section?  How much is melting that is hidden in the lack of change in the extent?
My regional postings are from NSIDC area - 5 day trailing average, which smooths daily data.

Fram export is confined to the Greenland sea. As far as I can see, unlike 2012, vast amounts of ice are not being hurled into the other Atlantic seas.

Therefore, in my totally not humble opinion ( IM not HO), Barents, Kara, Laptev are the ones to look at at this time of year for ice extent /area loss.

It is what the Arctic does, or used to do. Melt for a few days, go to sleep, do it again. I was expecting to only have to post the tables once a week or so in the main part of the melting season. Just my luck to look at area this year.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 22, 2018, 01:46:13 AM
The Chukchi Sea region is still cold enough to resurface itself with ice when big open ocean areas form.  This will stop soon, so I expect to see major drops in ice extent soon.
The Chukchi and Beaufort are going to begin opening wide and clear within the next 10 days. It is going to be a sight to see! More like a zipper instead of a gradual march.

Re: 2018 sea ice area and extent data. DATA!!!!!!!
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on April 22, 2018, 04:43:05 AM
The Chukchi Sea region is still cold enough to resurface itself with ice when big open ocean areas form.  This will stop soon, so I expect to see major drops in ice extent soon.
The Chukchi and Beaufort are going to begin opening wide and clear within the next 10 days. It is going to be a sight to see! More like a zipper instead of a gradual march.

Nothing short of nuclear war between Alaska and Eastern Siberia would put enough energy into the system to acheive this. It  takes more than hot air to melt ice.

Chukchi and the Beaufort take about three months of steady decline to lose their ice. Over that period they will lose about 1 M km^2 in total; A rapid decline would be losing that in 10 weeks. or about 100K per week.  I expect an unspectacular decline in May due to the lack of ice in the Bering with the extent being somewhere near the 2015 (10.8-11.0M) figure by May 31st.   
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 22, 2018, 06:10:11 AM
JAXA ASI Extent.

April 21st, 2018: 12,816,110 km2, a drop of 38,770 km2.
2018 is the lowest on record.
2018 is now 21,024 km2 under 2016.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on April 22, 2018, 06:50:26 AM
The Chukchi Sea region is still cold enough to resurface itself with ice when big open ocean areas form.  This will stop soon, so I expect to see major drops in ice extent soon.
The Chukchi and Beaufort are going to begin opening wide and clear within the next 10 days. It is going to be a sight to see! More like a zipper instead of a gradual march.

Nothing short of nuclear war between Alaska and Eastern Siberia would put enough energy into the system to acheive this. It  takes more than hot air to melt ice.

Chukchi and the Beaufort take about three months of steady decline to lose their ice. Over that period they will lose about 1 M km^2 in total; A rapid decline would be losing that in 10 weeks. or about 100K per week.  I expect an unspectacular decline in May due to the lack of ice in the Bering with the extent being somewhere near the 2015 (10.8-11.0M) figure by May 31st.   
Resurface with what? Nilas?

Ice in the Bering is *gone*.  Ice in the Chukchi is breaking up and retreating almost a month ahead of schedule.

I'm cognizant of the heat requirements to knock down the ice in the Beaufort and Chukchi, so I'm not anticipating a massive decline in May or even June, but I think we've passed the provenance of an 'unspectacular' decline, and the suggested persistent clear weather doesn't bode well for retention.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 23, 2018, 06:03:18 AM
JAXA ASI Extent.

April 22nd, 2018: 12,808,509 km2, a small drop of 7,601 km2.
2018 is the second lowest on record.
2018 is 60,757 km2 above 2016.  ;)
Title: Re: 2018 sea ice area and extent data
Post by: RikW on April 23, 2018, 09:49:22 AM
Recovery!

I'm curious to see if we will get a century-drop tomorrow to compensate...
Title: Re: 2018 sea ice area and extent data
Post by: Neven on April 23, 2018, 10:17:07 AM
Recovery!

I'm curious to see if we will get a century-drop tomorrow to compensate...

I think every lull will be followed by large declines, right now, because a lot of it is caused by last-ditch refreezing in the Chukchi. Okhotsk and Barentsz are also high and thus poised for big drops.

Whether it will be enough to keep up with 2016, I'm not sure.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 23, 2018, 03:08:14 PM
NSIDC Arctic Total Extent (daily extent) at 22 April  13.395 million km2.
The contrast with JAXA data is pronounced.

Extent is down by 109k km2, lower than 2017 by 97k and lower than 2016 by 147k, i.e. lowest in the satellite record.

NSIDC AREA DATA (5 day trailing average) AS AT 22 APRIL


The peripheral seas continue to decline at just over 30k per day, but the central seas are not, showing a net gain of +9k per day for the last 2 days. Hudson Bay is the exception, consistently losing about 6k per day for the last week.

N.B. The daily extent loss of 109k will likely feed into greater area 5-day average daily losses in the next 4 days.

Of interest is that Hudson Bay is losing area quite strongly at the moment despite all that snow in that corner of N. America.
The Chukchi Sea is also starting to show significant melt (Bering Strait is pretty well open now?)

Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on April 23, 2018, 04:09:16 PM
It looks like Hudson's bay will melt out early this year because the same weather that brought snow to eastern Canada helped bring in warm salty water that originated in the Gulf Stream and was advected around Iceland and Greenland into the Labrador sea. Labrador sea mixing went down to at least 2000m this late winter.

Ice is also melting rapidly offshore of the west coast of Greenland as the west Greenland current cranks up and advects heat northwards.

One piece of good news is that the weather has advected very little ice out of the Fram strait. There has been very little transport of ice out of the Arctic ocean all winter. The ice edge on the Barents sea has become the ice melting zone, but in the cold dark winter that's pretty good news for the ice.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on April 23, 2018, 04:23:07 PM
It looks like Hudson's bay will melt out early this year because the same weather that brought snow to eastern Canada helped bring in warm salty water that originated in the Gulf Stream and was advected around Iceland and Greenland into the Labrador sea. Labrador sea mixing went down to at least 2000m this late winter.

Ice is also melting rapidly offshore of the west coast of Greenland as the west Greenland current cranks up and advects heat northwards.

One piece of good news is that the weather has advected very little ice out of the Fram strait. There has been very little transport of ice out of the Arctic ocean all winter. The ice edge on the Barents sea has become the ice melting zone, but in the cold dark winter that's pretty good news for the ice.

Do you see the ice that seems to be getting entrained into Hudson Strait from Baffin Bay? It is thick, possibly multi-yr ice. I wonder how long it survives and if this is just a day or two blip or the start of something new.

Shifting the bulk of winter transport from Fram to Nares must have some sort of downstream impact. Perhaps this is it? (an aggressive salinity push N)
Title: Re: 2018 sea ice area and extent data
Post by: binntho on April 23, 2018, 05:36:55 PM
It looks like Hudson's bay will melt out early this year because the same weather that brought snow to eastern Canada helped bring in warm salty water that originated in the Gulf Stream and was advected around Iceland and Greenland into the Labrador sea. Labrador sea mixing went down to at least 2000m this late winter.

Do you see the ice that seems to be getting entrained into Hudson Strait from Baffin Bay? It is thick, possibly multi-yr ice. I wonder how long it survives and if this is just a day or two blip or the start of something new.
Well you have me baffled guys! Looking at Worldview over the month of April, no ice has moved (been "entrained") into Hudson Bay or Hudson Strait. The ice shifts a bit one way and then another, but the main movement in Hudson Strait seems to be towards the south.

The ice streaming down Baffin Bay is melting out where the Hudson Strait meets the Baffin Bay. And I've never heard of weather being able to advect Gulf stream waters around Iceland and Greenland (no less) and down Baffin Bay!

The Baffin Current is a continuation of the West Greenland Current, which itself is a continuation of the cold East Greenland Current and the warm Irminger Current. Generally the currents run clockwise around the bay - the same route that the Ice is taking.
Title: Re: 2018 sea ice area and extent data
Post by: Lord M Vader on April 23, 2018, 06:21:34 PM
Guys, you are forgetting that all that extra snow onto the ice in Hudson Bay will be transformed into water and exert pressure onto the ice which should melt even faster if the weather conditions are the right. While thick snow should be beneficial for the ice in the CAB the same might not be true for the peripheral ice.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 24, 2018, 05:44:40 AM
JAXA ASI Extent.

April 23rd, 2018: 12,803,197 km2, a small drop of 5,312 km2.
2018 is the second lowest on record.
2018 is 121,524 km2 above 2016 and 24,291 km2 under 2017.  :o
Title: Re: 2018 sea ice area and extent data
Post by: Wherestheice on April 24, 2018, 08:44:49 AM
I see a big drop coming sometime in the next few days
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 24, 2018, 09:39:20 AM
JAXA DATA - 12,803,197 km2(April 23, 2018)

Extent loss has stalled. I've got a déjà vu. Last year interminable speculations on how much below 4 million km2 the 2017 minimum was going to be - and it ended up at nearly 4.5 million km2. There is, on average,  just 10.7 % of the melting done. Early days.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 24, 2018, 06:20:54 PM
JAXA Analysis:

It is possible that 2018 drops more than 54.1K km2 average on the next 11 days, so I do not discard that could continue been the lowest on record. But I see a big probability that the average drop will be more than 20.6K km2. So, I think that -at least- 2018 will be second lowest on record at the end of April.

JAXA Analysis:

As gerontocrat says, extent loss has stalled on 2018. The average daily drop on the last two days is -6.5K km2. Meanwhile, the average drop of 2016 is -77.7K km2 and of 2017 is -52.8K km2.

Will 2018 become the third lowest registered? I do not believe so, at least, not in April. On the following days, 2017 is going to stall so much, that on the beginning of May, the competence for the second or third place will be with 2006.

On the other hand, Will 2018 become the lowest on record? I do not believe so. The drop of 2016 to April 30th is -60.8K km2. Furthermore, to 2018 match 2016 on April 30th, the average daily drop should be 76K km2.

So, from my point of view, 2018 is going to remain on second place, until the beginning of May.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 25, 2018, 05:51:30 AM
ADS NIPR JAXA, ASI Extent.

April 24th, 2018: 12,794,137 km2, a drop of -9,060 km2.
2018 is the second lowest on record.
2018 is 160,465 km2 above 2016 and 38,713 km2 under 2017.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 25, 2018, 10:40:53 AM
Nothing to add to Juan's posting except the tables but one thought.

Melting (and the reverse) seems to go in waves. My utterly unscientific speculation is that this reflects the relatively warm and relatively cold weather circulating around the polar region. Therefore maybe we are now about to enter another wave of melting as warmth gets into vulnerable areas of the periphery. I have no evidence for this whatsoever.
Title: Re: 2018 sea ice area and extent data
Post by: uniquorn on April 25, 2018, 06:55:31 PM
Quote
Melting (and the reverse) seems to go in waves
Your chart clearly shows a (possibly random) wave pattern. Does the area chart show a similar pattern? It may be that the way extent is measured/calculated amplifies the waves.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 25, 2018, 07:33:56 PM
Quote
Melting (and the reverse) seems to go in waves
Your chart clearly shows a (possibly random) wave pattern. Does the area chart show a similar pattern? It may be that the way extent is measured/calculated amplifies the waves.

JAXA data is a 2 day average.

NSIDC produce single day figures for total arctic extent, but the graphs on http://nsidc.org/arcticseaicenews/ are, I believe, based on the 5 day trailing average.

NSIDC use a 5 day trailing average for their regional sea area and extent spreadsheets. This smooths out variations in one day changes but makes comparisons of individual days more or less useless.

I try to avoid mixing the two sources (JAXA & NSIDC) as they use different instruments and different algorithms, or mixing area and extent as winds and currents can, for example, spread out sea ice resulting in extent measured higher while area may still drop.

That is why when I do postings on sea-ice data, one has JAXA data and the other will have NSIDC data. Never mix apples with ranges.

My non-scientific speculation will have to stay as a speculation on the JAXA data only.

Note: Over longer periods of time, measures of changes in area and extent  - 2-day,5-day,one day, follow each other pretty closely.
Title: Re: 2018 sea ice area and extent data
Post by: uniquorn on April 25, 2018, 08:22:23 PM
thank you Gerontocrat
Title: Re: 2018 sea ice area and extent data
Post by: RoxTheGeologist on April 25, 2018, 08:41:02 PM
Quote
Melting (and the reverse) seems to go in waves
Your chart clearly shows a (possibly random) wave pattern. Does the area chart show a similar pattern? It may be that the way extent is measured/calculated amplifies the waves.

Same here - there is a long term trend, and then a short periodicity on a wavelength of a few days that is likely to be the periodicity of weather changes. If someone wants to show me where the data is maybe a .csv, then I'll apply an FFT and maybe something will drop out.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 25, 2018, 08:50:17 PM
Quote
Melting (and the reverse) seems to go in waves
Your chart clearly shows a (possibly random) wave pattern. Does the area chart show a similar pattern? It may be that the way extent is measured/calculated amplifies the waves.

Same here - there is a long term trend, and then a short periodicity on a wavelength of a few days that is likely to be the periodicity of weather changes. If someone wants to show me where the data is maybe a .csv, then I'll apply an FFT and maybe something will drop out.

Below the graph on https://ads.nipr.ac.jp/vishop.ver1/vishop-extent.html you will see a download option for a .csv file. It's got the lot.

For NSIDC data go to https://nsidc.org/arcticseaicenews/sea-ice-tools/ for a range of spreadsheets.  The first one " All daily (single day and five-day trailing average) extent values in one file", updated daily has both one day and 5-day extents for the Arctic and Antarctica.

Enjoy.

Title: Re: 2018 sea ice area and extent data
Post by: Alexander555 on April 25, 2018, 08:59:03 PM
The Bering Sea is a month in advance, and we are close to the lowest extent. Than their has to be a place that has more extent than normal.  I have been looking on Nasa worldview. But the only place where there is more than the years before is west of the Kara Sea, near that long island. All the rest looks the same or less. North of Svalbard is big gap. The Ice in the Okhotsk Sea is almost gone. So where is that extra extent, or has it something to do with that 15 % ice cover.
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 25, 2018, 09:34:40 PM
The Bering Sea is a month in advance, and we are close to the lowest extent. Than their has to be a place that has more extent than normal.  I have been looking on Nasa worldview. But the only place where there is more than the years before is west of the Kara Sea, near that long island. All the rest looks the same or less. North of Svalbard is big gap. The Ice in the Okhotsk Sea is almost gone. So where is that extra extent, or has it something to do with that 15 % ice cover.
We are not at normal extent, we are far lower than normal, with only the abnormal 2017 and 2016 for company. But the best link for this question is Wipneus' AMSR2 regional page.  https://sites.google.com/site/arcticseaicegraphs/regional (https://sites.google.com/site/arcticseaicegraphs/regional)
Click on the left-hand chart for extent numbers, with the legend at the bottom. It shows the Barents running high compared to 2016/2017, and Okhotsk as well, while Bering, Baffin and Greenland Sea are lower.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on April 25, 2018, 10:43:46 PM
ADS NIPR JAXA, ASI Extent.

April 24th, 2018: 12,794,137 km2, a drop of -9,060 km2.
2018 is the second lowest on record.
2018 is 160,465 km2 above 2016 and 38,713 km2 under 2017.
Interesting how both 2017 and 2018 are currently running in parallel.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 26, 2018, 06:13:36 AM
[ADS-NIPR-JAXA] ASI Extent.

Well, the drop increased today.  ;)

April 25th, 2018: 12,761,033 km2, a drop of -33,104 km2.
2018 is the second lowest on record.

2018 is 165,215 km2 above 2016 and 65,325 km2 under 2017.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 26, 2018, 07:35:03 AM
JAXA DATA - Extent 12,761,033 km2(April 25, 2018)

Nothing to add to Juan's posting except the tables.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 27, 2018, 06:01:54 AM
[ADS-NIPR-JAXA] ASI Extent.

The drop is getting bigger:

April 26th, 2018: 12,708,674 km2, a drop of -52,359 km2.
2018 is the second lowest on record.

2018 is 138,269 km2 above 2016 and 101,601 km2 under 2017.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 27, 2018, 09:50:41 AM
JAXA Extent 12,708,674 km2(April 26, 2018)

Nothing to add to Juan's posting except the tables.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 27, 2018, 03:28:02 PM
NSIDC Arctic Total Extent (daily extent) at 26 April 13.443 million km2.
The contrast with JAXA data is pronounced.

Extent is up by 50k km2 from 4 days before, i.e. extent loss has stalled.

NSIDC AREA DATA (5 day trailing average) AS AT 26 APRIL

Overall area loss has also slowed to about 8k on the 26th. Excluding the Hudson and Okhotsk Seas (often considered as physically separate from the Arctic Ocean) area loss has morphed into area gain.
Total Area  without Hudson and Okhotsk   
Date   Area change Km2
18-Apr   -24251
19-Apr   -29493
20-Apr   -24356
21-Apr   76
22-Apr   2531
23-Apr   -190
24-Apr   12677
25-Apr   10548
26-Apr   5304

On any measure of extent or area NSIDC says the Arctic Ocean is having a mini(?)-break from the melting season.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 28, 2018, 05:51:24 AM
[ADS-NIPR-JAXA] ASI Extent.

April 27th, 2018: 12,679,541 km2, a drop of -29,133 km2.
2018 is the second lowest on record.
2018 is 180,543 km2 above 2016 and 120,798 km2 under 2017
Title: Re: 2018 sea ice area and extent data
Post by: Thomas Barlow on April 28, 2018, 09:48:33 PM
Is someone still doing the Arctic Ocean extent graph, year to year comparison?
ie. N. Hemisphere sea-ice, but with all peripheral seas and fjords taken out? - eg. Hudson Bay, Greenland Sea, CAA, Baffin Bay, Nares, taken out (only because I think the Arctic Ocean itself, without all that other stuff, is the best way to get an idea of the real state of the Arctic Ocean icepack )
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 28, 2018, 10:48:05 PM
Wipneus has nice charts of Arctic Basin (as he defines it) area and extent on his website,  I can post the link tomorrow if you can't find it.
Note at this time of year it's not very useful, it becomes much more interesting during summer.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 29, 2018, 06:29:46 AM
[ADS-NIPR-JAXA] ASI Extent.

April 28th, 2018: 12,641,635 km2, a drop of -37,906 km2.
2018 is the second lowest on record.
2018 is 227,801 km2 above 2016 and 116,518 km2 under 2017
Title: Re: 2018 sea ice area and extent data
Post by: oren on April 29, 2018, 07:25:38 AM
Wipneus has nice charts of Arctic Basin (as he defines it) area and extent on his website,  I can post the link tomorrow if you can't find it.
Note at this time of year it's not very useful, it becomes much more interesting during summer.
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png (https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png)
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png (https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png)
Note the charts are still not updated for 2018.
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on April 29, 2018, 09:58:27 AM
Note the charts are still not updated for 2018.

Fixed  :)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 29, 2018, 09:59:15 AM
JAXA EXTENT 12,641,635 km2(April 28, 2018)

Extent loss continues to dawdle as it has over the last week or so - below average but greater than 2017 so far.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 29, 2018, 03:44:13 PM
NSIDC Arctic Total Extent (daily extent) at 28 April 13.443 million km2.

Extent is down by 129k km2 from 2days before, i.e. extent loss has resumed. This is not showing in the 5-day area data YET.

NSIDC AREA DATA (5 day trailing average) AS AT 28 APRIL

Overall area loss is a modest 13k on the 28th. Excluding the Hudson and Okhotsk Seas (often considered as physically separate from the Arctic Ocean) area loss has morphed into area gain.
Total Area without Hudson and Okhotsk   
Date   Area change Km2
19-Apr   -29493
20-Apr   -24356
21-Apr   76
22-Apr   2531
23-Apr   -190
24-Apr   12677
25-Apr   10548
26-Apr   5304
27-Apr   2900
28-Apr   3416

On any measure of extent or area NSIDC says Arctic Ocean Area is having a mini(?)-break from the melting season at the moment.

Individual Seas
The Okhotsk Sea area loss was 21k (7% of remaining area).
Bering Sea area loss is now less than 2k per day, but that is still around 7% of remaining area er day. The Chukchi is now losing area again, the Beaufort has just started.
Other seas show marginal change.
Title: Re: 2018 sea ice area and extent data
Post by: Wherestheice on April 29, 2018, 07:07:55 PM
With all this stalling melt, a big drop seems likely right?
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on April 30, 2018, 06:27:26 AM
With all this stalling melt, a big drop seems likely right?

Hi, Wherestheice.

In my opinión, 2018 has not stall. 2016 was terrible on April and specially on May. So, it is pretty bad to be the second lowest on record.

Anyway, it is getting late for me and the JAXA data has not being updated yet. So, if anybody gets the information updated, please feel free to post it.
The link is: https://ads.nipr.ac.jp/vishop/#/extent (https://ads.nipr.ac.jp/vishop/#/extent)

Thanks!

Title: Re: 2018 sea ice area and extent data
Post by: oren on April 30, 2018, 06:59:48 AM
As I have dealings with the Japanese stock market, I happen to know that today is a holiday in Japan, so quite possibly there will be no data release today.
The same could happen on Thursday/Friday/Saturday this week, as all of these are national holidays as well.
Title: Re: 2018 sea ice area and extent data
Post by: Wherestheice on April 30, 2018, 08:49:21 AM
With all this stalling melt, a big drop seems likely right?

Hi, Wherestheice.

In my opinión, 2018 has not stall. 2016 was terrible on April and specially on May. So, it is pretty bad to be the second lowest on record.

Anyway, it is getting late for me and the JAXA data has not being updated yet. So, if anybody gets the information updated, please feel free to post it.
The link is: https://ads.nipr.ac.jp/vishop/#/extent (https://ads.nipr.ac.jp/vishop/#/extent)

Thanks!

Yes that makes sense. Thanks for reply!
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on April 30, 2018, 02:26:10 PM
NSIDC Daily Extent dropped by 2k km2 on 29th April
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on April 30, 2018, 02:56:50 PM
With all this stalling melt, a big drop seems likely right?

Hi, Wherestheice.

In my opinión, 2018 has not stall. 2016 was terrible on April and specially on May. So, it is pretty bad to be the second lowest on record.

Anyway, it is getting late for me and the JAXA data has not being updated yet. So, if anybody gets the information updated, please feel free to post it.
The link is: https://ads.nipr.ac.jp/vishop/#/extent (https://ads.nipr.ac.jp/vishop/#/extent)

Thanks!

Yes that makes sense. Thanks for reply!

The melt has stalled if you examine the last week only.  For the season, the total melt is slightly less than average.  However, the lower melt may be entirely due to the lower starting sea ice.  If you plot the melt compared to the maximum, 2018 falls squarely on the trend line.  The largest melts on this date occurred in 1989, 1990, and 1983.  The lowest occurred in 2009, 1999, and 2011.  April melt does not portend anything with regards to the September minimum.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 01, 2018, 07:18:08 AM
As I have dealings with the Japanese stock market, I happen to know that today is a holiday in Japan, so quite possibly there will be no data release today.
The same could happen on Thursday/Friday/Saturday this week, as all of these are national holidays as well.

Thank you for your answer, Oren.

Again, it is late for me and the JAXA data has not being updated. So, I appreciate if someone else brings the updated information.

The link is: https://ads.nipr.ac.jp/vishop/#/extent (https://ads.nipr.ac.jp/vishop/#/extent)
Good night or good morning!
Title: Re: 2018 sea ice area and extent data
Post by: Kica68 on May 01, 2018, 09:19:03 AM
Hi. Just checked ADS_NIPR on Twitter and found this tweet:

ADS_NIPR‏ @ADS_NIPR · 5h5 hours ago 
5月1日から2日までメンテナンスを実施するためADSのサービスは停止いたします。
ADS services is stopped to do H/W maintenance from May 1st to 2nd.

https://twitter.com/ads_nipr
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 01, 2018, 11:24:54 AM
Hi. Just checked ADS_NIPR on Twitter and found this tweet:

ADS_NIPR‏ @ADS_NIPR · 5h5 hours ago 
5月1日から2日までメンテナンスを実施するためADSのサービスは停止いたします。
ADS services is stopped to do H/W maintenance from May 1st to 2nd.

https://twitter.com/ads_nipr
I hope it is more to do Japan's Golden Week of holidays and they've gone to the beach or the park or.....

Dedication to duty can be overdone.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 01, 2018, 03:08:32 PM
It is May 1st and I am not out there protesting against something. Shame.

Before I start the notes of where NSIDC area data is at 30th April, Robertscribbler.com says "Major Arctic Warming Event Predicted For the Coming Week". Interestingly, he uses a cci-renalyzer image of the maximum temperatures over the next five days to make his point (maximum temperatures matter more than average temperatures  -says Gerontocrat).

NSIDC Total Area as at 30th April.(5 day trailing average)

The first table attached shows how area loss has increased to 40k on the 30th from less than 20k per day over the last two days. When Hudson Bay and the Okhotsk Sea are excluded, this goes down to a modest 18k.

Pacific Side
The Okhotsk has been losing area at 20k a day for nearly 10 days now, and is at a bit above 25% of its 1980's average maximum. (Graph attached below).
The Bering Sea is now at less than 5% of its average maximum and is now more or less irrelevant.
Instead the Chukchi Sea has lost area at a still modest but significant rate - on the 30th an area loss of 6k.
The Beaufort sea changes are minimal.

Atlantic Side
Baffin Bay has lost modest amounts.

Both the Greenland and Barents seas have gained area.
The Laptev and Kara seas have lost and gained area over the last 10 days.
The Central Arctic has gained area.

If it was not for the 20k a day area loss of ice in the Okhotsk, Arctic Sea Ice area would have increased over the last 10 days. I do call that a stall.

The question is what will the effect be of the major temperature increase on the Atlantic side over the next week ?
Title: Re: 2018 sea ice area and extent data
Post by: Thomas Barlow on May 01, 2018, 04:04:06 PM
Note the charts are still not updated for 2018.
Fixed  :)

Thanks, Wipneus and Oren.
This is great !
To me this is what really counts. The state of the Arctic Ocean.
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on May 01, 2018, 04:34:00 PM
It is May 1st and I am not out there protesting against something. Shame.

I know this is off-topic, but, it is May 1st and I am going to have my yearly shave -- head and beard.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on May 02, 2018, 02:16:55 AM
Reviewing April it seems to  be the worst predictor for summer extent. The attached graph shows the rankings (1 = Lowest) for the past 15 years based on the 31 year NSIDC record since they switched to daily reporting.  As can be seen some years ranked as high as 24.  Up until late March none of these years had ranked above 19. From the end of May only 2004 will rank higher than 18 until the end of September.

As an aside extent drops on May 1st have been around 200K for the last few years  for technical reasons so  we should expect a big drop tomorrow. 2017 dropped 259K between April 30 and May 1st.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 02, 2018, 02:17:24 PM
Hi. Just checked ADS_NIPR on Twitter and found this tweet:

ADS_NIPR‏ @ADS_NIPR · 5h5 hours ago 
5月1日から2日までメンテナンスを実施するためADSのサービスは停止いたします。
ADS services is stopped to do H/W maintenance from May 1st to 2nd.

https://twitter.com/ads_nipr
I hope it is more to do Japan's Golden Week of holidays and they've gone to the beach or the park or.....

Dedication to duty can be overdone.

Jaxa is on holiday but they have just put up data for the 29th April. Extent down by a slightly below average 39k.

Perhaps they will put Apr 30 and May 1 during the next few hours?
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 03, 2018, 06:14:13 AM
[ADS-NIPR-JAXA] ASI Extent.

Date             2006            2016              2017             2018        Drop 2018
April 28   12,782,805    12,413,834    12,758,153    12,641,635    
April 29   12,730,348    12,347,980    12,713,247    12,602,757    -38,878
April 30   12,661,451    12,293,447    12,674,471    12,574,787    -27,970
May   1    12,558,242    12,195,413    12,648,560    12,556,176    -18,611
May   2    12,444,466    12,164,312    12,585,016    12,521,612    -34,564


May 2nd, 2018: 12,521,612 km2.
2018 is the third lowest on record.
On May 2nd, the year 2018 is 357,300 km2 above 2016, 77,146 km2 above 2006 and 63,404 km2 under 2017.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 03, 2018, 06:39:14 AM
The northern hemisphere sea-ice extent (or volume) doesn't matter.
Only the Arctic Ocean sea-ice extent matters.

With the heat, specially on the Atlantic, I believe that we will see some drops on Okhotsk, Hudson, Baffin, Greenland Sea and Barentsz, so I think that 2018 will be the second lowest on record in a couple of weeks.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 03, 2018, 10:12:38 AM
The northern hemisphere sea-ice extent (or volume) doesn't matter.
Only the Arctic Ocean sea-ice extent matters.

There is 1.4 million km2 of open ocean on May 2 receiving a strong dose of solar radiation where in the 1980's there was ice-covered ocean. (In 2016 it was 1.8 million km2.) This is a positive feedback mechanism for increase in ocean heat content.

While the peripheral seas are ice-covered this inhibits the transfer of heat into and the effect of wind/wave action on the CAB.

Sea ice extent in the periphery certainly matters to polar bars and walruses, whales, orcas, etc who are moving into regions that were ice-covered.

Sea ice extent in the periphery certainly matters to the humans watching their shores eroded and their livelihood changed forever due to earlier sea-ice melt.

So I, for one, will continue to take a keen interest in changes to extent, area, and volume for the Arctic as a whole and individual seas within it (including the timing and extent of sea-ice loss in the central seas of the Arctic Basin as a whole and individually).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 03, 2018, 10:27:19 AM
JAXA has returned from holiday - Extent 12,521,612 km2(May 2, 2018)

Only to add to Juan's post that:
- the graph shows extent loss remains below average,
- the possibility of a minimum below 4 million km2 diminsihes,
BUT:
- only 15% of the melting season has passed,
- the data does not yet reflect the intensifying heat moving northwards into very high latitudes on the Atlantic side for the next week or so (that may even impact on the CAB seas).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 03, 2018, 04:16:32 PM
NSIDC Total Area as at 2nd AprilMAY.(5 day trailing average)
Another whoops


The first table attached shows how area loss has increased to 70k per day over the last two days. When Hudson Bay and the Okhotsk Sea are excluded, this is still 40k per day.
The 2nd of May saw area loss in all seas - a first for this melting season.

Pacific Side
The Okhotsk is still losing area at 20k a day.
The Bering Sea is now at 15k area (less than 5% of its average maximum) and is now more or less irrelevant. At this rate area will be zero in about two weeks
Instead the Chukchi Sea has lost area at a still modest but significant rate - on 2 May an area loss of 4k.
The Beaufort sea changes are still minimal.

Atlantic Side
Baffin Bay has lost modest amounts.

The Greenland has lost 20k of area in the last two days. The Barents area loss is small..
The Laptev Sea has lost 9k over the last two days. The Kara Sea losses of area are minimal.
The Central Arctic has gained area.

In the last two days area loss overall has increased strongly.

The question still is what will the effect of the major temperature increase on the Atlantic side be over the next week ?
Title: Re: 2018 sea ice area and extent data
Post by: Phil. on May 03, 2018, 09:44:03 PM
"NSIDC Total Area as at 2nd April.(5 day trailing average)"

Don't you mean May?
Title: Re: 2018 sea ice area and extent data
Post by: Thomas Barlow on May 03, 2018, 09:44:39 PM
The northern hemisphere sea-ice extent (or volume) doesn't matter.
Only the Arctic Ocean sea-ice extent matters.

There is 1.4 million km2 of open ocean on May 2 receiving a strong dose of solar radiation where in the 1980's there was ice-covered ocean. (In 2016 it was 1.8 million km2.) This is a positive feedback mechanism for increase in ocean heat content.

While the peripheral seas are ice-covered this inhibits the transfer of heat into and the effect of wind/wave action on the CAB.

Sea ice extent in the periphery certainly matters to polar bars and walruses, whales, orcas, etc who are moving into regions that were ice-covered.

Sea ice extent in the periphery certainly matters to the humans watching their shores eroded and their livelihood changed forever due to earlier sea-ice melt.

So I, for one, will continue to take a keen interest in changes to extent, area, and volume for the Arctic as a whole and individual seas within it (including the timing and extent of sea-ice loss in the central seas of the Arctic Basin as a whole and individually).
There could still be ice in Baffin Bay, CAA, and others, when the Arctic Ocean starts to warm up due to loss of albedo. A lot of talk is about 'lowest' or '2nd lowest'. So the lowest Arctic Ocean extent may be telling us something that the northern hemisphere extent is not. I'm talking about the overall picture of ice extent, not animals and people. That is a different topic. I'm asking the question, could a disaster unfold in the Arctic Ocean extent, even if the northern hemisphere extent is in 2nd or 4th place for the time of year? If blue ocean extends even a little more than usual in the Arctic Ocean, I'm hoping that the heating effect does not come to a tipping point in the ocean, or something more like exponential heating.
It would be interesting to compare the lowest northern hemisphere extents over the years in September, with the lowest Arctic Ocean extents over the years in September. I wonder if it would show correlations or very little precise correlation between northern hemisphere sea ice extent and Arctic Ocean sea ice extent. That could tell a lot about what is happening overall.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on May 03, 2018, 10:02:33 PM
The topic is 2018 sea ice area and extent data. Let's stay on it and take the more complex discussions elsewhere. Thank you.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 03, 2018, 10:08:29 PM
"NSIDC Total Area as at 2nd April.(5 day trailing average)"

Don't you mean May?
Whoops! Thanks - methinks I had better slow down - or stop.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 04, 2018, 12:14:07 PM
JAXA's on holiday - so so am I
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on May 04, 2018, 07:04:28 PM
Just a little proposal to move "Hudson Bay" into the peripherical seas table so both tables have the same number of columns, and Hudson Bay is quite far away from CAB.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 04, 2018, 07:19:15 PM
Just a little proposal to move "Hudson Bay" into the peripherical seas table so both tables have the same number of columns, and Hudson Bay is quite far away from CAB.

I am thinking of parking both Hudson Bay and the Okhotsk Sea to one side as they are so physically separate from the main Arctic Ocean.

But my brain hurts - even my computer is protesting at all the data lugged around dealing with all the NSIDC data linked to all my analyses. (I always work indirectly with the NSIDC spreadsheets to ensure they are never altered by me inside my machine)
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on May 05, 2018, 06:59:07 AM
Just a little proposal to move "Hudson Bay" into the peripherical seas table so both tables have the same number of columns, and Hudson Bay is quite far away from CAB.

I am thinking of parking both Hudson Bay and the Okhotsk Sea to one side as they are so physically separate from the main Arctic Ocean.


Add Bering, as it is functionally just a buffer that prevents early melt in the Arctic Proper... But your human health first, of course. These are hard times with people talking of f.e. healthy economy as if economy could have diseases. ::) ;) 8)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 05, 2018, 11:01:16 AM
Just a little proposal to move "Hudson Bay" into the peripherical seas table so both tables have the same number of columns, and Hudson Bay is quite far away from CAB.

I am thinking of parking both Hudson Bay and the Okhotsk Sea to one side as they are so physically separate from the main Arctic Ocean.


Add Bering, as it is functionally just a buffer that prevents early melt in the Arctic Proper... But your human health first, of course. These are hard times with people talking of f.e. healthy economy as if economy could have diseases. ::) ;) 8)
The Bering Sea is important - being the plug inhibiting warmth, waves etc entering the main Arctic Ocean. How quickly that plug is removed matters, which is why it needs to stay.

Incidentally, the Bering Sea is currently demonstrating that abrupt sea-ice loss can happen. (The Pacific end of the Arctic, especially the Bering and Chukchi areas, apparently have had the largest increase in air temperature within the Arctic over the last few years).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 05, 2018, 11:42:16 AM
But then again, abrupt sea ice loss can turn around into abrupt sea ice gain.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 05, 2018, 12:22:16 PM
NSIDC produced their April analysis on May 3rd. http://nsidc.org/arcticseaicenews/

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 05, 2018, 03:07:55 PM
NSIDC Total Area as at 4 May (5 day trailing average)

The first table attached shows how area loss has increased to 70k per day over the last 4 days. When Hudson Bay and the Okhotsk Sea are excluded, this is still over 50k per day.

Pacific Side
The Okhotsk is still losing area at 20k a day.
The Bering Sea is now at 15k area (less than 5% of its average maximum) and is now more or less irrelevant. At this rate area will be zero in about two weeks
Chukchi Sea area loss slowed to standstill.
The Beaufort sea changes are still minimal.

Atlantic Side

The question was what will the effect of the major temperature increase on the Atlantic side be over the next week ?
The answer so far is - significant. Except for Baffin Bay - increasing in area.

In contrast :
- The Greenland has lost 40k of area in the last two days.
- The Barents area loss has suddenly grown to 15k
- The Laptev and Kara Sea losses of area are small but measurable
- The Central Arctic has lost 10k per day for the last two days.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on May 05, 2018, 10:52:11 PM
There is something very striking about the conversation here tracking the beginning of the melt season. When I 1st came here, the conversation was about cloudless high pressure, insolation and melt ponds. We now talk about warm weather intrusions and 2m temperature anomalies.

I don't know that this is a good thing.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on May 05, 2018, 10:57:29 PM
There is something very striking about the conversation here tracking the beginning of the melt season. When I 1st came here, the conversation was about cloudless high pressure, insolation and melt ponds. We now talk about warm weather intrusions and 2m temperature anomalies.

I don't know that this is a good thing.

Not to go too far off-topic, but warm weather intrusions, inevitably coupled with cloudy conditions at this time of year, are important for melt onset, ie snow melting on top of the ice. This snow often refreezes, but is then more vulnerable to solar radiation. That's when the high pressure comes in and gets preconditioning through melt ponds on the road.

Both are important, depending on the timing.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on May 06, 2018, 07:32:48 AM
But then again, abrupt sea ice loss can turn around into abrupt sea ice gain.
Gain at this point in the Barentzs isn't necessarily a good thing, as probability indicates, it will all be gone by the end of the melt season.
Title: Re: 2018 sea ice area and extent data
Post by: Csnavywx on May 06, 2018, 02:23:41 PM
There is something very striking about the conversation here tracking the beginning of the melt season. When I 1st came here, the conversation was about cloudless high pressure, insolation and melt ponds. We now talk about warm weather intrusions and 2m temperature anomalies.

I don't know that this is a good thing.

Probably because we understand a bit more since the 2012 season.

Cloudless high pressure doesn't do nearly as much if it occurs on fresh, unbroken snowfall. Strong warm air advection followed by clear skies does significant damage, especially if there's some decent inversion-weakening or breaking wind to go with it.

There's a reason Chinook winds are called "snow-eaters".

The CAB had virtually no WAA events before July last year and as a result survived mostly intact.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 06, 2018, 04:18:30 PM
NSIDC Total Area as at 5 May (5 day trailing average)

The first table attached shows how area loss has increased to 70k per day over the last 5 days. When Hudson Bay, the Okhotsk Sea and the St. Lawrence are excluded, this is still over 50k per day.

Pacific Side
The Okhotsk is still losing area at 20k a day.
The Bering Sea at this rate area will be zero in about two weeks.

Chukchi Sea area loss slowed to standstill.
The Beaufort Sea is gainingb area.

Atlantic Side

The question was and still is what will the effect of the major temperature increase on the Atlantic side be over the next week ? The answer so far is - significant. Except for Baffin Bay - increasing in area.

In contrast :
- The Greenland has lost 58k of area in the last three days.
- The Barents area loss has grown to 23k on 5 May
- The Laptev and Kara Sea losses of area are small but measurable
- The Central Arctic has lost 40k per day over the last three days.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 07, 2018, 05:52:05 AM
[ADS-NIPR-JAXA] ASI Extent.

Date           2006              2016            2018         Drop 2018
May 1    12,558,242    12,195,413    12,556,176    
May 2    12,444,466    12,164,312    12,521,612      -34,564
May 3    12,405,456    12,144,447    12,451,489      -70,123
May 4    12,320,956    12,081,393    12,373,382      -78,107
May 5    12,249,753    12,039,085    12,257,814    -115,568
May 6    12,188,126    11,986,358    12,186,110      -71,704

May 6th, 2018: 12,186,110 km2.
2018 is the second lowest on record.
2018 is  199,752 km2 above 2016 and 2,016 km2 under 2006.
Title: Re: 2018 sea ice area and extent data
Post by: Nikita on May 07, 2018, 01:58:35 PM
...
Title: Re: 2018 sea ice area and extent data
Post by: Neven on May 07, 2018, 02:04:17 PM
Could you please update the graph at the end of June?  ;)
Title: Re: 2018 sea ice area and extent data
Post by: HapHazard on May 07, 2018, 08:53:27 PM
When I did the same sort of plot in early March, the line went up off the top of the chart. IDK what happened.

lol  ;)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 08, 2018, 05:58:45 AM
[ADS-NIPR-JAXA] ASI Extent.

May 7th, 2018: 12,115,492 km2, a drop of 70,618 km2.
2018 is the second lowest on record.
2018 is 202,913 km2 above 2016 and 52,876 km2 under 2006.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 08, 2018, 09:00:04 PM
JAXA short term analysis - May 8th, 2018.

2016 is the first lowest on record and the following two days drops are going to be 130K and 99K km2. Because today the difference between 2018 and 2016 is 203K km2, it is completely remote that 2018 will be the first on record, at least on the following two weeks.

On the other hand, 2006 is the second lowest on record and is going to stall on the following days. 2015 is going to become the second lowest on record, but like 2006, is not going to have important drops.

So, it is almost sure that 2018 will be the second lowest on record, at least on the following two weeks.

The interesting question is where 2018 will be on June 10th, when the years 2010, 2011, 2012, 2015 and 2017 are even, on the second lowest on record position, while 2016 starts to lose the first lowest on record position.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 09, 2018, 05:48:20 AM
[ADS-NIPR-JAXA] ASI Extent.

May 8th, 2018: 12,077,941 km2, a drop of 37,551 km2.
2018 is the second lowest on record.
2018 has 295,775 km2 more than 2016 and 73,643 km2 less than 2006.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on May 09, 2018, 08:11:17 AM
[ADS-NIPR-JAXA] ASI Extent.

May 8th, 2018: 12,077,941 km2, a drop of 37,551 km2.
2018 is the second lowest on record.
2018 has 295,775 km2 more than 2016 and 73,643 km2 less than 2006.

And with that 2004 loses its' last day in the top 3 for any day of the year. 2005 will stay in the list until Feb 6th when its sole day in the top 3 occurs.

2012 doesn't get a lowest 3 day until June 11th and if current trends continue 2018 will have more days in the lowest 3 by June 10th than 2012 has in the entire year. 
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 09, 2018, 11:53:22 AM
To be in a place for a few days with no laptop and no cell-phone signal.
Wonderful. Ho hum.

JAXA extent - 12,077,941 km2(May 8, 2018)

On average (of last 10 years), 18% (1.8 million km2) of extent loss is done, and 2018 extent loss is very close to that average, which if continued would lead to a minimum of just under 4 million km2. However, excluding 2012 (which I still regard as an outlier) the result would be more like 4.1 to 4.2 million km2 - low but not lowest.

But the next three months are the maximum months for insolation - so what does the brief Arctic summer have in store?.
Title: Re: 2018 sea ice area and extent data
Post by: Alexander555 on May 09, 2018, 12:22:21 PM
Still pretty big drops, and we are missing a big piece of easy ice in the Bering Sea. Does somebody knows how much ice the Bering Sea normaly loses at this time of the year ?
Title: Re: 2018 sea ice area and extent data
Post by: Phil. on May 09, 2018, 03:21:53 PM
[ADS-NIPR-JAXA] ASI Extent.

May 8th, 2018: 12,077,941 km2, a drop of 37,551 km2.
2018 is the second lowest on record.
2018 has 295,775 km2 more than 2016 and 73,643 km2 less than 2006.

And with that 2004 loses its' last day in the top 3 for any day of the year. 2005 will stay in the list until Feb 6th when its sole day in the top 3 occurs.

2012 doesn't get a lowest 3 day until June 11th and if current trends continue 2018 will have more days in the lowest 3 by June 10th than 2012 has in the entire year.
I'm not clear exactly what you're plotting here, a figure legend would help.  Thanks.
Title: Re: 2018 sea ice area and extent data
Post by: Aluminium on May 09, 2018, 03:30:41 PM
Does somebody knows how much ice the Bering Sea normaly loses at this time of the year ?
10-15 thousand km2/day. (https://sites.google.com/site/arcticseaicegraphs/regional)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fmasie_web.apps.nsidc.org%2Fpub%2FDATASETS%2FNOAA%2FG02186%2Fplots%2F4km%2Fr12_Bering_Sea_ts_4km.png&hash=224055da64e111c81d8f0d8246544c0b)
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on May 09, 2018, 03:33:03 PM
I'm not clear exactly what you're plotting here, a figure legend would help.  Thanks.
Hope this helps, Its a bar chart of the number of days rated in the lowest three in the IJIS Arctic Extent record.
Title: Re: 2018 sea ice area and extent data
Post by: Phil. on May 09, 2018, 03:38:30 PM
Thanks that's perfect.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 09, 2018, 07:17:46 PM
NSIDC Total Area as at 8 May (5 day trailing average)

The first table attached shows how area loss has moderated to 60k per day over the last 3 days. When Hudson Bay, the Okhotsk Sea and the St. Lawrence are excluded, it is just under 40k per day.

Pacific Side
The Okhotsk loss of area has slowed to about 12k. This reflects that area is now less than 15% of average maximum, and demonstrates that the less ice there is, the less there is to lose.
The Bering Sea area loss rate area has slowed to a crawl and is meaningless. (Last posting).

Chukchi Sea has gained a small amount of area.
The Beaufort Sea small area gains have stopped.

Atlantic Side

In contrast :
- The Greenland area loss in the last three days has slowed to effectively zero.
- The Barents area loss has grown to 34k on 8 May
- The Laptev is losing a bit and the Kara Sea gains a bit of of area.
- The Central Arctic has lost 50k in the last three days.

The great warming event has stopped for the moment. GFS say it will get going again from next weekend?
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 10, 2018, 06:26:01 AM
ADS-NIPR JAXA has delay the data for 45+ minutes  :(
So I invite you to look on their site, to see if they have updated the information:

https://ads.nipr.ac.jp/vishop/#/extent (https://ads.nipr.ac.jp/vishop/#/extent)

[In Mexico is 11:28 pm]  ;)
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 10, 2018, 10:08:46 AM
Still nothing, probably will only be tomorrow (though today isn't a holiday in Japan).
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 11, 2018, 05:55:09 AM
[ADS-NIPR-JAXA] ASI Extent.

May 9th, 2018: 12,021,992 km2, a drop of 55,949 km2.
May 10th, 2018: 11,933,172 km2, a drop of 88,820 km2.

2018 is the second lowest on record.
On May 10th:
2018 has 299,829 km2 more than 2016 and 151,697 km2 less than 2006.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 11, 2018, 10:37:26 AM
JAXA DATA AS AT 10 MAY 2018 11,933,172 km2

Just to add to Juan's post :
- daily extent loss well above average,
- a reminder of how exceptional 2016 extent loss was at this period in the melting season, and
- how 2012 extent on 10 May was 740,000 km2 less than 2017 and yet still ended up with a record low by 700,000 km2.

The last graph is just there to illustrate just how unpredictable the outcome for 2018 really is.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 11, 2018, 02:34:48 PM
NSIDC Total Area as at 10 May (5 day trailing average)

The first table attached shows how area loss has moderated to under 50k per day over the last 2 days. When Hudson Bay, the Okhotsk Sea and the St. Lawrence are excluded, it is just over 30k per day.

Pacific Side
The Okhotsk loss of area has slowed to 7k. This reflects that area at 90k is now about 10% of average maximum, and demonstrates that the less ice there is, the less there is to lose.
The Bering Sea area is just 9k, and yet could take a long time to get to zero.

Chukchi Sea has gained a small amount of area.
The Beaufort Sea small area gains have stopped.

Atlantic Side

In contrast :
- The Greenland area loss in the last three days has slowed to effectively zero.
- The Barents area loss is still in the 20+k per day range.
- The Laptev and the Kara Sea gains a bit of of area.
- The Central Arctic extent loss is down to 4k.

The great warming event has stopped for the moment. GFS say it will get going again after next week, but they always do, and just sometimes it arrives.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 11, 2018, 04:48:36 PM
There is every so often discussion on relevance of area vs extent. I think it is of use to think about lagging indicators, indicators on current status, and leading indicators. (Shocking to talk like an economist).

I illustrate this with a graph on the Okhotsk Sea and the melting thereof.

Extent loss always lags behind area loss, the lag reducing as the amount of ice left approaches zero. So extent is my lagging indicator, while area gives me the current status.

My leading indicator is weather forecasts. The 5 day average temperature forecast from GFS tells me the Okhotsk Sea Ice is toast. Wouldn't it be great to be able to look beyond that with a degree of confidence.

Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on May 11, 2018, 06:14:56 PM
[ADS-NIPR-JAXA] ASI Extent.

May 9th, 2018: 12,021,992 km2, a drop of 55,949 km2.
May 10th, 2018: 11,933,172 km2, a drop of 88,820 km2.

2018 is the second lowest on record.
On May 10th:
2018 has 299,829 km2 more than 2016 and 151,697 km2 less than 2006.

is this northern hemisphere only thread, not according to the title and globally we're lowest.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 11, 2018, 06:23:18 PM
[ADS-NIPR-JAXA] ASI Extent.

May 9th, 2018: 12,021,992 km2, a drop of 55,949 km2.
May 10th, 2018: 11,933,172 km2, a drop of 88,820 km2.

2018 is the second lowest on record.
On May 10th:
2018 has 299,829 km2 more than 2016 and 151,697 km2 less than 2006.

is this northern hemisphere only thread, not according to the title and globally we're lowest.
Yes - 'tis the Arctic. Within the Arctic Sea Ice Section you will find the topic "Global sea ice area and extent data" that combines N & S.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 12, 2018, 02:14:17 AM
It is interesting how NSIDC puts 2018 almost as bad as 2016, far away from any other year.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 12, 2018, 05:50:53 AM
[ADS-NIPR-JAXA] ASI Extent.

May 11th, 2018: 11,836,232 km2, an almost century drop of 96,940 km2.

2018 is the second lowest on record.
2018 has 263,128 km2 more than 2016 and 220,487 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 12, 2018, 10:40:52 AM
JAXA DATA AS AT 11 MAY 2018 11,933,172 km2

Just to add to Juan's post :
- 2018 extent is now 430,415 km2 less than 2017
- how 2012 extent was 780,000 km2 less than 2018 and yet still ended up with a record low by 700,000 km2.

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.05 million km2 as opposed to 3.88 million km2.

I have also attached an Albedo Warming Potential graph from Tealight aka Nico Sun. It shows the recent strong 2018 extent losses are starting to have an upward impact.
Title: Re: 2018 sea ice area and extent data
Post by: charles_oil on May 12, 2018, 05:51:16 PM

Any chance of including 2007 in the graph as that was a low one too - certainly shows 2012 standing out with a very rapid increase over the next couple of months.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 12, 2018, 06:56:16 PM

Any chance of including 2007 in the graph as that was a low one too - certainly shows 2012 standing out with a very rapid increase over the next couple of months.
Nope. I showed 2012 because it was unique in moving from above average extent in April to a record low in September. No other year has shown such a rapid change. To me it demonstrates both the unpredictability of a melting season at the beginning, and also the limit of that unpredictability. That limit tells me to forget a Blue Ocean Event this year.
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 12, 2018, 08:13:00 PM

Any chance of including 2007 in the graph as that was a low one too - certainly shows 2012 standing out with a very rapid increase over the next couple of months.
I think what you see standing out is 2016, which started the melting season with extreme losses and had the potential to become lowest on record, but was saved during June and July. Even eith that, it finished not far behind 2012 in area, and I believe its lead in albedo-warming potential played a significant part in that.
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 12, 2018, 08:35:13 PM
Neven - I have a small request. This thread is the first one I go to when on the forum. It would be nice if it could be bolded, like the late IJIS thread used to be.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on May 12, 2018, 08:38:39 PM
I think what you see standing out is 2016, which started the melting season with extreme losses and had the potential to become lowest on record, but was saved during June and July. Even eith that, it finished not far behind 2012 in area, and I believe its lead in albedo-warming potential played a significant part in that.

Well said, oren. If this year gets a similar start under its belt, it will take some very cold and cloudy weather during June and July to keep it out of the top 3. Mind you, 2016 ended with a bang (two GAC-like cyclones and then a huge dipole).
Title: Re: 2018 sea ice area and extent data
Post by: Neven on May 12, 2018, 08:39:05 PM
Neven - I have a small request. This thread is the first one I go to when on the forum. It would be nice if it could be bolded, like the late IJIS thread used to be.

Done!
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 12, 2018, 10:44:45 PM
A big thank you Neven.
Title: Re: 2018 sea ice area and extent data
Post by: charles_oil on May 13, 2018, 12:41:58 AM

I was looking at the red line for 2012 which seemed to have a very rapid increase from ca 8 June - and wondered if 2007 had a similar style as its the other unusually low year (at the time).

Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 13, 2018, 05:48:57 AM
[ADS-NIPR-JAXA] ASI Extent.

May 12th, 2018: 11,746,777 km2, a drop of 89,455 km2.

2018 is the second lowest on record.
2018 has 258,327 km2 more than 2016 and 236,615 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 13, 2018, 11:06:59 AM
JAXA DATA 11,746,777 km2(May 12, 2018)

Just to add to Juan's post :
- 2018 extent is now 442,157 km2 less than 2017
- how 2012 extent was 798,275 km2 more than 2018 on this date and yet still ended up with a record low by 700,000 km2.

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.02 million km2 as opposed to 3.85 million km2.
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 13, 2018, 12:06:24 PM
Just fix the recurring typo, 2012 was more on this date, not less...
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 13, 2018, 12:48:56 PM
Just fix the recurring typo, 2012 was more on this date, not less...

Thanks - post less, edit more?
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 13, 2018, 01:15:55 PM
You keep doing your fabulous stuff, I'm just nitpicking.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 13, 2018, 02:35:29 PM
Ok, Oren

NSIDC Total Area as at 12 May (5 day trailing average)

The first table attached shows how area loss is around 50k per day over the last 4 days. When Hudson Bay, the Okhotsk Sea and the St. Lawrence are excluded, it is now just over 45k per day.

Pacific Side
The Okhotsk loss of area has slowed to 5k and will soon be more or less irrelevant. This reflects that area at 80k is less than 10% of average maximum, and demonstrates that the less ice there is, the less there is to lose.
The Bering Sea area is stuck at 9k, and is irrelevant.

However, in the last two days:-
Chukchi Sea has lost 20k km2 in area,
The Beaufort Sea has lost 18k km2 in area.
The melting season has arrived in the Pacific side of the Arctic Basin?

Atlantic Side

- Warmth moving up Baffin Bay has caused an area loss of about 10k over the last 4 days.
- The Greenland area loss in the last three days has slowed to effectively zero.
- The Barents area loss has slowed, but still a 39k loss in the last two days.
- The Laptev Sea gains a bit of of area.
- The Kara Sea loses a tiny bit of area,
- Other Central Seas extent loss is minimal.


The great warming event has stopped for the moment. GFS say it will get going again after next week, but they always do, and just sometimes it arrives.
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Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on May 13, 2018, 03:02:35 PM
Thanks for the detailed graphics, G-crat. The warmth will continue over the Arctic ocean according to the ECMWF. The pattern of heat advecting in from the Atlantic and Pacific basins that we have seen on and off for 2 years is still on. It looks to me like the intensification of ocean ridges and Arctic blocking highs is going to be a new normal.



Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 14, 2018, 05:45:45 AM
[ADS-NIPR-JAXA] ASI Extent.

May 13th, 2018: 11,721,268 km2, a drop of 25,509 km2.
2018 is the second lowest on record.
2018 has 350,144 km2 more than 2016 and 209,789 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on May 14, 2018, 06:19:52 PM
Melting in the Arctic Basin is now starting in earnest.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on May 14, 2018, 06:26:40 PM
While area is lower than every year except for 2016, it seems the timing of the onset of serious melting is similar to most years on the chart.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 14, 2018, 08:03:49 PM
While area is lower than every year except for 2016, it seems the timing of the onset of serious melting is similar to most years on the chart.
It depends on which bit of the Arctic you look at, so here goes:-

JAXA AREA as at 13th May 2018

For a change, graphs, lots of graphs so probably several posts.

I have taken each sea and ordered them into - Pacific, Atlantic, Central, and the others (sort of bit players).
For each category I have put them into the order in which the melt usually happens.

PACIFIC

The first image has the Bering and Chukchi.

It was as good as over for the Bering by the middle of April (less than 10% of the maximum in the 1980's). Probably 7+ months with ice less than that. If 2018 is now the norm, maximum sea ice will be well under 50% of the maximum of the 1980s.

The Chukchi (after a blip down in late Feb) started losing area consistently about one to two weeks earlier than average and is now well below the 2010's average. How far down will it go?

The next image is the Beaufort and East-Siberian.( We who live in the west say the Beaufort in in the far west of the Arctic, Russians say the East-Siberian is in the Far East.Different points of view).

Both seas have been making a mockery of the expected effect of invasion of warm water from the Pacific, though the Beaufort has just started to lose area.

The next post will look at the Atlantic side. I'm off for a coffee.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 14, 2018, 08:29:38 PM
ATLANTIC side graphs

The first image is just the Baffin, significant as when it melts out it unplugs the numerous passages into the Arctic Basin proper.

It has been very cold in that N.E. quarter of Canada. Melt is also late in Greenland. Now warmth is starting to show in the Baffin.

Next is the Greenland and Barentz Seas

The Greenland Sea area is still 50,000 km2 greater than on March 1 - the Great Late February temperature spike. I guess there is warming heading north meeting additional ice down the Fram Strait.
The Barents Sea reached a maximum above the 1990's average in early April, but is now reducing strongly.

Next are the Kara and Laptev Seas, both at or above 1980's average. AGW, what AGW?

Too much like hard work. Another coffee required.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 14, 2018, 08:53:21 PM
THE CENTRAL ARCTIC and the CANADIAN ARCHIPELAGO

The Archipelago is till solid, above 1980's average.

The Central Arctic is very interesting. The February temperature spike really clobbered it, but recovery was complete. But now there is a significant early area loss. Will the much higher area loss so far in the 2010's be repeated.

OTHER SEAS

The Hudson is a consolation prize for bbr2314
Melt is late.
Question:- 
Is late ice melt and above average snow + late snow melt a result of the persistent cold in the NE quarter of Canada, or
Is  persistent cold in the NE quarter of Canada and late ice melt a result of above average snow + late snow melt ?

The Okhotsk melted late and area is now well below the 2010's average.

The St Lawrence melted a week or two early and area is now just bouncing around.

I think I will give the graphs another outing just after May21 - one month before solstice - if people think they are useful.
 
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 14, 2018, 09:18:38 PM
These graphs are highly useful and thanks for posting them, a revisit will be most welcome.
One point about the CAB, in reality it is bunch of areas that have different ice melt characteristics. The area north of Svalbard is undergoing Atlantification, and by rights should now be treated separately from the CAB proper. The other area hit in February was the Lincoln Sea/North-of-Greenland area, which also has its own peculiar characteristics. In general, it would be best if NSIDC decided to split the CAB into several sub-geographies, with reprocessing of past regional data, as rapid changes in a small sub-area are masked by bundling into the CAB super-area. An easy split could be taking away the external parts of the CAB according to the area they are facing - CAB North-of-Laptev sector, CAB North-of-Kara sector, CAB North-of-ESS sector, CAB North-of-CAA sector and so on, leaving the inner circle around the pole as the remaining Central CAB. Just thinking out loud here, more like wishful thinking really.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on May 14, 2018, 09:49:54 PM
That's a pretty good idea, oren.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 15, 2018, 05:54:58 AM
[ADS-NIPR-JAXA] ASI Extent.

May 14th, 2018: 11,677,808 km2, a drop of 43,460 km2.
2018 is the second lowest on record.
2018 has 384,082 km2 more than 2016 and 213,548 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 15, 2018, 12:05:34 PM

One point about the CAB, in reality it is bunch of areas that have different ice melt characteristics. In general, it would be best if NSIDC decided to split the CAB into several sub-geographies, with reprocessing of past regional data, as rapid changes in a small sub-area are masked by bundling into the CAB super-area.

Too many graphs! But wouldn't it be nice if the image in your post, made very transparent, (plus some lines dividing up the Central Arctic Sea in line with your idea), was used as a watermark to put on some of the sea ice extent, area, concentration and thickness images. At least then remarks on where things were happening could easily be related to their physical location.

But well beyond my capability with graphics.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 15, 2018, 02:26:32 PM
NSIDC Total Area as at 14 May (5 day trailing average)

The first table attached shows how area loss has increased to 70k+ over the last 2 days. When Hudson Bay, the Okhotsk Sea and the St. Lawrence are excluded, it is 68k.

Pacific Side
The Okhotsk loss of area has slowed to 1k and will soon be more or less irrelevant.
The Bering Sea area is 7k, and is irrelevant.

However, in the last two days:-
Chukchi Sea has lost 29k km2 in area,
The Beaufort Sea has lost 26k km2 in area.
The melting season has arrived in the Pacific side of the Arctic Basin?

Atlantic Side

- Warmth moving up Baffin Bay has caused an area loss of about 28k over the last 2 days.
- The Greenland area loss in the last two days was 13k.
- The Barents area loss has slowed a bit , but still a 30k loss in the last two days.
- The Laptev Sea and  Kara Sea are stable,
- Other Central Seas area loss is minimal.


The great warming event has stopped for the moment. GFS say it will get going again after next week, but they always do, and just sometimes it arrives.
[/quote]
[/quote]
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 15, 2018, 05:28:04 PM
Just to complete the discussion, this is the map used by Wipneus for the AMSR2 regional graphs, based on the Cryosphere Today mask. In this map the CAB is larger than on the NSIDC map, with the Beaufort, Chukchi, ESS and Laptev all smaller, and also a slightly different cutoff at the Fram.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on May 15, 2018, 05:32:24 PM
Just to complete the discussion, this is the map used by Wipneus for the AMSR2 regional graphs, based on the Cryosphere Today mask. In this map the CAB is larger than on the NSIDC map, with the Beaufort, Chukchi, ESS and Laptev all smaller, and also a slightly different cutoff at the Fram.

It would make sense to use the same map.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 15, 2018, 06:22:32 PM
Just to complete the discussion, this is the map used by Wipneus for the AMSR2 regional graphs, based on the Cryosphere Today mask. In this map the CAB is larger than on the NSIDC map, with the Beaufort, Chukchi, ESS and Laptev all smaller, and also a slightly different cutoff at the Fram.
I am confused again - so please remind me which is the goddam NSIDC map.
Please please please.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on May 15, 2018, 09:15:40 PM
Just to complete the discussion,

Hold on, I want to say one more thing.

It'd be interesting to divide the CAB up to 80N, or perhaps up to the pole hole, but only after July is over, because most regions have melted out by then, except for the ESS. Or let me put it this way, I wouldn't report on any of those inner CAB regions until then on the ASIB (unless there's something like a Laptev bite). It would otherwise be very confusing for newcomers.

"The ESS hasn't fully melted out yet, but already in the ESSiCAB region there is divergence, which means that..."  ;)
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 15, 2018, 10:11:37 PM
Neven - you are right. indeed, the CAB used to be one geographical region - the place that never melted. But nowadays there's the CAB region that barely ever freezes (north of Svalbard), the areas that often melt in July and August, and the core that still remains unmelted, though barely. But most of the year everything lumped into the CAB will show very stable extent numbers.
Gerontocrat - the original image I posted was of NSIDC regions, while the second one was of CT regions, which Wipneus uses for his AMSR2 calculations as well. Why the two maps are different is beyond my pay grade, but I'm sure someone knows the history of that.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 16, 2018, 05:53:49 AM
[ADS-NIPR-JAXA] ASI Extent.

May 15th, 2018: 11,671,777 km2, a small drop of -6,031 km2.
2018 is the second lowest on record.
2018 has 409,416 km2 more than 2016 and 195,504 km2 less than 2015.

Just by sight, I think that a freeze on Hudson Bay made a contribution to have the small drop.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 17, 2018, 06:33:56 AM
[ADS-NIPR-JAXA] ASI Extent.

May 16th, 2018: 11,630,844 km2, a drop of -40,933 km2.
2018 is the second lowest on record.
2018 has 432,935 km2 more than 2016 and 175,676 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 17, 2018, 11:58:18 AM
JAXA DATA 11,630,844 km2(May 16, 2018)

Just to add to Juan's post :
- Extent loss has been below average for the last 4 days, hence 2018 extent is now just 298k km2 less than 2017,
- 2012 extent was 633k km2 more than 2018 on this date and yet still ended up with a record low by 700,000 km2.

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.12 million km2 as opposed to 3.96 million km2.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 18, 2018, 05:43:47 AM
[ADS-NIPR-JAXA] ASI Extent.

May 17th, 2018: 11,588,270 km2, a drop of -42,574 km2.
2018 is the second lowest on record.
2018 has 443,551 km2 more than 2016 and 163,294 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 19, 2018, 05:51:16 AM
[ADS-NIPR-JAXA] ASI Extent.

May 18th, 2018: 11,520,403 km2, a drop of -67,867 km2.
2018 is the second lowest on record.
2018 has 416,150 km2 more than 2016 and 155,259 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 19, 2018, 12:58:18 PM
JAXA DATA 11,520,403 km2(May 18, 2018)

Just to add to Juan's post :
- Extent loss was below average for the previous 4 days, but on 18th May up a bit above avergae, hence 2018 extent is now just 306k km2 less than 2017,
- 2012 extent was 646k km2 more than 2018 on this date and yet still ended up with a record low by 700,000 km2. We are approaching the time when 2012 extent loss started to accelerate

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.13 million km2 as opposed to 3.97 million km2. The range of outcomes from the last 10 years remaining melt is 2.5 to 4.5 million km2.
Title: Re: 2018 sea ice area and extent data
Post by: Lord M Vader on May 19, 2018, 06:14:10 PM
NSIDC reports a big fat Century Break. Down 110K to 12,088 Mn km2.
Title: Re: 2018 sea ice area and extent data
Post by: Sigmetnow on May 20, 2018, 12:16:15 AM
“#Arctic sea ice extent has remained more than 2 standard deviations below the climatological average for nearly all of 2018 to-date
Graphics: http://sites.uci.edu/zlabe/arctic-sea-ice-extentconcentration/  “

https://twitter.com/zlabe/status/997883514925211648
Image below.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 20, 2018, 05:44:19 AM
[ADS-NIPR-JAXA] ASI Extent.

May 19th, 2018: 11,434,743 km2, a drop of -85,660 km2.
2018 is the second lowest on record.
2018 has 393,517 km2 more than 2016 and 176,359 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 21, 2018, 06:44:14 AM
[ADS-NIPR-JAXA] ASI Extent.

May 20th, 2018: 11,374,694 km2, a drop of 60,049 km2.
2018 is the second lowest on record.
2018 has 384,740 km2 more than 2016 and 138,836 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 22, 2018, 05:49:09 AM
[ADS-NIPR-JAXA] ASI Extent.

May 21st, 2018: 11,304,168 km2, a drop of 70,526 km2.
2018 is the second lowest on record.
2018 has 352,325 km2 more than 2016 and 136,626 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 23, 2018, 05:44:02 AM
[ADS-NIPR-JAXA] ASI Extent.

May 22nd, 2018: 11,269,417 km2, a drop of 34,751 km2.
2018 is the second lowest on record.
2018 has 345,454 km2 more than 2016 and 104,006 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 23, 2018, 05:36:55 PM
To be away from any telecomms signal for days again - it was bliss!
Postings will continue to be somewhat erratic for a month or so.

JAXA Extent 11,269,417 km2(May 22, 2018)

Just to add to Juan's post :
- Extent loss for the melting season to date is, at 2.62 million km2, almost exactly the average for the last 10 years.
- 2017 was a slow year at this time, hence 2018 extent is 446k (4%) below 2017,
- 2012 extent was 655k km2 more than 2018 on this date and yet still ended up with a record low by a bit more than 800,000 km2. We are approaching the time when 2012 extent loss started to accelerate.
- 2007 has a similar story - extent 620k more than 2018 on this date but melt accelerated late in the season.
- on average 26% of the melting is done for this season - still a long way to go,

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.11 million km2 as opposed to 3.95 million km2. The range of outcomes from the last 10 years remaining melt is 2.5 to 4.4 million km2.

Some non-data, non-scientific comments:-
- The Arctic in 2018 is a bit warmer so far than 2017,
- Global Ocean Heat Content has increased strongly in the last 12 months, some will head north.
- ENSO neutral conditions apply in 2018 as opposed to weakish La Nina in 2017.

These indicate a stronger melt this year than last year - maybe.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 24, 2018, 05:51:29 AM
[ADS-NIPR-JAXA] ASI Extent.

May 23rd, 2018: 11,226,696 km2, a drop of -42,721 km2.
2018 is the second lowest on record.
2018 has 346,377 km2 more than 2016 and 89,751 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on May 24, 2018, 02:01:14 PM
Thus far, 2018 has been roughly paralleling the melt years of 2009, 11, and 15.  Those years finished 11th, 4th, and 5th lowest minima respectively, after reaching 10th, 5th, and 3rd highest maxima.  That pace, should it continue, would place 2018 at 4th lowest.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on May 24, 2018, 03:28:03 PM
Thus far, 2018 has been roughly paralleling the melt years of 2009, 11, and 15.  Those years finished 11th, 4th, and 5th lowest minima respectively, after reaching 10th, 5th, and 3rd highest maxima.  That pace, should it continue, would place 2018 at 4th lowest.
For me, quasi-statistical estimations based on graph morphology  like this have failed miserably every time I've made one.  Based on that, the only guess I'll hazard at this juncture is the season will finish somewhere between 1st  and 10th lowest minima. 😁
Title: Re: 2018 sea ice area and extent data
Post by: Archimid on May 24, 2018, 03:44:09 PM
Quote
quasi-statistical estimations based on graph morphology

Thanks for that. I tend to do this a lot. Your description of the method really puts in perspective for me.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on May 24, 2018, 04:30:11 PM
Quote
quasi-statistical estimations based on graph morphology

Thanks for that. I tend to do this a lot. Your description of the method really puts in perspective for me.

The graphs and data are very good at telling us where we've been, and pretty good at telling us where we are.
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on May 24, 2018, 04:43:39 PM
Thus far, 2018 has been roughly paralleling the melt years of 2009, 11, and 15.  Those years finished 11th, 4th, and 5th lowest minima respectively, after reaching 10th, 5th, and 3rd highest maxima.  That pace, should it continue, would place 2018 at 4th lowest.
For me, quasi-statistical estimations based on graph morphology  like this have failed miserably every time I've made one.  Based on that, the only guess I'll hazard at this juncture is the season will finish somewhere between 1st  and 10th lowest minima. 😁
That is about the best we can do.  Any individual year can have idiosyncrasies that lead to a much higher or lower minimum than expected otherwise.  Currently, I would say we have a low probability of a 1st or 10st lowest minimum, and higher probability of landing in between.  As the melting season proceeds, we can start eliminating other values, as being similarly unlikely.  In the end, several factors will come together, resulting in the final measurement, leaving everyone scratching their heads as to why this year did exactly what it did.
Title: Re: 2018 sea ice area and extent data
Post by: Wherestheice on May 24, 2018, 07:30:43 PM
Thus far, 2018 has been roughly paralleling the melt years of 2009, 11, and 15.  Those years finished 11th, 4th, and 5th lowest minima respectively, after reaching 10th, 5th, and 3rd highest maxima.  That pace, should it continue, would place 2018 at 4th lowest.

Based on the extent currently being 2nd lowest. A lot can happen. I think it’s fair to say if the conditions are right, a record low minimum is likely, but maybe we will luck out and have another summer like last year.... i doubt that. The arctic is transitioning into an ice-free state, so using past data won’t do much
Title: Re: 2018 sea ice area and extent data
Post by: litesong on May 24, 2018, 07:38:31 PM
   Any individual year can have idiosyncrasies that lead to a much higher or lower minimum than expected otherwise.
Do you think 2018 or other near future years will return to the high Arctic sea ice extents & volumes of the average of the 1980's?
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on May 24, 2018, 08:34:02 PM
   Any individual year can have idiosyncrasies that lead to a much higher or lower minimum than expected otherwise.
Do you think 2018 or other near future years will return to the high Arctic sea ice extents & volumes of the average of the 1980's?
Not in 2018 or the near future.  Eventually, yes.

Title: Re: 2018 sea ice area and extent data
Post by: Hyperion on May 24, 2018, 11:10:50 PM
   Any individual year can have idiosyncrasies that lead to a much higher or lower minimum than expected otherwise.
Do you think 2018 or other near future years will return to the high Arctic sea ice extents & volumes of the average of the 1980's?
Not in 2018 or the near future.  Eventually, yes.
I agree. Possibly about 130 million years from now it may. Earth has roughly followed a 50million year glaciated, 100 million year ice free hothouse cycle for about the last billion years. The unprecedented in the last billion years rate of warming, and ecocide humans have achieved virtually guarantees that we have ended the recent 50 million year glacial. If we are lucky we may not have set off a Venus style runaway water vapour greenhouse warming. Let's cross our fingers and hope that near or all non photosynthetic life will be wiped out instead, and extremophile cyanobacteria put the earth in a snowball state for a hundred million years or so to reboot the ecosphere.
Planet scale bio-sterilization would not be a nice Karmic burden for the human soul-family
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 25, 2018, 06:03:37 AM
[ADS-NIPR-JAXA] ASI Extent.

May 24th, 2018: 11,162,193 km2, a drop of -64,503 km2.
2018 is the second lowest on record.
2018 has 369,528 km2 more than 2016 and 113,469 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 25, 2018, 10:37:08 AM
JAXA Extent 11,162,193 km2(May 24, 2018)

Just to add to Juan's post :
- Extent loss for the melting season to date is, at 2.73 million km2, almost exactly the average for the last 10 years.
- 2017 was a slow year at this time, hence 2018 extent is 439k (3.9%) below 2017,
- 2012 extent was 684k km2 more than 2018 on this date and yet still ended up with a record low by a bit more than 800,000 km2. We are approaching the time when 2012 extent loss started to accelerate.
- 2007 has a similar story - extent 622k more than 2018 on this date but melt accelerated late in the season.
- on average 28% of the melting is done for this season - still a long way to go,

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.11 million km2 as opposed to 3.95 million km2. The range of outcomes from the last 10 years remaining melt is 2.5 to 4.4 million km2.

Some non-data, non-scientific comments:-
- The melt this year for some time has seen very little variation from plodding along at 2nd place, hence this post shows little variation from the previous post,
- The Arctic in 2018 is a bit warmer so far than 2017,
- Global Ocean Heat Content has increased strongly in the last 12 months, some will head north.
- ENSO neutral conditions apply in 2018 as opposed to weakish La Nina in 2017.

These indicate a stronger melt this year than last year - maybe. But pure speculation without data belongs not on this thread nor on the 2018 melting season thread.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 25, 2018, 02:34:34 PM
NSIDC Total Area as at 24 May (5 day trailing average) 10,402,675 km2

The great warming event continues to be promised by GFS, but always at the end of the 10 day forecast period. However, it is warming up from the Russian side.

I is tired so here are the tables without comments. Methinks I will post the area graphs soon as they show more.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on May 25, 2018, 02:45:11 PM
gerontocrat...

I want to thank you for these great posts! You have made this thread a must visit for me. Every morning, I come to review yours and Juan's data and analysis every day.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on May 25, 2018, 02:58:17 PM
Thought I would post the regional extent graphs with a few comments.

CAB: Recent melt as placed the CAB in the lead as compared to other seasons.
Greenland Sea: With low extent throughout the winter, this sea continues to remain historically low.
Baffin/Newfoundland Bay: After a 2 month stall, melt has ramped up with extent about average at this point in the season.
Chukchi: The early melt has kept this sea in the lead.
Bering: With an historically low winter maximum, the Bering is completely melted out and will have no more impact on the extent number for the remainder of the season.
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on May 25, 2018, 03:02:08 PM
And here are the regional area graphs.

Kara Sea: Stubbornly resisting melt early in the season.

I've always thought that comparing area to extent performance could reveal insights about the melt season but I don't see anything of note at the moment. Area and extent for the regions seem to be tracking closely.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 26, 2018, 06:12:47 AM
Sorry, guys...

There is a delay of 30+ minutes on JAXA data.
It makes me think that we will not have information this weekend.
You can check if the data has been updated:

https://ads.nipr.ac.jp/vishop/#/extent (https://ads.nipr.ac.jp/vishop/#/extent)
Title: Re: 2018 sea ice area and extent data
Post by: epiphyte on May 26, 2018, 06:31:33 AM
And here are the regional area graphs.

Kara Sea: Stubbornly resisting melt early in the season.

I've always thought that comparing area to extent performance could reveal insights about the melt season but I don't see anything of note at the moment. Area and extent for the regions seem to be tracking closely.

It appears to me that right now the land is keeping the ice cold, rather than the other way round.

...That can't be good.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 27, 2018, 02:27:11 PM
I've always thought that comparing area to extent performance could reveal insights about the melt season but I don't see anything of note at the moment. Area and extent for the regions seem to be tracking closely.

The two tables below show a summary of extent loss and area loss for the 10th to 26th May (NSIDC data).

You will see that extent loss especially for the Central Seas is much less than area loss simply because of the 15% rule for registering extent). In most of the peripheral seas extent loss is now playing catch-up with area. Area loss therefore will show when melting is underway earlier - while extent is a lagging indicator. It is also a better indicator of the true extent to which each sea is ice-covered.

I will always use extent for the multi-year Arctic /Antarctic total stuff simply because that's the way it is, and who am I to take on NASA, the NOAA, the NSIDC etc etc etc?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 27, 2018, 03:15:18 PM
NSIDC Total Area as at 26 May (5 day trailing average)

The table attached in the post above shows how area loss has switched to lower in the peripheral seas and much higher in the Central Seas and is maintaining a 50+k km2 loss per day.

Pacific Side
- The Okhotsk Sea area is down to 38k km2, well under 5% of historical average maximum, daily - loss has slowed to 1 to 2k and is more or less irrelevant.
- The Bering Sea area is 4k, and is irrelevant (except to see for how long the vestiges of ice will persist).
- Chukchi and Beuafort Sea losses are modest.

Atlantic Side

- Area loss in the Baffin, Greenland, and Barents Seas seems to have slowed somewhat. area loss in the last two days was 13k.
- The Laptev Sea lost 26k on the 26th May, over half the loss of the Central seas.
- The Kara Sea is steadily losing area.
- Other Central Seas area loss is minimal.

Other seas
- St Lawrence continues to hang on to its area of 13k,
- Hudson Bay increased in extent in the last two days.

The great warming event predicted by GFs is again postponed to the end of the 10 day forecast However,GFS from cci-reanalyzer.org shows  there is a believable significant influx of warm air from the Russian side happening now and in the next few days.

Warmth looks as if it will hit the southern half of Hudson Bay as well. Can I believe the BBC when its says next Tuesday temps in Churchill will max at 21 degrees celsius?
Title: Re: 2018 sea ice area and extent data
Post by: numerobis on May 27, 2018, 04:29:41 PM
According to Windy: forecast for Tuesday 3pm in Churchill has ECMWF at 15 C, GFS at 19 C, NEMS at 20 C.

The temperature gradient from inshore to the sea is very steep. In all three models you get mid-20s not far from Churchill. I presume there must not be much snow left inland (the rail line got wiped out by flooding in April last year, so that must be about when the snow largely melts).
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on May 27, 2018, 08:10:08 PM
According to Windy: forecast for Tuesday 3pm in Churchill has ECMWF at 15 C, GFS at 19 C, NEMS at 20 C.

The temperature gradient from inshore to the sea is very steep. In all three models you get mid-20s not far from Churchill. I presume there must not be much snow left inland (the rail line got wiped out by flooding in April last year, so that must be about when the snow largely melts).

Looks like some decent melt yesterday but still roughly 2X avg SWE across NA:

(https://ccin.ca/home/sites/default/files/snow/snow_tracker/plot_anom_sdep.png)

(https://ccin.ca/home/sites/default/files/snow/snow_tracker/na_swe.png)

I wonder if the cliff at the end of April acted as a much smaller equivalent to Lake Agassiz? Obviously everything is still going to melt, but North America lost roughly half of its accumulated SWE (~800KM^3) in the span of a week to ten days. With the following plateau in losses and the discussion re: AMOC crazy in the melt season thread, it is certainly an interesting development.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on May 27, 2018, 10:47:07 PM
With the following plateau in losses and the discussion re: AMOC crazy in the melt season thread, it is certainly an interesting development.

I still think that in the WACCy weather the Cold is only in comparison to the speed the Ocean is warming, but I will admit that more humidity in Winter means more snow -- and probably more ice downwind.
Title: Re: 2018 sea ice area and extent data
Post by: ghoti on May 27, 2018, 10:54:12 PM
Numerobis how's the snow in Iqaluit? The snow depth anomaly map seems to suggest you are living in the heart of the deep snow of North America.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 28, 2018, 12:06:15 AM
There is  a thread called northern hemisphere snow cover.
This thread is about 2018 arctic sea ice extent and area data.

So - geroff.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 28, 2018, 05:52:18 AM
[ADS-NIPR-JAXA] ASI Extent.

Date             Extent           Drop
May 25th:   11,119,821   -42,372
May 26th:   11,088,039   -31,782
May 27th:   11,048,329   -39,710

May 27th, 2008:
2018 is the second lowest on record.
2018 has 417,153 km2 more than 2016 and -76,051 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 28, 2018, 09:06:58 AM
JAXA Extent 11,048,329 km2(May 27, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 2.84 million km2, now 70k below the average for the last 10 years. Consistently slightly slower than average daily melt.
- 2017 was a slow year also, hence 2018 extent is 416k (4%) below 2017,
- 2012 extent was 605k km2 more than 2018 on this date and yet still ended up with a record low by a bit more than 800,000 km2. We are approaching the time when 2012 extent loss started to accelerate.
- 2007 has a similar story - extent 550k more than 2018 on this date but melt accelerated late in the season.
- on average 29% of the melting is done for this season - still a long way to go,

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.16 million km2 as opposed to 3.99 million km2. The range of outcomes from the last 10 years remaining melt is 2.53 to 4.43 million km2.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 28, 2018, 02:19:53 PM
I've always thought that comparing area to extent performance could reveal insights about the melt season but I don't see anything of note at the moment. Area and extent for the regions seem to be tracking closely.

Shared Humanity, you are as bad as Oren - making me think.

I thought I had better test my speculation on whether area is a more current indicator of sea ice loss or gain than extent. So after a couple of false starts I ended up with the two graphs below, which look at daily change from 1st March to date.. (NSIDC data)

The first graph looks at the Central Arctic - i.e. those seas that in theory are the last to finish gaining ice extent and the last to start melting.
The second graph looks at the peripheral seas (excluding Hudson, Okhotsk and St. Lawrence).

Some surprises.
- The Peripheral Seas gained area for as long as the Central Seas gained area. (The Central Seas stopped gaining extent because they were full up of ice with 85% or more coverage),
- There is no significant variation in amount or timing of extent vs area gains and losses in the peripheral seas so far,
- Since the beginning of May area loss in the Central Seas has been significantly greater than extent loss. Will this continue?

Perhaps I am half right in my speculation?
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on May 28, 2018, 03:22:21 PM
You may also be half wrong.  8) Thanks for the charts.
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on May 28, 2018, 04:31:33 PM
I suspect that large melt ponds are forming in the central seas.  These appear as open water in the area calculations, but not extent.  This is less an issue in the peripheral seas.
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 28, 2018, 08:27:54 PM
There is no need to suspect, as Worldview comes in handy. These are not melt ponds with their telltale bluish tinge. When leads open between floes, as is happening in mass in the Beaufort, sea ice concentration goes down. But with NSIDC's large grid of roughly 25 x 25 km, when concentration remains above 15% you get full extent but a reduction in area. Area is a leading indicator of extent at this time of year. Melt ponds and wet snow have much more influence in June-August.
Note: posting this here because of the data discussion. Can be developed further in the melting season thread.
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on May 28, 2018, 09:28:28 PM
I analysed the last 38 years of JAXA extent date. I took the average values of the 80s, 90s, 00s and 10s (up to now) at each end of a quarter (first table) and in the middle of the quarter (second table) and looked for trends in differences from one season to the next one over these four decades.

Extent [mio km²]            
   March 31   June 30   Sep 30   Dec 31
80s   15,22   11,14   7,76           13,84
90s   14,83   10,48   7,10           13,48
00s   14,24     9,75   5,94           12,88
10s   13,94     8,95   4,95           12,35
Gains (+) and losses (-) [mio km²]            
80s   +1,38      -4,08   -3,38   +6,08
90s   +1,35   -4,35   -3,38   +6,38
00s   +1,36   -4,49   -3,81   +6,94
10s   +1,59   -4,99   -4,00   +7,40
            
Extent [mio km²]            
   Feb 15   May 15   Aug 15   Nov 15
80s   15,32   13,27   7,88           11,00
90s   14,96   12,87   7,24           10,54
00s   14,43   12,43   6,33             9,91
10s   13,84   11,99   5,40            9,26
Gains (+) and losses (-) [mio km²]            
80s   +4,32   -2,05   -5,39   +3,12
90s   +4,42   -2,09   -5,63   +3,30
00s   +4,52   -2,00   -6,10   +3,58
10s   +4,58   -1,85   -6,59   +3,86

From these values I see the sharp decrease in the melting over summer (July/Aug) in the latest decade, but also a pronounced increase in winter and early spring, and - surprisingly - a pronounced slower melting in the period between Feb 15 and May 15 in the latest decade. This is in line with the actual observations of a "slightly slower than average" decrease of sea ice extent in the last weeks.
The generally lower maximum (supposedly more in the periphery than in the CAB) could explain this behaviour (when less ice is available in the more peripherical parts which gain sun and warmth at first then the melting starts a little earlier).
The much lower minima in September also lead to a stronger increase towards the winter which explains the higher gains in the latest decade (compared to the earlier ones).

Just some points to discuss...

kind regards from Germany.


Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on May 29, 2018, 05:11:12 AM
This helps me understand why the recent losses in extent can be so sluggish at a time when recent high pressure systems have been hovering around and over the CAB, mainly towards the Pacific side, and storms and warm waters have been going to work on the Atlantic side.  Thank you. (And thank you gerontocrat for your graphs on this subject -- they got me thinking).

There is no need to suspect, as Worldview comes in handy. These are not melt ponds with their telltale bluish tinge. When leads open between floes, as is happening in mass in the Beaufort, sea ice concentration goes down. But with NSIDC's large grid of roughly 25 x 25 km, when concentration remains above 15% you get full extent but a reduction in area. Area is a leading indicator of extent at this time of year. Melt ponds and wet snow have much more influence in June-August.
Note: posting this here because of the data discussion. Can be developed further in the melting season thread.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 29, 2018, 05:47:16 AM
[ADS-NIPR-JAXA] ASI Extent.

May 28th, 2018: 11,018,676 km2, a drop of -29,653 km2.
2018 is the second lowest on record.
2018 has 441,245 km2 more than 2016 and 47,283 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 29, 2018, 02:15:01 PM
NSIDC Total Area as at 28 May (5 day trailing average)  10,170,053 km2

The first table attached shows how area loss has switched to lower in the peripheral seas and much higher in the Central Seas and is maintaining a 50+k km2 loss per day.

Pacific Side
- The Okhotsk Sea area is down to 35k km2, well under 5% of historical average maximum, daily - loss has slowed to 1 to 2k and is more or less irrelevant.
- The Bering Sea area is 4k, and is irrelevant (except to see for how long the vestiges of ice will persist).
- Chukchi and Beaufort Sea losses are modest.

Atlantic Side

- Area loss in the Baffin, Greenland, and Barents Seas seems to have slowed somewhat. Area loss on the last two days was a mere 9k.
- The Laptev Sea lost another 16k on the 28th May, nearly  half the loss of the Central seas.
- The Kara Sea is steadily losing area.
- Other Central Seas area loss is minimal.

Other seas
- St Lawrence continues to hang on to its area of 13k,
- Hudson Bay area loss was 9k per day in the last two days.

GFS from cci-reanalyzer.org shows  there is a believable significant influx of warm air from the Russian side happening now and in the next few days, and warmth looks as if it will continue to hit the southern half of Hudson Bay as well.

GFS continues to predict loads of warmth over most of the Arctic starting in about 7 days. They need a new crystal ball?
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 30, 2018, 05:47:29 AM
[ADS-NIPR-JAXA] ASI Extent.

May 29th, 2018: 10,979,066 km2, a drop of -39,610 km2.
2018 is still the second lowest on record.
2018 has 454,224 km2 more than 2016 and only 18,593 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 30, 2018, 10:05:13 AM
JAXA Extent 10,979,066 km2(May 29, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 2.91 million km2, now 80k below the average for the last 10 years. Consistently slightly slower than average daily melt.
- 2017 was a slow year also, hence 2018 extent is still 369k (3.4%) below 2017,
- 2012 extent was 616k km2 more than 2018 on this date and yet still ended up with a record low by a bit more than 800,000 km2. We are approaching the time (2nd week of June) when 2012 extent loss started to accelerate.
- 2007 has a similar story - extent 589k more than 2018 on this date but melt accelerated later in the season.
- on average 30% of the melting is done for this season - still a long way to go,

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.17 million km2 as opposed to 4.01 million km2. The range of outcomes from the last 10 years remaining melt is 2.56 to 4.47 million km2.

I am willing to believe GFS (from cci-reanalyzer) as far as Saturday (but no further), that shows large areas of the Arctic getting a dose of real warmth increasing from today onwards. Perhaps a burp upwards in melting?
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on May 31, 2018, 05:50:18 AM
[ADS-NIPR-JAXA] ASI Extent.

May 30th, 2018: 10,915,129 km2, a drop of -63,937 km2.
2018 is still the second lowest on record.
2018 has 434,439 km2 more than 2016 and 22,971 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 31, 2018, 12:21:45 PM
JAXA Extent 10,915,129 km2(May 30, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 2.98 million km2, now 60k below the average for the last 10 years. Consistently slightly slower than average daily melt.
- 2017 was a slow year also, hence 2018 extent is still 368k (3.4%) below 2017,
- 2012 extent was 600k km2 more than 2018 on this date and yet still ended up with a record low by a bit more than 800,000 km2. We are swiftly approaching the time (2nd week of June) when 2012 extent loss started to accelerate.
- 2007 has a similar story - extent 594k more than 2018 on this date but melt accelerated starting in June,
- on average 30.5% of the melting is done for this season - still a long way to go,

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.15 million km2 as opposed to 3.99 million km2. The range of outcomes from the last 10 years remaining melt is 2.58 to 4.45 million km2.

I am willing to believe GFS (from cci-reanalyzer) as far as Sunday (but no further), that still  shows large areas of the Arctic getting a dose of real warmth increasing from today onwards (http://cci-reanalyzer.org/wx/fcst/#gfs.arc-lea.t2). Perhaps a burp upwards in melting of which the 64k on 30th May is the first instalment?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 31, 2018, 03:17:05 PM
NSIDC Total Area as at 30 May (5 day trailing average)   10,030,069 km2

The first table attached shows how area loss has switched to lower in the peripheral seas and much higher in the Central Seas and total area lost an impressive 75k.

Pacific Side
- The Okhotsk Sea area is down to 33 k km2, well under 5% of historical average maximum, daily - loss has slowed to 1 to 2k and is more or less irrelevant.
- The Bering Sea area is 4k, and is irrelevant (except to see for how long the vestiges of ice will persist).
- Chukchi and Beaufort Sea losses are modest but consistent.

Atlantic Side

- Area loss in the Baffin, Greenland, and Barents Seas increased to 16 k on the last day.
- The Laptev Sea lost reduced to 8k.
- The Kara Sea is steadily losing area.
- Other Central Seas area loss is going up - a gain 0f 15k on the last day.

Other seas
- St Lawrence has increased area to 16k,
- Hudson Bay area loss has accelerated to 25k on the last day.

GFS from cci-reanalyzer.org shows  there is a believable significant influx of warm air from the Russian side happening now and in the next few days, and warmth looks as if it will continue to hit the southern half of Hudson Bay as well.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 31, 2018, 06:06:59 PM
NSIDC Area - Leaders and Laggards of ice loss by each regional sea

Explanatory Note:-

When you look at these graphs you may wonder why I am not using the super graphs from https://sites.google.com/site/arcticseaicegraphs/regional as provided by Wipneus.

Two reasons ;-
- unless I expand them they are too small for my aged eyes (I kid you not),
- they only have recent years.

I developed these graphs so I could see 'em, and to look at the current year in comparison with  10 year averages from the 80s, 90s 00s, and the 2010's to date (2010 to 2017). This tells me if the current year is likely (or not) to drag down the 2010's average area and also give an idea of trends in ice-free days (5%, 15% and 50%).

So here goes (this may take a few days).

1) Okhotsk and Bering.
Both are more or less melted out.

The Bering from the beginning of the year has looked like a very different sea from previous years. The maximum extent was less than 50 percent of average maximum, and area went to less than 5% of that maximum by the end of April, more than a month before the 2010's average.
Is that the sign of things to come, or will the sea ice recover?

The Okhotsk started late (it was very cold there early in the season), but finished early, area went to less than 5% of the average maximum by 20th May, some two weeks+ before the 2010's average. The Okhotsk is therefore likely to also be ice-free for more days this year than the 2010's average. Definitely a leader, but not yet kaput.

1) Leaders 2, Laggards Nil

2) Chukchi and Beaufort Seas

The Chukchi is a leader and looks set to continue the increase in ice-free days.
The Beaufort  is a laggard- I think I read from the melting season thread that last year it gained a lot of thick stuff. Will it catch up ?

2) Leaders 1, Laggards 1

c.fwd to next post Leaders 3, Laggards 1
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on May 31, 2018, 06:30:13 PM
"Beaufort is a laggard", but only by about 75,000Km2.

That's not a lot to make up.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 31, 2018, 06:34:13 PM
"Beaufort is a laggard", but only by about 75,000Km2.

That's not a lot to make up.
No predictions - simply what is at 30th May. (A-team has posted in the melting season thread a super 31 day animation of ice in the Amundsen Gulf - and something is certainly afoot on the Pacific side).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 31, 2018, 07:03:20 PM
NSIDC Area - Leaders and Laggards of ice loss by each regional sea (continued)

Explanatory Note:
I developed these graphs to look at the current year in comparison with  10 year averages from the 80s, 90s 00s, and the 2010's to date (2010 to 2017). This tells me if the current year is likely (or not) to drag down the 2010's average area and also give an idea of trends in ice-free days (5%, 15% and 50%).
-------------
3) Baffin, Greenland and Barents

Baffin - laggard, it has been really cold in that part of Canada,
Greenland - leader, but very little new ice from Fram export.
Barents - laggard, due to big area increase March & April.

3) Leaders 1, Laggards 2

b.fwd from last post Leaders 3, Laggards 1,

c.fwd to next post    Leaders 4, Laggards 3
Title: Re: 2018 sea ice area and extent data
Post by: oren on May 31, 2018, 08:28:35 PM
Gerontocrat, thank you for these wonderful graphs and analysis. Just wanted to throw a quick word on Wipneus' regional charts, they are showing AMSR2 data, with much better resolution than NSIDC, and using Wip's "home brew" algorithm for filtering all kinds of wrong stuff from the data. So indeed unsuitable for your purposes due to lack of long history and due to being incompatible with NSIDC, but very useful for comparing recent years.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on May 31, 2018, 09:22:05 PM
Just wanted to throw a quick word on Wipneus' regional charts, they are showing AMSR2 data, with much better resolution than NSIDC, and using Wip's "home brew" algorithm for filtering all kinds of wrong stuff from the data. So indeed unsuitable for your purposes due to lack of long history and due to being incompatible with NSIDC, but very useful for comparing recent years.

It's a case of "horses for courses".  Always a shame when you can't go backwards and use the new technology / software etc on the older data. But for the purpose I am using the graphs for - a longer-term view, the NSIDC data is more than OK.

And we should not complain - but be very thankful for - that the  USAF coughed up the loot to put the satellites up there as far back as 1979 and let NSIDC et al have access to the data.

Will that beneficial synergy survive in today's USA ? Hope so.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 01, 2018, 06:08:32 AM
[ADS-NIPR-JAXA] ASI Extent.

May 31st, 2018: 10,891,345 km2, a drop of -23,784 km2.
2018 is the third lowest on record.
2018 has 464,301 km2 more than 2016 and 12,774 km2 more than 2015.

It is interesting to note that 2016, 2015 and 2018 are so low in values, that the fourth lowest is the 2010's average published by ADS NIPR. And 2018 is 254,489 km2 less than 2010's average.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on June 01, 2018, 06:21:21 AM
I expect an unspectacular decline in May due to the lack of ice in the Bering with the extent being somewhere near the 2015 (10.8-11.0M) figure by May 31st.   

I think I nailed it! Only a 13K difference according to Jaxa.   May be the only time though.
Title: Re: 2018 sea ice area and extent data
Post by: Brigantine on June 01, 2018, 07:31:09 AM
the fourth lowest is the 2010's average published by ADS NIPR. And 2018 is 254,489 km2 less than 2010's average.
To clarify - that's the 2010-2017 average right? 2018 data hasn't been included in the average yet?
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on June 01, 2018, 09:15:40 AM
the fourth lowest is the 2010's average published by ADS NIPR. And 2018 is 254,489 km2 less than 2010's average.
To clarify - that's the 2010-2017 average right? 2018 data hasn't been included in the average yet?
No that average includes 2018, if you  leave 2018 out, 2011 scrapes in below the average and 2010 just  misses out.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 01, 2018, 11:08:39 AM
JAXA Extent 10,891,345 km2(May 31, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.00 million km2, now 100k below the average for the last 10 years. Consistently slightly slower than average daily melt.
- 2017 was a slow year also, hence 2018 extent is still 320k (2.9%) below 2017,
- 2012 extent was 590k km2 more than 2018 on this date and yet still ended up with a record low by a bit more than 800,000 km2. We are swiftly approaching the time (2nd week of June) when 2012 extent loss started to accelerate.
- 2007 has a similar story - extent 580k more than 2018 on this date but melt accelerated starting in June,
- on average 31% of the melting is done for this season - still a long way to go,

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.19 million km2 as opposed to 4.03 million km2. The range of outcomes from the last 10 years remaining melt is 2.6 to 4.5 million km2.

i was surprised by the May 31 small extent drop. But I am still willing to believe GFS (from cci-reanalyzer) as far as Monday (but no further), that still  shows large areas of the Arctic getting a dose of real warmth increasing from today onwards.

Perhaps a burp upwards in melting will happen, perhaps not.

ps: On May 31 Arctic Sea Ice extent became lower than Antarctic Sea Ice Extent.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 01, 2018, 12:06:03 PM
NSIDC Area - Leaders and Laggards of ice loss by each regional sea (continued)

4) Kara and Laptev Seas

Kara - laggard, extremely so.
Laptev - leader, very much so.

4) Leaders 1, Laggards 1

b.fwd from last post Leaders 4, Laggards 3

c.fwd to next post    Leaders 5, Laggards 4

_____________________________________
Explanatory Note:
I developed these graphs to look at the current year in comparison with  10 year averages from the 80s, 90s 00s, and the 2010's to date (2010 to 2017). This tells me if the current year is likely (or not) to drag down the 2010's average area and also give an idea of trends in ice-free days (5%, 15% and 50%).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 01, 2018, 12:11:50 PM
NSIDC Area - Leaders and Laggards of ice loss by each regional sea (continued)

5) East-Siberian, Canadian Archipelago, CENTRAL ARCTIC

East-Siberian - not started yet,
Canadian Archipelago -- not started yet,

CENTRAL ARCTIC The most important as when it goes, so does the Arctic Ocean. And it is a leader. Look at the last graph and tell me the Arctic Sea Ice is not heading for oblivion at least in summer.

5) Leaders 1, Laggards 0, Non-Players 2

b.fwd from last post Leaders 5, Laggards 4

c.fwd to next post    Leaders 6, Laggards 4, Non-players 2

_____________________________________
Explanatory Note:
I developed these graphs to look at the current year in comparison with  10 year averages from the 80s, 90s 00s, and the 2010's to date (2010 to 2017). This tells me if the current year is likely (or not) to drag down the 2010's average area and also give an idea of trends in ice-free days (5%, 15% and 50%).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 01, 2018, 05:22:59 PM
NSIDC Area - Leaders and Laggards of ice loss by each regional sea (continued)

6) Hudson Bay and St Lawrence

Both are oddities.

Hudson Bay, despite its relatively low latitude (about 55 to 65) it is late to start. Damn cold for damn long in that part of Canada - not called "The Barrens" for nothing. Brrrr. High snow-fall and persistent cold meant a late start to melting (pace bbr 2314). Now catch-up taking place but still a laggard.

St Lawrence, at just 48 degrees north, is the smallest Arctic sea, a maximum of 150,000 km2 of sea ice. So it is sort of insignificant. It was slow to start melting due to the high snowfall and persistent cold, got ahead of the game and has now stalled at just over 10k sea ice area, i.e. a non-player.


6) Leaders 0, Laggards 1, Non-Players 1

b.fwd from last post Leaders 6, Laggards 4, Non-players 2

Overall Totals    Leaders 6, Laggards 5, Non-players 3

But of them all, I guess that in the end what happens to the Central Arctic perhaps matters most.

You won't see this exercise again for some time - too much like hard work
_____________________________________
Explanatory Note:
I developed these graphs to look at the current year in comparison with  10 year averages from the 80s, 90s 00s, and the 2010's to date (2010 to 2017). This tells me if the current year is likely (or not) to drag down the 2010's average area and also give an idea of trends in ice-free days (5%, 15% and 50%).
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on June 01, 2018, 06:22:20 PM
NSIDC Area - Leaders and Laggards of ice loss by each regional sea (continued)

6) Hudson Bay and St Lawrence

Both are oddities.

Hudson Bay, despite its relatively low latitude (about 55 to 65) it is late to start. Damn cold for damn long in that part of Canada - not called "The Barrens" for nothing. Brrrr. High snow-fall and persistent cold meant a late start to melting (pace bbr 2314). Now catch-up taking place but still a laggard.

St Lawrence, at just 48 degrees north, is the smallest Arctic sea, a maximum of 150,000 km2 of sea ice. So it is sort of insignificant. It was slow to start melting due to the high snowfall and persistent cold, got ahead of the game and has now stalled at just over 10k sea ice area, i.e. a non-player.


6) Leaders 0, Laggards 1, Non-Players 1

b.fwd from last post Leaders 6, Laggards 4, Non-players 2

Overall Totals    Leaders 6, Laggards 5, Non-players 3

But of them all, I guess that in the end what happens to the Central Arctic perhaps matters most.

You won't see this exercise again for some time - too much like hard work
_____________________________________
Explanatory Note:
I developed these graphs to look at the current year in comparison with  10 year averages from the 80s, 90s 00s, and the 2010's to date (2010 to 2017). This tells me if the current year is likely (or not) to drag down the 2010's average area and also give an idea of trends in ice-free days (5%, 15% and 50%).

I think Kara is equally odd, and the situation there seems similar to Hudson Bay as well (relatively low latitude, but anomalous snowcover this year!)

The May pause in NA's SWE volume #s is even more bizarre, but probably the reason this is happening (IMO).

(https://ccin.ca/home/sites/default/files/snow/snow_tracker/plot_anom_sdep.png)

You can see that both Hudson and Kara are still benefitting from anomalous pack/adjacent land with very high albedo relative to normal. SWE hemispherically is over 2X normal, but the key holdout areas that aren't full of 10K'+ mountains are adjacent to Hudson, and the Kara.

(https://ccin.ca/home/sites/default/files/snow/snow_tracker/nh_swe.png)

This is not to drag the thread OT into snowcover, it is merely to state X reason why Y outcome seems to be occurring. With anomalies now worsening again, perhaps June will prove even more bizarre -- the stage certainly seems to be set for worsening high-latitude ice melt, while HB/Kara see general weather that is much more favorable to preservation of ice.

I think that as we head deeper into summer, this will inevitably end, but the problem is that June is the month that the High Arctic normally needs shielding the most -- the fact that it will bear the brunt of both continental and oceanic heat, instead of the peripheral seas, could setup a late-summer extent/area cliff as HB/Kara eventually melt out anyways.

Bringing the convo back to ice-specific data, Hudson Bay's current area is the highest in 25 years, with the exception of 2014.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fice-glaces.ec.gc.ca%2Fprods%2FCVCHDCTHB%2F20180528180000_CVCHDCTHB_0010055351.gif&hash=58b9c30c20904ee8172cd68da6b2d404)

Furthermore, it looks like current area anomalies versus 1981-2010 normals are focused in Baffin, not Hudson. I would think the reds in Hudson are due to persistent NW'erly cold winds partially derived from the anomalous snowcover in Nunavut. This has had the effect of thickening most of the ice, while leaving a few bare batches.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fice-glaces.ec.gc.ca%2Fprods%2FWIS54DPTCT%2F20180528180000_WIS54DPTCT_0010055308.gif&hash=b537dc8805f05be855ac5298fe7a3fd8)

It may take another few weeks, but I would bet that by early July, we will see some very impressive positive area anomalies across both Hudson and Baffin.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fice-glaces.ec.gc.ca%2Fprods%2FWIS54SD%2F20180528180000_WIS54SD_0010055301.gif&hash=2a52c6414a4890eb95e327e4997ac6a8)
Title: Re: 2018 sea ice area and extent data
Post by: ghoti on June 01, 2018, 07:36:19 PM
I'd love to see the effect of Alberto on Hudson Bay - it just brought rain there but World View just shows the associated cloud cover.

I'd expect we could see what looks like melt ponds at least on the James Bay part. Though rain might just e hidden by snow cover.
Title: Re: 2018 sea ice area and extent data
Post by: Sebastian Jones on June 01, 2018, 07:59:35 PM
I'd love to see the effect of Alberto on Hudson Bay
The seven day Environment Canada forecast for Moosonee, at the edge of James Bay, calls for mostly sunny and temperatures in the double digits. I expect that there will indeed be melt ponds- and general melting. https://weather.gc.ca/city/pages/on-113_metric_e.html (https://weather.gc.ca/city/pages/on-113_metric_e.html)
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on June 01, 2018, 09:47:12 PM
NSIDC Area - Leaders and Laggards of ice loss by each regional sea (continued)

[...]

Very well done, gerontocrat. Thanks a million!
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 02, 2018, 05:49:18 AM
[ADS-NIPR-JAXA] ASI Extent.

June 1st, 2018: 10,820,711 km2, a drop of -70,634 km2.
2018 is the second lowest on record again.
2018 has 415,625 km2 more than 2016 and 25,074 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on June 02, 2018, 06:15:43 AM
2018 Quickly regains its presumptive second ranking and enters a month where the two leading years 2015 and 2016 have very low melt rates. If 2018 keeps up its dogged decline who knows where it will be by the end of the month. Looking at the IJIS record a decline of at least 2M seems probable putting 2018 well ahead by July 1st.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 03, 2018, 06:11:13 AM
It seems that we will not have ADS NIPR JAXA data today…  :'(
You can try it yourself. Good luck!

https://ads.nipr.ac.jp/vishop/#/extent (https://ads.nipr.ac.jp/vishop/#/extent)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 03, 2018, 02:51:25 PM
NSIDC Total Area as at 2nd June (5 day trailing average)  9,855,689 km2

Area loss at around 60k per day for the last 3 days
Pacific Side
- The Okhotsk Sea area is down to 26 k km2, well under 5% of historical average maximum, daily - loss has slowed to 1 to 2k and is more or less irrelevant.
- The Bering Sea area is 5k, and is irrelevant (except to see for how long the vestiges of ice will persist).
- Chukchi and Beaufort Sea losses are modest but consistent. - Pacific warmth surely must hit these seas over the next few days.
Atlantic Side

- Area loss in the Baffin, Greenland, and Barents Seas increased to 27 k on the last day.
- The Laptev Sea lost reduced to 8k.
- The Kara Sea is steadily losing area.
- Other Central Seas area loss is going up - a loss of 18k on the last day, mostly in the ESS and Central Arctic (see graph).

Other seas
- St Lawrence is at least losing ice, down to 11k,
- Hudson Bay area loss is significant.

GFS from cci-reanalyzer.org still shows  there is a believable significant influx of warm air from Eastern Russia and the Pacific Ocean happening now and in the next few days, and warmth looks as if it will continue to hit the southern half of Hudson Bay as well.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 03, 2018, 11:55:16 PM
Worldview confirms what AMSR2 hints ... the north Kara Sea is now a bowl of ice cubes.   The first image is a bit hazy in places, so I magnified the hazy portion, and played with the contrast to produce the second image.  The field of ice floes go from the Russian coast all the way out towards Franz Josef Land (and from there it is open ocean to Svalbard).  Maybe there is a little refreezing in there, but that can't last long.
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on June 04, 2018, 03:18:21 AM
Worldview confirms what AMSR2 hints ... the north Kara Sea is now a bowl of ice cubes.   The first image is a bit hazy in places, so I magnified the hazy portion, played with the contrast and the broken floes all the way out towards Svalbard are clearly visible.  Maybe there is a little refreezing in there, but it can't last long.

a good example to illustrate that extent number don't tell the whole story and j can see that area as well does not entirel mirror the poor state of the ice once the gaps in the ice are to small for sensor resolution
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 04, 2018, 05:56:42 AM
[ADS-NIPR-JAXA] ASI Extent.

Day             Extent            Drop
June 1st    10,820,711   
June 2nd   10,736,166     -84,545
June 3rd   10,691,716     -44,450


June 3rd.
2018 is the second lowest on record.
2018 has 340,996 km2 more than 2016 and 61,344 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 04, 2018, 07:44:49 AM
On behalf of all, thank you again JCG and grntc for your timely data updates.
Title: Re: 2018 sea ice area and extent data
Post by: Lord M Vader on June 04, 2018, 08:55:20 AM
Sorry Juan CG, but we it should be second lowest for June 3......

Thank you for posting and updating us about the SIE in Arctic :)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 04, 2018, 12:31:08 PM
JAXA Extent 10,691,716 km2(June 3, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.20 million km2, down to 50k below the average for the last 10 years. Consistently slightly slower than average daily melt.
- 2017 was a slow year also, hence 2018 extent is still 331k (3.0%) below 2017,
- 2012 extent was 662k km2 more than 2018 on this date and yet still ended up with a record low by a bit more than 800,000 km2. We are swiftly approaching the time (2nd week of June) when 2012 extent loss started to accelerate.
- 2007 has a similar story - extent 652k more than 2018 on this date but melt accelerated starting very soon,
- on average 33% of the melting is done for this season - still a long way to go,

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.14 million km2 as opposed to 3.97 million km2. The range of outcomes from the last 10 years remaining melt is 2.5 to 4.4 million km2.

GFS (from cci-reanalyzer) still  shows large areas of the Arctic getting a dose of real warmth increasing from today onwards. I am surprised that the effect on extent loss data is not obvious yet.

Perhaps a burp upwards in melting will happen, perhaps not.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 04, 2018, 06:52:41 PM
The Central Arctic Sea shows the most dramatic difference between Area and Extent loss. Here it is. (NSIDC data)
Title: Re: 2018 sea ice area and extent data
Post by: Buddy on June 04, 2018, 08:13:19 PM
With the CAB being attacked from three sides (Atlantic, Pacific, and “the hole” off the central Russian coast) ....  another new record low in ice at the end of the season becomes more probable.  The next week of warmth along the central and eastern Russian coast will not help things as well ...
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 05, 2018, 05:59:32 AM
On behalf of all, thank you again JCG and grntc for your timely data updates.
You are welcome, Oren.
I am glad to contribute on this Forum. I have learn a lot and it also matters to me a lot!  ;)


[ADS-NIPR-JAXA] ASI Extent.

June 4th, 2018: 10,649,695 km2, a drop of -42,021 km2.
2018 is the second lowest on record.
2018 has 295,438 km2 more than 2016 and 39,273 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 05, 2018, 10:43:06 AM
Thanks for the thanks about these posts, not entirely deserved as I am feeding my own curiosity about these events by doing the analysis.

JAXA Extent 10,649,695 km2(June 4, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.24 million km2, down to 40k below the average for the last 10 years. Consistently slightly slower than average daily melt.
- 2017 was a slow year also, hence 2018 extent is still 346k (3.0%) below 2017,
- 2012 extent was 703k km2 more than 2018 on this date and yet still ended up with a record low by a bit more than 800,000 km2. We are swiftly approaching the time (2nd week of June) when 2012 extent loss started to accelerate.
- 2007 has a similar story - extent 637k more than 2018 on this date but melt accelerated starting very soon,
- on average 33% of the melting is done for this season - still a long way to go, on average 100 days.

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.14 million km2 as opposed to 3.97 million km2. The range of outcomes from the last 10 years remaining melt is 2.5 to 4.4 million km2.

GFS (from cci-reanalyzer) still  shows large areas of the Arctic getting a dose of real warmth increasing from today onwards.

I am surprised that the effect on extent loss data is not obvious yet. Perhaps the effect on the seas in the CAB is more a case of thinning, fracturing and opening of leads rather than larger areas of open water at less than 15% ice covered apearing. Perhaps a burp upwards in area loss will show up first, perhaps not. But something has got to give way - see temp map for tomorrow.
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on June 05, 2018, 02:42:38 PM
This Greenland Sea situation starts to look like it could be called the Icy Atlantic and not anymore Exit of Arctic Ocean. Thanking gerontocrat too, having done some reports of the whole Arctic on one earlier year I know it's not just adding the numbers to appropriate columns, graphing them again etc. Big hand for these border sea graphs.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 05, 2018, 03:46:11 PM
The Greenland sea situation is extreme indeed, but not totally unique. 2016 was quite similar though a teeny bit higher, at least in terms of AMSR2 area.
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 05, 2018, 04:16:13 PM
Arctic Basin (Beaufort, Chukchi, ESS, Laptev and CAB) extent is lowest for the date. Area withholds, waiting for a June cliff.
Title: Re: 2018 sea ice area and extent data
Post by: Richard Rathbone on June 05, 2018, 10:48:36 PM
That interdecile range doesn't look right. I count what looks like a quintile (8) rather than a decile (4) worth of data lines below it on some dates.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 06, 2018, 05:49:16 AM
[ADS-NIPR-JAXA] ASI Extent.

June 5th, 2018: 10,585,063 km2, a drop of -64,632 km2.
2018 is the second lowest on record.
2018 has  231,748 km2 more than 2016 and 32,564 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 06, 2018, 07:32:32 AM
JAXA short term analysis - May 8th, 2018.

...
So, it is almost sure that 2018 will be the second lowest on record, at least on the following two weeks.

The interesting question is where 2018 will be on June 10th, when the years 2010, 2011, 2012, 2015 and 2017 are even, on the second lowest on record position, while 2016 starts to lose the first lowest on record position.
JAXA short term analysis - June 5th, 2018.

Until today, 2018 manage to be the second lowest on record almost every day (just one day it was the third lowest).

What will happen now?

We have reach the point where the two competences (2016 and 2015) stall at the same time. The average daily drop for 2015 for the next seven days is -22.8K km2 and for 2016 is -31.8K km2.

On the other hand, it is the time when 2012 start to lose extent at a high speed. On average, 2012 had 130.5K km2 daily drops on the following 8 days!  A total of 1,043,983 km2!  :o So, even that 2012 is not the leader at the end of these 8 days, it starts to be the competence that we should follow.

So, what do I expect?

There is a lot of heat in the Arctic today, so I don’t think that 2018 will stall, like 2015 and 2016 did. So, 2018 could become the first lowest on record around June 14th, when we have the lowest average daily record drop (-59K km2) to match 2016.

           <------------ Daily Drop ------------->    Avg. Daily Drop
Date   Drop 2015   Drop 2016   Drop 2012   2018 to match 2016
June 6     -28.3            -20.2            -95.3            252.0
June 7       -0.5            -35.3          -144.6            143.6
June 8        1.7            -19.1          -182.4            102.1
June 9       -2.3            -41.3          -152.6              86.9
June 10   -45.9            -47.0          -124.9              78.9
June 11   -36.5            -35.4          -102.2              71.7
June 12   -48.0            -24.4          -122.9              64.9
June 13   -55.1            -29.9          -119.1              60.6
June 14   -65.5            -46.4            -58.0              59.0
June 15   -53.5            -60.6            -31.3              59.1
June 16   -76.3            -62.5            -71.6              59.4
June 17   -69.6            -60.5            -32.9              59.5
June 18   -27.0            -74.3            -53.9              60.7
June 19   -14.2            -65.3            -73.4              61.0
June 20     -9.7            -94.6            -96.2              63.2

Title: Re: 2018 sea ice area and extent data
Post by: oren on June 06, 2018, 07:44:06 AM
It seems 2018 is going to miss to the downside the June 11th "meeting point", unless the storm causes temporary dispersion. It could indeed be 1st on record if it doesn't stall.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 06, 2018, 09:17:36 AM
The 2018 trend line shouldn't stall in the next few days, and so it will shake off 2015. Somehow I don't feel it will go rogue after that, and should be close to the low years at the end of the month (2010, 2011, 2012, 2014 and 2016).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 06, 2018, 09:50:16 AM
JAXA Extent 10,585,063 km2(June 5, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.31 million km2, down to 40k below the average for the last 10 years. Consistently slightly slower than or at average daily melt.
- 2017 was a slow year also, hence 2018 extent is still 346k (3.0%) below 2017,
- 2012 extent was 682k km2 more than 2018 on this date and yet still ended up with a record low by a bit more than 800,000 km2. We are swiftly approaching the time (2nd week of June) when 2012 extent loss started to accelerate.
- 2007 has a similar story - extent 637k more than 2018 on this date but melt accelerated starting very soon,
- on average 34% of the melting is done for this season - still a long way to go, on average 100 days.

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.13 million km2 as opposed to 3.97 million km2. The range of outcomes from the last 10 years remaining melt is 2.5 to 4.4 million km2.

GFS (from cci-reanalyzer) still shows large areas of the Arctic having had, getting, and will get a dose of real warmth increasing from today onwards.

BUT - I am increasingly surprised that the effect on extent data is still not obvious yet. Perhaps the effect on the seas in the CAB is more a case of thinning, fracturing and opening of leads rather than larger areas of open water at less than 15% ice covered appearing.
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 06, 2018, 02:14:31 PM
That interdecile range doesn't look right. I count what looks like a quintile (8) rather than a decile (4) worth of data lines below it on some dates.

The percentiles are computed from the 1981-2010 period (WMO preferred climate standard, similar to what NSIDC uses). I will fix the legend next time.
Title: Re: 2018 sea ice area and extent data
Post by: Hautbois on June 06, 2018, 10:44:04 PM
Days in the bottom 3, cumulative, from January 1 to May 31.

By the end of May, 2018 had only had 6 days that weren't. And had also just overtaken 2012's total for the year.
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on June 06, 2018, 11:00:57 PM
Days in the bottom 3, cumulative, from January 1 to May 31.

By the end of May, 2018 had only had 6 days that weren't. And had also just overtaken 2012's total for the year.

that's it, the big picture that i like so much, can safe many petty discussion about daily and weekly ups and downs and ranks because they're absolutely irrelevant.

last but not least, this trend is so obvious and so strong, one could easily get afraid of what's gonna happen if that speed of development will keep up or even accelerate?

thanks of this especially for the idea.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 06, 2018, 11:25:36 PM
NSIDC has done the May analysis (http://nsidc.org/arcticseaicenews/)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 07, 2018, 05:43:25 AM
[ADS-NIPR-JAXA] ASI Extent.

June 6th, 2018:  10,518,855 km2, a drop of -66,208 km2.
2018 is the second lowest on record.
2018 has 185,748 km2 more than 2016 and 70,481 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on June 07, 2018, 04:11:49 PM
[ADS-NIPR-JAXA] ASI Extent.

June 6th, 2018:  10,518,855 km2, a drop of -66,208 km2.
2018 is the second lowest on record.
2018 has 185,748 km2 more than 2016 and 70,481 km2 less than 2015.
Looks like 2018 should go crashing through 2016 in the next few days as the cyclone accelerates this year past that year's June stall.
Title: Re: 2018 sea ice area and extent data
Post by: ArcticMelt1 on June 07, 2018, 11:16:20 PM
According ice extent in the Central Basin, June 2018 it stably comes first, with a big gap from the rest of the years since 2006.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 08, 2018, 05:48:21 AM
[ADS-NIPR-JAXA] ASI Extent.

June 7th, 2018: 10,482,795 km2, a drop of -36,060 km2.
2018 is the second lowest on record.
2018 has 184,983 km2 more than 2016 and 106,089 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 08, 2018, 10:40:26 AM
JAXA Extent 10,482,795 km2(June 7, 2018)

GFS (from cci-reanalyzer) still shows large areas of the Arctic having had, getting, and will continue to get a dose of real warmth. I am increasingly surprised that the effect on extent data is still not obvious yet. Perhaps the effect on the seas in the CAB is more a case of thinning, fracturing and opening of leads rather than larger areas of open water.

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.41 million km2, 60k below the average for the last 10 years. Consistently slightly slower than or at average daily melt.
- 2017 was a slow year also, hence 2018 extent is still 314k (3.0%) below 2017,
- 2012 extent was 544k km2 more than 2018 on this date and yet still ended up with a record low by a bit more than 800,000 km2. We are now in the time (2nd week of June) when 2012 extent loss accelerated.
- 2007 has a similar story - extent 647k more than 2018 on this date but melt accelerated starting very soon,
- on average 35% of the melting is done for this season - still a long way to go, on average 97 days.

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.14 million km2 as opposed to 3.99 million km2. The range of outcomes from the last 10 years remaining melt is 2.6 to 4.4 million km2.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 08, 2018, 03:05:07 PM
NSIDC Total Area as at 7th June (5 day trailing average)   9,552,410 km2

Area loss at around 60k per day for the last 5 days, now mostly in the Central Seas
Pacific Side
- The Okhotsk Sea area is down to 16 k km2, well under 5% of historical average maximum, daily loss <1k and is more or less irrelevant.
- The Bering Sea area is 1k, and is irrelevant (except to see for how long the vestiges of ice will persist).
- Chukchi and Beaufort Sea losses are modest but consistent. - Pacific warmth surely must hit these seas over the next few days.
Atlantic Side
- Area loss in the Baffin, Greenland, and Barents Seas in range 15 to 25 k per day.
- The Laptev Sea los increased to 19 k .
- The Kara Sea is lost 65 k area in the last 3 days  .
- Other Central Seas area loss has stalled.
Other seas
- St Lawrence has at last lost about all remaining ice in the last 5 days, area is <1k,
- Hudson Bay area loss is more than occasional days of gain.

GFS from cci-reanalyzer.org still shows  there is a believable significant influx of warm air from Eastern Russia and the Pacific Ocean happening now and in the next few days, and warmth looks as if it will continue to hit the southern half of Hudson Bay as well. We are having had this big cyclone - Kara Sea seems to be the place where it has a significant effect so far.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 08, 2018, 03:17:03 PM
The St Lawrence is interesting. No matter that area in winter is declining substantially over the years, the final collapse seems to be the first week in June regardless. The start of winter area gain seems also the same no matter what.
Title: Re: 2018 sea ice area and extent data
Post by: lanevn on June 08, 2018, 03:50:08 PM
The St Lawrence is interesting. No matter that area in winter is declining substantially over the years, the final collapse seems to be the first week in June regardless. The start of winter area gain seems also the same no matter what.

It's alwayse "false ice" near shores detectes and 1 June is probably day when they remove that region from calculations at all.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 08, 2018, 04:47:04 PM
The St Lawrence is interesting. No matter that area in winter is declining substantially over the years, the final collapse seems to be the first week in June regardless. The start of winter area gain seems also the same no matter what.

It's alwayse "false ice" near shores detectes and 1 June is probably day when they remove that region from calculations at all.
Nope

Date    Area km2
May   31    14,515
June   1    12,839
June   2    11,008
June   3    6,079
June   4    3,644
June   5    1,880
June   6    1,720
June   7    936
Title: Re: 2018 sea ice area and extent data
Post by: RoxTheGeologist on June 08, 2018, 05:53:58 PM
JAXA Extent 10,482,795 km2(June 7, 2018)

GFS (from cci-reanalyzer) still shows large areas of the Arctic having had, getting, and will continue to get a dose of real warmth. I am increasingly surprised that the effect on extent data is still not obvious yet. Perhaps the effect on the seas in the CAB is more a case of thinning, fracturing and opening of leads rather than larger areas of open water.



83 cm of rain at 1C to will melt 1 cm of ice, and the melting ice buffers the temperature of the water, and, that water at 0C, is fresh and floats. The latent heat of fusion of water soaks up an enormous amount of energy. The ice in the middle of the pack will thin and warm, but not lose extent. this is what Neven calls "Pre-conditioning" it accelerates the July and August extent losses.

Sea ice melts from the edges of the pack. The water at the edges of the pack is dark and heats up quickly, throughout the photic zone, and across a wide area. It is mixed with the ice at the edge of the pack, by wind or wave action, and by some night/day convection as the surface cools and sinks at night. I imagine the best conditions for ice to melt are sunny days with the ice being blown towards open water. I think understanding the mechanism of melt, that heat energy over a wide are of ocean is transferred to the point of melting is critical to understanding the rate of extent loss.

On the Atlantic side, I think A team has made a very good case that the boundary of the sea ice is determined by the bathymetry. The position is relatively stable. The relatively thick cold ice meets the warm dense Atlantic waters, There is enough warm water to melt the ice, and the melting ice cools the water, causing it to sink, a mechanism that tracks the shelf edge. Only when there isn't enough ice to cool the incoming waters will this boundary progress further into the Basin.


Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 08, 2018, 07:17:37 PM
Thanks for the explanation, Rox the Geologist.

So the question is, will the warmth, cyclones  (if they persist) lead to an unusually large extent/area loss later in the season ? Or is this still in the lap of the gods.
Title: Re: 2018 sea ice area and extent data
Post by: Ken Feldman on June 08, 2018, 09:52:10 PM
Quote
83 cm of rain at 1C to will melt 1 cm of ice

That would be a huge amount of rain anywhere (well, maybe not India during the monsoon season), much less the Arctic.  Here are some facts about the Arctic climate:

https://en.wikipedia.org/wiki/Climate_of_the_Arctic (https://en.wikipedia.org/wiki/Climate_of_the_Arctic)

Quote
The Arctic Basin is one of the driest parts of the Arctic. Most of the Basin receives less than 250 mm (9.8 in) of precipitation per year, qualifying it as a desert. Smaller regions of the Arctic Basin just north of Svalbard and the Taymyr Peninsula receive up to about 400 mm (16 in) per year (Serreze and Hurst 2000).

Monthly precipitation totals over most of the Arctic Basin average about 15 mm (0.59 in) from November through May, and rise to 20 to 30 mm (0.79 to 1.18 in) in July, August, and September (Serreze and Hurst 2000).
Title: Re: 2018 sea ice area and extent data
Post by: Ken Feldman on June 08, 2018, 10:31:29 PM
Here's a letter from Environmental Research Letters in 2014 discussing the climate of Svalbard, which is wetter than most of the Arctic:

http://iopscience.iop.org/article/10.1088/1748-9326/9/11/114021/pdf (http://iopscience.iop.org/article/10.1088/1748-9326/9/11/114021/pdf)

Quote
Daily amount of precipitation (measured once or twice
daily (at 0600/1800 h) and covering the previous 12/24 h
period) has been recorded continuously for multiple decades
at three manned weather stations in Spitsbergen (the largest
island on Svalbard, Stations 1–3, figure 1(a)): the small
research settlement Ny-Ålesund (population ∼30 year-round;
Norwegian Meteorological Institute, data available at http://
eklima.no), the Russian settlement of Barentsburg (population
∼435; data available at www.tutiempo.net/en/Climate/
BARENCBURG/07-1973/201070.htm), and Svalbard Airport.
At all three weather stations, several heavy rainfalls were
associated with the two-week warm spell (figure 1(c),
table 1). The most striking event was recorded in Ny-Ålesund
on January 30th when 98 mm rain fell (Tmax = 4.3 °C), which
had (prior to this event) a return period of >500 years following
the Norwegian manual for calculation of probable
extreme daily precipitation values (Førland 1992),

Note that the letter refers to 98mm as being a 500 year event.  That's about 1/10th of what someone asserted fell in this cyclone in a drier part of the Arctic.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 08, 2018, 11:43:04 PM
Off-Topic alert.  Reminding this is the extent and area thread.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 08, 2018, 11:46:35 PM
Off-Topic alert.  Reminding this is the extent and area thread.

Thanks, oren.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 09, 2018, 05:47:01 AM
[ADS-NIPR-JAXA] ASI Extent.

June 8th, 2018: 10,457,617 km2, a drop of -25,178 km2.
2018 is the second lowest on record.
2018 has 178,906 km2 more than 2016 and 132,929 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 09, 2018, 08:54:16 AM
JAXA Extent 10,457,617 km2(June 8, 2018)

GFS (from cci-reanalyzer) still shows large areas of the Arctic having had, getting, and will continue to get a dose of real warmth. I am even more surprised that the effect on extent data is still not obvious yet. Perhaps the effect on the seas in the CAB is more a case of thinning, fracturing and opening of leads rather than larger areas of open water. But when will all this apparently amazing weather show up in the extent data ? Perhaps it will not.

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.41 million km2, 60k below the average for the last 10 years. Consistently slightly slower than or at average daily melt, a very low 36k and 25k in the last 2 days.
- 2017 was a slow year also, but 2018 extent is a much reduced 261k (3.0%) below 2017,
- 2012 extent has dropped from 544k to 350k km2 more than 2018 on this date. We are now truly in the time (2nd week of June) when 2012 extent loss accelerated.
- 2007 has a similar story - extent 650k more than 2018 on this date but melt accelerated later than 2012,
- on average 35% of the melting is done for this season - still a long way to go, on average 96 days.

I have added a line on the first table to show the effect of removing 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.16 million km2 as opposed to 4.02 million km2. The range of outcomes from the last 10 years remaining melt is 2.8 to 4.4 million km2.
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 09, 2018, 03:02:10 PM
The storm has initiated the drop in area known as the "June cliff".
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 09, 2018, 04:30:00 PM
NSIDC Total Area as at 8th June (5 day trailing average)  9,475,797 km2

Area loss 77k, 57k in the Central Seas

Pacific Side
- The Okhotsk Sea area is 18 k.
- The Bering Sea area is 1k.
- Chukchi Sea - k, Beaufort Sea +1k.
Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 21k.
- The Laptev Sea area loss increased to 24 k .
- The Kara Sea area loss 16k.

- The Central Arctic Sea loss 20k.

Other seas
- St Lawrencearea is <1k,
- Hudson Bay area loss is more than occasional days of gain.

GFS from cci-reanalyzer.org still shows  there is a believable significant influx of warm air from Eastern Russia and the Pacific Ocean happening now and in the next few days, and warmth looks as if it will continue to hit the southern half of Hudson Bay as well.

See Wipneus graphs above re start of the June cliff
Title: Re: 2018 sea ice area and extent data
Post by: ArcticMelt1 on June 09, 2018, 09:26:55 PM
Over the past two days, the gap between 2018 and the remaining years has only increased.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 10, 2018, 05:49:31 AM
[ADS-NIPR-JAXA] ASI Extent.

June 9th, 2018: 10,412,759 km2, a drop of -44,858 km2.
2018 is the second lowest on record.
2018 has 175,390 km2 more than 2016 and 175,459 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 10, 2018, 10:54:16 AM
JAXA Extent 10,412,759 km2(June 9, 2018)

GFS (from cci-reanalyzer) still shows large areas of the Arctic having had, getting, and will continue to get a dose of real warmth. I am even more surprised that the effect on extent data is still not obvious yet. The effect is showing in area data, especially in the Central Seas.

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.48 million km2, 110k below the average for the last 10 years. Consistently slightly slower than or at average daily melt, a very low 36k and 25k and 44k in the last 3 days.
- 2017 was a slow year also, but 2018 extent is a much reduced 231k (2.2%) below 2017,
- 2012 extent has dropped from 350k to 279k km2 more than 2018 on this date. We are now truly in the time (2nd week of June) when 2012 extent loss accelerated.
- 2007 has a similar story - extent 686k more than 2018 on this date but melt accelerated later than 2012,
- on average 36% of the melting is done for this season - still a long way to go, on average 96 days.

Excluding 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.16 million km2 as opposed to 4.03 million km2. The range of outcomes from the last 10 years remaining melt is 2.9 to 4.4 million km2.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 10, 2018, 02:30:18 PM
NSIDC Total Area as at 9th June (5 day trailing average)   9,411,713 km2

Area loss 64k, 41k in the Central Seas

Pacific Side
- The Okhotsk Sea area is 18 k.
- The Bering Sea area is 2k.
- Chukchi Sea -7 k, Beaufort Sea +3k.
Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 23k.
- The Laptev Sea area loss 23 k .
- The Kara Sea area loss 9k.

- The Central Arctic Sea loss down from 20k to 2k.

Other seas
- St Lawrence area is <2k,
- Hudson Bay area loss is more than occasional days of gain.

No drama, really.
Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on June 10, 2018, 02:33:34 PM
Cyclones cause dispersion of ice. Stormy Junes are generally good for ice. Because this storm hit its max intensity over open water in the Barents sea it advected a warm sector over the Laptev sea causing warm offshore winds and melting so it doesn't fit the general mold of June storms. It very likely caused a large amount of melting. However, the dispersion it caused offset the drop in sea ice extent in the Laptev sea.

Any time there's a large shift in wind direction in the Arctic's melt season  the rate of decline in extent slows down.

Because of dispersion this warm storm caused a volume drop but not an extent drop.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 10, 2018, 03:48:26 PM
Several on the melting season thread (oren, subgeometer etc.) strongly agree with you.  Winds from the cyclone pushed mobile ice from the northern/eastern Kara into the Barents over the past few days, increasing extent while simultaneously making the ice more vulnerable to melting.  And subgeometer shows images of huge tendrils of melting ice north of Svalbard billowing out into the ocean, which probably also increase measured extent. 

So the extent data are somewhat deceptive right now, but of course still wholly valid for broad year-on-year comparisons.  If I had to bet on this, then I would say that extent is probably going to drop steeply in the near future, putting this year in 'first' place at some point in June.  I hope I am wrong, and who knows what will happen past that ... I certainly don't.

Cyclones cause dispersion of ice. Stormy Junes are generally good for ice. Because this storm hit its max intensity over open water in the Barents sea it advected a warm sector over the Laptev sea causing warm offshore winds and melting so it doesn't fit the general mold of June storms. It very likely caused a large amount of melting. However, the dispersion it caused offset the drop in sea ice extent in the Laptev sea.

Any time there's a large shift in wind direction in the Arctic's melt season  the rate of decline in extent slows down.

Because of dispersion this warm storm caused a volume drop but not an extent drop.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 11, 2018, 05:54:50 AM
[ADS-NIPR-JAXA] ASI Extent.

June 10th, 2018: 10,389,973 km2, a drop of -22,786 km2.
2018 is the second lowest on record.
2018 has 199,592 km2 more than 2016 and 152,322 km2 less than 2015.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 11, 2018, 10:49:43 AM
JAXA Extent 10,389,973 km2(June 10, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.50 million km2, 150k below the average for the last 10 years. Consistently slightly slower than or at average daily melt, a very low 36k and 25k and 44k and 23k in the last 4 days.
- 2017 was a slow year also, but 2018 extent is a much reduced 172k (1.6%) below 2017,
- 2012 extent has dropped from 279k to 177k km2 more than 2018 on this date. We are now truly in the time (2nd week of June) when 2012 extent loss accelerated.
- 2007 has a similar story - extent 696k more than 2018 on this date but melt accelerated later than in 2012,
- on average 37% of the melting is done for this season - still a long way to go, on average 96 days.

Excluding 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.19 million km2 as opposed to 4.07 million km2. The range of outcomes from the last 10 years remaining melt is 3.0 to 4.4 million km2.

GFS (from cci-reanalyzer) still shows large areas of the Arctic having had, getting, and will continue to get a dose of real warmth. Meanwhile extent loss for the last 4 days has been very much below average.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 11, 2018, 03:15:00 PM
NSIDC Total Area as at 10th June (5 day trailing average) = 9,349,082 km2

Area loss 63k, 42k in the Central Seas

Pacific Side
- The Okhotsk Sea area is 18 k.
- The Bering Sea area is 3k.
- Chukchi Sea -1 k, Beaufort Sea +1 k.
Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 17k.
- The Laptev Sea area loss 27 k .
- The Kara Sea area loss 4 k.

- The Central Arctic Sea loss 3k.
- The Canadian Archipelago - first significant loss of the season - 8k

Other seas
- St Lawrence area is <2k,
- Hudson Bay area loss is more than occasional days of gain.

No drama, really. But of note is -
- that area loss far exceeds extent loss in the Central Seas, while the opposite sometimes happens in the peripheral seas. In total, area loss is still consistently ahead of extent area loss. Whoops.

- the Laptev Sea Ice is disappearing fast.
Title: Re: 2018 sea ice area and extent data
Post by: Phil. on June 11, 2018, 06:03:08 PM
<em> In total, area loss is still consistently ahead of area loss.</em>?????
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 11, 2018, 07:08:19 PM
Ok, clever-clogs.

<em> In total, area loss is still consistently ahead of extent area loss.</em>?????

Title: Re: 2018 sea ice area and extent data
Post by: Hyperion on June 12, 2018, 03:04:34 AM
With warm and moist air flooding in off all continental coasts and strong winds flowing out into Atlantic and Pacific side kill zones the pack is sprawling outwards and big extent losses will no doubt shortly follow the big volume losses that are no doubt already in progress.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 12, 2018, 06:00:55 AM
[ADS-NIPR-JAXA] ASI Extent.

June 11th, 2018: 10,375,064 km2, a drop of -14,909 km2.
2018 is the second lowest on record.
2018 has 220,120 km2 more than 2016 and 90,032 km2 less than 2012 (Which appears for the first time).
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 12, 2018, 10:58:24 AM
JAXA Extent 10,375,064 km2(June 11, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.52 million km2, 180k below the average for the last 10 years. That is a significant amount. Consistently slightly slower than or at average daily melt, a very low 36k and 25k and 44k and 23k and now just 15kin the last 5 days.
- 2017 was a slow year also, but 2018 extent is a much reduced 127k (1.6%) below 2017,
- 2012 extent has dropped from 177k to just 90k km2 more than 2018 on this date. We are now truly in the time (2nd week of June) when 2012 extent loss accelerated.
- 2007 has a similar story - extent 684k more than 2018 on this date but melt accelerated later than in 2012,
- on average 37% of the melting is done for this season - still a long way to go, on average 96 days.

Excluding 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.22 million km2 as opposed to 4.11 million km2. The range of outcomes from the last 10 years remaining melt is 3.1 to 4.5 million km2.

GFS (from cci-reanalyzer) still shows large areas of the Arctic having had, getting, and will continue to get a dose of real warmth. Meanwhile extent loss for the last 5 days has been very very much below average.

Indeed, if one look at this extent data only for a view of the September minimum one would be thinking more like 4.5 million rather than circa 4.0 million km2 a week or two ago.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on June 12, 2018, 10:59:47 AM
[ADS-NIPR-JAXA] ASI Extent.
2018 has 220,120 km2 more than 2016 and 90,032 km2 less than 2012 (Which appears for the first time).

That's the first  time this year 2012 has appeared in the lowest three for the day. It currently has a total of 150 days in the lowest three compared to 2018's 154. 2018 can only increase its number from here while 2012 is likely to drop a few. 2018 currently has the third highest number in the top 3 behind 2016 (276) and 2017 (186).  2018 could catch 2017 (with 174 each) on July 1st.  2012 has only two century breaks left in this run before dropping back to an average rate of decline for the remainder of the month.  2018 needs to lose 152K in the next two days to retain second lowest place but we have seen it kick off when threatened before.

Still it is what happens in September that counts.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 12, 2018, 02:36:54 PM
An illustration of why for the Central Seas of the CAB especially area is so much better as an indicator of the reality.

I will be posting more on area later today - but wait small, biznis to do first. (Why is retirement so bloody busy?)
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 12, 2018, 02:54:52 PM
Terrific graph.  Shows as clearly as any other chart I have seen why looking at extent right now is not so useful.  The digression in trends since June 7 is quite dramatic.

Also, while that extent trend appears linear over this period, the area trend has an ominously exponential look to it... 
 

 
An illustration of why for the Central Seas of the CAB especially area is so much better as an indicator of the reality.

I will be posting more on area later today - but wait small, biznis to do first. (Why is retirement so bloody busy?)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 12, 2018, 04:36:21 PM
NSIDC Total Area as at 11th June (5 day trailing average) =  9,257,434 km2

Area loss 92k, 61k in the Central Seas Wow?
Pacific Side
- The Okhotsk Sea area is 18 k.
- The Bering Sea area is 3k.
- Chukchi Sea +2 k, Beaufort Sea 0 k.
Pacific side stalled...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 12k.
- The Laptev Sea area loss 27 k again  .
- The Kara Sea area loss 11 k.

- The Central Arctic Sea loss 13k.
- The Canadian Archipelago - 2nd significant loss of the season - 10k

Other seas
- St Lawrence area is <2k,
- Hudson Bay area loss 19k, but still well behind 2010's average area.

But of note is -
- that area loss far exceeds extent loss in the Central Seas (see above posting), while the opposite sometimes happens in the peripheral seas. In total, area loss is still consistently ahead of extent loss. .

- the Laptev Sea Ice is disappearing really fast.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 12, 2018, 04:45:43 PM
Time to rest the eyes from all those numbers a bit. Some area graphs.

Examples of leaders and laggards this melting season.
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on June 12, 2018, 07:27:57 PM
Maybe that enhanced area loss will soon become an enhanced extent loss when all these smaller ice packs along the border between open seas and the more or less compact CAB ice will melt out due to a higher surface to volume ratio?
I think the next two weeks should decide whether we will have another "slower" year as 2017 was or whether the whole thing speeds up and becomes more like 2016, 2007 or even 2012...
Title: Re: 2018 sea ice area and extent data
Post by: Buddy on June 12, 2018, 07:54:23 PM
FYI ..... ending Arctic sea ice EXTENT 1984 vs 2012..... and where we are NOW in CONCENTRATION (I know.... extent is NOT concentration).  The concentration shows a better highlight of where the ice will melt NEXT (the light blue areas show up as "white" on the extent).





Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 13, 2018, 06:28:43 AM
[ADS-NIPR-JAXA] ASI Extent.

June 12th, 2018: 10,378,230 km2, a small increase of 3,166 km2.
2018 is the third lowest on record and very close to the fourth lowest.

Lowest      Year         Extent       Difference
1st.         2016       10,130,495    -247,735
2nd.        2012       10,342,187      -36,043
4th.         2017       10,382,216         3,986

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 13, 2018, 10:25:38 AM
JAXA Extent 10,378,230 km2(June 12, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.51 million km2, 250k below the average for the last 10 years. That is a significant amount. Consistently slightly slower than or at average daily melt, a very low 36k, 25k, 44k, 23k and 15k in the last 5 days, and now an increase of 3k.
- 2017 was a slow year also, but 2018 extent now just 4k (0.0%) below 2017,
- 2012 extent has changed from 90k km2 to juts 36kmore than 2018 to on this date. We are now truly in the time (2nd week of June) when 2012 extent loss accelerated.
- 2007 has a similar story - extent 647k more than 2018 on this date but melt accelerated later in the season than in 2012,
- on average 38% of the melting is done for this season - still a long way to go, on average 96 days.

Excluding 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.28 million km2 as opposed to 4.18 million km2. The range of outcomes from the last 10 years remaining melt is 3.2 to 4.5 million km2.

All is confusion ?:- (I am confused, anyway)

On 11th June NSIDC daily area loss was 90k. I expect (ha-ha)something like that again for the 12th.

GFS (from cci-reanalyzer) still shows large areas of the Arctic having had, getting, and will continue to get a dose of real warmth.

Meanwhile extent loss for the last 5 days has been very, very much below average. Indeed, if one look at this extent data only for a view of the September minimum one would be thinking more like 4.5 million rather than circa 4.0 million km2 a week or two ago.

I recommend readers have a good long read of the melting season thread over the last few days - melting ponds / surface water confusing the area data? Ice spread out confusing the extent data?

Time will make things clearer but I think my choices for the June poll for the September minimum requires "Mystic Meg's" assistance urgently.
Title: Re: 2018 sea ice area and extent data
Post by: Brigantine on June 13, 2018, 10:58:24 AM
- Extent loss for the melting season to date is, at 3.51 million km2, 250k below the average for the last 10 years. That is a significant amount.
A whole bin!
Title: Re: 2018 sea ice area and extent data
Post by: Alexander555 on June 13, 2018, 01:20:10 PM
Maybe there is an explanation for the Jaxa data, that's about that 15 % cover. There is less ice than normal on the Bering side, and on the Atlantic side. The ice at the siberian side is thicker than normal. And the ice on the Greenland side is backed by a big chunk of ice. So that should be the last to go. And first you had that cyclon. And now the last few days the wind is blowing the ice further into the open ocean.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 13, 2018, 02:34:50 PM
AREA VS EXTENT

More than one post today as this area and extent variation is getting really interesting.

NSIDC Total Area      as at 12th June (5 day trailing average) =  9,167,062 km2
NSIDC Total EXTENT as at 12th June (5 day trailing average) = 10,959,702 km2


AREA     total loss 90k, 63k  loss in the Central Seas,  9 k loss in the periphery
EXTENT total loss 30k,   4k  gain in the Central Seas, 36 k loss in the periphery

See the graphs and the tables for a bit more history.

Extent loss is playing catch up in the peripheral seas.
Is Area loss in the Central Seas an exaggeration due to melt ponds?
Is Extent loss in the Central Seas under-recorded due to the 15% rule?

Lots of discussion in the melting season thread.
Perhaps Wipneus with the AMRS2 data will shed some light.

But this is the NSIDC data. Make of it what you will.


Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on June 13, 2018, 02:42:39 PM
By comparison, the sea ice area is looking healthier than the extent (based on historical data).  The area is only 5th lowest, compared to extent, which is 2nd lowest (based on NORSEX algorithm).  Although the extent looks like it will become 3rd or 4th lowest rather soon.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fweb.nersc.no%2FWebData%2Farctic-roos.org%2Fobservation%2Fssmi_ice_area.png&hash=d9d961f72b1feca6193f0ee22d92e48e)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fweb.nersc.no%2FWebData%2Farctic-roos.org%2Fobservation%2Fssmi1_ice_ext.png&hash=56a8baf5e4355602ef2f0104785f69e2)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 13, 2018, 03:38:44 PM
NSIDC Total Area  as at 12th June (5 day trailing average) =  9,167,062 km2


Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 18 k.
- The Bering Sea area is 3k.
- Chukchi Sea +1 k, Beaufort Sea -1 k.
i.e. Pacific side stalled...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 9k.
- The Laptev Sea area loss 29 k again  .
- The Kara Sea area loss 7 k.

CAB
- The Central Arctic Sea loss 8k.
- The Canadian Archipelago loss 13k.
- East Siberian Sea 5k

Other seas
- St Lawrence area is <3k,
- Hudson Bay area loss 18k, but still well behind 2010's average area.

But of note is -
- that area loss far exceeds extent loss in the Central Seas (see above posting), while the opposite sometimes happens in the peripheral seas. In total, area loss is still consistently ahead of extent loss. .

- the Laptev Sea Ice is disappearing really fast.
[/quote]
Title: Re: 2018 sea ice area and extent data
Post by: Lord M Vader on June 13, 2018, 05:09:41 PM
Daily NSIDC Extent reveals an UPTICK of +17K. How unusual is this during the months June-July when the melting is at its largest pace?
Title: Re: 2018 sea ice area and extent data
Post by: miki on June 13, 2018, 05:24:22 PM
Daily NSIDC Extent reveals an UPTICK of +17K. How unusual is this during the months June-July when the melting is at its largest pace?

Maybe it's just spreading a bit ?
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on June 13, 2018, 06:20:12 PM
[quote author3=Lord M Vader link=topic=2223.msg158597#msg158597 date=1528902581]
Daily NSIDC Extent reveals an UPTICK of +17K. How unusual is this during the months June-July when the melting is at its largest pace?
[/quote]
Dispersal could do this, especially considering how fragmented the ice is.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 13, 2018, 07:03:28 PM
[quote author3=Lord M Vader link=topic=2223.msg158597#msg158597 date=1528902581]
Daily NSIDC Extent reveals an UPTICK of +17K. How unusual is this during the months June-July when the melting is at its largest pace?
Dispersal could do this, especially considering how fragmented the ice is.
[/quote]
Add to this quite a fierce warming event on the Russian side - even more melting & dispersion. Presumably if that warmth continues it will start to appear in extent data in the next few days.

if not - I will stop making comment entirely and just post the data.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 13, 2018, 07:51:01 PM
Daily NSIDC Extent reveals an UPTICK of +17K. How unusual is this during the months June-July when the melting is at its largest pace?
Finally an easy question about arctic sea ice...
According to NSIDC extent data, this happens about 2 times per month in June, and another 1.3 times in July, so nothing to worry about. The typical maximal upward tick is around 40k in June and 25k in July. Even 2012 saw 2 upticks during its spectacular June (but it also saw 13 century breaks).
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on June 13, 2018, 09:23:17 PM
Daily NSIDC Extent reveals an UPTICK of +17K. How unusual is this during the months June-July when the melting is at its largest pace?
Finally an easy question about arctic sea ice...
According to NSIDC extent data, this happens about 2 times per month in June, and another 1.3 times in July, so nothing to worry about. The typical maximal upward tick is around 40k in June and 25k in July. Even 2012 saw 2 upticks during its spectacular June (but it also saw 13 century breaks).

not sure if the uptick as such is the issue, my point has always been that certain physical conditions must be met for ice to grow or stay equal over all while there is definitely huge melting going on in some places.

the conclusion from this is that the models are not reliable and unfortunately not only that, but at times very very far of.

if dispersion would be the problem, at temps around or above zero, there is no refreeze between fragments, hence area should go down somehow in relation to extent and to me it does not look like it, just show me where i overlook something if that is the case.

IMO data are wrong, a bit rude and a bit too simple perhaps but as i said IMO and IMO mean exactly that, not more but also not less ;)

if there were (there were of course) such upticks in earlier years that only tells me they were wrong as well because without freezing conditions ice cannot freeze, hence it can compact and loose extent but gain area through closed gaps, or it can disperse, gain extent but loose area by opining gaps.

something along that line, while if bot numbers grow or stay level at those temps, something can't be rigth.

again i'm gladly looking forward for input that would explain that in a comprehensive manner.
Title: Re: 2018 sea ice area and extent data
Post by: dosibl on June 13, 2018, 10:03:34 PM
I believe extent data is measured and not modeled (I wouldn't count any light post-processing of measurements as modeling), so I'm inclined to decently trust these numbers. With dispersion I'd expect to see a moderate loss of area with neutral or rising extent, which would mean lower compaction. Compaction has indeed been going down over the past several days, so dispersion seems like a reasonable conclusion.

https://sites.google.com/site/cryospherecomputing/daily-data (https://sites.google.com/site/cryospherecomputing/daily-data)
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on June 13, 2018, 10:15:57 PM
I think that unusual winds push ice back again into already open waters (Beaufort, Chukchi, NE Barents, Hudson, ..., see e.g. in the animation of Universität Bremen). The loss in Kara and Laptev can't make up for that. This is IMO the reason for the slow-down of extent loss of the last week. As temps are around or slightly above zero in the most areas a refreeze does not happen. I think the ice volume still decreases although the extent is more or less stable.
So if melting goes on and wind directions re-change the extent loss will return to its "roughly as expected" pace in the second half of June. But the run for second lowest extent is probably lost for this year.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 13, 2018, 10:45:05 PM
if dispersion would be the problem, at temps around or above zero, there is no refreeze between fragments, hence area should go down somehow in relation to extent and to me it does not look like it, just show me where i overlook something if that is the case.
Gerontocrat posted this chart up-thread showing exactly what you describe, area going down relative to extent. Dispersion.

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=2223.0;attach=102498;image)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 14, 2018, 06:05:04 AM
[ADS-NIPR-JAXA] ASI Extent.

June 13th, 2018: 10,363,905 km2, a drop of -14,325 km2.
2018 is the fifth lowest on record.

Lowest   Year     Extent          Difference
   1st.   2016     10,100,637    -263,268
  2nd.   2012     10,223,116    -140,789
   3rd.   2017     10,299,545      -64,360
   4th.   2011     10,334,450      -29,455
   6th.   2015     10,402,787        38,882
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 14, 2018, 11:40:08 AM
JAXA Extent 10,363,905 km2(June 13, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.53 million km2, 290k below the average for the last 10 years. That is a significant amount. Consistently slightly slower than or at average daily melt, a very low 36k, 25k, 44k, 23k and 15k, an increase of 3k, and now a drop of 14k.

Extent is now just 67k (0.7%) below the average for 2010-2017.

On average 38% of the melting is done for this season - still a long way to go, on average 96 91 days.

Excluding 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.33 million km2 as opposed to 4.22 million km2. The range of outcomes from the last 10 years remaining melt is 3.3 to 4.6 million km2.

All is confusion ?:- (I am confused, anyway)

On 11th and 12th June NSIDC daily area loss was 90k per day. I expect (ha-ha)something like that again for the 13th.

GFS (from cci-reanalyzer) still shows large areas of the Arctic having had, getting, and will continue to get a dose of real warmth.

Meanwhile extent loss for the last 7 days has been very, very much below average. See the graph Indeed, if one look at this extent data only for a view of the September minimum one would be thinking more like 4.5 million rather than circa 4.0 million km2 a week or two ago.

I continue to recommend readers have a good long read of the melting season thread - melting ponds / surface water confusing the area data? Ice spread out confusing the extent data?

Time will make things clearer but I think my choices for the June poll for the September minimum requires "Mystic Meg's" assistance even more urgently.
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on June 14, 2018, 12:39:22 PM
Over the past nine days, JAXA Arctic extent has dropped by just 286k. That's precisely as much as was lost during the same span in 2015, and 33k more than was lost in 2016. In fact, of the past four seasons (including this one), only 2017 lost more over the span, with a nine-day loss of 696k. (2012 is still the winner for the period by a long shot, dropping a whopping 1.13M km2, or nearly four times as much as this year's loss.)

It will take more time to know for sure, of course, but my guess is that the seeming disappearance of what used to be known as the early June "cliff" is a new (and perhaps temporary) normal, a complex product of lower spring maximums and numerous other factors.

Anyway: JAXA extent is today in 5th place--somewhere it hasn't been since mid-March--and unless it drops by at least 20k tomorrow, 2018 will fall back to 7th place, somewhere it hasn't been this year. 2018 JAXA extent has spent 20 days in 3rd place, 69 days in 2nd, and 66 days in 1st; just nine days have fallen outside the top three.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 14, 2018, 02:17:25 PM
NSIDC Total Area  as at 13th June (5 day trailing average) =   9,109,264 km2

Total Area loss 58k, Central Seas 35k Periphery 6k, Other (Hudson) 17k.   

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 17 k.
- The Bering Sea area is 3k.
- Chukchi Sea +1 k, Beaufort Sea -6 k (Canadian (western) end?).
i.e. Pacific side slow...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 6 k.
- The Laptev Sea area loss 23 k again  .
- The Kara Sea area loss 7 k.

CAB
- The Central Arctic Sea gained 22k.
- The Canadian Archipelago loss 13k.
- East Siberian Sea loss 13k

Other seas
- St Lawrence area is <3k,
- Hudson Bay area loss 17k, but total area still well behind 2010's average area.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 14, 2018, 02:54:16 PM
Just a note to say that this year the melting season has seen a couple of noteworthy events, even if in overall terms things are looking average to slow.

Over half of the sea ice in the Bering Sea was never there, and the remainder disappeared in April and May,

Just one week ago the Laptev Sea started to lose ice at an extraordinary rate and at the moment it is hard to see that not continuing.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 14, 2018, 11:19:57 PM
I like that you take the last nine days of data and interpret from that, rather than the last couple of days or so.  In my opinion (derived from observations on Worldview and the arguments of others) much of the declining loss (and even small gain) of extent comes from the floes streaming out of the north/east Kara Sea and into the Barents, where they contribute to extent but are rapidly melting out (see image below, fine ribbons of ice at right (S of FJL) that probably still count as extent).

I am a little surprised (no doubt there is a reason) that the Charctic Interactive graph is not mentioned more often here.  I know it has a 5 day trailing average, but that is not dissimilar to your taking the last nine days as a guide to events.  On Charctic, 2018 is still just in second place, although the rate of decline of extent has slowed.  Still, it provides some perspective on what some seem to regard as a baffling or even poor melting year.  Personally, I am rooting for even slower rates of decline, but I think I will be disappointed.  Charctic image attached.  Insight on this would be most welcome.

Over the past nine days, JAXA Arctic extent has dropped by just 286k. That's precisely as much as was lost during the same span in 2015, and 33k more than was lost in 2016. In fact, of the past four seasons (including this one), only 2017 lost more over the span, with a nine-day loss of 696k. (2012 is still the winner for the period by a long shot, dropping a whopping 1.13M km2, or nearly four times as much as this year's loss.)

It will take more time to know for sure, of course, but my guess is that the seeming disappearance of what used to be known as the early June "cliff" is a new (and perhaps temporary) normal, a complex product of lower spring maximums and numerous other factors.

Anyway: JAXA extent is today in 5th place--somewhere it hasn't been since mid-March--and unless it drops by at least 20k tomorrow, 2018 will fall back to 7th place, somewhere it hasn't been this year. 2018 JAXA extent has spent 20 days in 3rd place, 69 days in 2nd, and 66 days in 1st; just nine days have fallen outside the top three.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 15, 2018, 05:52:57 AM
[ADS-NIPR-JAXA] ASI Extent.

June 14th, 2018: 10,317,955 km2, a drop of -45,950 km2.
2018 is the fifth lowest on record.

Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 15, 2018, 08:57:59 AM
Over the past nine days, JAXA Arctic extent has dropped by just 286k. That's precisely as much as was lost during the same span in 2015, and 33k more than was lost in 2016. In fact, of the past four seasons (including this one), only 2017 lost more over the span, with a nine-day loss of 696k. (2012 is still the winner for the period by a long shot, dropping a whopping 1.13M km2, or nearly four times as much as this year's loss.)

It will take more time to know for sure, of course, but my guess is that the seeming disappearance of what used to be known as the early June "cliff" is a new (and perhaps temporary) normal, a complex product of lower spring maximums and numerous other factors.


About 230k of the slow decline in the begin of June can be explained by a particular "quirk" in the algorithm that Jaxa is using to calculate sea ice concentration with a "smooth" in the calculation to prevent an ugly bump in extent.

The adapted Bootstrap Algorithm that Jaxa uses switches on the first of June from dry ice surface to melting. The switch back to dry ice is set at 15th October. Some may remember old versions of the Jaxa extent graphs (at the time produced by a cooperation of IARC and Jaxa , known as IJIS), that did show visible "bumps" on these dates. A refinement in the calculation did a way with those, presumably by gradually smoothing the results.

The changeover can be observed in some of my graphics, showing extent calculated from Uni Hamburg and from Jaxa Sea Ice concentration. During the freezing season they mostly track each other quite well, but in June-September Jaxa extent is persistently higher.

Attached is a close-up what happens in the beginning of June. Plotted is the average extent in 6 years 2013-2018 from 25th May to 13th June.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 15, 2018, 10:29:03 AM
JAXA Extent 10,317,955 km2(June 14, 2018)

Again,just to add to Juan's post :
- Extent loss for the melting season to date is, at 3.57 million km2, 320k below the average for the last 10 years. That is a significant amount. See the graph on how consistently slower than or average daily melt has been over the last week.

Extent is now just 46k (0.4%) below the average for 2010-2017.

On average 39% of the melting is done for this season - still a long way to go, on average 90 days.

Excluding 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.34 million km2 as opposed to 4.24 million km2. The range of outcomes from the last 10 years remaining melt is 3.3 to 4.6 million km2.

I continue to recommend readers have a good long read of the melting season thread - melting ponds / surface water confusing the area data? Ice spread out confusing the extent data?

Also read the Wipneus post above, suggesting that JAXA changing its algorithm on 1st June is at least partly responsible for the recorded low daily extent losses. Yet another reason for lpw confidence in any prediction of outcomes this early in the season.

Time will make things clearer but I think my choice later today for the June poll for the JAXA September daily minimum requires "Mystic Meg's" assistance even more urgently.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 15, 2018, 02:52:53 PM
NSIDC Total Area  as at 14th June (5 day trailing average) =    9,021,998 km2

Total Area loss 87k, Central Seas 62k Periphery 8k, Other Seas 18k.   

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 16 k.
- The Bering Sea area is 2 k.
- Chukchi Sea +6 k, Beaufort Sea -11 k (Canadian (western) end?).
i.e. Pacific side slow...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 8 k.
- The Laptev Sea area loss 19 k .
- The Kara Sea area loss 10 k.

CAB
- The Central Arctic Sea gained 12k.
- The Canadian Archipelago loss 21k.
- East Siberian Sea loss 19k

Other seas
- St Lawrence area is 2 k,
- Hudson Bay area loss 16k, but total area still well behind 2010's average area.


PS:- NSIDC ONE DAY DAILY EXTENT DROPPED BY 110 K
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 15, 2018, 04:20:53 PM
NSIDC Area - Leaders and Laggards of ice loss by each regional sea

I last did this at the end of May. As I am in a dither about what bin to choose for the JAXA June poll, I thought I would give it another whirl.

Explanatory Note:
I developed these graphs to look at the current year in comparison with  10 year averages from the 80s, 90s 00s, and the 2010's to date (2010 to 2017). This tells me if the current year is likely (or not) to drag down the 2010's average area and also give an idea of trends in ice-free days (5%, 15% and 50%).
-------------
1) Pacific End

Bering - leader
Chukchi - laggard (was leader)
Beaufort - laggard
East Siberian Sea - laggard

c.fwd to next post    Leaders 1, Laggards 3
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 15, 2018, 04:28:27 PM
NSIDC Area - Leaders and Laggards of ice loss by each regional sea (continued)

I last did this at the end of May. As I am in a dither about what bin to choose for the JAXA June poll, I thought I would give it another whirl.

Explanatory Note:
I developed these graphs to look at the current year in comparison with  10 year averages from the 80s, 90s 00s, and the 2010's to date (2010 to 2017). This tells me if the current year is likely (or not) to drag down the 2010's average area and also give an idea of trends in ice-free days (5%, 15% and 50%).
-------------
2) Atlantic End

b.fwd from previous post    Leaders 1, Laggards 3

Baffin - laggard
Greenland Sea -  leader (still)
Barents - neutral
Kara Sea - laggard
Laptev Sea - leader (by a country mile)

c.fwd to next post    Leaders 3, Laggards 5, Neutral 1
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 15, 2018, 04:37:28 PM
NSIDC Area - Leaders and Laggards of ice loss by each regional sea (continued)

I last did this at the end of May. As I am in a dither about what bin to choose for the JAXA June poll, I thought I would give it another whirl.

Explanatory Note:
I developed these graphs to look at the current year in comparison with  10 year averages from the 80s, 90s 00s, and the 2010's to date (2010 to 2017). This tells me if the current year is likely (or not) to drag down the 2010's average area and also give an idea of trends in ice-free days (5%, 15% and 50%).
-------------
3) CENTRAL ARCTIC

b.fwd from previous post    Leaders 3, Laggards 5, Neutral 1

Canadian Archipelago - Neutral
Central Arctic Sea - Leader (but could become laggard very soon)

4) Other Seas

Hudson - Laggard,
Okhotsk - Leader,
St Lawrence - Neutral

Totals    Leaders 5, Laggards 6, Neutral 4

CONCLUSION - Somewhat of a average year or a bit slow. No help at all.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on June 15, 2018, 06:30:14 PM
Apples->Apples question... while 2018 has 320k +/- less than average melt did wasn't the difference between average max and 2018 much higher than that?
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on June 15, 2018, 09:45:26 PM

About 230k of the slow decline in the begin of June can be explained by a particular "quirk" in the algorithm that Jaxa is using to calculate sea ice concentration with a "smooth" in the calculation to prevent an ugly bump in extent.

The adapted Bootstrap Algorithm that Jaxa uses switches on the first of June from dry ice surface to melting. The switch back to dry ice is set at 15th October. Some may remember old versions of the Jaxa extent graphs (at the time produced by a cooperation of IARC and Jaxa , known as IJIS), that did show visible "bumps" on these dates. A refinement in the calculation did a way with those, presumably by gradually smoothing the results.

that's extremely useful to know, many thanks for this one
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 16, 2018, 05:51:27 AM
[ADS-NIPR-JAXA] ASI Extent.

June 15th, 2018: 10,236,731 km2, a drop of -81,224 km2.
2018 is the fifth lowest on record.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 16, 2018, 10:32:45 AM
JAXA Extent 10,236,731 km2(June 15, 2018)

Again,just to add to Juan's post ( I like the table, Juan):
- Extent loss for the melting season to date is, at 3.65 million km2, 300k below the average for the last 10 years. That is a significant amount. See the graph on how consistently slower than or average daily melt has been over the last week.

Extent is now just 66k (0.6%) below the average for 2010-2017.

On average 40% of the melting is done for this season - still a long way to go, on average 89 days.

Excluding 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.33 million km2 as opposed to 4.22 million km2. The range of outcomes from the last 10 years remaining melt is 3.3 to 4.6 million km2, (The average September minimum of the last 10 years is 4.41 million km2)

I continue to recommend readers have a good long read of the melting season thread - melting ponds / surface water confusing the area data? Ice spread out confusing the extent data?

ps: Mystic Meg and The Farmers' Almanac gave me no help for my guess at the September minimum.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 16, 2018, 02:32:41 PM
NSIDC ONE DAY DAILY EXTENT DROPPED BY:-

112 k 15th June
110 k 14th June

First double century break of the season? Now the June cliff starts (or not) ?

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 16, 2018, 02:42:29 PM
NSIDC Total Area  as at 15th June (5 day trailing average) = 8,918,224 km2

Total Area loss 104k, Central Seas 72k Periphery 12k, Other Seas 20k.   

First century area loss of the season?

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 15 k.
- The Bering Sea area is 2 k.
- Chukchi Sea -2 k, Beaufort Sea -7 k (Canadian (western) end?).
i.e. Pacific side slow...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 12 k.
- The Laptev Sea area loss 12 k .
- The Kara Sea area loss 21 k.

CAB
- The Central Arctic Sea gained 13k. Ice pushed in from CAA and ESS the last three days?
- The Canadian Archipelago loss 16k.
- East Siberian Sea loss 26 k

Other seas
- St Lawrence area is still 2 k,
- Hudson Bay area loss 19k, but total area still well behind 2010's average area.
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on June 16, 2018, 10:33:02 PM
NSIDC ONE DAY DAILY EXTENT DROPPED BY:-

112 k 15th June
110 k 14th June

First double century break of the season? Now the June cliff starts (or not) ?

this is a correction of the recent glitch in sensor reading and/or algorithms IMO

i mean it, not kidding
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 16, 2018, 10:47:23 PM
NSIDC ONE DAY DAILY EXTENT DROPPED BY:-

112 k 15th June
110 k 14th June

First double century break of the season? Now the June cliff starts (or not) ?

this is a correction of the recent glitch in sensor reading and/or algorithms IMO

i mean it, not kidding
What glitch ? - Both NSIDC and JAXA extent loss slowed a lot for the week before two days ago, and JAXA extent loss increased a bit on the 14th and rose above average on the 15th.

Independent data sets, different technology and different algorithms.

NSIDC area loss (5 day average) also accelerated on the 14th and 15th.

The data is consistent across all the measures.

Statements without evidence are not very helpful.

Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on June 16, 2018, 11:42:29 PM
Independent data sets, different technology and different algorithms.

NSIDC area loss (5 day average) also accelerated on the 14th and 15th.

The data is consistent across all the measures.

The weather has been hot for awhile...do we have any clue why the data just picked up in the last couple of days?
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on June 16, 2018, 11:45:13 PM
What glitch ? - Both NSIDC and JAXA extent loss slowed a lot for the week before two days ago, and JAXA extent loss increased a bit on the 14th and rose above average on the 15th.

Independent data sets, different technology and different algorithms.

NSIDC area loss (5 day average) also accelerated on the 14th and 15th.

The data is consistent across all the measures.

Statements without evidence are not very helpful.

most theories that were later proven correct lacked evidence initially.

IMO those data were incorrect, it could be seen with naked eyes.

some believe in formulas even though they are based on past conditions that do not apply anymore.

the same is the reason why we have to work so hard to convince people to change their life style, it was working in the past and there is no evidence how exactly future will deal with certain changes, so we can lean back and live in the past until it's too late.

that said i have no problem with different points of view but will certainly keep mine until proven otherwise, thinking out of the box with an open ear for different opinions has often proven to be a good thing.

if i write IMO it means "in my opinion" and opinions are free and only i know my quota of ultimately having had the feel. perhaps it's poor perhaps it's close to 100% LOL.

thanks however for all the great contributions, my full respect and appreciation for sure.  ;)

EDIT: someone, i think it was WIP, even posted one possible explanation for possible flaws in algorithms leading possibly to errors (misinterpretation of readings)

i for one often think (without evidence) that we should perhaps start to pay more attention to water vapor and clouds as possible causes for spikes and throughs in the graphs. just an idea, really dunno and cant' prove anything but here i paste my reasoning, posted earler this week in the melting season thread:

a) almost the entire arctic is(was) around or above zero, (hence no refreeze is possible)

b) parts of the ice cover are/was hit with temps way above melting temps and in places above 30C
.   (and more widely spread between 20 and 25C)

c) ice is thin and mobile and the winter was warm

d) there have been extraordinarily strong winds recently and rain throwing water on the surface, 
.   (lowering albedo significantly)

the logics tell us that there has definitely been significant melt in some places but there has
certainly not been any refreeze because temps were far away from freezing point for see-ice.

the result is that there must have been a reduction in ice over all, melt versus no freeeze.

the charts/numbers were showing more or less the same like the day before and the above considered that's not possible without good explanation that evades me.

in the wake of this i believe that the numbers were wrong, without knowing how much, but if they were wrong they can as well be significantly wrong and sooner or later, once the reason for the glitch has gone aways, there would be a correction, this is what apparently is happening now.

no, this is not a proof, but it's also not totally of, not enough off to say it's useless to think about it and consider the possibility for errors of the kind WIP mentioned and/or others.
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on June 17, 2018, 03:26:11 AM
Independent data sets, different technology and different algorithms.

NSIDC area loss (5 day average) also accelerated on the 14th and 15th.

The data is consistent across all the measures.

The weather has been hot for awhile...do we have any clue why the data just picked up in the last couple of days?

that's exactly the question that made me think further and Wipneus posted somewhere a possible explanation.

again it's interesting how we have to loose ourselves in more or less personal (useless post) arguments, even though, at least i for my part, am so much in agreement with what is said here
and the general line of thinking is so often so similar. it's basically a waste somehow because if i remember correctly the same people themselves were very surprised as well and had difficulties to believe the numbers, while they obviously, other then myself, came to the decisions to believe the numbers more or less blindly while if i see a contradiction between condition and numbers someone would have to proof they're right and not only the other way around.

i believe that the algorithms are based on conditions decades ago when things were easier to calculate, high freeboards, stable ice cover with less fissures where the water can drain instead of ponding etc. etc. who can tell for sure that those calculations have the same accuracy and reliability nowadays like they had 10-15 years ago.

i don't insist that they don't but i suspect that they don't always and simply throw that into the round. gladly listing to proper explanation why my suspicion is wrong. after all i was thinking this is a place to discuss and not one to believe. if we were believers and not seekers for the truth, we could still believe that the earth is a disk. the guy who dared to suspect otherwise has almost been killed and history is full of such examples.

and no, galileo did not have proof in form of an image from space, he just made a logical assumption based on observations. other who did the same were wrong, he was right, so who knows exactly what we shall find out soon what the truth is.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on June 17, 2018, 04:04:45 AM

if i write IMO it means "in my opinion" and opinions are free and only i know my quota of ultimately having had the feel. perhaps it's poor perhaps it's close to 100% LOL.

a) almost the entire arctic is(was) around or above zero, (hence no refreeze is possible)

b) parts of the ice cover are/was hit with temps way above melting temps and in places above 30C
.   (and more widely spread between 20 and 25C)

c) ice is thin and mobile and the winter was warm

d) there have been extraordinarily strong winds recently and rain throwing water on the surface, 
.   (lowering albedo significantly)

the logics tell us that there has definitely been significant melt in some places but there has
certainly not been any refreeze because temps were far away from freezing point for see-ice.

the result is that there must have been a reduction in ice over all, melt versus no freeeze.

the charts/numbers were showing more or less the same like the day before and the above considered that's not possible without good explanation that evades me.

no, this is not a proof, but it's also not totally of, not enough off to say it's useless to think about it and consider the possibility for errors of the kind WIP mentioned and/or others.

The issue here is that extent is only a loose proxy for melt.  Because of the 15% threshhold for extent it is possible to go from 100% cover to 50 % cover without a drop in extent. In fact  it  is possible to  spread that 50% over double the area and double the extent. 

In my view that  is what we are seeing over the past few years. Extent within the central area starts June at very close to 100%. The ice is no longer cohesive so is easily spread by the prevailing winds so the extent decline in June is actually decreasing even though the melt is not.  Because the ice is loose right through the pack there is a brownian motion effect on the ice so that it is spread out into the space available. This was less common when the individual ice sheets were larger. This could even be affecting the PIOMAS modelling. 

Looking at 2015 we see a very low extent loss in June.  But the total volume loss from June 1 was nearly as high as 2012.  2017 on the other hand had a very high extent loss in June but ended with a low volume loss.  The prevailing winds appear to be much more important to the extent values in June than they were even a few years ago.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 17, 2018, 05:28:48 AM
Magnamentis, thanks for your thoughts.  I think it necessary to comment on a couple of your statements in the interests of accuracy.  First, sea ice extent is just sea ice extent.   There seems to be nothing wrong with the AMSR 2 measurements  -- they simply are what they are, and nothing more.  Processing the measurements through two different  algorithms and getting similar results for extent is pretty persuasive evidence that all is well. 

To challenge these measurements just because we think there has been a lot of melting of the ice is rather like challenging an accurate measurement of a person's height just because we think they have lost some weight.  One is not directly linked to the other.   

Second, Galileo was not persecuted for suggesting the Earth was a sphere and not a disk.  He was supporting Copernicus' idea, aided by evidence he, Galileo, had gathered, that the Earth orbited the Sun.  This was theologically perilous because it meant the Earth was not the center of the Universe. 

BTW, there was ample evidence that the Earth was a sphere by Galileo's time, and it had been gathered and mathematically analyzed.  An ancient Greek, Eratosthenes, had made a pretty good calculation of the size of the Earth.  And about a hundred years before Galileo was put on trial, Columbus had set sail to the west to get to the East Indies, a journey that would be irrational, if not suicidal, on a flat Earth.   

Independent data sets, different technology and different algorithms.

NSIDC area loss (5 day average) also accelerated on the 14th and 15th.

The data is consistent across all the measures.

The weather has been hot for awhile...do we have any clue why the data just picked up in the last couple of days?

that's exactly the question that made me think further and Wipneus posted somewhere a possible explanation.

i believe that the algorithms are based on conditions decades ago when things were easier to calculate, high freeboards, stable ice cover with less fissures where the water can drain instead of ponding etc. etc. who can tell for sure that those calculations have the same accuracy and reliability nowadays like they had 10-15 years ago.

i don't insist that they don't but i suspect that they don't always and simply throw that into the round. gladly listing to proper explanation why my suspicion is wrong. after all i was thinking this is a place to discuss and not one to believe. if we were believers and not seekers for the truth, we could still believe that the earth is a disk. the guy who dared to suspect otherwise has almost been killed and history is full of such examples.

and no, galileo did not have proof in form of an image from space, he just made a logical assumption based on observations. other who did the same were wrong, he was right, so who knows exactly what we shall find out soon what the truth is.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 17, 2018, 05:53:41 AM
JAXA Extent 10,236,731 km2(June 15, 2018)

Again,just to add to Juan's post ( I like the table, Juan):
Thanks, gerontocrat  :)
___________________________________
[ADS-NIPR-JAXA] ASI Extent.

June 16th, 2018: 10,169,264 km2, a drop of -67,467 km2.
2018 is the fifth lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 17, 2018, 10:35:24 AM
JAXA Extent 10,169,264 km2(June 16, 2018)

Again,just to add to Juan's post ( I like the table, Juan):
- Extent loss for the melting season to date is, at 3.72 million km2, 300k below the average for the last 10 years. That is a significant amount. See the graph on how consistently slower than or average daily melt was been over the week before the last two days.

Extent is now just 62k (0.6%) below the average for 2010-2017.

On average 40% of the melting is done for this season - still a long way to go, on average 88 days.

Excluding 2012 from the 10 year average extent loss. The outcome for the minimum then comes in at 4.33 million km2 as opposed to 4.22 million km2. The range of outcomes from the last 10 years remaining melt is 3.3 to 4.6 million km2, (The average September minimum of the last 10 years was 4.41 million km2)

I continue to recommend readers have a good long read of the melting season thread - melting ponds / surface water confusing the area data? Ice spread out confusing the extent data?

ps: Mystic Meg and The Farmers' Almanac gave me no help for my guess at the September minimum.
[/quote]
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 17, 2018, 10:48:19 AM
Independent data sets, different technology and different algorithms.

NSIDC area loss (5 day average) also accelerated on the 14th and 15th.

The data is consistent across all the measures.

The weather has been hot for awhile...do we have any clue why the data just picked up in the last couple of days?

that's exactly the question that made me think further and Wipneus posted somewhere a possible explanation.

I believe that the algorithms are based on conditions decades ago when things were easier to calculate, high freeboards, stable ice cover with less fissures where the water can drain instead of ponding etc. etc. who can tell for sure that those calculations have the same accuracy and reliability nowadays like they had 10-15 years ago.


Hullo magnamentis,

In your original post when you said "glitch" I thought you meant a temporary problem with the hardware or software used by NSIDC. If that was so, they would tell us ( hope). Hence my demand for evidence.

But when you say "based on conditions decades ago when things were easier to calculate" I think you may very well have a point, especially when looking at just one, two or three days observations.

Let's see what the NSIDC and JAXA data show us for the second half of June, because by the looks of it, Arctic temperatures (especially in Central Siberia) are looking warm to hot for the rest of the month.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 17, 2018, 02:48:39 PM
NSIDC Total Area  as at 16th June (5 day trailing average) = 8,823,778 km2

Total Area loss 94k, Central Seas 64k Periphery 17k, Other Seas 13k.   

Another big loss.

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 15 k.
- The Bering Sea area is 2 k.
- Chukchi Sea -2 k, Beaufort Sea -7 k (Canadian (western) end?).
i.e. Pacific side slow...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 17 k, of which the Baffin was 15k
- The Laptev Sea area loss just 5 k .
- The Kara Sea area loss 21 k.

CAB
- The Central Arctic Sea gained 19k. Ice pushed in from CAA and ESS the last fourdays?
- The Canadian Archipelago loss 24k.
- East Siberian Sea loss 23 k

Other seas
- St Lawrence area is still 2 k,
- Hudson Bay area loss 13k, but total area still well behind 2010's average area.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 17, 2018, 02:52:24 PM
NSIDC ONE DAY DAILY EXTENT DROPPED BY:-

  96 k 16th June
112 k 15th June
110 k 14th June


Now looking increasingly at odds with JAXA extent loss data. Time will tell.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 17, 2018, 03:39:07 PM
NSIDC area has been dropping as well, but not that much faster than extent, and so compactness is still relatively high (at last year's level now):
Title: Re: 2018 sea ice area and extent data
Post by: ArcticMelt1 on June 17, 2018, 06:20:54 PM
In the Central Arctic is still a record.
Title: Re: 2018 sea ice area and extent data
Post by: ArcticMelt1 on June 17, 2018, 06:37:03 PM
Now there is less ice around Svalbard than usually in September.  :'(
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 18, 2018, 05:57:05 AM
[ADS-NIPR-JAXA] ASI Extent.

June 17th, 2018: 10,126,025 km2, a drop of -43,239 km2.
2018 is the fifth lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 18, 2018, 12:09:39 PM
JAXA Extent 10,126,025 km2(June 17, 2018)

Again,just to add to Juan's post :
Extent loss for the melting season to date is, at 3.77 million km2, 310k below the average for the last 10 years. That is a significant amount. See the graph on how consistently slower than or average daily melt has been for some time.

Extent is now just 45k (0.4%) below the average for 2010-2017.

On average 41% of the melting is done for this season - still a long way to go, on average 87 days.

Excluding 2012 from the 10 year average remaining extent loss. The outcome for the minimum then comes in at 4.35 million km2 as opposed to 4.24 million km2. The range of outcomes from the last 10 years remaining melt is 3.3 to 4.6 million km2, (The average September minimum of the last 10 years was 4.41 million km2).

There is a contrast developing with NSIDC data, which has recently showed strong extent and area losses.
Title: Re: 2018 sea ice area and extent data
Post by: Aluminium on June 18, 2018, 12:34:55 PM
JAXA Extent 110,126,025 km2(June 17, 2018)
Wow. :)
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on June 18, 2018, 12:57:00 PM
JAXA Extent 110,126,025 km2(June 17, 2018)
Wow. :)
I had to check if 11 or 10 was the correct one. I've been doing this for too long 8) 8).
Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on June 18, 2018, 01:11:21 PM
Yes, Pmt1111500.
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on June 18, 2018, 02:31:36 PM
Magnamentis, thanks for your thoughts.  I think it necessary to comment on a couple of your statements in the interests of accuracy.  First, sea ice extent is just sea ice extent.   There seems to be nothing wrong with the AMSR 2 measurements  -- they simply are what they are, and nothing more.  Processing the measurements through two different  algorithms and getting similar results for extent is pretty persuasive evidence that all is well. 

To challenge these measurements just because we think there has been a lot of melting of the ice is rather like challenging an accurate measurement of a person's height just because we think they have lost some weight.  One is not directly linked to the other.   

Second, Galileo was not persecuted for suggesting the Earth was a sphere and not a disk.  He was supporting Copernicus' idea, aided by evidence he, Galileo, had gathered, that the Earth orbited the Sun.  This was theologically perilous because it meant the Earth was not the center of the Universe. 

BTW, there was ample evidence that the Earth was a sphere by Galileo's time, and it had been gathered and mathematically analyzed.  An ancient Greek, Eratosthenes, had made a pretty good calculation of the size of the Earth.  And about a hundred years before Galileo was put on trial, Columbus had set sail to the west to get to the East Indies, a journey that would be irrational, if not suicidal, on a flat Earth.   


Good points.  The extent is what it is, and allows for a good comparison to similar historical measurements.  Extent varies differently from area or volume, due to its different measurement. 

I would like to add that Galileo was prosecuted largely because he proclaimed that heliocentrism was not just a theory, but fact.  He knew he was right, but lacked the proof to counter the age old theories documented by Aristotles (which included spherism).  His arrogance got in the way, not to mention the envy of his astronomical peers.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 18, 2018, 03:39:18 PM
JAXA Extent 110,126,025 km2(June 17, 2018)
Wow. :)
I had to check if 11 or 10 was the correct one. I've been doing this for too long 8) 8).
So have I - damn and blast
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 18, 2018, 03:55:20 PM
NSIDC Total Area  as at 17th June (5 day trailing average) =  8,723,055 km2

Total Area loss 101k, Central Seas 58 k Periphery 17k, Other Seas 26k.   

Another big loss.

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 16 k (It just will not die).
- The Bering Sea area is 2 k.
- Chukchi Sea -3 k,
- Beaufort Sea -6 k (Canadian (western) end?).
i.e. Pacific side slow...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 17 k, of which the Baffin was 11k
- The Laptev Sea area loss just 0 k (zero) .
- The Kara Sea area loss 13 k.

CAB
- The Central Arctic Sea gained 9k. Ice pushed in from CAA and ESS the last five days?
- The Canadian Archipelago loss 32 k (wow?).
- East Siberian Sea loss 13 k

Other seas
- St Lawrence area is still 2 k,
- Hudson Bay area loss 27k, but area still behind 2010's average area.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 18, 2018, 07:52:49 PM

JAXA Extent 110,126,025 km2(June 17, 2018)
[/quote]
NSIDC Total Area  as at 17th June (5 day trailing average) =  8,723,055 km2
[/quote]

Pardon my ignorance, but why is there such a big difference between the JAXA and NSIDC extents?  Do they define the edge of the ice, or minimum concentration to be counted, differently?
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on June 18, 2018, 08:46:56 PM
I think it necessary to comment on a couple of your statements in the interests of accuracy. 

thanks for the kind and useful feedback, agree to lack of accuracy and i'm glad that someone provided information that helps to see things more clearly and getting rid of a few mix-ups ;)

at times i'm a bit sloppy when trying to say too much in too little time and rightly so it backfires, point taken :-)

my main issue with extent measurement is that once the area with between "not 100%" and 15% threshold was relatively small while the rest was a more or less coherent ice mass and nowadays that the ice is more fractured i somehow see this 15% threshold as not contemporary. the numbers IMO are nowadays farther from telling the whole story (the big picture) than they were 1-2 decades ago.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 18, 2018, 09:00:55 PM
JAXA Extent 10,126,025 km2(June 17, 2018)

NSIDC Total Area  as at 17th June (5 day trailing average) =  8,723,055 km2

Pardon my ignorance, but why is there such a big difference between the JAXA and NSIDC extents?  Do they define the edge of the ice, or minimum concentration to be counted, differently?
A. You are mixing JAXA extent and NSIDC area.
B. The algorithms have different resolutions, so will produce diffetent results for the 15% rule.
C. The data comes from different satellites with different microwave wavelengths and all that stuff.
D. Different coastal masks and other minor issues.
Wipneus can explain in full, but even when you compare extents they will be very different.
Title: Re: 2018 sea ice area and extent data
Post by: Pmt111500 on June 18, 2018, 09:14:21 PM

JAXA Extent 110,126,025 km2(June 17, 2018)
NSIDC Total Area  as at 17th June (5 day trailing average) =  8,723,055 km2


Pardon my ignorance, but why is there such a big difference between the JAXA and NSIDC extents?  Do they define the edge of the ice, or minimum concentration to be counted, differently?
Yes. As for the reasons, they might be related to navigational hazards. Of course we here in ASIForum.would like to use most accurate data possible, but we'll have to do with any internally consistent data we get our hands into. If you have info on better sources of data, please make them publicly known. It's common knowledge some instances may withold these off public so release them as soon as is convenient. And the earth is nearly round, just to be sure.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 18, 2018, 09:27:38 PM
When extent goes up by 43K, and area drops by 145K, Compactness drops by almost 2%:
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 18, 2018, 09:29:27 PM

JAXA Extent 110,126,025 km2(June 17, 2018) Error by Gerontocrat - 10,126,025 km2

NSIDC Total Area  as at 17th June (5 day trailing average) =  8,723,055 km2


Pardon my ignorance, but why is there such a big difference between the JAXA and NSIDC extents?  Do they define the edge of the ice, or minimum concentration to be counted, differently?

Extent is measured by saying if ice cover estimate for each pixel greater than 15% then ice cover = 100%
Area is measured by saying if ice cover estimate for each pixel equals, say, 50%, then ice cover = 50%.

Area estimate is, therefore, always less than extent, whether using NSIDC or JAXA measurements.
My posts use JAXA for extent, NSIDC for area as NSIDC produce area data for each sea daily easily uploaded from NSIDC (https://nsidc.org/arcticseaicenews/sea-ice-tools/). If JAXA produced the same data I would use JAXA data in the interests of consistency.

I try to avoid mixing NSIDC and JAXA extent data as they are always a bit different.

The graph below shows the difference between NSIDC area and NSIDC extent monthly averages for May

Hope that helps.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 19, 2018, 01:36:57 AM
Thank you so much, gerontocrat, for being so patient and kind.  Your reply also provides me with much new learning.

And I REALLY have to learn to read.  I completely missed the words 'area' versus 'extent' and hence my error.  I thought, no, I assumed they were both extent.  A sadder but a wiser man. 

I am just off to put on my dunce cap and stand in the corner for a while...


JAXA Extent 110,126,025 km2(June 17, 2018) Error by Gerontocrat - 10,126,025 km2

NSIDC Total Area  as at 17th June (5 day trailing average) =  8,723,055 km2


Pardon my ignorance, but why is there such a big difference between the JAXA and NSIDC extents?  Do they define the edge of the ice, or minimum concentration to be counted, differently?

Extent is measured by saying if ice cover estimate for each pixel greater than 15% then ice cover = 100%
Area is measured by saying if ice cover estimate for each pixel equals, say, 50%, then ice cover = 50%.

Area estimate is, therefore, always less than extent, whether using NSIDC or JAXA measurements.
My posts use JAXA for extent, NSIDC for area as NSIDC produce area data for each sea daily easily uploaded from NSIDC (https://nsidc.org/arcticseaicenews/sea-ice-tools/). If JAXA produced the same data I would use JAXA data in the interests of consistency.

I try to avoid mixing NSIDC and JAXA extent data as they are always a bit different.

The graph below shows the difference between NSIDC area and NSIDC extent monthly averages for May

Hope that helps.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 19, 2018, 06:13:15 AM
[ADS-NIPR-JAXA] ASI Extent.

June 18th, 2018: 10,130,433 km2, a small increase of 4,408 km2.  :o
2018 is the seventh lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on June 19, 2018, 06:34:56 AM
[ADS-NIPR-JAXA] ASI Extent.

June 18th, 2018: 10,130,433 km2, a small increase of 4,408 km2.  :o
2018 is the seventh lowest on record.
I'll point out here, what separates us from 2016 (current #1) is 3-4 days of decent melt, or a week of middling.I'll add that area took a very big hit while extent rose (-140K in fact per Neven).

While "7th" , things are closer than that number might seem to indicate.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 19, 2018, 07:19:33 AM
OTOH, while 2018 was 2nd in extent a while back, its area was relatively high to begin with as shown by Neven's compactness graph, so it's a mixed case.
The jury is still out IMHO.
Title: Re: 2018 sea ice area and extent data
Post by: Wherestheice on June 19, 2018, 07:44:53 AM
The trends are showing we might not be headed for a record low this year.... Gonna need some rapid melting here soon for that to happen.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on June 19, 2018, 09:21:14 AM
[ADS-NIPR-JAXA] ASI Extent.

June 18th, 2018: 10,130,433 km2, a small increase of 4,408 km2.  :o
2018 is the seventh lowest on record.
I'll point out here, what separates us from 2016 (current #1) is 3-4 days of decent melt, or a week of middling.I'll add that area took a very big hit while extent rose (-140K in fact per Neven).

While "7th" , things are closer than that number might seem to indicate.

Since 2003 there has only been 5 daily increases in the JAXA record between June 1st and August 21st. All of these occurred since 2013 with two this year and one in 2013, 2015 and 2016. Most  of the declines less than 10000 km^2 also occurred in these recent years. This suggests a change in the pattern of the melting behavior since the very low extent and volume of 2012.  Perhaps due to easier dispersion of the thinner ice.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 19, 2018, 10:13:39 AM
JAXA Extent 10,130,433 km2(June 18, 2018)

Again,just to add to Juan's post :
Extent loss for the melting season to date is, at 3.76 million km2, 380k below the average for the last 10 years. That is a significant amount. See the graph on how consistently slower than or average daily melt has been for some time.

Extent is now just 22k (0.2%) above the average for 2010-2017.

On average 42% of the melting is done for this season - still a long way to go, on average 86 days.

Excluding 2012 from the 10 year average remaining extent loss. The outcome for the minimum then comes in at 4.43 million km2 as opposed to 4.31 million km2. The range of outcomes from the last 10 years remaining melt is 3.33 to 4.72 million km2, (The average September minimum of the last 10 years was 4.41 million km2).

There is a contrast developing with NSIDC data, which has recently showed strong area losses. jdallen has pointed out that this fall from 2nd to 7th place only represents about a week of middling melt. Nevertheless, rather than seeing the June Cliff, in June we have seen a gradual slowing of extent loss to below the average.

Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 19, 2018, 11:07:53 AM
JAXA Extent 10,126,025 km2(June 17, 2018)

NSIDC Total Area  as at 17th June (5 day trailing average) =  8,723,055 km2

Pardon my ignorance, but why is there such a big difference between the JAXA and NSIDC extents?  Do they define the edge of the ice, or minimum concentration to be counted, differently?
A. You are mixing JAXA extent and NSIDC area.
B. The algorithms have different resolutions, so will produce diffetent results for the 15% rule.
C. The data comes from different satellites with different microwave wavelengths and all that stuff.
D. Different coastal masks and other minor issues.
Wipneus can explain in full, but even when you compare extents they will be very different.

That sums it up nicely.

Gridsize is probably the main cause: 25x25km for NSIDC and 10x10km for Jaxa. The instantaneous field of view (IFOV) sizes differ even more: up to 45x73km for NSIDC.
(http://nsidc.org/sites/nsidc.org/files/technical-references/SeaIce_CDR_CATBD_final.pdf).

That means NSIDC will see more extent along the ice edge (the mentioned 15% rule) and that more microwave emissions from land (land spill-over) is contaminating the measurements over water (land is seen as >>100% sea ice concentration).

Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 19, 2018, 11:17:28 AM
Most of the extent losses are still away from the high arctic. For instance Hudson should be nosediving now, but seems a bit late.

The inner Arctic Basin extent is second lowest right behind 2017 for Uni Hamburg, Jaxa and NSIDC. Area is a bit behind for the NSIDC data.

The idea is of course that the current Arctic Basin is more relevant for September extent and area than more peripheral regions.

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 19, 2018, 02:16:39 PM
NSIDC Total Area  as at 18th June (5 day trailing average) = 8,611,220 km2
This is 142k above the 2010-2017 average on this date.


Total Area loss 111k, Central Seas 67 k Periphery 16k, Other Seas 28k.   

Another big loss.

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 17 k (It just will not die).
- The Bering Sea area is 3k.    (It just will not die)
- Chukchi Sea loss 2 k,
- Beaufort Sea gain 2 k
i.e. Pacific side slow...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 16 k,
of which the Baffin loss was 10k
- The Laptev Sea area loss just 5 k  .
- The Kara Sea area loss 13 k.

CAB
- The Central Arctic Sea lost13k. after significant gains in the last five days?
- The Canadian Archipelago loss 27 k (120k in the last five days - wow?).
- East Siberian Sea loss 8 k

Other seas
- St Lawrence area is still 2 k,
- Hudson Bay area loss 30 k, area now at 1990's average - i.e.a bit of catch-up.

Area loss this year to date has followed the 2010-17 average very closely indeed. Individual seas leaders matched by the laggards.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 19, 2018, 02:32:37 PM
Thank you oren, gerontocrat, Wipneus -- my extent of understanding is expanding.  Learning can be embarrassing because one makes mistakes, but it is a whole lot easier when one has understanding, patient mentors.

 
A. You are mixing JAXA extent and NSIDC area.
B. The algorithms have different resolutions, so will produce diffetent results for the 15% rule.
C. The data comes from different satellites with different microwave wavelengths and all that stuff.
D. Different coastal masks and other minor issues.
Wipneus can explain in full, but even when you compare extents they will be very different.

That sums it up nicely.

Gridsize is probably the main cause: 25x25km for NSIDC and 10x10km for Jaxa. The instantaneous field of view (IFOV) sizes differ even more: up to 45x73km for NSIDC.
(http://nsidc.org/sites/nsidc.org/files/technical-references/SeaIce_CDR_CATBD_final.pdf).

That means NSIDC will see more extent along the ice edge (the mentioned 15% rule) and that more microwave emissions from land (land spill-over) is contaminating the measurements over water (land is seen as >>100% sea ice concentration).
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on June 19, 2018, 03:19:40 PM
Both deviation (from the mean values of each month between Jan 79 and May 18) of extent as well as of volume are above the linear trend line from Jan 1979 to May 2018 (last update May 2018 averages). See attached figures.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 19, 2018, 04:19:18 PM
Both deviation (from the mean values of each month between Jan 79 and May 18) of extent as well as of volume are above the linear trend line from Jan 1979 to May 2018 (last update May 2018 averages). See attached figures.

The latest values on these plots are for May2018, so we can expect both plots to drop further and therefore probably below the mean as further melting occurs in June, July and August, correct?

It is interesting and worrying to note the greater variability in both plots in the past decade or so.  Systems often fluctuate more as they move towards threshold conditions.
Title: Re: 2018 sea ice area and extent data
Post by: El Cid on June 19, 2018, 04:27:05 PM


The idea is of course that the current Arctic Basin is more relevant for September extent and area than more peripheral regions.

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png

Great charts as always! Thank you. I think we need to concentrate on Arctic Basin Area (Extent? I am not so sure), everything else is just smokescreen, eg. the Hudson will melt out anyway, it does not matter in the greater scheme of things...
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 19, 2018, 06:26:25 PM
With NSIDC extent going up another 67K, and area going down a modest 37K, Compactness drops by another percentage point:
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on June 19, 2018, 06:40:19 PM
Couldn't we just take the three different extent sources (JAXA, NSIDC, Uni Hamburg) to quantify the day-to-day differences in extent calculation? This would probably solve some discussion here.
Maybe this difference is season-dependent, randomly distributed or maybe increasing over the years?
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on June 19, 2018, 07:03:55 PM

The latest values on these plots are for May2018, so we can expect both plots to drop further and therefore probably below the mean as further melting occurs in June, July and August, correct?

It is interesting and worrying to note the greater variability in both plots in the past decade or so.  Systems often fluctuate more as they move towards threshold conditions.

To achieve this the average extent in April should have been 0,21 mio. km² smaller than it has been - for May the difference between the actual value and the trend line was 0,22 mio. km². So a jump might "help" to reach the trend line. But the development of the last 10 days or so do not make it very likely at the moment. I will update this graph monthly.   
Title: Re: 2018 sea ice area and extent data
Post by: Darvince on June 19, 2018, 07:56:47 PM
The latest values on these plots are for May2018, so we can expect both plots to drop further and therefore probably below the mean as further melting occurs in June, July and August, correct?

It is interesting and worrying to note the greater variability in both plots in the past decade or so.  Systems often fluctuate more as they move towards threshold conditions.
There was a change with the 2007 season towards lower summer/early fall extents without also lower winter extents, causing the yearly rise and fall of extent and volume anomalies. It is moreso a new yearly behavior than a growing instability.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 20, 2018, 05:51:00 AM
[ADS-NIPR-JAXA] ASI Extent.

June 19th, 2018: 10,106,748 km2, a drop of -23,685 km2.
2018 is the seventh lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 20, 2018, 09:45:10 AM
JAXA Extent 10,106,748 km2(June 19, 2018)

Again,just to add to Juan's post :
Extent loss for the melting season to date is, at 3.78 million km2, 430 k below the average for the last 10 years. That is a significant amount. See the graph on how consistently slower than or average daily melt has been for some time.

Extent is now 65k (0.6%) above the average for 2010-2017.

On average 42% of the melting is done for this season - still a long way to go, on average 85 days.

Excluding 2012 from the 10 year average remaining extent loss. The outcome for the minimum then comes in at 4.46 million km2 as opposed to 4.35 million km2. The range of outcomes from the last 10 years remaining melt is 3.38 to 4.41 million km2, (The average September minimum of the last 10 years was 4.41 million km2).

There is a contrast developing with NSIDC data, which has recently showed strong area losses. jdallen has pointed out that this fall from 2nd to 7th place only represents about a week of middling melt. Nevertheless, rather than seeing the June Cliff, in June we have seen a gradual slowing of extent loss to more and more below the average.
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on June 20, 2018, 02:02:36 PM
The June slowing of the melt corresponds quite well to the Arctic temperatures dipping below average.  May was warmer, and the sea ice responded accordingly.

http://ocean.dmi.dk/arctic/meant80n.uk.php (http://ocean.dmi.dk/arctic/meant80n.uk.php)
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 20, 2018, 02:08:22 PM
You're comparing Arctic-wide melt with modelled temps from 80N to the North Pole. The relation is tenuous at best, especially now. The Arctic has actually been above average temperature-wise, but a lack of winds is keeping winds static, and only the Siberian side is enduring a solar attack. There was more easy ice to melt during May, especially on the Pacific side.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 20, 2018, 02:25:36 PM
NSIDC Total Area  as at 18th June (5 day trailing average) = 8,513,017 km2
This is 149k above the 2010-2017 average on this date.


Total Area loss 98k, Central Seas 67 k Periphery 18k, Other Seas 31k.   
     
Another big loss, but a 7k below the 2010-2017 average.

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 19 k, +2k on the day(It just will not die).
- The Bering Sea area is 3k.    (It just will not die)
- Chukchi Sea loss 2 k,
- Beaufort Sea gain 7 k
i.e. Pacific side slow loss or even a slow gain...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 18 k,
of which the Baffin loss was 12k
- The Laptev Sea area loss just 12 k  .
- The Kara Sea area loss 5 k.

CAB
- The Central Arctic Sea loss 17k
- The Canadian Archipelago loss 18 k
- East Siberian Sea loss 4 k

Other seas
- St Lawrence area is still 2 k,
- Hudson Bay area loss 33 k, area now at 1990's average - i.e.a bit of catch-up.

Area loss this year to date has followed the 2010-17 average very closely indeed. Individual seas leaders matched by the laggards.
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on June 20, 2018, 04:07:19 PM
You're comparing Arctic-wide melt with modelled temps from 80N to the North Pole. The relation is tenuous at best, especially now. The Arctic has actually been above average temperature-wise, but a lack of winds is keeping winds static, and only the Siberian side is enduring a solar attack. There was more easy ice to melt during May, especially on the Pacific side.

True, but most of the ice resides north of the 80th parallel.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 20, 2018, 05:03:31 PM
You're comparing Arctic-wide melt with modelled temps from 80N to the North Pole. The relation is tenuous at best, especially now. The Arctic has actually been above average temperature-wise, but a lack of winds is keeping winds static, and only the Siberian side is enduring a solar attack. There was more easy ice to melt during May, especially on the Pacific side.

True, but most of the ice resides north of the 80th parallel.

"True, but most of the ice resides north of the 80th parallel."

Nope.

The area of the Arctic Ocean is 14.06 million Km2.
The area of the Arctic above 80 degrees North is 3.875 million km2, just under 28% of the area of the Arctic ocean

Quote
Arctic Ocean - Wikipedia
https://en.wikipedia.org/wiki/Arctic_Ocean
The Arctic Ocean occupies a roughly circular basin and covers an area of about 14,056,000 km2 (5,427,000 sq mi), almost the size of Antarctica. The coastline is 45,390 km (28,200 mi) long. It is surrounded by the land masses of Eurasia, North America, Greenland, and by several islands.

ps: Apart from the Atlantic side, nearly all melt to date is well below 80+ North (and some not in the Arctic Ocean at all)

Data - such a nuisance
Title: Re: 2018 sea ice area and extent data
Post by: Daniel B. on June 20, 2018, 05:45:10 PM
You're comparing Arctic-wide melt with modelled temps from 80N to the North Pole. The relation is tenuous at best, especially now. The Arctic has actually been above average temperature-wise, but a lack of winds is keeping winds static, and only the Siberian side is enduring a solar attack. There was more easy ice to melt during May, especially on the Pacific side.

True, but most of the ice resides north of the 80th parallel.

"True, but most of the ice resides north of the 80th parallel."

Nope.

The area of the Arctic Ocean is 14.06 million Km2.
The area of the Arctic above 80 degrees North is 3.875 million km2, just under 28% of the area of the Arctic ocean

Quote
Arctic Ocean - Wikipedia
https://en.wikipedia.org/wiki/Arctic_Ocean
The Arctic Ocean occupies a roughly circular basin and covers an area of about 14,056,000 km2 (5,427,000 sq mi), almost the size of Antarctica. The coastline is 45,390 km (28,200 mi) long. It is surrounded by the land masses of Eurasia, North America, Greenland, and by several islands.

ps: Apart from the Atlantic side, nearly all melt to date is well below 80+ North (and some not in the Arctic Ocean at all)

Data - such a nuisance

You are right.  I was looking at the Arctic at summer minimum.  Most of the melt to date, has been south of the 80 parallel.  Still, I think that the temperature north of 80 does show a good correlation.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 20, 2018, 06:32:31 PM
The temperature of the central arctic ocean in summer is pegged to the melting point, as long as ice is still there. Moreover, when the ice is covered with snow, the air is pegged to 0oC, but when the snow is gone and the ice is in partial melt the air is pegged to -1.8oC. So your "cooler summer temps" are nothing but a mirage signalling the deterioration of the arctic.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on June 20, 2018, 09:53:22 PM
The temperature of the central arctic ocean in summer is pegged to the melting point, as long as ice is still there. Moreover, when the ice is covered with snow, the air is pegged to 0oC, but when the snow is gone and the ice is in partial melt the air is pegged to -1.8oC. So your "cooler summer temps" are nothing but a mirage signalling the deterioration of the arctic.

BTW -- my preferred definition of an ice free Arctic is when the DMI 80N is no longer pegged near 0 in Summer.  When there is no longer enough ice to keep it cold then it is effectively ice free.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 21, 2018, 05:57:06 AM
[ADS-NIPR-JAXA] ASI Extent.

June 20th, 2018: 10,050,224 km2, a drop of -56,524 km2.
2018 is the sixth lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: El Cid on June 21, 2018, 09:11:15 AM


BTW -- my preferred definition of an ice free Arctic is when the DMI 80N is no longer pegged near 0 in Summer.  When there is no longer enough ice to keep it cold then it is effectively ice free.

That sounds like the best definition to me!
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 21, 2018, 10:29:47 AM
At 10.07 a.m. GMT (UTC) time today it will be the Summer Solstice with the Earth's tilt towards the sun at its maximum of 23.44 degrees. By 11.08 a.m. the sun will have started its apparent southward movement.

JAXA Extent 10,050,224 km2(June 20, 2018)

Again,just to add to Juan's post :
Extent loss for the melting season to date is, at 3.84 million km2, 440 k below the average for the last 10 years. That is a significant amount, about one weeks average melt for the time of year. See the graph on how consistently slower than or average daily melt has been for some time.

Extent is now 78k (0.8%) above the average for 2010-2017.

On average 43% of the melting is done for this season - still a long way to go, on average 84 days.

Excluding 2012 from the 10 year average remaining extent loss. The outcome for the minimum then comes in at 4.47 million km2 as opposed to 4.37 million km2. The range of outcomes from the last 10 years remaining melt is 3.42 to 4.85 million km2, (The average September minimum of the last 10 years was 4.41 million km2).

There is a contrast developing with NSIDC data, which has recently showed strong area losses. Rather than seeing the June Cliff, in June we have seen a gradual slowing of extent loss to more and more below the average.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 21, 2018, 10:58:56 AM
BTW -- my preferred definition of an ice free Arctic is when the DMI 80N is no longer pegged near 0 in Summer.  When there is no longer enough ice to keep it cold then it is effectively ice free.

I've often thought about this moment because it would be so seminal, but never viewed it from the ice-free perspective. I hope I'll remember this quote when it happens and write about it. If I don't, remind me.  :)
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on June 21, 2018, 02:04:39 PM
BTW -- my preferred definition of an ice free Arctic is when the DMI 80N is no longer pegged near 0 in Summer.  When there is no longer enough ice to keep it cold then it is effectively ice free.

I've often thought about this moment because it would be so seminal, but never viewed it from the ice-free perspective. I hope I'll remember this quote when it happens and write about it. If I don't, remind me.  :)

Several of us had a discussion about this awhile ago.  I'm not sure if I was the one who came up with this definition, but I wasn't the only one who liked it.
Title: Re: 2018 sea ice area and extent data
Post by: Richard Rathbone on June 21, 2018, 02:32:47 PM
The temperature of the central arctic ocean in summer is pegged to the melting point, as long as ice is still there. Moreover, when the ice is covered with snow, the air is pegged to 0oC, but when the snow is gone and the ice is in partial melt the air is pegged to -1.8oC. So your "cooler summer temps" are nothing but a mirage signalling the deterioration of the arctic.

Top melt happens at 0, bottom melt at -1.8. See the buoy thread for profiles if you want to check how the temperature in the ice changes with the season. There's not nearly enough of the bottom of the ice in contact with air other than via the top of the ice to move the peg down yet.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 21, 2018, 02:39:00 PM
NSIDC Total Area  as at 20th June (5 day trailing average) =  8,439,254 km2
This is 170k above the 2010-2017 average on this date.


Total Area loss 74 k, Central Seas 35 k Periphery 14k, Other Seas 24k.   

The slow down in June melt now showing in these 5 day averages. Current day is 30k below the 2010-2017 average area loss.

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 20 k, +1k on the day (It just will not die).
- The Bering Sea area is 3k.    (It also just will not die)
- Chukchi Sea loss 10 k,
- Beaufort Sea gain 11 k
i.e. Pacific side slow loss or even a slow gain...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 14 k,
of which the Baffin loss was 11k and the Barents 3k
- The Laptev Sea area loss just 3 k  .
- The Kara Sea area gain 3 k.

CAB
- The Central Arctic Sea loss 19k
- The Canadian Archipelago loss 13 k
- East Siberian Sea loss 5 k

Other seas
- St Lawrence area is still 2 k,
- Hudson Bay area loss 25 k, area now just below 1990's average - i.e.a bit of catch-up.

Area loss this year to date has followed the 2010-17 average very closely indeed, but is slowing. Individual seas leaders matched by the laggards.
Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on June 21, 2018, 04:15:58 PM
Looking at Extent graphs on the ASIG Regional Graphs (https://sites.google.com/site/arcticseaicegraphs/regional) page, and projecting all the graphs that are not the CAB into mid-September reveals (to me) the potential of a total of about 200k sq km of area above experienced minimums in September 2018.  As the difference between the two lowest CAB graphs is about 400k sq km of area, I continue to believe that (virtually) only the CAB matters when it comes to determining if the September SIE is a record or not.  I certainly understand that lingering 'regional' sea ice extent will delay CAB ice loss in the region borders.  But when I see CAB extent setting a current date minimum, I do not discount the possibility of a new minimum. 

That SIA is only near the current date minimum puts a small damper on this 'pessimistic view' of ice survival.  The two graphs suggest that CAB ice compaction is higher now than in other years, and that is sure to put a damper on future internal CAB melt.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 21, 2018, 05:29:02 PM
I continue to believe that (virtually) only the CAB matters when it comes to determining if the September SIE is a record or not.  I certainly understand that lingering 'regional' sea ice extent will delay CAB ice loss in the region borders.  But when I see CAB extent setting a current date minimum, I do not discount the possibility of a new minimum. 

That SIA is only near the current date minimum puts a small damper on this 'pessimistic view' of ice survival.  The two graphs suggest that CAB ice compaction is higher now than in other years, and that is sure to put a damper on future internal CAB melt.

If one just looks at the Central Arctic Sea and the Canadian Archipelago then NSIDC area loss data to date does suggest a low September minimum - but..........
Title: Re: 2018 sea ice area and extent data
Post by: LDorey on June 21, 2018, 05:38:54 PM
Huh. After all the "bickering" over how to define a Blue Ocean event ( Aka sign of the Apocalypse that 4 year term politico's can't ignore), this is by far the one I like the best. I don't know that "Ice free Arctic" is the right term for it, perhaps something fancy like End of Arctic Temperature Forcing ) EATF (unless the acronym taken already). Anyways It feels like a MUCH better (real) indicator of a large paradigm shift than declaring that a small abritary amount of ice left means "ice free".

Liam

The temperature of the central arctic ocean in summer is pegged to the melting point, as long as ice is still there. Moreover, when the ice is covered with snow, the air is pegged to 0oC, but when the snow is gone and the ice is in partial melt the air is pegged to -1.8oC. So your "cooler summer temps" are nothing but a mirage signalling the deterioration of the arctic.

BTW -- my preferred definition of an ice free Arctic is when the DMI 80N is no longer pegged near 0 in Summer.  When there is no longer enough ice to keep it cold then it is effectively ice free.

Title: Re: 2018 sea ice area and extent data
Post by: jdallen on June 21, 2018, 05:39:59 PM
<snippage>
That SIA is only near the current date minimum puts a small damper on this 'pessimistic view' of ice survival.  The two graphs suggest that CAB ice compaction is higher now than in other years, and that is sure to put a damper on future internal CAB melt.
I agree - the peripheral seas are secondary to what's happening in the basin proper, which will have the greatest immediate impact on seasonal weather.

While the central basin - particularly the western hemisphere side - hasn't suffered the scorching the rest of the basin has, I'm still concerned about the area immediately north of the Beaufort/Chukchi and on the Atlantic side generally.

If the Kara, Barents and Laptev melt continues as it has or accelerates, that could render the higher CAB compaction and more favorable ice retention conditions moot. 

Of further concern is the possible set-up of high pressure over the Beaufort.  While extent and compaction are better than some years, other factors like ice age and thickness are decidedly *not*.  Late June heat and melt ponds could easily make up for (in that area) a lazy June.

All hinges on the weather.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 22, 2018, 05:49:39 AM
[ADS-NIPR-JAXA] ASI Extent.

June 21st, 2018: 9,988,672 km2, a drop of -61,552 km2.
2018 is the sixth lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 22, 2018, 10:41:41 AM
JAXA Extent 9,988,672 km2(June 21, 2018)

Again,just to add to Juan's post :
Extent loss for the melting season to date is, at 3.90 million km2, 460 k below the average for the last 10 years. That is a significant amount, about one weeks average melt for the time of year. See the graph on how consistently slower than or average daily melt has been for some time.

Extent is now 86k (0.9%) above the average for 2010-2017.

On average 44% of the melting is done for this season - still a long way to go, on average 84 days.

Excluding 2012 from the 10 year average remaining extent loss. The outcome for the minimum then comes in at 4.49 million km2 as opposed to 4.38 million km2. The range of outcomes from the last 10 years remaining melt is 3.41 to 4.88 million km2, (The average September minimum of the last 10 years was 4.41 million km2).

Rather than seeing the June Cliff, in June we continue to see a gradual slowing of extent loss to more and more below the average.

ps: Juan got the data just in time - JAXA seems to be offline now.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 22, 2018, 03:54:31 PM
NSIDC Total Area  as at 21st June (5 day trailing average) =   8,388,639 km2
This is 211k above the 2010-2017 average on this date.


Total Area loss 51 k, Central Seas 14 k Periphery 12k, Other Seas 25k (Hudson 26k).   

The slow down in June melt is now showing in these 5 day averages. Current day is 41k below the 2010-2017 average area loss.

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 20 k, +1k on the day (It just will not die).
- The Bering Sea area is 3k.    (It also just will not die)
- Chukchi Sea loss 11 k,
- Beaufort Sea gain 16 k
i.e. Pacific side slow - loss or even sometimes a slow gain...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 14 k,
of which the Baffin loss was 8k and the Barents 4k
- The Laptev Sea area gain 8 k  .
- The Kara Sea area gain 3 k.

CAB
- The Central Arctic Sea loss 13k
- The Canadian Archipelago loss 1 k
- East Siberian Sea loss 2 k

Other seas
- St Lawrence area is up 1 to 3 k,
- Hudson Bay area loss 26 k, area now just below 1990's average - i.e.a bit of catch-up.

Area loss this year to date has followed the 2010-17 average very closely indeed, but is slowing. Individual seas leaders matched by the laggards.
[/quote]
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 23, 2018, 05:55:21 AM
Sorry guys. No ADS this weekend…  :P
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 23, 2018, 08:13:31 AM
Possible outage(s) with NSIDC as well:

Quote
DMSP F18 to undergo testing late June, early July
June 22, 2018


The Defense Meteorological Satellite Program (DMSP) F18 satellite will be undergoing testing from June 25 to 29 and from July 9 to 12. During this time, data from the Special Sensor Microwave Imager/Sounder (SSMIS) sensor on F18 may have degraded quality or may not be collected. DMSP F18 is the primary sensor that provides NSIDC with near-real-time data for sea ice monitoring (nsidc-0081, the Sea Ice Index, and the Arctic Sea Ice News and Analysis web page). If the data quality does not meet operational standards, NSIDC will remove the resulting sea ice fields or NSIDC may not distribute data from the F18 SSMIS during the test periods.

link (http://nsidc.org/arcticseaicenews/2018/06/dmsp-f18-to-undergo-testing/)
Title: Re: 2018 sea ice area and extent data
Post by: Steven on June 23, 2018, 08:45:06 PM
Compactness is quite high at the moment:

(https://i.imgur.com/quR2HDq.png)

(https://i.imgur.com/OUrDRhQ.png)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 23, 2018, 09:29:52 PM
NSIDC Total Area  as at 22nd June (5 day trailing average) =   8,370,055 km2
This is 296k above the 2010-2017 average on this date.

     
Total Area loss a mere 19 k, Central Seas GAIN 12 k Periphery 16k, Other Seas 14k (Hudson 13k).

Crash bang wallop?   

The slow down in June melt is now showing in these 5 day averages. Current day area loss is 85k below the 2010-2017 average area loss.

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 20 k, -1k on the day (It just will not die).
- The Bering Sea area is 3k.    (It also just will not die)
- Chukchi Sea loss 4 k,
- Beaufort Sea loss 1 k
i.e. Pacific side slow - loss or even sometimes a slow gain...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 16 k,
of which the Baffin loss was 10k and the Barents 4k
- The Laptev Sea area gain 11 k  .
- The Kara Sea area loss 5 k.

CAB
- The Central Arctic Sea gain 5k
- The Canadian Archipelago gain[/b 7 k
- East Siberian Sea loss 1 k

Other seas
- St Lawrence area no change in area at 3 k,
- Hudson Bay area loss 213 k, area now just below 1990's average.

Area loss this year to date has followed the 2010-17 average very closely indeed, but is slowing.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 25, 2018, 10:46:14 PM
NSIDC Total Area  as at 24 June (5 day trailing average) =    8,344,893 km2
This is 461k above the 2010-2017 average on this date.

     
Total Area loss a mere 9 k, Central Seas GAIN 16 k Periphery 17k, Other Seas 9k

Area loss lowed to a crawl for the last three days.

The slow down in June melt is now showing in these 5 day averages. Current day area loss is approaching 100k below the 2010-2017 average daily area loss.

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 17 k, -2k on the da.
- The Bering Sea area is 3k.
- Chukchi Sea loss 7 k,
- Beaufort Sea gain 4  k
i.e. Pacific side slow - loss or even sometimes a slow gain...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas just 17 k,
of which the Baffin loss was 8 k, the Greenland 6k and  the Barents 3k
- The Laptev Sea area gain 7 k  .
- The Kara Sea area loss 13 k.

CAB
- The Central Arctic Sea gain 19k
- The Canadian Archipelago gain 4 k
- East Siberian Sea gain 3 k

Other seas
- St Lawrence area no change in area at 2 k,
- Hudson Bay area loss 7 k, area now just below 1990's average.

Area loss this year to date followed the 2010-17 average very closely indeed, but is slowing to well below average. I will not resist a comment about melting season posts predicting catastrophic loss of Arctic Sea Ice - always just around the corner.

last post for a bit on NSIDC data - they are out of commission for a few days.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on June 25, 2018, 10:50:06 PM
(https://media.giphy.com/media/38fblIIrHLMPe/giphy.gif)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 26, 2018, 06:05:26 AM
Sorry guys. No ADS this weekend…  :P


ADS NIPR (JAXA) has not come back yet.
I am going to bed, so you can look at:

https://ads.nipr.ac.jp/vishop/#/extent (https://ads.nipr.ac.jp/vishop/#/extent)
Title: Re: 2018 sea ice area and extent data
Post by: psymmo7 on June 26, 2018, 10:10:45 AM
Does anyone (perhaps someone who understands japanese) have any idea why the JAXA website is still down or know to whom we could address an enquiry?
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 26, 2018, 10:49:26 AM
Their twitter page (https://twitter.com/ADS_NIPR?ref_src=twsrc%5Etfw&ref_url=https%3A%2F%2Fads.nipr.ac.jp%2Fportal%2Findex.action) can reveal little secrets in English.
Quote
Our service will be stopped from June 22 to 25 by planed electrical  outage for legal inspection.
8:41 PM - 22 Jun 2018
Quote
Now ADS service is down due to system failure from 25th June.
6:54 PM - 25 Jun 2018
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 26, 2018, 11:58:32 AM
NSIDC Data Outage

Every time DMSP sateliite F18 goes off-line for maintenance I am reminded that the data on which so many of us depend for so much hangs by a single electronic thread.

F18 is the last man standing and I believe is already operating beyond its design life. Thanks to the US Congress "what happens next" is still up in the air.

From a post last November.

Quote
NSIDC DATA - Nearing the end?

https://www.theguardian.com/science/2017/nov/05/donald-trump-accused-blocking-satellite-climate-change-research

It seems that NASA have decided that DMSP satellite F-19 cannot be made operational, and has been abandoned.
DMSP satellite F-20 was destroyed by order of Congress.
The current satellites are already working beyond their shelf-life and the earliest replacement date is 2023.
It is highly likely that NSIDC data will be interrupted temporarily or permanently.

“This is like throwing away the medical records of a sick patient,” said David Gallaher of the National Snow and Ice Data Center in Boulder, Colorado. “Our world is ailing and we have apparently decided to undermine, quite deliberately, the effectiveness of the records on which its recovery might be based. It is criminal.”

However, this criminal act lies not with Trump but at the door of Rep. US Senator Lamar Smith, current chairman of the U.S. House Science, Space and Technology Committee.
He is not standing for re-election next year, and the hurrahs vs eulogies have already started.

http://beta.latimes.com/business/hiltzik/la-fi-hiltzik-lamar-smith-20171103-story.html
https://www.texastribune.org/2017/11/02/lamar-smith-retiring-congress/
Title: Re: 2018 sea ice area and extent data
Post by: weatherdude88 on June 26, 2018, 06:54:16 PM
The NSIDC northern hemisphere arctic sea ice extent value for 6.25.2018 is 10.241 millions of square kilometers. This places 2018 northern hemisphere sea ice extent in 7th place for the date.

ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on June 27, 2018, 05:46:55 AM
ADS-NIPR-JAXA has a server problem…  :-\
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 27, 2018, 10:53:19 AM
Better than a satellite problem, but still something of a PITA, as I'm curious to see how extent will react to current weather conditions.
Title: Re: 2018 sea ice area and extent data
Post by: weatherdude88 on June 27, 2018, 01:46:00 PM
The NSIDC northern hemisphere arctic sea ice extent value for 6.26.2018 is 10.297 millions of square kilometers (gain of 56 thousand square kilometers). This places 2018 northern hemisphere sea ice extent in 8th place for the date.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 27, 2018, 01:47:43 PM
Thanks for these updates weatherdude.
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 27, 2018, 03:08:30 PM
Ah, but NSIDC area dropped -256k.  Maybe not so unexpected considering that area is relatively high, now at the 11th lowest for the day.

Drops everywhere, in and outside the Arctic Basin:

Regional Arctic Sea Ice Extent and Area calculated from NSIDC NASA Team concentration data
Date: 2018-06-26 12:00  Values in 1000 km^2

Extent (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  4282.5   -5.3  -162.2    935.1   +0.0   +15.1    534.7   -2.0  -154.7
               Kara Sea             Barents Sea           Greenland Sea
   750.0  -15.3   -68.8    134.4  +19.1  -257.9    321.7  +12.2  -272.6
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
   657.2   -4.8   -23.6     23.4  +18.7   +18.1    943.7   -8.1   +61.6
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   711.8   +2.6    +1.1    500.7   -5.0   +29.9    370.2  -13.8   -94.7
             Bering Sea          Sea of Okhotsk                   Lakes
    32.5  +23.2   -10.2     80.1  +21.2    +7.3    183.9  -35.8   +57.3
          Other regions       Total (ex. lakes)
    19.3  +13.2   +16.0  10297.2  +55.9  -895.6

Area (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  4079.1  -65.4   -37.1    795.9  -22.2   +54.2    358.3   -1.3  -154.7
               Kara Sea             Barents Sea           Greenland Sea
   451.4  -30.7  -143.7     61.1   +1.1  -157.7    206.2   +1.7  -133.1
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
   330.9  -57.2   -83.8      6.4   +5.0    +4.8    506.8  -71.3   -25.3
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   489.5   +1.0   -32.2    391.3  -12.5   +34.5    245.5  -19.0  -119.3
             Bering Sea          Sea of Okhotsk                   Lakes
     7.9   +5.0    -4.0     23.2   +6.4    -3.5    105.2   -2.6   +41.4
          Other regions       Total (ex. lakes)
     6.0   +3.4    +4.9   7959.6 -256.1  -796.0


This is also shown in the delta map. Here red/blue pixels indicate that ice concentration goes below/above 15%. Pinkish/blueish colors indicate that concentration changed more than 7% (down/up).
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 27, 2018, 04:17:52 PM
Ah, but NSIDC area dropped -256k.

Indeed, and if extent by contrast goes up by 55K, compactness drops by a massive 3 percentage points. May I point out that his melting season is a bit crazy?
Title: Re: 2018 sea ice area and extent data
Post by: Shared Humanity on June 27, 2018, 04:26:18 PM
Indeed, and if extent by contrast goes up by 55K, compactness drops by a massive 3 percentage points. May I point out that his melting season is a bit crazy?

It is fascinating. I cannot turn away from watching it and I haven't a clue what is happening or why.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 27, 2018, 05:17:28 PM
Why is it that I am stuck offline (apart from a rubbish phone) just when things start to move again?
Hoping to resume this weekend.
Title: Re: 2018 sea ice area and extent data
Post by: lurkalot on June 27, 2018, 06:14:01 PM
Charctic shows a loss of 47k not a gain of 56k but maybe I'm looking at 5 day smoothed and weatherdude at single day - or vice versa?
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 27, 2018, 06:21:14 PM
Yes, there are differences.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on June 27, 2018, 06:57:53 PM
The #s for 2018 do not reflect the "reality" due to the abundance of HB / Kara ice. The high latitudes are IMO worst ever.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on June 27, 2018, 07:30:20 PM
Warm ice and clouds.  Interesting combination, and very unpredictable end game.
Title: Re: 2018 sea ice area and extent data
Post by: dnem on June 27, 2018, 08:30:45 PM
Really interesting and I think indicative of the expected increase in variability and unpredictable behavior as we inch closer to the final collapse of arctic summer ice cover.  Curve fitting or even physical explanations such as more open water leading to cooler, cloudier summers and a "slow transition" will not be useful in predicting the (IMO) unpredictable end game.  This will be apparent within the next at most 10 (and probably less) melt seasons.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 27, 2018, 09:04:30 PM
Back in circulation again- I hope (technology permitting)

NSIDC Total Area as at 26 June (5 day trailing average) = 8,252,513 km2
This is 545k above the 2010-2017 average (and only 129k below the 2000's average on this date).

That's a lot of ice. 545k km2 of ice even at an average thickness of 1/2 a metre is 270+ gigatonnes, nearly the average annual volume loss according to PIOMAS.
     
Total Area loss recovered over the two days from a mere 9 k, to 83 k, still 20k below average for the day.
Central Seas 16 k Periphery 35k, Other Seas 19k

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 18 k,
- The Bering Sea area is 4k.
- Chukchi Sea loss 15 k,
- Beaufort Sea loss 2  k
i.e. Pacific side slow - loss or even sometimes a slow gain...

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 29 k,
of which the Baffin Sea loss was a high 22 k, the Greenland Sea 6k and  the Barents 2k
- The Laptev Sea area loss 2 k  .
- The Kara Sea area loss 18 k.

CAB
- The Central Arctic Sea loss 2k
- The Canadian Archipelago gain 1 k
- East Siberian Sea gain 2 k

Other seas
- St Lawrence area up at 3 k,
- Hudson Bay area loss 20 k, area now below 1990's average.

Area loss this year to date followed the 2010-17 average very closely indeed, but slowed to well below average since June 10. I again will not resist a comment about melting season posts predicting catastrophic loss of Arctic Sea Ice - always just around the corner.

perhaps on Sunday a good idea to give the area graphs an airing.
Title: Re: 2018 sea ice area and extent data
Post by: Brigantine on June 28, 2018, 12:38:04 AM
This is 545k above the 2010-2017 average (and only 129k below the 2000's average on this date).[/b]
That's a lot of ice. 545k km2 of ice even at an average thickness of 1/2 a metre is 270+ gigatonnes, nearly the average annual volume loss according to PIOMAS.

Except it isn't necessarily a difference between 0.5m thick ice and seawater. More likely much of the difference is where there is dry ice* or snowed-over or frozen over melt ponds, in the place of meltwater.

(meltwater having the same appearance to the satellite/algorithm as seawater so not counting towards ice area, even if there's 0.5+m of ice underneath.)

*- here meaning water 100% in the solid phase, not to be confused with CO2 "dry ice"
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on June 28, 2018, 06:01:26 AM
NSIDC Total Area as at 26 June (5 day trailing average) = 8,252,513 km2
This is 545k above the 2010-2017 average (and only 129k below the 2000's average on this date).

That's a lot of ice. 545k km2 of ice even at an average thickness of 1/2 a metre is 270+ gigatonnes, nearly the average annual volume loss according to PIOMAS.
The average loss from PIOMAS over the past 40 years is 16,900 km^3. 545K km^2 of area half a meter thick is only 272 km^3 and represents only 1.6% of the average loss. 

The way the Beaufort is looking today, light blue rather than white or dark blue, I  suspect that a lot of that extra area isn't very thick at all. Also that other parts of the Arctic are not as thick as usual.  With  the ice as broken up as it seems to be I have the feeling that the water in the CAB is seeing a lot more insolation than usual which may lead to the same rapid late melt out that we saw in 2016. 
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 28, 2018, 12:25:10 PM
NSIDC Total Area as at 26 June (5 day trailing average) = 8,252,513 km2
This is 545k above the 2010-2017 average (and only 129k below the 2000's average on this date).

That's a lot of ice. 545k km2 of ice even at an average thickness of 1/2 a metre is 270+ gigatonnes, nearly the average annual volume loss according to PIOMAS.
The average loss from PIOMAS over the past 40 years is 16,900 km^3. 545K km^2 of area half a meter thick is only 272 km^3 and represents only 1.6% of the average loss. 

I perhaps was unclear as to what I meant by "annual average loss". here is a quote  from the Polar Science Center

"To melt the additional 280 km3 of sea ice, the amount we have have been losing on an annual basis based on PIOMAS calculations, it takes roughly 8.6 x 10^19 J or 86% of U.S. energy consumption."

Also, I was not saying the average thickness of the ice that has not melted compared with the average is 50 cms; just saying that IF it was, the current melting season is 270 gt behind the curve as at the end of June.
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 28, 2018, 02:51:57 PM
The current NSIDC values are in all likeliness wrong , drop in area -750k. See also the delta map for the mess.

I expect a correction or withdrawal of the data.
Title: Re: 2018 sea ice area and extent data
Post by: RikW on June 28, 2018, 03:10:47 PM
or we have a real cliff ;)

This is the first time I remember seeing such a strange result, does it happen often?
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 28, 2018, 03:16:47 PM
or we have a real cliff ;)

This is the first time I remember seeing such a strange result, does it happen often?

Oh, I forgot to mention this:
https://forum.arctic-sea-ice.net/index.php/topic,2223.msg160176.html#msg160176

which, I think, is the real reason.
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on June 28, 2018, 03:27:34 PM
Here's a rough attempt to "predict" the missing JAXA values, based on the recent JAXA history plus the subsequent NSIDC extent data (up to 26 June, so not including today's presumably erroneous value):

22 June: 9.95
23 June: 9.87
24 June: 9.84
25 June: 9.80
26 June: 9.82

Disclaimer -- I did that hastily, and a more careful approach would probably give better predictions.  But I didn't have time for a more careful method, so this will do for now....
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 28, 2018, 03:40:09 PM
Thanks Ned. I do think a better aporoximation would be by taking UH AMSR2 numbers whch I suspect would have lower results, but I am away from my PC and  cannot do the analysis.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 28, 2018, 04:20:55 PM
That seems extremely important.  Maybe it would be better for them to suspend their publication of data during testing, so as not to produce misleading information that needs to be corrected later?  And avoid the confusions that tend to proliferate as a result?


Oh, I forgot to mention this:
https://forum.arctic-sea-ice.net/index.php/topic,2223.msg160176.html#msg160176

which, I think, is the real reason.
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on June 28, 2018, 05:01:10 PM
Thanks Ned. I do think a better aporoximation would be by taking UH AMSR2 numbers whch I suspect would have lower results, but I am away from my PC and  cannot do the analysis.
I have zero time to be doing this, but you have provoked me into doing it anyway  ;)

DateJaxa(Avg)Jaxa(NSIDC)Jaxa(Bremen)
22 June9.929.959.94
23 June9.859.879.87
24 June9.769.849.82
25 June9.699.809.81
26 June9.619.829.73
27 June9.53n/a9.64

All three columns of data are predictions for the missing days of JAXA extent:
First = based on last reported value and average rate of decline on this date (2007-2017)
Second = based on last reported value and NSIDC
Third = based on last reported value and Uni Bremen

Title: Re: 2018 sea ice area and extent data
Post by: oren on June 28, 2018, 07:19:37 PM
Thanks again. Superb!
Title: Re: 2018 sea ice area and extent data
Post by: Hyperion on June 28, 2018, 07:58:18 PM
The current NSIDC values are in all likeliness wrong , drop in area -750k. See also the delta map for the mess.

I expect a correction or withdrawal of the data.
We did have something like a week of compaction, wind,waves and low levels moisture blowing into that area,  followed by the reverse for the last few days. Is it possible that it may have expanded into the threshold where gaps between floes cross the threshold where they are noticed by the sensors? SMOS seem to be showing a similar thing. And where I find a few rare gaps in the cloud and fog there it seems to be a field of floes dispersed in open water. It could be errors on both sides of the temporal range?
Title: Re: 2018 sea ice area and extent data
Post by: Tor Bejnar on June 28, 2018, 09:03:53 PM
Quote from: Wipneus on Today at 08:51:57 AM

It looks more like a giant alien spider (8 legs - or maybe it's a Purple People Eater (https://youtu.be/X9H_cI_WCnE)) sitting on the North Pole - poor Santa.  (I'm glad I'm not purple!)
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 29, 2018, 12:35:36 AM
The current NSIDC values are in all likeliness wrong , drop in area -750k. See also the delta map for the mess.

I expect a correction or withdrawal of the data.

As long as there's no correction, compactness dropped 6 percentage points, but not quite enough to go lowest on record (71.2% vs 2007's 71.1%).  ;)
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 29, 2018, 07:28:54 AM
Surely the data is wrong? The artifacts are clearly visible in Wipneus' map.  ???
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 29, 2018, 09:05:31 AM
Of course it's wrong. I just thought it was funny to show what the effect on compactness was, especially given that it dropped to almost lowest on record (difference 0.1%). That's why I labelled the graph 'NSIDC data error'. Has it been seized upon by climate risk deniers yet to show how we alarmists have gone nuts?  ;)
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on June 29, 2018, 09:13:52 AM
Of course it's wrong. I just thought it was funny to show what the effect on compactness was, especially given that it dropped to almost lowest on record (difference 0.1%). That's why I labelled the graph 'NSIDC data error'. Has it been seized upon by climate risk deniers yet to show how we alarmists have gone nuts?  ;)
Perhaps its been wrong for the past  two  weeks and now we are getting the correction  ;)

Maybe that's why they  were checking the satellite.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 29, 2018, 09:24:13 AM
Yes, that's definitely a possibility, although the slowdown also appeared in AMSR2 data. We'll see what happens when everything comes on line again. Bad time of the year for both ADS-NIPR and NSIDC dropping out. But patience is a virtue.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 29, 2018, 09:51:36 AM
My patience with JAXA wears thin, and my sense of humor failed. Sorry Neven I didn't notice the chart label...
Title: Re: 2018 sea ice area and extent data
Post by: pauldry600 on June 29, 2018, 12:26:33 PM
Fed up waiting on JAXA too

I reckon Ill look again when it is 4.5m on September 9th 2018
Title: Re: 2018 sea ice area and extent data
Post by: weatherdude88 on June 29, 2018, 01:44:53 PM
The NSIDC northern hemisphere arctic sea ice extent value for 6.28.2018 is 10.031 millions of square kilometers. This places 2018 northern hemisphere sea ice extent in 8th place for the date.

ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on June 29, 2018, 02:26:49 PM
My patience with JAXA wears thin ...
For now I've switched to looking at Uni Bremen's AMSR2 extent.  It's not a perfect analogue for JAXA.   During the winter UB extent is about 600k greater than JAXA, and during the summer that difference drops to around 200k.  So during June it tends to show larger daily decreases than JAXA does, in order to make up  most of that 400k difference.

Having said that, here are the last week's daily AMSR2 extent decreases via UB:

21 June: 121k
22 June: 57k
23 June: 95k
24 June: 63k
25 June: 05k
26 June: 87k
27 June: 113k

Or taking into account the fact that at this time of year, the UB decreases are about 8k to 6k bigger than JAXA decreases, here are the UB daily decreases modified to be more JAXA-ish:

21 June: 113k
22 June: 49k
23 June: 87k
24 June: 56k
25 June: -02k (increase)
26 June: 80k
27 June: 107k



Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 29, 2018, 03:20:24 PM
NSIDC Total Area as at 28 June (5 day trailing average) =  7,848,090 km2

I attach the data without commentary because:-

Is the data good or bad ?
[/b]
Remember this is the 5 day trailing average from the NSIDC regional data spreadsheet in "sea ice tools"
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on June 29, 2018, 03:36:47 PM
Yesterday's data (ice date 2018-06-27) has not been corrected. Today's data (ice date 2018-06-28) looks much better with a jump in area of +471k.

Is the data good or bad? I am not sure, attached is a delta of two days skipping the obvious faulty 27th.
Title: Re: 2018 sea ice area and extent data
Post by: magnamentis on June 29, 2018, 07:11:28 PM
Fed up waiting on JAXA too

I reckon Ill look again when it is 4.5m on September 9th 2018

and felt it happens always when things are most interesting, this could be a subjective impression but still, unfortunately didn't write down the dates but always when key events unfold or final seasonal results are approaching we are without data.

BTW i was thinking whether to buy a few guys a webcam. one after the other drops out and is not replaces in most cases. no buoy-cams no webcams a pitty.

does anyone know the guy in kimmirut perhaps i can send him a new one, at least if he wasn't using a multi-thousand dollar equipment LOL
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 29, 2018, 07:32:49 PM
Fed up waiting on JAXA too

I reckon Ill look again when it is 4.5m on September 9th 2018

and felt it happens always when things are most interesting, this could be a subjective impression but still, unfortunately didn't write down the dates but always when key events unfold or final seasonal results are approaching we are without data.


Below is why I get the shivers every time the satellites go into testing mode.
Things not any better since the article was published last year?
Note the reference to JAXA below

https://www.scientificamerican.com/article/ageing-satellites-put-crucial-sea-ice-climate-record-at-risk/

Ageing Satellites Put Crucial Sea Ice Climate Record at Risk
Scientists scramble to avert disruption to dataset that has tracked polar ice since the late 1970s

By Alexandra Witze, Nature magazine on October 27, 2017

Quote
Scientists all over the world rely on the sea-ice record compiled by the US National Snow and Ice Data Center (NSIDC) in Boulder, Colorado. But the US military satellites that collect the data, by measuring ice extent using microwave sensors, are approaching the end of their lives. Three are still working but ageing, and their intended successor started experiencing glitches in 2016, before conking out for good this month. The next possible replacement won't launch until at least the early 2020s.

That means the most complete and most scientifically significant sea-ice record is at risk of breaking. Any gap in satellite coverage is not just a short-term problem: it would compromise future research, because scientists would not be able to accurately compare observations made before the gap with those from afterward.....

Centre analysts have begun testing the inclusion of sea-ice data from a Japanese satellite, but that spacecraft—designed to last five years—is now five years old. Experts looking to avert the looming gap will gather to debate other options, including the potential use of data from a Chinese satellite, in December, at a meeting of the American Geophysical Union in New Orleans, Louisiana.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on June 29, 2018, 11:35:15 PM
I tend to forget about this.   For the Earth, this would be like going partially blind when in the middle of a challenging and exposed trail. 

Below is why I get the shivers every time the satellites go into testing mode.
Things not any better since the article was published last year?
Note the reference to JAXA below

https://www.scientificamerican.com/article/ageing-satellites-put-crucial-sea-ice-climate-record-at-risk/
Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on June 30, 2018, 12:00:19 AM
Republicans in the U.S. congress ordered the already built follow on satellite destroyed to intentionally blind us in the Arctic and berated the U.S. military for building and storing the satellite. What those people have done on climate is a crime against future generations. Of course, U.S. law allows crimes against future generations, so no one can be punished.

It's as if they put sticks in our eyes and blinded us because they didn't like what we were seeing.
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on June 30, 2018, 02:23:10 AM
Republicans in the U.S. congress ordered the already built follow on satellite destroyed to intentionally blind us in the Arctic and berated the U.S. military for building and storing the satellite.

No, actually.  The story behind DMSP-20 is much more complicated and less conspiratorial than that, and the decision to cancel it had basically nothing to do with the Arctic.

DMSP-20 was built in the mid-1990s, had been in (expensive) storage for two decades, and was both ageing and technologically obsolescent.  The cost to launch it would be high, and many people were debating whether it was worth it.  An Air Force study in the summer of 2014 recommended against launching DMSP-20, keeping it in storage was running $40 million per year, and every additional year made it more likely that something would go wrong if it were launched. 

The DMSP constellation was not intended for monitoring Arctic sea ice, it was intended to provide support for weather forecasting by the US Air Force.  The program was not planned to be perpetual and it had been assumed that "something else" would replace the F-series satellites after DMSP-20.  First that "something else" was going to be a joint military/civilian mission (NPOESS), then the military part got moved to DWSS (Defense Weather Satellite System), then that got killed and replaced by something called WSF-M. 

There are lots of angles to this story we could talk about.  One of them is a longstanding argument within the US earth observation satellite industry about the relative merits of building large expensive multi-purpose systems vs smaller, lighter, cheaper platforms.  Both approaches have been tried and both have had their problems (ICESat GLAS was an example of what happens when the faster, cheaper approach turns out not to also be "better"). 

Another and related angle is that since the end of the 1990s the Bush and then Obama administrations waffled back and forth repeatedly on how to move forward with ALL the US earth observation satellite programs.  In the early 2000s the Bush administration was gripped with a mania for "privatization" of the nation's EO assets and wasted years going down a road (privatize some systems, reorganize others) that turned out to be a complete dead end.  More than a decade ago Bush's science advisor admitted to me that he knew that yes, in retrospect they had basically screwed up and wasted critical time, given that the US government process for developing and building new satellites is insanely slow and sclerotic.

Yet another strand to this fiasco is a total lack of understanding by policymakers (in the White House and in Congress) of the differences among different types of EO systems and why those differences matter.  Former students of mine now working at NASA are tearing their hair out trying to justify why they have to spend hundreds of millions to build and launch a handful of extremely complex systems when a private company (Planet Labs) can build (and pay someone to launch) 200 tiny cubesats for a fraction of the cost.  There are actually reasonable answers to that question but it takes a lot of bringing people up to speed before they can understand the answers, and in order to shepherd a satellite through the decade-plus-long development process you keep needing to explain the issues over and over again to generation after generation of White House staff and Congressional fact-finders. 

I could go on and on about this.  Yes, the US government's (mis)management of its earth observation satellite programs has often been infuriating and fiascos abound.  Yes, Congress keeps going back to the idea that we could save money by just buying data from someone else, and every time someone comes up with that idea it wreaks massive havoc on all the future plans. 

But no, Congress did not kill DMSP-20 to "intentionally blind us in the Arctic".  All of us here on ASIF are rather obsessed with the Arctic but that was absolutely not a factor in the decisionmaking process. 

Title: Re: 2018 sea ice area and extent data
Post by: Reallybigbunny on June 30, 2018, 02:44:08 AM
NASA is due to send up ICESat - 2 in a few weeks, I wander if this will provide a clearer picture regarding sea ice area and extent data...

After launch, the fast-firing laser and sensitive detectors aboard ICESat-2 will allow it to collect precise measurements of Earth’s height. The mission is designed to focus on changes in the ice sheets and sea ice in Antarctica and the Arctic, where warming temperatures are having dramatic effects. The satellite will track the changes in these polar regions and around the globe.

Launch is scheduled for Sept. 12, 2018


For more information on ICESat-2, visit: https://icesat-2.gsfc.nasa.gov/

For updates on ICESat-2 and its Delta II at Vandenberg, visit: https://blogs.nasa.gov/icesat2/

For more information about NASA launches, visit: https://www.nasa.gov/centers/kennedy/launchingrockets/index.html
Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on June 30, 2018, 03:04:44 AM
Thanks, Ned W for your insight and expertise on the satellite issue. I am aware of the arguments for smaller and cheaper satellites. I am aware of the limitations of this series of military satellites. I am aware these satellites weren't developed to monitor sea ice.

I am also aware of other uses you didn't mention. This series of satellites was very useful for hurricane forecasting. The microwave imager sees through the high cloud overcast into the developing eyes of hurricanes. I have personally used information derived from these satellites by CIMSS to predict rapid intensification of hurricanes successfully. The NHC and JTWC use the derived data on a regular basis for hurricanes with eyes that can only be seen by microwave sensing.

I didn't come up with the theory that this was malicious destruction based on internet rumor, fake news, or misinterpretation. I read the transcript of the congressional meeting with the DoD representative. That particular congressman viciously attacked the DoD spokesman. He has a record of attacking climate science. He led the charge to destroy the DMSP satellite. He was angry that the NSIDC made a case for keeping it to monitor sea ice decline.

https://www.dailykos.com/stories/2017/9/6/1696633/-Alabama-Republican-Rep-Rogers-DESTROYED-Key-Hurricane-Monitoring-Satellite
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on June 30, 2018, 03:56:30 AM
Yes, there are other uses for the DMSP satellites, but Congress has always had trouble seeing it as more than a USAF program and has generally focused on that. 

DMSP-20 had been on and off the chopping block for years before that hearing.  Of course Rep Rogers wouldn't respond positively to pleas that it was needed to study Arctic sea ice, but that is not the reason that it was canceled.

I'm also not arguing for "smaller and cheaper satellites" exactly.  It's a lot more complicated than that and hard to sum up easily -- as I pointed out above, the wiring failures on the ICESat-1 lasers were a consequence of trying to build it "smaller and cheaper".  But it's extremely hard to justify keeping a heavy (i.e., expensive-to-launch) satellite on mothballs for 20+ years. 

In general, Congresses and White House staff of both parties have really had trouble understanding how the US earth observation satellite program works and how well-intentioned but bad decisions on their part keep screwing it up.  This is only the latest instance in a long sordid history going back to Reagan's attempt to privatize the entire constellation of meteorological satellites back in the 1980s. 

I wish that DMSP-20 were launched, though I understand both sides of the debate that raged over that question and that long predated Rep Rogers's involvement.  Even better would have been to not screw up plans for the follow-on mission by changing horses in midstream again and again. 
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on June 30, 2018, 05:01:15 AM
In general, Congresses and White House staff of both parties have really had trouble understanding ... 
Should have noted that Al Gore was a notable exception to this rule.  In the alternate universe where Gore became President in 2001, the USA in 2018 has a much stronger and better developed earth observation satellite program.

OK, sorry for wandering so far off topic.  Back to the ice.
Title: Re: 2018 sea ice area and extent data
Post by: Feeltheburn on June 30, 2018, 05:16:41 AM
Compactness is quite high at the moment:

(https://i.imgur.com/quR2HDq.png)

(https://i.imgur.com/OUrDRhQ.png)

Where do you find this information? I made a few observations and guesses a month ago based on the DMI modeled ice thickness that melting would be slow. Compactness as shown on DMI map suggested melting around the edges, followed by a slowdown.
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 30, 2018, 06:15:51 AM
Great. Back to JAXA/ADS. Extent for June 30th is...???  >:( :(
Title: Re: 2018 sea ice area and extent data
Post by: Neven on June 30, 2018, 12:35:36 PM
Where do you find this information? I made a few observations and guesses a month ago based on the DMI modeled ice thickness that melting would be slow. Compactness as shown on DMI map suggested melting around the edges, followed by a slowdown.

The first graph comes from Wipneus' website somewhere (Arctische Pinguin). The second one is made by Steve and relies on NSIDC extent and area data. If you divide area by extent you get an idea of how much open water is within the ice pack (either real open water or melt ponds), in other words: compactness.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 30, 2018, 02:38:12 PM
ASSUMES THE DATA IS GOOD.
No messages on NSIDC to say otherwise.

If the data is good, the June Cliff started 3 days ago - i.e. in June (just).

NSIDC Total Area as at 29 June (5 day trailing average) =  7,690,066 km2
This is now down to 319k above the 2010-2017 average


Total Area loss 158,017    
Central Seas 121 k Periphery 13k, Other Seas 25k


Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 18 k,
- The Bering Sea area is 7k.
- Chukchi Sea loss 22 k,
- Beaufort Sea loss 33  k
i.e. Pacific side loss accelerating.

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 13 k,
of which the Baffin Sea loss was a high 14 k, the Greenland Sea gain 2k,and  the Barents loss 1k
- The Kara Sea area loss 22 k.
- The Laptev Sea area loss 11 k  .

CAB
- The Central Arctic Sea loss 30k
- The Canadian Archipelago gain 1 k
- East Siberian Sea gain 4 k

Other seas
- St Lawrence area at 3 k,
- Hudson Bay area loss 25 k, area now below 1990's average.
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on June 30, 2018, 05:49:17 PM
I wonder where that Bering ice is as both NOAA as well as climate reanalyzer show water temperatures above +4-+6°C and SST anomalies between +3 and more than +6°C. Is that really ice what they detect? The same is almost true for the Okhtsk Sea (maybe just in the SW-most corner some ice could have survived...)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on June 30, 2018, 06:03:45 PM
I wonder where that Bering ice is as both NOAA as well as climate reanalyzer show water temperatures above +4-+6°C and SST anomalies between +3 and more than +6°C. Is that really ice what they detect? The same is almost true for the Okhtsk Sea (maybe just in the SW-most corner some ice could have survived...)
Click on the attached image and wander around the fringes.
You will see little bits of sea ice in nooks and crannies all over the place.

Local winds and currents may have piled up sea ice into these sheltered places + local ocean currents bringing up colder water, and thus take longer to finally expire.

It is why on my percentage area graphs I chose 5% of maximum to determine ice-free day numbers for each sea.

Or maybe Oren is right (see next post) or maybe we are both right.

https://nsidc.org/data/seaice_index/images/daily_images/N_daily_concentration_hires.png
Title: Re: 2018 sea ice area and extent data
Post by: oren on June 30, 2018, 06:05:21 PM
NSIDC often see coastal ice that is really non-existent. It usually winks on and off.
Check out Uni Hamburg AMSR2 3.125km maps, I would expect this ice doesn't appear there. Even better, one of Wipneus' Home Brew maps/animations, as he filters out the false detections by various algorithms.
Title: Re: 2018 sea ice area and extent data
Post by: Alexander555 on June 30, 2018, 08:51:39 PM
Looks like the thick ice in the ESS is going to take a hit in a couple days.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on July 01, 2018, 06:42:18 AM
JAXA links are now throwing up their twitter feed. Not a tweet  since 25/6 but perhaps news is on the way. The feed says they  had a system failure on the 25th but nothing more.

https://twitter.com/ADS_NIPR/status/1011427490932244480
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 01, 2018, 02:05:55 PM
ASSUMES THE DATA IS GOOD.
No messages on NSIDC to say otherwise.

If the data is good, the June Cliff started 4 days ago - i.e. in June (just).

NSIDC Total Area as at 30 June (5 day trailing average) =   7,546,287  km2
This is down to 262k above the 2010-2017 average


Total Area loss 144K    
Central Seas 113 k Periphery 12k, Other Seas 19k
 

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 17 k,
- The Bering Sea area is 7k.
- Chukchi Sea loss 13 k,
- Beaufort Sea loss 31  k
i.e. Pacific side loss accelerating.

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 13 k,
of which the Baffin Sea loss was 12 k, the Greenland Sea gain 2k,and  the Barents loss 2k
- The Kara Sea area loss 20 k.
- The Laptev Sea area loss 17 k  .

CAB
- The Central Arctic Sea loss 28k
- The Canadian Archipelago gain 5 k
- East Siberian Sea loss 9 k

Other seas
- St Lawrence area at 3 k,
- Hudson Bay area loss 18 k, area now below 1990's average.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 01, 2018, 04:23:11 PM
Area graphs as at 30 June -derived from NSIDC Regional Sea Data 5 Day Trailing Average

1st 4 Graphs attached below.
PACIFIC END
Bering Sea.
The question is for me - will the low winter maximum and early melt mean late 2018 re-freeze will be delayed and winter sea ice increase even less ?

Chukchi Sea.
Early melt giving area well below 2010's average area, followed by June slowdown, followed by late June accelerated melt giving below 2010's average area again.

Beaufort Sea
Mid-June strong growth in area followed by strong melt in late June, but area now at 1990's average.

East Siberian Sea
Area still well above 1980's average.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 01, 2018, 04:50:18 PM
Area graphs as at 30 June -derived from NSIDC Regional Sea Data 5 Day Trailing Average

Graphs 5 to 7 attached below.

Atlantic Seas (1)

Baffin Sea
Despite cold temperatures, and "snowmageddon" in NE Canada, steady melting in the Baffin Sea - area now just above 2000's average.

Greenland Sea.
Area extremely low. How much is due to year by year reduction in Fram Export? Current low north of Greenland may be upping export a bit, hence recent blip upwards in area. Waiting for Wipneus' fram export graph for June to match against Greenland Sea area change.

Barents Sea
After a surprisingly high March maximum, strong melt has brought area back to the 2010's average. Melt to near zero area should be completed this month.
Title: Re: 2018 sea ice area and extent data
Post by: bbr2314 on July 01, 2018, 05:00:52 PM
Area graphs as at 30 June -derived from NSIDC Regional Sea Data 5 Day Trailing Average

Graphs 5 to 7 attached below.

Can you do Hudson Bay and Okhotsk please  ;D

I know Okhotsk is all gone but curious to see how early vs. other decades.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 01, 2018, 05:01:19 PM
Area graphs as at 30 June -derived from NSIDC Regional Sea Data 5 Day Trailing Average

Graphs 8 and 9 attached below.

Atlantic Seas (2)

Kara Sea
Maximum area was at 1980's average or above. Since late May strong melt has brought area approaching 2010's average

Laptev Sea.
Despite two strong hiccups in melt, area is well below the 201's average.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 01, 2018, 05:02:19 PM
Area graphs as at 30 June -derived from NSIDC Regional Sea Data 5 Day Trailing Average

Graphs 5 to 7 attached below.

Can you do Hudson Bay and Okhotsk please  ;D

I know Okhotsk is all gone but curious to see how early vs. other decades.

wait small - (pidgin). Ah, the impatience of youth
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 01, 2018, 05:17:11 PM
Area graphs as at 30 June -derived from NSIDC Regional Sea Data 5 Day Trailing Average

Graphs 10 and 11 attached below.

Central Arctic

Canadian Archipelago
Melt currently stalled, but area still below 2010's average
BUT, this seems to be a normal occurrence at this time of year.

Central Arctic Sea
The same remarks apply, i.e.
Melt currently stalled, but area still below 2010's average
BUT, this seems to be a normal occurrence at this time of year.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 01, 2018, 05:35:53 PM
Area graphs as at 30 June -derived from NSIDC Regional Sea Data 5 Day Trailing Average

Graphs 12, 13 and 14 attached below.

Seas with little direct contact with or influence on the Arctic Ocean
Hudson Bay
The persistent cold in NE Canada delayed melt, but since June melt has closely followed the 1990's average graph line.
Of note is that for all years the minimum is reached at the same date within a week or two

Okhotsk Sea
It was very cold there for a long time this spring (and may have helped to accelerate the melt in the Bering Sea.
Despite a high late maximum and late melting start, by early May area was below the 2010's average.

St Lawrence
Also very cold there in the spring.
A high maximum followed by a catastrophic drop in area.
Of note is that final melt happens at the same time for all years - at about the first of June

This exercise is too much like hard work - not to be done very often
Title: Re: 2018 sea ice area and extent data
Post by: Neven on July 01, 2018, 05:37:06 PM
Assuming NSIDC data is correct, and having fixed the obvious outlier (by dividing the two-day drop in two), compactness has dropped quite a bit, reaching the middle of the pack:
Title: Re: 2018 sea ice area and extent data
Post by: Feeltheburn on July 01, 2018, 09:57:13 PM
Graphs are visually appealing, but sometimes raw data are also illustrative. I miss Espen's simple presentation of arctic sea extent data. To that end, here is the NSIDC arctic ice extent data for 30 June 2018 in descending order (for historical context). Interesting, ice extent in 2018 is barely lower than 2001 and 2005 on 30-06-18.

2010 - 9.257
2016 - 9.334
2012 - 9.335
2017 - 9.421
2011 - 9.532
2014 - 9.617
2006 - 9.820
2018 - 9.939
2007 - 9.952
2015 - 10.008
2013 - 10.015
2008 - 10.199
2005 - 10.211
2001 - 10.297
2003 - 10.624
1995 - 10.630
2002 - 10.767
2004 - 10.814




Title: Re: 2018 sea ice area and extent data
Post by: Neven on July 01, 2018, 11:56:09 PM
Interesting, ice extent in 2018 is barely lower than 2001 and 2005 on 30-06-18.

Even more interesting is the explanation for why this is so, and what it means. But my guess is you're not really interested.  ::)
Title: Re: 2018 sea ice area and extent data
Post by: oren on July 02, 2018, 12:26:19 AM
FTB, did you perhaps mix 2008 and 2018 in your textual analysis?
Title: Re: 2018 sea ice area and extent data
Post by: FishOutofWater on July 02, 2018, 04:28:32 AM
Good news from Japan. They are finally making progress at restoring the ADS server.

https://twitter.com/ADS_NIPR/status/1013577603247034368
Title: Re: 2018 sea ice area and extent data
Post by: CameraMan on July 02, 2018, 05:33:58 AM
Interesting, ice extent in 2018 is barely lower than 2001 and 2005 on 30-06-18.
Which says more about the limitations of extent as a meaningful gauge of overall ice condition going into summer than it does about this year vs others.  Consider where the ice is, condition, and likely weather ahead -- I wouldn't make too much of daily numbers, especially extent.   
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on July 02, 2018, 06:54:24 AM
Interesting, ice extent in 2018 is barely lower than 2001 and 2005 on 30-06-18.
Which says more about the limitations of extent as a meaningful gauge of overall ice condition going into summer than it does about this year vs others.  Consider where the ice is, condition, and likely weather ahead -- I wouldn't make too much of daily numbers, especially extent.
Another way of looking at this is that both 2001 and 2005 were record lows for June 30th and 2018 is a few hundred thousand  km^2 below both of them on this date despite having a much bigger extent than 6 of the past 10 years. 

There is also the point that the average decline from this point has increased by about 500K km^2 since 2001 and is largely unrelated to the extent on this date.
Title: Re: 2018 sea ice area and extent data
Post by: DavidR on July 02, 2018, 10:44:31 AM
JAXA is back up. July 1st extent is 9,282,553 km^2 putting it 461K behind the record low for that day. It is in 8th place 276K behind 6th. 

The June decline was just 1,459,260 making it the lowest since 2015  and the third lowest in the Jaxa record since 2003.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 02, 2018, 11:43:31 AM
JAXA Extent 9,282,553 km2(July 1, 2018)

So, JAXA rises from the dead. here we go again.

Extent loss for the melting season to date is, at 4.61 million km2, 580 k below the average for the last 10 years. That is a significant amount, about one weeks average melt for the time of year. See the graph on how consistently slower than or average daily melt has been for some time.

Extent is now 233k (2.5%) above the average for 2010-2017.

On average 52% of the melting is done for this season - not such a long way to go, on average 73 days.

Excluding 2012 from the 10 year average remaining extent loss. The outcome for the minimum then comes in at 4.61 million km2 as opposed to 4.51 million km2. The range of outcomes from the last 10 years remaining melt is 3.52 to 5.23 million km2, (The average September minimum of the last 10 years was 4.41 million km2).

Rather than seeing the June Cliff, in June we continued to see a slowing of extent loss to more and more below the average.

ps: JAXA extent data not showing the strong area loss shown in NSIDC area data in the last 4 days of June
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on July 02, 2018, 01:19:13 PM
OK, here's an updated version of the table showing attempts to "predict" the missing JAXA values based on either NSIDC or Uni Bremen. 

Turns out that they were both biased slightly too high.  Ignoring the other extent metrics and just taking the average decline (2007-2017) for each day would have been slightly too low, but better.

DateJaxa(actual!)Jaxa(Avg)Jaxa(NSIDC)Jaxa(Bremen)
22 June9.909.929.959.94
23 June9.849.859.879.87
24 June9.779.769.849.82
25 June9.709.699.809.81
26 June9.639.619.829.73
27 June9.569.53n/a9.64

This is somewhat galling.  Incorporating knowledge of extent from NSIDC and Bremen made the predictions worse?  I guess the "problem" is just that 2018 was too close to the average during this six-day period to leave room for much improvement.


Thanks Ned. I do think a better aporoximation would be by taking UH AMSR2 numbers whch I suspect would have lower results, but I am away from my PC and  cannot do the analysis.
I have zero time to be doing this, but you have provoked me into doing it anyway  ;)

DateJaxa(Avg)Jaxa(NSIDC)Jaxa(Bremen)
22 June9.929.959.94
23 June9.859.879.87
24 June9.769.849.82
25 June9.699.809.81
26 June9.619.829.73
27 June9.53n/a9.64

All three columns of data are predictions for the missing days of JAXA extent:
First = based on last reported value and average rate of decline on this date (2007-2017)
Second = based on last reported value and NSIDC
Third = based on last reported value and Uni Bremen
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 02, 2018, 01:29:17 PM
.......attempts to "predict" the missing JAXA values based on either NSIDC or Uni Bremen. 

Turns out that they were both biased slightly too high.  Ignoring the other extent metrics and just taking the average decline (2007-2017) for each day would have been slightly too low, but better.

This is somewhat galling.  Incorporating knowledge of extent from NSIDC and Bremen made the predictions worse?  I guess the "problem" is just that 2018 was too close to the average during this six-day period to leave room for much improvement.

Different instruments, different algorithms ? Hidden inbuilt biases ? NSIDC pixel size 625 km2, AMSR2 pixel size 100 km2 ?

If JAXA produced area data a la NSIDC, I would use that to make consistency with the JAXA extent data.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on July 02, 2018, 01:47:35 PM
[ADS-NIPR-JAXA] ASI Extent.

July 1st, 2018: 9,282,553 km2, a drop of -78,898 km2.
2018 is the 8th. lowest on record.

Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 02, 2018, 02:01:35 PM
NSIDC Total Area as at 1 July (5 day trailing average) =    7,425,509   km2
This is down to 249 k above the 2010-2017 average


Total Area loss 121K    
Central Seas 101 k Periphery 9k, Other Seas 11k
 

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 14 k (down 4k),
- The Bering Sea area is 6k 9down 1k),
- Chukchi Sea loss 8 k,
- Beaufort Sea loss 25  k,
i.e. Pacific side loss accelerating.

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 9 k,
of which the Baffin Sea loss was 4 k, the Greenland Sea gain 0k,and  the Barents loss 4k
- The Kara Sea area loss 15 k.
- The Laptev Sea area loss 20 k  .

CAB
- The Central Arctic Sea loss 30 k
- The Canadian Archipelago gain 4 k
- East Siberian Sea loss 7 k

Other seas
- St Lawrence area at 2 k down 1 k,
- Hudson Bay area loss 6 k,.

Central Arctic Sea area loss remains impressive
Title: Re: 2018 sea ice area and extent data
Post by: oren on July 02, 2018, 03:49:27 PM
Not a single JAXA century break throughout the whole month, if I am not mistaken. Impressive.
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on July 02, 2018, 04:19:19 PM
That's right, although there were also no June century breaks in 2003, 2004, 2008, and 2016. 

The biggest single-day loss of ice in June 2018 was 92.389k (21 to 22 June).  That nearly broke the record for the lowest maximum daily loss in June (2004's maximum loss was 92.334, just a hair lower).

2018 did set a record for the largest 1-day *gain* of ice in June (4.408k, from 17-18 June).

The average daily loss in June 2018 was 50.9965k.  That was fourth lowest, after 2004, 2015, and 2016.
Title: Re: 2018 sea ice area and extent data
Post by: Richard Rathbone on July 02, 2018, 07:50:54 PM
Century increase in NSIDC tomorrow? (as the faulty data of 27th drops out of the 5 day average)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on July 03, 2018, 05:54:52 AM
[ADS-NIPR-JAXA] ASI Extent.

July 2nd, 2018: 9,188,596 km2, a drop of 93,957 km2.
2018 is the seventh lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: Lord M Vader on July 03, 2018, 01:46:55 PM
Another century break from NSIDC. Now down to 9,631 Mn km2. The trailing 5 day-average is now 9,868 Mn km2. Still about 500K above 2012 and 700K above 2010 which was lowest for the date. Still 8th lowest but by tomorrow we'll likely be 9th lowest as 2007 should take over our 8th place. And remark, we can't rule out that 2013 will put us down to 10th lowest place(!)

Arctic is surely a strange place!!
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 03, 2018, 07:11:01 PM
Quote
Richard Rathbone

Century increase in NSIDC tomorrow? (as the faulty data of 27th drops out of the 5 day average)


Increase - yes, but not a century, just 18k, and especially marked in the CAA and Central Arctic Sea. See below for a fairly odd variation between seas.

NSIDC Total Area as at 2 July (5 day trailing average = 7,443,232 km2
This is up to 372 k above the 2010-2017 average


Total Area GAIN 18K    
Central Seas GAIN 29 k Periphery GAIN 8k, Other Seas LOSS 19k
 

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 11 k (down 3k),
- The Bering Sea area is 3k (down 3k),
- Chukchi Sea loss 10 k,
- Beaufort Sea loss 9 k,
i.e. Pacific side loss did continue.

Atlantic Side
- Total area GAIN of the Baffin, Greenland, and Barents Seas 11 k,
of which the Baffin Sea Gain was 10 k, the Greenland Sea gain 0k,and  the Barents GAIN 1 k
- The Kara Sea area loss 10 k.
- The Laptev Sea area loss 23 k  .

CAB
- The Central Arctic Sea GAIN 51 k
- The Canadian Archipelago gain 33 k
- East Siberian Sea loss 3 k

Other seas
- St Lawrence area at 2 k down 1 k,
- Hudson Bay area loss 16 k.

Central Arctic Sea area still at 2010's average despite large gain (correction?)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on July 04, 2018, 06:07:55 AM
[ADS-NIPR-JAXA] ASI Extent.

July 3rd, 2018: 9,135,523 km2, a drop of -53,073 km2.
2018 is the ninth lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 04, 2018, 11:19:11 AM
JAXA Arctic Sea Ice Extent 9,135,523 km2(July 3, 2018)

There is nothing really to add to Juan's post except the attached tables and graph, but I will add:-
- extent loss is slow, really slow,
- average resulting minimum now above 4.5 million km2,
- 54% of melting done (average).


Title: Re: 2018 sea ice area and extent data
Post by: Neven on July 04, 2018, 03:07:47 PM
A small drop in NSIC extent, a big drop in area, and so a big drop in compactness. 2018 still in the middle of the pack:
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on July 04, 2018, 03:14:35 PM
2018 JAXA ASI extent continues its underperforming ways. The June 3rd decrease of 53k marked the 11th consecutive day with a drop less than the 10-year (2008-2017) average for the day. In fact, only two of the last 27 days have seen a decrease larger than that average. The total 27-day change over that 10-year period has averaged 1.96M km2; this year a drop of only 1.38M. (The leader for the period was 2012, which fell by a fairly massive 2.43M over the same stretch.)

In another four weeks, the parabola starts flaring out toward the minimum, so if 2018 is to stay in, say, the bottom ten, it'll need to go on a tear. Most likely guess as of now: a tepid minimum of around 5M.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 04, 2018, 03:32:44 PM
Normal service has been resumed (I assume)

NSIDC Total Area as at 3 July (5 day trailing average =  7,322,463 km2
This is 359 k above the 2010-2017 average


Total Area loss 121K    
Central Seas loss 84 k Periphery loss 11k, Other Seas loss 26k
 

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 8 k (down 3k),
- The Bering Sea area is 3k ,
- Chukchi Sea loss 13 k,
- Beaufort Sea loss 11 k,

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 11 k,
of which the Baffin Sea loss was 8 k, the Greenland Sea gain 0k,and  the Barents Sea loss 3 k
- The Kara Sea area loss 13 k.
- The Laptev Sea area loss 24 k  .

CAB
- The Central Arctic Sea loss 6 k
- The Canadian Archipelago gain 1 k
- East Siberian Sea loss 18 k

Other seas
- St Lawrence area at 2 k,
- Hudson Bay area loss 24 k.

ps: Laptev Sea Area has been 18 days lowest in satellite record since 11 June.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 04, 2018, 03:35:37 PM
The June 3rd decrease of 53k

Making so many typos myself, I am glad of a chance to correct someone other than myself - JULY 3rd decrease methinks.
Title: Re: 2018 sea ice area and extent data
Post by: oren on July 04, 2018, 04:09:53 PM
I expect July melt to catch up some of the ground (un)lost in June, including some century breaks, due to losses in the periphery.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on July 05, 2018, 05:46:15 AM
I expect July melt to catch up some of the ground (un)lost in June, including some century breaks, due to losses in the periphery.

In support of that, the South Kara Sea ice (below, unaltered image) is looking particularly dark and gray these days, and the Hudson ice seems a similar shade.  So albedo is getting lower, and both are currently receiving a good deal of insolation.
Title: Re: 2018 sea ice area and extent data
Post by: jdallen on July 05, 2018, 05:53:42 AM
I expect July melt to catch up some of the ground (un)lost in June, including some century breaks, due to losses in the periphery.

In support of that, the South Kara Sea ice (below, unaltered image) is looking particularly dark and gray these days, and the Hudson ice seems a similar shade.  So albedo is getting lower, and both are currently receiving a good deal of insolation.
Watching ice like that, typically at this stage it's about 7-10 days from disappearing.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on July 05, 2018, 06:10:20 AM
[ADS-NIPR-JAXA] ASI Extent.

It has passed 30+ minutes of the usual time and ADS NIPR has no data.
So, I appreciate if someone else post the data, at least extent and daily drop.
Thanks!

https://ads.nipr.ac.jp/vishop/#/extent (https://ads.nipr.ac.jp/vishop/#/extent)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 05, 2018, 07:27:43 AM
It has passed 30+ minutes of the usual time and ADS NIPR has no data.
So, I appreciate if someone else post the data, at least extent and daily drop.
Thanks!
Glad to oblige, Juan.

JAXA Arctic Sea Ice Extent - 9,079,816 km2(July 4, 2018)

A daily drop of just 56k, well over 30k less than the average for the time of year.
Extent loss to date is 640k km2 (12%) below the 2010's average, with 55% of the average melting season done.
A September minimum of above 4.5 million km2 looks more likely every day.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on July 05, 2018, 02:49:37 PM
With compactness dropping another 1.5%, 2018 is slowly moving to the lower range of the pack:
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 05, 2018, 03:23:01 PM
NSIDC Total Area as at 4 July (5 day trailing average =  7,190,592 km2
This is 334 k above the 2010-2017 average


Total Area loss 161K    
Central Seas loss 121 k Periphery loss 21 k, Other Seas loss 19 k
 

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 6 k (down 2k),
- The Bering Sea area is 2 k,
- Chukchi Sea loss 10 k,
- Beaufort Sea loss 13 k,

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 20 k,
of which the Baffin Sea loss was 10 k, the Greenland Sea loss 6k,and  the Barents Sea loss 4 k
- The Kara Sea area loss 10 k.
- The Laptev Sea area loss 24 k  .

CAB
- The Central Arctic Sea loss 45 k
- The Canadian Archipelago gain 2 k
- East Siberian Sea loss 22 k

Other seas
- St Lawrence area at 1 k,
- Hudson Bay area loss 17 k.

NSIDC Area is sitting between the 2010's average and the 2000's average, very much as in JAXA EXTENT.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on July 06, 2018, 05:54:50 AM
It has passed 30+ minutes of the usual time and ADS NIPR has no data.
So, I appreciate if someone else post the data, at least extent and daily drop.
Thanks!
Glad to oblige, Juan.


Thanks, gerontocrat.  :)
_______________________________

[ADS-NIPR-JAXA] ASI Extent.

July 5th, 2018: 9,013,080 km2, a drop of -66,736 km2.
2018 is the tenth lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: oren on July 06, 2018, 07:42:16 AM
A strange season. While JAXA extent is 10th (!), the Inner Basin extent is 1st or 2nd in the 2012-2018 data as shown by Wipneus. Which version of this tale will win?
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on July 06, 2018, 08:12:02 AM
Yes, some regions outside the Basin are slow to melt-out (Hudson, Baffin, Kara). Here is an update of the Basin-only graphs based on NSIDC data.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 06, 2018, 09:09:14 AM
JAXA Arctic Sea Ice Extent - 9,013,080 km2(July 5, 2018)

A daily drop of just 66k, about 30k less than the average for the time of year.
Extent loss to date is 670k km2 (12%) below the 2010's average, with 56% of the average melting season done.
Resulting minimum from average remaining melt = 4.6 million km2, (excluding 2012 from the average 4.7 million km2). Range of results from last ten years is 3.63 to 5.25 million km2.

With, on average, just 44% of further extent loss to go, a September minimum of 4.5 to 5.0 million km2 looks more likely every day.
Title: Re: 2018 sea ice area and extent data
Post by: RikW on July 06, 2018, 09:25:38 AM
The big question for me is: "Will Hudson Bay and Kara sea completely melt out?"
And on a sidenote, what will the effect be on the next years that they will have had much more ice-cover during peak-insolation compared to previous years

If the 400/450k area/ the 1M extent surplus, compared to record years, still completely melts out, we will still be in/near record-low extent territory.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 06, 2018, 10:40:59 AM
The big question for me is: "Will Hudson Bay and Kara sea completely melt out?"

No reason to suppose Hudson Bay will not melt out completely. Already well over half gone.
Kara Sea will probably almost completely melt out as usual. Also well over half gone.
They are just a bit late this year.
Title: Re: 2018 sea ice area and extent data
Post by: Frivolousz21 on July 06, 2018, 11:54:15 AM
The atlantc side is skewing the inner basin drops.

The Pacific side has been well protected.

So a slow down is very likely as we go along
Title: Re: 2018 sea ice area and extent data
Post by: Cid_Yama on July 06, 2018, 02:01:17 PM
90+% is a foot (30cm) or less in thickness this year.  That's the difference.

In 2012 50+% was >50 cm.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 06, 2018, 02:20:56 PM
NSIDC June Analysis posted on http://nsidc.org/arcticseaicenews/
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on July 06, 2018, 03:44:59 PM
The big question for me is: "Will Hudson Bay and Kara sea completely melt out?"

No reason to suppose Hudson Bay will not melt out completely. Already well over half gone.
Kara Sea will probably almost completely melt out as usual. Also well over half gone.
They are just a bit late this year.
Ditto to this.  The Kara and Hudson have melted out completely or almost completely for the last 15 years.  But I realize it is perfectly possible that you were being ironical.  If so, I have felt the burn on this issue, and I have been converted (with much reluctance) to emoticons.  May I recommend  :o or  ;D or  8) ....   

I think you highlight that we should remember that these melting seas will continue to add to the magnitude of extent and area drops through July -- something well worth remembering.
Title: Re: 2018 sea ice area and extent data
Post by: Pagophilus on July 06, 2018, 04:14:17 PM
Agreed on the first two points, but we are seeing the ESS and Chukchi taking a lot of heat right now ...  I hope you are right, but there is a long ways to go yet.


The atlantc side is skewing the inner basin drops.

The Pacific side has been well protected.

So a slow down is very likely as we go along
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on July 07, 2018, 05:50:49 AM
[ADS-NIPR-JAXA] ASI Extent.

July 6th, 2018: 8,945,371 km2, a drop of -67,709 km2.
2018 is the tenth lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 07, 2018, 11:17:56 AM
JAXA Arctic Sea Ice Extent - 8,945,371 km2(July 6, 2018)

A daily drop of just 68k, about 25k less than the average for the time of year.
Extent loss to date is 690k km2 (12.2%) below the 2010's average, with 57% of the average melting season done.
Resulting minimum from average remaining melt = 4.62 million km2, (excluding 2012 from the average 4.72 million km2). Range of results from last ten years is 3.70 to 5.28 million km2.

There is, on average, just 43% of further extent loss to go. Within three weeks daily extent loss is, on average, already in decline. A September minimum of 4.5 to 5.0 million km2 looks more likely every day.
[/quote]
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 07, 2018, 02:39:44 PM
NSIDC Total Area as at 6 July (5 day trailing average =  6,876,736 km2
This is down to 224 k above the 2010-2017 average

 
Total Area loss 153K, Central Seas 113k, Periphery loss 219 k, Other Seas loss 21 k  

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 4,
- The Bering Sea area is 2 k,
- Chukchi Sea loss 16 k,
- Beaufort Sea loss 6 k,

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 19 k,
of which the Baffin Sea loss was 11 k, the Greenland Sea loss 5k,and  the Barents Sea loss 3 k
- The Kara Sea area loss 13 k.
- The Laptev Sea area loss 18 k  .

CAB
- The Central Arctic Sea loss 15 k
- The Canadian Archipelago loss 3 k
- East Siberian Sea loss 42 k (106k in three days)

Other seas
- St Lawrence area at 1 k,
- Hudson Bay area loss 17 k.

Area loss accelerated a bit over the last few days - though NSIDC Area is still sitting between the 2010's average and the 2000's average, very much as in JAXA EXTENT.

Added NSIDC concentration map as at 6 July.
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on July 07, 2018, 08:10:11 PM
East Siberian Sea had been "asleep" for almost the whole melting season this year. The extraordinary high temperatures that arrived there a week ago or so (max. around 20-30° according to Climate Reanalyzer) now start the big melt there...
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on July 08, 2018, 05:57:08 AM
[ADS-NIPR-JAXA] ASI Extent.

July 7th, 2018: 8,884,111 km2, a drop of -61,260 km2.
2018 is the tenth lowest on record [and tomorrow could become the 11th  8) ]
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 08, 2018, 07:55:17 AM
JAXA Arctic Sea Ice Extent - 8,884,111 km2(July 7, 2018)

Once again, Just to add to Juan's post:-
- A daily drop of just 61k, about 30k less than the average for the time of year.
Extent loss to date is 720k km2 (12.6%) below the 2010's average, with 58% of the average melting season done.
Resulting minimum from average remaining melt = 4.65 million km2, (excluding 2012 from the average 4.76 million km2). Range of results from last ten years is 3.69 to 5.32 million km2.

There is, on average, just 42% of further extent loss to go. Within three weeks daily extent loss is, on average, already in decline. A September minimum of 4.5 to 5.0 million km2 looks more (and more) likely every day.
Title: Re: 2018 sea ice area and extent data
Post by: pauldry600 on July 08, 2018, 11:50:16 AM
This is because we in the British Isles are getting a Summer.

When we get a Summer the Arctic melt is slow.

Thats why Im sure JAXA will end 4.5 to 5m
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on July 08, 2018, 03:28:38 PM
JAXA Arctic SIE is still on its very slow decline, seeing its 15th consecutive day--and 29th out of the last 31--with a decline less than the 10-year (2008-2017) average.

2018 has also seen the longest May/June/July stretch on record with no century decreases. The last century break was on May 5, and, in fact, there have only been two so far this year. By way of comparison, the 10-year average by this date has been 9.7, with 2012 seeing 23 by now.

(Last sentence edited; thanks Ned W)
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 08, 2018, 03:44:31 PM
NSIDC Total Area as at 7 July (5 day trailing average =  6,690,737 km2
This is down to just 137 k above the 2010-2017 average


Total Area loss 186K, Central Seas 141 k, Periphery loss 20 k, Other Seas loss 25 k  

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 4k,
- The Bering Sea area is 2 k,
- Chukchi Sea loss 9 k,
- Beaufort Sea loss 11 k,

Atlantic Side
- Total area loss of the Baffin, Greenland, and Barents Seas 120 k,
of which the Baffin Sea loss was 7 k, the Greenland Sea loss 10 k,and  the Barents Sea loss 3 k
- The Kara Sea area loss 14 k.
- The Laptev Sea area loss 14 k  .

CAB
- The Central Arctic Sea loss 50 k
- The Canadian Archipelago loss 9 k
- East Siberian Sea loss 33 k (140 k in four days)

Other seas
- St Lawrence area at 2 k,
- Hudson Bay area loss 25 k.

Area loss accelerated somewhat over the last few days - NSIDC Area now down close to the 2010's average (see graph below). This is not yet reflected in JAXA EXTENT rate of loss.
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on July 08, 2018, 03:47:11 PM
2018 has also seen the longest May/June/July stretch on record with no century decreases. The last century break was on May 5, and, in fact, there have only been two so far this year. By way of comparison, the 10-year average by this date has been 19, with 2012 seeing 40 by now.

Are you quite sure of that?  I get rather smaller numbers - a ten-year average (2008-2017) of 9.7, a maximum of 23 (in 2012), and the following for each year:

20033
20047
20054
20068
200711
20084
20099
20109
20118
201223
201313
201413
20157
20165
20176
20182

Disclaimer: I am on my way out the door and rushed through this calculation in a hurry.  I probably messed something up and am making a fool of myself by hitting "Post". 

 :)

---------------

Edited to add: Jim, is it possible that you're comparing 2018's year-to-date value (for number of century breaks) to previous years' 365-day totals, rather than year-to-date?  Because if I do that, I do get a value of 40 for 2012, and a ten-year average of 19.4, which match yours.

2018 is still an outlier -- the fewest in the 2003-present JAXA daily record, and only 20% of the ten-year average.
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on July 08, 2018, 03:58:25 PM
This is now 10 almost consecutive days of a "century loss" in area - will this trend continue? And will it also be visible soon in the extent data?
Title: Re: 2018 sea ice area and extent data
Post by: Neven on July 08, 2018, 04:25:42 PM
As long as area keeps dropping fast , and extent doesn't respond, compactness will drop fast too. Right now it's lowest in the 2005-2018 record:
Title: Re: 2018 sea ice area and extent data
Post by: Stephan on July 08, 2018, 04:58:07 PM
This plot shows a big variety in compactness. Less than a month ago we saw a maximum and now a minimum. I suggest a return to the "middle of the pack" soon - by a remarkable extent loss in the next week(s). Let's re-visit this hypothesis end of July...
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on July 08, 2018, 06:04:02 PM
Isn't that basically the story of 2018, so far?

(1) We started out in May with abnormally high compactness and thus relatively low extent. 

(2) Over the past five weeks, there was a big decrease in area, but also a huge decrease in compactness, from (near) record-high to (near) record-low.  So extent loss slowed to a crawl.

This can be seen in the JAXA daily predictions for the end-of-season minimum.  I noted the hockey-stick shape a few days ago:

(https://i.imgur.com/Ot1K1eh.png)

Looking ahead ... as Stephan says, it seems unlikely that the ssslllooowww extent decreases will continue.  Something's gotta change there.  I'm surprised it's lasted this long, actually.  Not many years have such a radical change in compactness during the melt season.
Title: Re: 2018 sea ice area and extent data
Post by: Dharma Rupa on July 08, 2018, 06:11:05 PM
Looking ahead ... as Stephan says, it seems unlikely that the ssslllooowww extent decreases will continue.  Something's gotta change there.  I'm surprised it's lasted this long, actually.  Not many years have such a radical change in compactness during the melt season.

Not clear to me anything will change during the summer, but it wouldn't surprise me too much if Winter took a vacation.

I'll be looking very carefully at how quickly the seas fill with ice come Fall.
Title: Re: 2018 sea ice area and extent data
Post by: Ned W on July 08, 2018, 06:12:52 PM
Here's the chart version of the table I posted earlier -- number of JAXA extent century breaks so far this year, compared to the same period in previous years:

(https://i.imgur.com/sIHCKjm.png)
Title: Re: 2018 sea ice area and extent data
Post by: Wipneus on July 08, 2018, 07:20:53 PM
Remarkable: -163k loss in NSIDC extent, of which Hudson takes -150k.

Regional Arctic Sea Ice Extent and Area calculated from NSIDC NASA Team concentration data
Date: 2018-07-07 12:00  Values in 1000 km^2

Extent (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  4323.3   -6.6  -117.6    915.0   +3.9   +10.9    397.1   +0.1  -268.6
               Kara Sea             Barents Sea           Greenland Sea
   610.9  -16.7  -129.8     64.7   -4.8  -209.7    278.6   +6.1  -239.0
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
   547.4  +23.4   +10.6      5.7   +0.5    +5.7    567.7 -149.5   -61.4
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   694.3   +0.0    -3.4    436.1  -25.1    +3.7    269.9   +7.6  -134.1
             Bering Sea          Sea of Okhotsk                   Lakes
     3.0   +0.6    -1.7     13.6   -2.8   +13.6    218.8  -21.7   +83.4
          Other regions       Total (ex. lakes)
     2.9   +0.0    +2.9   9130.2 -163.1 -1118.0

Area (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3581.8 -131.8  -290.8    625.1  +24.7   -45.8    195.1   +0.3  -270.3
               Kara Sea             Barents Sea           Greenland Sea
   301.9  -12.6  -185.3     21.6   -2.9  -122.4    153.9  -18.9  -108.5
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
   256.6   +0.8   -38.4      1.7   +0.0    +1.7    306.6  -62.4   -17.1
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   475.9  -19.3   -33.0    272.1   -7.5   -32.4    164.0  +10.8  -121.9
             Bering Sea          Sea of Okhotsk                   Lakes
     1.7   +0.1    +0.5      3.7   -1.4    +3.7    102.7   -3.3   +39.9
          Other regions       Total (ex. lakes)
     2.2   -0.0    +2.2   6364.0 -220.2 -1257.8


Title: Re: 2018 sea ice area and extent data
Post by: jdallen on July 08, 2018, 07:21:37 PM
As long as area keeps dropping fast , and extent doesn't respond, compactness will drop fast too. Right now it's lowest in the 2005-2018 record:
I've been watching the divergence in behavior between area and extent with considerable interest.

I think it speaks to the fundamental changes in the structure of the pack.  I'm hesitant to make any specific conclusions about it yet, but anecdotally it appears we are seeing more smaller floes being dispersed over a larger area, and a lot more melting inside the core extent of the pack than we've typically seen in the past.  That there may be the key distinction between 2018 and previous melt seasons.

[Edit:]  A pack with smaller more mobile floes would also help explain the wide variation in and rapid changes to compactness.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on July 08, 2018, 09:34:18 PM
Here's the chart version of the table I posted earlier -- number of JAXA extent century breaks so far this year, compared to the same period in previous years:

(https://i.imgur.com/sIHCKjm.png)

Keep in mind that the amount of century breaks for 2012 is somewhat inflated, because the numbers are based on Windsat, as the dataset hovered between AMSR-E and AMSR2.

I've been watching the divergence in behavior between area and extent with considerable interest.

I think it speaks to the fundamental changes in the structure of the pack.  I'm hesitant to make any specific conclusions about it yet, but anecdotally it appears we are seeing more smaller floes being dispersed over a larger area, and a lot more melting inside the core extent of the pack than we've typically seen in the past.  That there may be the key distinction between 2018 and previous melt seasons.

[Edit:]  A pack with smaller more mobile floes would also help explain the wide variation in and rapid changes to compactness.

That's possible, but it could also be that compactness is now finally going down because there's widespread melt ponding on the Siberian side of the Arctic (and divergence in the Beaufort/Chukchi). I'm not sure if resolution is high enough to catch what you're describing (change in the pack structure). The compactness graphs I'm posting are based on NSIDC extent and area, which have really low resolution (25 km vs 3.125 km for AMSR2).
Title: Re: 2018 sea ice area and extent data
Post by: Steven on July 08, 2018, 10:19:57 PM
As long as area keeps dropping fast , and extent doesn't respond, compactness will drop fast too. Right now it's lowest in the 2005-2018 record:

Indeed, there has been a "July Cliff" for NSIDC sea ice area in the past week:

(https://i.imgur.com/PlHyZ3K.png)

But weather forecasts seem to be favorable for ice retention in the next several days, so I guess there will be a reduction in melt ponding and the cliff will fizzle out (and maybe bounce back upwards a bit, although that remains to be seen...)
Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on July 08, 2018, 11:29:40 PM
Edited to add: Jim, is it possible that you're comparing 2018's year-to-date value (for number of century breaks) to previous years' 365-day totals, rather than year-to-date?

You are correct; I'd never bothered calculating that metric before, so I inadvertently threw in the whole-year instead of YTD count. Thanks for pointing that out. Still, while the difference isn't nearly as stark, it is indeed noticeable; the current YTD count of 2 is two standard deviations below that average of 9.7, and something you'd expect to see just two or three times every 100 years. (And, yes, I realize the sample size is too small to draw any meaningful conclusions.)

(FWIW, generally-speaking, a direct message to the OP will trigger an email, and that almost always means a quicker correction.)
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on July 09, 2018, 05:56:07 AM
[ADS-NIPR-JAXA] ASI Extent.

After only 2 century breaks on 2018, finally another century break:
 
July 8th, 2018: 8,762,912 km2, a drop of -121,199 km2.
2018 is still the tenth lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 09, 2018, 07:59:47 AM
JAXA Arctic Sea Ice Extent - 8,762,912 km2(July 8, 2018)

Once again, Just to add to Juan's post:-
- A daily drop of just 121k, about 30k GREATER than the average for the time of year.
Extent loss to date is 690k km2 (11.9%) below the 2010's average, with 58% of the average melting season done.
Resulting minimum from average remaining melt = 4.62 million km2, (excluding 2012 from the average 4.73 million km2). Range of results from last ten years is 3.68 to 5.30 million km2.

Perhaps JAXA extent losses will, over the next few days, catch up a bit with the greater than average area losses recoreded by NSIDC over the last few days. However, there is, on average, just 42% of further extent loss to go. Within three weeks daily extent loss, on average, will be already in decline. A September minimum of 4.5 to 5.0 million km2 looks more (and more) likely every day.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 09, 2018, 02:31:25 PM
NSIDC Total Area as at 8 July (5 day trailing average =  6,540,856 km2
This is down to just 81 k above the 2010-2017 average


Total Area loss 150K, Central Seas 107 k, Periphery loss 22 k, Other Seas loss 21 k  

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 5k,
- The Bering Sea area is 2 k,
- Chukchi Sea loss 4 k,
- Beaufort Sea loss 7 k,
Area loss slowed.
Atlantic Side
- Baffin Sea loss 8 k,
- Greenland Sea loss 12 k,
- Barents Sea loss 2 k
- The Kara Sea area loss 10 k.
- The Laptev Sea area loss 6 k  .

CAB
- The Central Arctic Sea loss 57 k,
- The Canadian Archipelago loss 9 k,
- East Siberian Sea loss 14 k .

Other seas
- St Lawrence area at 2 k,
- Hudson Bay area loss 21 k.

Area loss accelerated somewhat over the last few days - NSIDC Area now down close to the 2010's average (see graph below). JAXA EXTENT loss was 121k - more century breaks to come?
Title: Re: 2018 sea ice area and extent data
Post by: Feeltheburn on July 10, 2018, 02:38:13 AM
The good times may not last, but July 8, 2018 is now closer to July 8, 1995 than July 8, 2017 according to NSIDC:

In ascending order:

2011 - 8.537
2016 - 8.559
2012 - 8.572
2017 - 8.681
2014 - 8.708
2007 - 8.722
2010 - 8.746
2013 - 8.909
2006 - 9.045
2018 - 9.201
2009 - 9.292
2015 - 9.304
2005 - 9.355
2008 - 9.450
2001 - 9.578
1995 - 9.672




Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on July 10, 2018, 03:31:03 AM
[ADS-NIPR-JAXA] ASI Extent Analysis.

On July 17th, there is an important difference between the 7th and the 8th lowest, that is, between 2014 and 2010. So, it is possible that 2018 will become the 8th lowest on record that day, if it has an average drop between 93.9 and 131.8K km2.

Will it make it?

We can use the table to calculate were 2018 will be, given the average drops that 2018 will have on the following days.
Title: Re: 2018 sea ice area and extent data
Post by: Juan C. García on July 10, 2018, 05:51:42 AM
[ADS-NIPR-JAXA] ASI Extent.

July 9th, 2018: 8,737,858 km2, a drop of only -25,054 km2.
(Very small drop, on this time of the year).

2018 is still the tenth lowest on record.
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 10, 2018, 07:38:44 AM
JAXA Arctic Sea Ice Extent - 8,737,858 km2(July 9, 2018)

Once again, Just to add to Juan's post:-
- A daily drop of just 25k is about 65 to 70 k less than the average for the time of year,
- Extent is 422k (4.8%) below the 2010's average extent on this date,
- Extent loss to date is 770k km2 (12.9%) below the 2008-2017 average, with 59% of the average melting season done.

Resulting minimum from average remaining melt = 4.69 million km2, (excluding 2012 from the average 4.79 million km2). Range of results from last ten years is 3.81 to 5.39 million km2.

Yesterday, I said :-
Quote
Perhaps JAXA extent losses will, over the next few days, catch up a bit with the greater than average area losses recorded by NSIDC over the last few days.

Now I am getting that 2017 feeling - a big extent loss one day merely flatters to deceive. There is, on average, just 41% of further extent loss to go. In less than three weeks daily extent loss, on average, will be already in significant decline. A September minimum of 4.5 to 5.0 million km2 looks more and more) likely every day.

Thus the divergence between extent and area seems set to increase. Perhaps this deserves a look-see at the end of the melting season for each sea (using NSIDC data)?
Title: Re: 2018 sea ice area and extent data
Post by: colchonero on July 10, 2018, 12:20:59 PM
Gerontocrat (or somebody else who knows the answer :D), I have to ask does Jaxa provide/calculate new "numbers" or "stats" (Idk how should I call it) every day, or is it 2-day average?
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 10, 2018, 12:22:52 PM
Gerontocrat (or somebody else who knows the answer :D), I have to ask does Jaxa provide/calculate new "numbers" or "stats" (Idk how should I call it) every day, or is it 2-day average?
2 day.
Title: Re: 2018 sea ice area and extent data
Post by: colchonero on July 10, 2018, 12:33:53 PM
Ok thanks, then I think if my math is correct, we can see an increase tomorrow, if there is not much melting today, because we had some 60k drops for a couple of days. and then yesterday 2-day average came down to 120k. So it should mean that there was a 170-180k drop yesterday. So I was expecting another bigger than average drop today. But today we are seeing a 2 day average drop of only 25k with that big one from yesterday counting. So that means there was a substantial increase in extent by Jaxa calculations.

Title: Re: 2018 sea ice area and extent data
Post by: Jim Pettit on July 10, 2018, 02:13:03 PM
NSIDC ASI extent increased for a second day, dropping that metric back even further, to 12th place. July daily increases aren't unheard of, but they are fairly rare; since 2010, there have only been 12 of them, with two of those over the past two days. And in fact, yesterday's increase of 71k was the single largest one-day July increase since at least 2000.

At this moment, it seems likely (though no way guaranteed) that 2018 NSIDC extent will end up at or above 5M km2. Even a finish identical to 2012's monstrous August drop would render a rather quotidian 4.38M km2.
Title: Re: 2018 sea ice area and extent data
Post by: Neven on July 10, 2018, 02:36:34 PM
When extent goes up, and area goes down, area divided by extent (in other words, compactness) will inevitably go down. 2018 still lowest on record:
Title: Re: 2018 sea ice area and extent data
Post by: gerontocrat on July 10, 2018, 04:30:52 PM
NSIDC Total Area as at 8 July (5 day trailing average =  6,410,311 km2
This is down to just 45 k above the 2010-2017 average


Total Area loss 131K, Central Seas 89 k, Periphery loss 27 k, Other Seas loss 24 k  

Analysis of individual seas.

Pacific Side
- The Okhotsk Sea area is 5k,
- The Bering Sea area is 2 k,
- Chukchi Sea loss 3k,
- Beaufort Sea gain 1 k,
Area loss slowed even more.
Atlantic Side
- Baffin Sea loss 10 k,
- Greenland Sea loss 5 k,
- Barents Sea loss 2 k - Barents Sea area is 22k, less than 3% of 1980's maximum, i.e. melting finished for all practical purposes.
- The Kara Sea area loss 13 k.
- The Laptev Sea area gain 2 k  .

CAB
- The Central Arctic Sea loss 52 k,
- The Canadian Archipelago loss 7 k,
- East Siberian Sea loss 18 k .

Other seas
- St Lawrence area at 2 k,
- Hudson Bay area loss 24 k.

It is the Central Arctic Sea that is providing the drama at the moment - 159k loss over the last three days.

Area loss accelerated still above average - NSIDC Area now down close to the 2010's average. Contrast with daily extent increases - see Jim's post below

Quote
Posted by: Jim Pettit
Today at 02:13:03 PM
NSIDC ASI extent increased for a second day, dropping that metric back even further, to 12th place. July daily increases aren't unheard of, but they are fairly rare; since 2010, there have only been 12 of them, with two of those over the past two days. And in fact, yesterday's increase of 71k was the single largest one-day July increase since at least 2000.

At this moment, it seems likely (though no way guaranteed) that 2018 NSIDC extent will end up at or above 5M km2. Even a finish identical to 2012's monstrous August drop would render a rather quotidian 4.38M km2.
Title: Re: 2018 sea ice area and extent data
Post by: Phil. on July 10, 2018, 04:43:41 PM