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Ned W

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Re: 2018 sea ice area and extent data
« Reply #1200 on: July 28, 2018, 02:33:23 PM »
Re this graph I posted earlier, showing the difference between 15% vs 30% thresholds for extent:


Replies to subsequent comments:

Actually I think that's very interesting, when I look at that it looks like the gap between the two is increasing, esp on "Bad" years, aka 2007, 2012, those big spikes are showing there's a lot more Ice in between 15% and 30% than there was, esp on iffy years, how far along in 2018 did you process?

The gap is not actually increasing perceptibly -- it's larger in some months and smaller in others, but the increase itself is close to 0 and not statistically significant.  I stopped with December 2017 (i.e., this doesn't include the current year) because the source I obtained the raw concentration data from (here) hasn't updated with 2018 data yet.  I could probably obtain the 2018 data elsewhere and add them in, but since there was no significant trend in 40 years I'm not sure that adding one more year in would be worth the time.   

Would you mind sharing the numerical data for this as well? It indeed looks like there is no long term trend, but I'm sure others can find interesting ways to present this data as well. Thanks in any case, this looks like it's settled the question quite well.

I don't have the data file with me right now, but 'll post a csv file or something when I get back home.

--------------------------

Edited to add:

OK, I attached the results as a comma-delimited text file.  I think.  This is the first time I've tried including an attachment here, as opposed to just linking to something elsewhere on the www.
« Last Edit: July 28, 2018, 04:48:34 PM by Ned W »

Ned W

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Re: 2018 sea ice area and extent data
« Reply #1201 on: July 28, 2018, 04:07:59 PM »
I've been noting how bizarrely closely 2018's extent has been following 2015.  Neven pointed out that while the two years' extents have been similar, volume has been lower in 2018.

Here's a "snake plot" showing extent vs volume for all years in the 2010s.  It shows how daily extent and volume have evolved during the summer melt season.  It's basically a scatterplot showing the combination of the two variables on each date.

This seems like an interesting data visualization method.  I'd appreciate any feedback on how this could be improved -- so I can do an updated version when the remainder of the July PIOMAS data are published.



The fine print:

Data cover the period from June 1 to July 14 of each year.  The "head" of each year's snake is the end-date (July 14).  Circular "heads" are odd years, squares are even years. 

Volume from PIOMAS via Arctische Pinguin, using the total of CAB+CAA only, and converting each date's volume to an anomaly relative to the 2010-2018 mean for that day of year.  Extent from JAXA, for the entire Arctic, converting each date's extent to an anomaly relative to the 2010-2018 mean for that day of year.  After July 14 of this year, the extent anomaly dropped to right around 0 (i.e., to the average extent for this date).

Pmt111500

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Re: 2018 sea ice area and extent data
« Reply #1202 on: July 28, 2018, 05:17:28 PM »
I've been noting how bizarrely closely 2018's extent has been following 2015.  Neven pointed out that while the two years' extents have been similar, volume has been lower in 2018.

Here's a "snake plot" showing extent vs volume for all years in the 2010s.  It shows how daily extent and volume have evolved during the summer melt season.  It's basically a scatterplot showing the combination of the two variables on each date.

This seems like an interesting data visualization method.  I'd appreciate any feedback on how this could be improved -- so I can do an updated version
Normalized values might be an interesting option, that is, for each year, set midpoints of each plotted value to one (1) and recalculate the rest accordingly. It'll come out a mess near normal values but deviations from year to year should show up well if you don't cramp too many on single graph
« Last Edit: July 28, 2018, 06:13:18 PM by Pmt111500 »
Cooling the outside by heat pump.

Red

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Re: 2018 sea ice area and extent data
« Reply #1203 on: July 28, 2018, 07:26:40 PM »


- St Lawrence area at 2 k, gained 1k!
 
Qu2. How long before the St. Lawrence finally  gets to zero ice? The sea where the ice apparently persists beyond reason.
There hasn't been any ice in the Gulf of St Lawrence since the end of April. Makes one wonder how accurate the rest of the numbers are? Maybe their counting the ice cubes the beach goers spill from their drinks ;)

Steven

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Re: 2018 sea ice area and extent data
« Reply #1204 on: July 28, 2018, 07:41:46 PM »
I've been noting how bizarrely closely 2018's extent has been following 2015. 

I think the similarity with 2015 had much to do with Hudson and Baffin Bay.  Both 2018 and 2015 had slow extent losses in those regions during June and early July.

In the graph below, I used NSIDC regional extent data (from Wipneus website), but the conclusion should be similar for JAXA extent.  The anomalies are relative to the 2010s average.  For Hudson Bay there are some erroneous values on 13 and 14 July 2018, which I replaced by interpolation of the previous and next days.



Ned W

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Re: 2018 sea ice area and extent data
« Reply #1205 on: July 28, 2018, 07:42:45 PM »
There hasn't been any ice in the Gulf of St Lawrence since the end of April. Makes one wonder how accurate the rest of the numbers are? Maybe their counting the ice cubes the beach goers spill from their drinks ;)

When the sensor's instantaneous field of view includes a mixture of land and water -- in other words, along coastlines -- the microwave signal can be misinterpreted as ice.  So it's not uncommon to have minor errors with reported "ice" showing up along coastlines where no ice is present. 

Ned W

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Re: 2018 sea ice area and extent data
« Reply #1206 on: July 28, 2018, 07:44:23 PM »
Thanks, Steven.  Very cool.

Red

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Re: 2018 sea ice area and extent data
« Reply #1207 on: July 28, 2018, 07:56:23 PM »
A few temperatures from around the gulf provide by NOAA. Ice may have a short life span around here.
Newfoundland
Stephenville Sea Temperature
(Today) 28th Jul 2018
15.6°C / 60°F
Channel-Port aux Basques Sea Temperature
(Today) 28th Jul 2018
16.1°C / 61°F
Quebec
Baie-Comeau Sea Temperature
(Today) 28th Jul 2018
Gaspé Sea Temperature
(Today) 28th Jul 2018
16.1°C / 61°F12.2°C / 54°
FHavre-Saint-Pierre Sea Temperature
(Today) 28th Jul 2018
This one is by the Strait of Belle Isle
Saint-Augustin Sea Temperature
(Today) 28th Jul 2018
11.7°C / 53°F14.4°C / 58°F

Red

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Re: 2018 sea ice area and extent data
« Reply #1208 on: July 28, 2018, 07:57:38 PM »
There hasn't been any ice in the Gulf of St Lawrence since the end of April. Makes one wonder how accurate the rest of the numbers are? Maybe their counting the ice cubes the beach goers spill from their drinks ;)

When the sensor's instantaneous field of view includes a mixture of land and water -- in other words, along coastlines -- the microwave signal can be misinterpreted as ice.  So it's not uncommon to have minor errors with reported "ice" showing up along coastlines where no ice is present.
Thanks Ned

oren

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Re: 2018 sea ice area and extent data
« Reply #1209 on: July 28, 2018, 07:58:00 PM »
With the pacific-CAB showing major signs of slush, the CAB AMSR2 area chart is showing the results, which are quite sharp and early. This most important chart provides the greatest effect on the September minimum. Extent has started to follow and it seems has quite a way to go.

Shared Humanity

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Re: 2018 sea ice area and extent data
« Reply #1210 on: July 28, 2018, 11:12:03 PM »
It is getting interesting.

Sam

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Re: 2018 sea ice area and extent data
« Reply #1211 on: July 28, 2018, 11:23:02 PM »
“It is getting interesting.”

“Interesting” - is that what you call it when you reach the top of roller coaster, head down the slope at high speed, only to see that ahead of you there is no track?! - that it has been torn down!

As current volume trends continue, we are looking at the first ice free arctic September in 2022-23 plus or minus a few years. Subtract a year for breaking through the 1 million square kilometer “ice free” level.

After that, the wheels come off and we enter free fall. The atmospheric and oceanic circulations are already changing in major ways. Soon that will be dramatic. Not long after that the conditions will be properly described as extreme. And then to use your word - things get “exciting”.

Sadly, I am going to get to live long enough to see us all the way through to a year round ice free arctic. I am not looking forward to that, or to the inevitable droughts, pandemics, deluges, wars, disease, and climate catastrophes that will come with it.

I am only thankful that I will not live long enough to see an ice free Greenland.

I fully expect to die in the foregoing disasters long before then.

Sam


magnamentis

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Re: 2018 sea ice area and extent data
« Reply #1212 on: July 29, 2018, 02:59:07 AM »
“It is getting interesting.”

“Interesting” - is that what you call it when you reach the top of roller coaster, head down the slope at high speed, only to see that ahead of you there is no track?! - that it has been torn down!

As current volume trends continue, we are looking at the first ice free arctic September in 2022-23 plus or minus a few years. Subtract a year for breaking through the 1 million square kilometer “ice free” level.

After that, the wheels come off and we enter free fall. The atmospheric and oceanic circulations are already changing in major ways. Soon that will be dramatic. Not long after that the conditions will be properly described as extreme. And then to use your word - things get “exciting”.

Sadly, I am going to get to live long enough to see us all the way through to a year round ice free arctic. I am not looking forward to that, or to the inevitable droughts, pandemics, deluges, wars, disease, and climate catastrophes that will come with it.

I am only thankful that I will not live long enough to see an ice free Greenland.

I fully expect to die in the foregoing disasters long before then.

Sam

in general one can look at things the way you do but until we see year-round ice-free arctic it will take centuries IMO while ice free Augusts and Septembers are most probable to happen not too far out IMO.

miki

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Re: 2018 sea ice area and extent data
« Reply #1213 on: July 29, 2018, 03:58:54 AM »
but until we see year-round ice-free arctic it will take centuries

I very much doubt about that plural.

pearscot

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Re: 2018 sea ice area and extent data
« Reply #1214 on: July 29, 2018, 04:23:15 AM »
It is really insane what has been going on. I'll be honest, I somewhat wrote this season of because it was looking so predictable to 2015 and 2016, but then all the sudden it has become so evident how thin and mobile a seemingly large portion of the pack has become. I think this year does show how the next few summers will be highlighted by the ever growing trend of Atlanticification of the Arctic but from all sides. I think I will weep the day the ice is all gone.
pls!

bbr2314

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Re: 2018 sea ice area and extent data
« Reply #1215 on: July 29, 2018, 04:34:20 AM »
It is really insane what has been going on. I'll be honest, I somewhat wrote this season of because it was looking so predictable to 2015 and 2016, but then all the sudden it has become so evident how thin and mobile a seemingly large portion of the pack has become. I think this year does show how the next few summers will be highlighted by the ever growing trend of Atlanticification of the Arctic but from all sides. I think I will weep the day the ice is all gone.
Good news: you'll probably be dead by then, thanks to the wars, famine, droughts, and hunger that ensue well before a BOE. Chin up, no tears for you!  ;D

Also: not to be a nagging nelly but all this talk of BOE belongs in the BOE thread and not the one for 2018 data.

Wherestheice

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Re: 2018 sea ice area and extent data
« Reply #1216 on: July 29, 2018, 04:36:39 AM »
“It is getting interesting.”

“Interesting” - is that what you call it when you reach the top of roller coaster, head down the slope at high speed, only to see that ahead of you there is no track?! - that it has been torn down!

As current volume trends continue, we are looking at the first ice free arctic September in 2022-23 plus or minus a few years. Subtract a year for breaking through the 1 million square kilometer “ice free” level.

After that, the wheels come off and we enter free fall. The atmospheric and oceanic circulations are already changing in major ways. Soon that will be dramatic. Not long after that the conditions will be properly described as extreme. And then to use your word - things get “exciting”.

Sadly, I am going to get to live long enough to see us all the way through to a year round ice free arctic. I am not looking forward to that, or to the inevitable droughts, pandemics, deluges, wars, disease, and climate catastrophes that will come with it.

I am only thankful that I will not live long enough to see an ice free Greenland.

I fully expect to die in the foregoing disasters long before then.

Sam

in general one can look at things the way you do but until we see year-round ice-free arctic it will take centuries IMO while ice free Augusts and Septembers are most probable to happen not too far out IMO.

I think a year round ice free Arctic is only a few decades away. We need to recognize that once we get the blue ocean event there will be rapid amounts of warming from the latent heat effect as well as loss of albedo that will inhibit ice from re-freezing. The age of ice in the Arctic is coming to an end.
"When the ice goes..... F***

Ned W

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Re: 2018 sea ice area and extent data
« Reply #1217 on: July 29, 2018, 04:39:07 AM »
This discussion would be excellent material for one of the threads on "when will the Arctic Ocean be ice-free?"  I'd gently suggest moving follow-up posts over there.  Thanks!

Viggy

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Re: 2018 sea ice area and extent data
« Reply #1218 on: July 29, 2018, 05:27:44 AM »
“It is getting interesting.”

“Interesting” - is that what you call it when you reach the top of roller coaster, head down the slope at high speed, only to see that ahead of you there is no track?! - that it has been torn down!

As current volume trends continue, we are looking at the first ice free arctic September in 2022-23 plus or minus a few years. Subtract a year for breaking through the 1 million square kilometer “ice free” level.

After that, the wheels come off and we enter free fall. The atmospheric and oceanic circulations are already changing in major ways. Soon that will be dramatic. Not long after that the conditions will be properly described as extreme. And then to use your word - things get “exciting”.

Sadly, I am going to get to live long enough to see us all the way through to a year round ice free arctic. I am not looking forward to that, or to the inevitable droughts, pandemics, deluges, wars, disease, and climate catastrophes that will come with it.

I am only thankful that I will not live long enough to see an ice free Greenland.

I fully expect to die in the foregoing disasters long before then.

Sam

This is a forum about the live and historic condition of the Arctic sea ice, the factors that influence it and a discussion of the science behind it all. So yes, given current conditions, it is undoubtedly getting 'interesting'.

Please take your fake concern and melodrama elsewhere. Everyone here understands the implications of an ice-free Arctic. No one is cheer-leading it and there is no value to your insinuations otherwise.

Viggy
« Last Edit: July 29, 2018, 06:23:19 AM by Viggy »

Juan C. García

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Re: 2018 sea ice area and extent data
« Reply #1219 on: July 29, 2018, 06:01:54 AM »
[ADS-NIPR-JAXA] ASI Extent.

July 28th, 2018: 6,786,817 km2, a drop of -91,786 km2.
2018 is the seventh lowest on record.
« Last Edit: July 29, 2018, 06:20:15 AM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

stjuuv

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Re: 2018 sea ice area and extent data
« Reply #1220 on: July 30, 2018, 12:01:13 AM »
Re this graph I posted earlier, showing the difference between 15% vs 30% thresholds for extent:
OK, I attached the results as a comma-delimited text file.  I think.  This is the first time I've tried including an attachment here, as opposed to just linking to something elsewhere on the www.
Thanks for the data!

For what it's worth, it seems that it used to be the case that there was a peak of differences in 15% and 30% concentration extents in July at the height of melting, followed by a slight minimum in September, with the rest of the year mostly stable. However, a lot of the recent years (with some exceptions) have another peak of extent in the 15-30% concentration range in October as well.

Probably says something about the refreeze.

magnamentis

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Re: 2018 sea ice area and extent data
« Reply #1221 on: July 30, 2018, 12:17:50 AM »
but until we see year-round ice-free arctic it will take centuries

I very much doubt about that plural.

in fact i believe that as long as this planet is supporting life, means temps are withing a range that allows for life and as long as there will be 5-6 months wihout sunshine, that we NEVER shall see year round ice-free arctic. after all there will always be winter and even regions with 20C summer water temps and up to 35C air temps are frozen nowadays during winter and that even more south where is no zero sun in winter.

while opinions remain free, my opinion is that headline like buzzwords are not target leading, we should keep it realistic.

jdallen

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Re: 2018 sea ice area and extent data
« Reply #1222 on: July 30, 2018, 02:49:31 AM »
but until we see year-round ice-free arctic it will take centuries

I very much doubt about that plural.

in fact i believe that as long as this planet is supporting life, means temps are withing a range that allows for life and as long as there will be 5-6 months wihout sunshine, that we NEVER shall see year round ice-free arctic. <snippage>

Sorry to disabuse you, but we have geological evidence of exactly that - year round ice free Arctic - in the Pliocene - 3.7-2.2 MYBP. - under current atmospheric conditions.

https://www.scientificamerican.com/article/ice-free-arctic-in-pliocene-last-time-co2-levels-above-400ppm/
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Archimid

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Re: 2018 sea ice area and extent data
« Reply #1223 on: July 30, 2018, 03:11:48 AM »

Sorry to disabuse you, but we have geological evidence of exactly that - year round ice free Arctic - in the Pliocene - 3.7-2.2 MYBP. - under current atmospheric conditions.

https://www.scientificamerican.com/article/ice-free-arctic-in-pliocene-last-time-co2-levels-above-400ppm/

 Homo species timeline from: https://phys.org/news/2014-07-scientists-timeline-human.html

Right on schedule.

I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Ned W

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Re: 2018 sea ice area and extent data
« Reply #1224 on: July 30, 2018, 04:06:58 AM »
This discussion would be excellent material for one of the threads on "when will the Arctic Ocean be ice-free?"  I'd gently suggest moving follow-up posts over there.  Thanks!

Again ...

This thread is for discussions of 2018 sea ice area and extent data

Please move discussions about the future of the ice, the consequences of an ice-free Arctic, paleoclimate, human evolution, and other topics elsewhere. 

Juan C. García

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Re: 2018 sea ice area and extent data
« Reply #1225 on: July 30, 2018, 05:50:05 AM »
[ADS-NIPR-JAXA] ASI Extent.

July 29th, 2018: 6,666,937 km2, a century drop of -119,880 km2.
2018 is the sixth lowest on record.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1226 on: July 30, 2018, 11:11:52 AM »
JAXA ARCTIC EXTENT 6,666,937 km2(July 29, 2018)

So I got Sunday off - these things happen.

Just to add to Juan's post....
- An extent loss of 120 k is about 40k above the average for this date,
- Extent is now just 33 km2  (0.5%) above the 2010's average extent on this date,
- and just 94 k (2.0%) above 2017,
- Extent loss to date is now 420k km2 (5.5 %) below the 2008-2017 average, with 76.7 % of the average melting season done.

Resulting minimum from average remaining melt is down to 4.35 million km2, (excluding 2012 from the average 4.43 million km2). Range of results from last ten years remaining melt is 3.64 to 4.81 million km2.

.In the 13 days from July13 to July 29, extent loss is 1.47 million km2, an average of 113k per day. Impressive, if not s full cliff at least a mini-cliff. That 2017 feeling fades yet but still lingers on- extent losses are not still yet enough to catch up on the slow melt to date. There is, on average, just 23.3 % (45 days) of further extent loss to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss sharply reduce? Yes.

As a result of these persistent higher than average extent loss, a September minimum down one in the range of 4.25 to 4.75 million km2, and perhaps even another bin lower, now looks increasingly possible or even likely. But that is still possibly approaching 0.5 0.4 million km2 above 2nd place and over 1 million km2 above the 2012 outlier.
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gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1227 on: July 30, 2018, 02:34:47 PM »
NSIDC Total Area as at 29 July (5 day trailing average) =  4,810,854 km2
This is 122 k above the 2010-2017 average area


Total Area loss 57 K, Central Seas loss 43k, Periphery loss 10 k, Other Seas loss 4 k  
Analysis of individual seas.

Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 14 k, area is now well below the 2010's average,
Atlantic Side
- Baffin Sea loss 6 k,
- Greenland Sea loss 5 k,
- Barents Sea - finished,
- The Kara Sea area loss 2 k, Area now just 56 k.
- The Laptev Sea area loss 6 k.
CAB
- Beaufort Sea loss 5 k,
- The Central Arctic Sea loss 11 k,
- The Canadian Archipelago loss 3 k,
- East Siberian Sea loss zero k .
Other seas
- St Lawrence -finished,
- Hudson Bay area loss 4 k, Area now 75k and just about at 2010's average.
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply - on this day to 50k. Thus a modest area loss of 57k is still 5k above average. Daily extent loss in contrast was a mighty 211k (after 3 slow days). Extent losses are still catching up with area losses again, both NSIDC and JAXA daily measures.

Qu1. The question is - will above average area losses follow the big NSIDC daily extent loss (and the impressive JAXA extent losses over the last 13 days)?
Qu2. How low will Greenland Sea Ice Area go ? If export of ice down the FRAM strait is finished for this season and that warmth keeps drifting up from the Atlantic then.... Graph attached as thankyou to JamesW for spotting my last whoops.
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FishOutofWater

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Re: 2018 sea ice area and extent data
« Reply #1228 on: July 30, 2018, 03:15:01 PM »
Because of the weather and the lack ice export through the Fram strait and record low ice in the Greenland sea a very anomalous amount of heat is building up on the Atlantic side of the Arctic. With the forecast of very warm southerly winds from the Greenland sea across the Lincoln sea and towards the Canadian side of the north pole we could see unusual melting patterns that reduce ice area north of Greenland and Canada over the next week. This is a very interesting melt season.

magnamentis

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Re: 2018 sea ice area and extent data
« Reply #1229 on: July 30, 2018, 06:40:12 PM »
but until we see year-round ice-free arctic it will take centuries

I very much doubt about that plural.

in fact i believe that as long as this planet is supporting life, means temps are withing a range that allows for life and as long as there will be 5-6 months wihout sunshine, that we NEVER shall see year round ice-free arctic. <snippage>

Sorry to disabuse you, but we have geological evidence of exactly that - year round ice free Arctic - in the Pliocene - 3.7-2.2 MYBP. - under current atmospheric conditions.

https://www.scientificamerican.com/article/ice-free-arctic-in-pliocene-last-time-co2-levels-above-400ppm/

that says:

ice free but not year-round

also it mentions 14C more in summer which will never be enough to keep it above -10 in winter
sorry i still disagree with year-round ice free at all and then i somehow mentioned and considered that far fetched possibility in a few millenia as well as under conditons that the rest of the planet is so hot that it would be close to unlivable in most places but again that will take a very long time, albeit much quicker than nature did it in the past, hence millenia instead of millions of years ;)

BTW no reason to be sorry, it's quite an important topic and independent of personal opinions and points of few your input is always valuable and welcome. Good results come from good discussions for which a certain amount of disagreement are the starting points ;)
« Last Edit: July 30, 2018, 06:55:59 PM by magnamentis »

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Re: 2018 sea ice area and extent data
« Reply #1230 on: July 30, 2018, 07:04:21 PM »
Has the Greenland Sea been ice free before ?

Steven

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Re: 2018 sea ice area and extent data
« Reply #1231 on: July 30, 2018, 07:14:56 PM »
NSIDC sea ice area is currently 7th lowest for the date:


Ned W

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Re: 2018 sea ice area and extent data
« Reply #1232 on: July 30, 2018, 07:32:32 PM »
Has the Greenland Sea been ice free before ?

Not in the NSIDC record.  Here's a plot showing 2018 vs the (pre-2018) lowest value on each date (Min_1979_2017), and also the 2007-2017 average extent.


GoSouthYoungins

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Re: 2018 sea ice area and extent data
« Reply #1233 on: July 30, 2018, 07:33:36 PM »
Has the Greenland Sea been ice free before ?

i'm sure. but definitely not in the last 10,000 years
big time oops

Steven

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Re: 2018 sea ice area and extent data
« Reply #1234 on: July 30, 2018, 07:36:20 PM »
Here's a "snake plot" showing extent vs volume for all years in the 2010s. 
...
I'd appreciate any feedback on how this could be improved.

A few suggestions:

(1) The range of the horizontal axis could be made smaller. 
(2) Perhaps the color of the 2012 "snake" could be made more distinctive, to find it more easily among the other years. 
(3) Another suggestion is to animate the image, so that the snakes slowly "grow" by gradually adding data in chronological order.  But that would probably be laborious.

anaphylaxia

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Re: 2018 sea ice area and extent data
« Reply #1235 on: July 30, 2018, 07:44:54 PM »
Has the Greenland Sea been ice free before ?

Not in the NSIDC record.  Here's a plot showing 2018 vs the (pre-2018) lowest value on each date (Min_1979_2017), and also the 2007-2017 average extent.

Are you sure about this? 1979 to 2017 ave a good 100 k lower than 2007 to 2017? Maybe some mixup in the legends.

gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1236 on: July 30, 2018, 08:14:51 PM »
Has the Greenland Sea been ice free before ?

Not in the NSIDC record.  Here's a plot showing 2018 vs the (pre-2018) lowest value on each date (Min_1979_2017), and also the 2007-2017 average extent.
Yes, there have been years where both extent and area have been lower. But this year it seems to me that the Greenland Sea is ripe for a really bad end of season. Thin ice, no Fram export (and even if there is no or very little thick MYI to be exported), and as far as the UK metoffice is concerned, that big Atlantic blocking high sending warmth up there for the next 14 days at least.

Atlantification?
« Last Edit: July 30, 2018, 09:39:18 PM by gerontocrat »
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Re: 2018 sea ice area and extent data
« Reply #1237 on: July 30, 2018, 08:40:11 PM »
Has the Greenland Sea been ice free before ?

Not in the NSIDC record.  Here's a plot showing 2018 vs the (pre-2018) lowest value on each date (Min_1979_2017), and also the 2007-2017 average extent.

Are you sure about this? 1979 to 2017 ave a good 100 k lower than 2007 to 2017? Maybe some mixup in the legends.

Nope.  I'm showing both the *lowest* value on each date (from the entire record), and also the *average* value from the past decade.   

The green line shows the lowest extent that the Greenland Sea has had in NSIDC data during *any year* prior to 2018.  For most of the year, 2018 has been setting daily records in this particular body of water.

Ned W

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Re: 2018 sea ice area and extent data
« Reply #1238 on: July 30, 2018, 08:48:33 PM »
Here's a "snake plot" showing extent vs volume for all years in the 2010s. 
...
I'd appreciate any feedback on how this could be improved.

A few suggestions:

(1) The range of the horizontal axis could be made smaller. 
(2) Perhaps the color of the 2012 "snake" could be made more distinctive, to find it more easily among the other years. 
(3) Another suggestion is to animate the image, so that the snakes slowly "grow" by gradually adding data in chronological order.  But that would probably be laborious.

Weird.  I thought I replied to this, but must not have hit "Post".

Thanks for the good ideas, Steven.  But I probably won't do the last one, since I really dislike animations.

I *am* considering some other ways to indicate the passage of time.  Maybe put a "band" or a "dot" on the back of each snake at regular intervals?  (E.g., the 1st and 15th of each month...)


Stephan

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Re: 2018 sea ice area and extent data
« Reply #1239 on: July 30, 2018, 10:35:07 PM »

Has the Greenland Sea been ice free before ?

Yes, there have been years where both extent and area have been lower. But this year it seems to me that the Greenland Sea is ripe for a really bad end of season. Thin ice, no Fram export (and even if there is no or very little thick MYI to be exported), and as far as the UK metoffice is concerned, that big Atlantic blocking high sending warmth up there for the next 14 days at least.

Atlantification?

Does it mean that a low Greenland Sea ice cover (due to almost no Fram Strait export) helps the remaining ice in the CAB not to decrease so much?
In other words: Where would the CAB extent or area be with a fully active Fram Strait export this year?
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gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1240 on: July 30, 2018, 11:53:10 PM »

Does it mean that a low Greenland Sea ice cover (due to almost no Fram Strait export) helps the remaining ice in the CAB not to decrease so much?
In other words: Where would the CAB extent or area be with a fully active Fram Strait export this year?

I don't know. But attached is a graph posted by Wipneus on the PIOMAS thread showing Fram export 2017 and 2018. In both years Fram export is reversed at the beginning of July. Maybe its the same most years - maybe not. My guess is the significance of Fram export is in decline as MYI has declined to very little (I think A-team posted something about that not so long ago).
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Re: 2018 sea ice area and extent data
« Reply #1241 on: July 31, 2018, 12:09:53 AM »
On topic, NSIDC compactness refuses to go down further:
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Juan C. García

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Re: 2018 sea ice area and extent data
« Reply #1242 on: July 31, 2018, 05:36:01 AM »
Today, it really looks on bad shape…
I think the same problem that was plaguing us in the Hudson around the middle of the month is currently plaguing us in the Beaufort, as if you visit Worldview, you can see that there is very thick cloud cover over the area that processed AMSR2 currently thinks is open water. A few days ago there was pretty sorry looking ice there, but I doubt that it has entirely poofed and is a sizeable chunk of time out (perhaps August 7th-15th?) from melting completely.

Well, it is going to take time to know what is happening...  :(
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

uniquorn

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Re: 2018 sea ice area and extent data
« Reply #1243 on: July 31, 2018, 01:25:02 PM »
snip - wrong thread
« Last Edit: July 31, 2018, 01:53:48 PM by uniquorn »

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Re: 2018 sea ice area and extent data
« Reply #1244 on: July 31, 2018, 02:03:46 PM »
Massive drop in NSIDC SIE (253K, following 211K yesterday), second lowest on record now, causing massive uptick in compactness. Glitch or real?
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gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1245 on: July 31, 2018, 02:22:17 PM »
NSIDC Total Area as at 30 July (5 day trailing average) =  4,750,693 km2
This is 120 k above the 2010-2017 average area


Total Area loss 69 K, Central Seas loss 43k, Periphery loss 8 k, Other Seas loss 3 k  
Analysis of individual seas.

Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 14 k, area is now well below the 2010's average,
Atlantic Side
- Baffin Sea loss 4 k,
- Greenland Sea loss 4 k,
- Barents Sea - finished,
- The Kara Sea area loss 3 k, Area now just 53 k.
- The Laptev Sea area loss 7 k.
CAB
- Beaufort Sea loss 16 k,
- The Central Arctic Sea gain 9 k,
- The Canadian Archipelago loss 3 k,
- East Siberian Sea loss 14 k .
Other seas
- St Lawrence -finished,
- Hudson Bay area loss 3 k, Area now 72k and just about at 2010's average.
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply - on this day to 58k. Thus a modest area loss of 57k is still 3k above average. Daily extent loss in contrast was a mighty 211k on the 29th, and then even higher at 253k on the 30th . Extent losses are still catching up with area losses again.

Qu1. The question is - will above average area losses follow the big NSIDC daily extent losses ?

Qu2. How low will Greenland Sea Ice Area go ? If export of ice down the FRAM strait is finished for this season and that warmth keeps drifting up from the Atlantic then....

Qu 3. Commenters have suggested the massive ice loss in Beaufort etc may be a mirage. NSIDC image attached - different sensor, same result. Illusion or reality ?
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Re: 2018 sea ice area and extent data
« Reply #1246 on: July 31, 2018, 03:34:56 PM »
Massive drop in NSIDC SIE (253K, following 211K yesterday), second lowest on record now, causing massive uptick in compactness. Glitch or real?

It seems plausible to me. The CAB seems compact, everything else is (mostly) slush, and as slush melts out now quickly, only the compact "part" remains.

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Re: 2018 sea ice area and extent data
« Reply #1247 on: July 31, 2018, 03:36:48 PM »
Beaufort scored a regional century (-126k) in extent.
Regional Arctic Sea Ice Extent and Area calculated from NSIDC NASA Team concentration data
Date: 2018-07-30 12:00  Values in 1000 km^2

Extent (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  4120.9  -69.9  -288.8    739.5  -29.4   +16.0    166.9  -12.8  -312.7
               Kara Sea             Barents Sea           Greenland Sea
   101.5  -15.4  -376.0     15.8   +3.9  -102.6    148.4  -12.3  -203.7
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
   124.9  -22.8  -119.5      7.3   +1.0    +7.3    160.9   +5.9   -53.5
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   577.1   -6.2   -38.9    270.4 -125.6   -93.4     97.5  +25.5  -184.2
             Bering Sea          Sea of Okhotsk                   Lakes
    10.2   +1.8    +5.9     17.6   +2.7   +17.6    163.0   +0.4   +38.9
          Other regions       Total (ex. lakes)
     2.9   +0.0    +2.9   6561.6 -253.5 -1723.7

Area (value, one day change, anomaly):
   Central Arctic Basin       East Siberian Sea              Laptev Sea
  3402.9  -32.0  -261.6    391.7   +7.4   -62.9     71.4   -7.5  -211.8
               Kara Sea             Barents Sea           Greenland Sea
    44.9   -8.4  -226.6      3.0   +0.3   -45.1     66.2   -3.6   -98.0
Baffin/Newfoundland Bay            St. Lawrence              Hudson Bay
    52.0   -6.9   -49.1      1.9   -0.1    +1.9     62.5   +0.0   -24.0
   Canadian Archipelago            Beaufort Sea             Chukchi Sea
   365.3   +1.1   -19.4    144.4  -47.3   -75.0     31.9   +2.3  -121.6
             Bering Sea          Sea of Okhotsk                   Lakes
     2.3   -0.0    +1.1      4.9   +1.0    +4.9     86.7   -4.2   +30.9
          Other regions       Total (ex. lakes)
     2.2   +0.0    +2.2   4647.4  -93.7 -1184.9
« Last Edit: July 31, 2018, 03:49:31 PM by Wipneus »

gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1248 on: July 31, 2018, 04:04:04 PM »
Beaufort scored a regional century (-126k) in extent.


Hullo Wipneus,

Qu1. You reckon these losses are real?

Qu2 - off-topic. I (and others) have looked for a definitive map of NSDC's 14 Arctic Seas with boundaries, and failed. Is there such a map, there must be, and could you post it on the Arctic Maps thread - https://forum.arctic-sea-ice.net/index.php/topic,417.0.html

It really helps when looking at the data sea by sea to have a map.

Cheers,

gerontocrat

ps: The best I found was this (attached) which is not much use
« Last Edit: July 31, 2018, 04:16:26 PM by gerontocrat »
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Re: 2018 sea ice area and extent data
« Reply #1249 on: July 31, 2018, 04:50:52 PM »
RE: Beaufort



It's the same thing that happened to Kara. Poof! Just wait til these losses don't stop as everything else also gives out simultaneously.