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A-Team

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Re: The 2017/2018 freezing season
« Reply #150 on: October 03, 2017, 07:12:58 PM »
Quote
Given the still warm SST anomalies especially north of Alaska, it is difficult to see how the Arctic can cool to a level that would bring the DMI N80 graph close to the 1958-2002 mean.
Looking below at Arctic surface temperatures and surface energy flux from ESRL from 04 Sep to 02 Oct 17 and noting the forecast out 09 Oct is featured at their web site, it seems that regardless of clouds, fading sun, and blanketing snow that the surface energy flux has been almost entirely negative (ie the top half of the palette is barely used.

Further, although how the energy flux is calculated is buried somewhere in the model used, it is apparent that over this time frame, the flux is (unsurprisingly) strongly correlated with temperature. That's somewhat less evident in the 6 hourly forecast as the palettes are set.

Technical note: Here "RASM-ESRL net energy flux at surface" appears in three different figures. Arctic 14.gif and Arctic23.gif are identical whereas Arctic24 is colored differently, with the scale extending to 105 to -120 w/m2 instead of 70 to -80 like the other two. Its legend is also displaced slightly and its title is worded slightly differently but it has the needed land mask. All three use the same diverging paired palette which is unsystematically constructed with respect to lightness, luminosity, saturation, hue and perception. These are shown in columns below relative to the palette chosen.

This time of year, all the fluxes are moderately negative; there is no use at all of the positive side of the scale. However extreme negative energy flues are observed down to -120, establishing that -80 is inadequate (lumps values that should be distinguished). Again, white should not be used as zero as it becomes conflated with non-ice surface white. It's rather unusual to use the same palette for temperature and energy flux as the units are very different but it works fairly well here because the latter is in part derived from the former. In summary, we could do this product significantly better if the netCDF files were available.
« Last Edit: October 03, 2017, 07:30:34 PM by A-Team »

A-Team

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Re: The 2017/2018 freezing season
« Reply #151 on: October 03, 2017, 07:43:31 PM »
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Peter Wadhams interview on Radio NZ - Oct. 2 2017"You can't measure ice thickness from space...well, only with extreme difficulty...so the best way to measure thickness is to sail underneath the ice, and use an upward-looking echo-sounder."
http://www.radionz.co.nz/national/programmes/afternoons/audio/201860805/peter-wadhams-preparing-for-an-arctic-without-ice
That may be, provided the sub can keep a perfectly level course despite passing through waters of different buoyancy. However, the expense is colossal, it only provides a very narrow swath of thicknesses, and it's not likely to be repeated regularly during the year.

It may not be any more accurate than em induction thicknesses based from helicopter or plane. If those are coordinated with ice augering from a surface ship, a fairly wide swath can be obtained with direct calibration. However there won't be repeat measurements at the same site over the year; repeat data from the same drifting floe is probably more informative.

Cryostat2 is the only device whose swaths add up to areal coverage. However it has problematic aspects such as problems with snow cover, thin ice with negligible freeboard, and the month needed to complete orbital coverage means each swath has a different time stamp. That leaves ice thickness modeling which is fraught with issues as well.

In summary, ice thickness remains very difficult to measure despite its importance and the decades of effort. Thickness is not the whole story because the ice temperature profile is also important to melt thermodynamics and mechanical state of the ice. More buoys could be deployed, 1000x of what is planned for 2018, for a tiny fraction of submarine or surface ship charter costs.
« Last Edit: October 03, 2017, 07:53:16 PM by A-Team »

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #152 on: October 03, 2017, 08:15:15 PM »
Peter Wadhams interview on Radio NZ - Oct. 2 2017.
""You can't measure ice thickness from space...well, only with extreme difficulty...so the best way to measure thickness is to sail underneath the ice, and use an upward-looking echo-sounder.""

http://www.radionz.co.nz/national/programmes/afternoons/audio/201860805/peter-wadhams-preparing-for-an-arctic-without-ice

Having accurate measures of thickness is important to evaluate the Arctic but it is insufficient. I am concerned about the quality of the ice of any thickness. Is today's 3 meter thick MYI the same as ice of 20 years ago or even 10 years ago when you have winters like the winter past and compare it to 2004?

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #153 on: October 03, 2017, 08:20:14 PM »
The 1st three months of 2017 look remarkably similar to the start of 2016. It remains to be seen if 2017 closes out the year in a fashion similar to 2016 but these warm winters must be having a deleterious effect on the quality of the ice and not just thickness but the physical properties of the ice as well.

Pavel

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Re: The 2017/2018 freezing season
« Reply #154 on: October 03, 2017, 09:06:24 PM »
Despite the warmer temperatures the freezing season north of 80 latitude still long and melting season is short and weak. The ice could be melted only if it will be exported. From the last melting season I'm convinced sea ice in the high Arctic is well protected, it's almost impossible to get SIE below 3 mln despite the warmer winters

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #155 on: October 04, 2017, 02:19:16 PM »
You've missed my point entirely. My concern is not about SIE or its annual rise and fall that coincide with the freeze and melt seasons. My concern is about a qualitative shift in the ice that remains at the end of any melt season. A freeze season with temperature anomalies of 5C to 10C has to have an effect on this MYI ice and not a good one.

There have been reports of "buttery" MYI by crews on ships that traverse the heart of the CAB where MYI predominates. This is in contrast to the rigid, rock solid ice that was virtually impassable in the past. Many far more knowledgeable individuals on this site could speak to the possible transitions we can expect in the quality of the ice.

I will be following this freeze season closely and hope the temperature anomalies are mild and do not come close to 2016.

Thomas Barlow

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Re: The 2017/2018 freezing season
« Reply #156 on: October 05, 2017, 04:20:54 AM »
Quote
Peter Wadhams interview on Radio NZ - Oct. 2 2017"You can't measure ice thickness from space...well, only with extreme difficulty...so the best way to measure thickness is to sail underneath the ice, and use an upward-looking echo-sounder."
http://www.radionz.co.nz/national/programmes/afternoons/audio/201860805/peter-wadhams-preparing-for-an-arctic-without-ice
Quote
That may be, provided the sub can keep a perfectly level course despite passing through waters of different buoyancy.
Pretty sure they accounted for that  ::)

Quote
However, the expense is colossal
It's paid for by Her Majesty's Royal Navy. On a Navy sub.

Quote
it only provides a very narrow swath of thicknesses, and it's not likely to be repeated regularly during the year.
Apparently not, according the Wadhams .. expert on the topic.

Quote
It may not be any more accurate than em induction thicknesses based from helicopter or plane.
Again, the actual expert claims otherwise. I suggest you get several papers published in respected peer-reviewed journals on the topic, and then, maybe, you can take it up with him.


slow wing

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Re: The 2017/2018 freezing season
« Reply #157 on: October 05, 2017, 05:19:34 AM »
...More buoys could be deployed, 1000x of what is planned for 2018, for a tiny fraction of submarine or surface ship charter costs.
Yes, true and important. The graphical display of the models is getting so much better but the models have insufficient calibration data from the water. A 1000x bigger deployment of buoys was discussed in last year's freezing season thread, 11 months ago - e.g. #481 - with links to further discussion. A major scale-up of buoy deployment really deserves a thread of its own.

meddoc

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Re: The 2017/2018 freezing season
« Reply #158 on: October 05, 2017, 11:52:01 AM »
Hycom is showing ongoing Fram Export & Thinning, Desintegration in the CAA- I guess, the Garlic Press is still active.

https://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif

Adam Ash

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Re: The 2017/2018 freezing season
« Reply #159 on: October 05, 2017, 12:43:18 PM »
Ice thicness measurements taken from above are based on the above water freeboard, as I understand it.
However measurements of the ice bottom surface taken from below looking up would gave ten times the resolution, and give an estimate of volume whuch is thus an order of magnitude better than top down.
Of course we then run into issues with frequency and distributiin of transects compared with from the sky.  But there some ROV gliders which may have the required endurance to get more ice depth data.

Big bucks, either way. Some may ask; Are we just paying for a better view of the sinking of the Titanic?  The ship is lost, whether we measure it more accurately or not.

Daniel B.

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Re: The 2017/2018 freezing season
« Reply #160 on: October 05, 2017, 03:45:28 PM »
You've missed my point entirely. My concern is not about SIE or its annual rise and fall that coincide with the freeze and melt seasons. My concern is about a qualitative shift in the ice that remains at the end of any melt season. A freeze season with temperature anomalies of 5C to 10C has to have an effect on this MYI ice and not a good one.

There have been reports of "buttery" MYI by crews on ships that traverse the heart of the CAB where MYI predominates. This is in contrast to the rigid, rock solid ice that was virtually impassable in the past. Many far more knowledgeable individuals on this site could speak to the possible transitions we can expect in the quality of the ice.

I will be following this freeze season closely and hope the temperature anomalies are mild and do not come close to 2016.

The short answer is, "it depends."  If the ice has frozen from the sea water, then yes, 3M thick ice will look the same today as it did 20 years ago.  However, if the ice has contributions from land-based glacial ice, then the answer is no, as the glacial ice is much denser.  That said, much of the ice in the open ocean, particularly in the Barents, Chukchi, and other areas that melt every summer, will refreeze similarly to that in the past.  It requires the same loss in energy to form the same thickness of ice today, as it did 20 years ago.

mdoliner

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Re: The 2017/2018 freezing season
« Reply #161 on: October 05, 2017, 07:12:05 PM »
The sun heats the earth and the earth re-radiates some of that heat into cold space. How much it radiates is a function of its temperature. Heat always moves from hot to cold. When it reaches the poles it melts ice. It takes latent heat, heat that does not raise the temperature, to melt ice. When ice melts and temperature stays the same the amount of heat re-radiated into space remains the same. So the imbalance remains. If all the extra heat was latent heat, the earth would continue to absorb extra heat until all the ice was gone. This would be true even if the incoming-outgoing imbalance were small. Only an increase in the earth's temperature can restore the balance.

Total melting doesn't happen with small imbalances because of the inefficiencies in the transfer of heat to the poles. Much of the extra heat does raise the temperature and never gets to the poles simply because of the inefficiency of winds and currents. Re-radiation increases. The deformation of the jet stream and the disruption of currents will, given the second law of thermodynamics, tend to reduce these inefficiencies. So, paradoxically, since there is an imbalance, no global warming, where all the heat goes into melting ice, is worse than global warming, because it won't stop until all the ice is gone.

Niall Dollard

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Re: The 2017/2018 freezing season
« Reply #162 on: October 05, 2017, 08:55:45 PM »
ESRL forecast chart indicates the Laptev Sea will be almost ringed by thin ice in about a weeks time.

 

A-Team

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Re: The 2017/2018 freezing season
« Reply #163 on: October 06, 2017, 01:02:51 AM »
ESRL forecast for the Atlantic Water area above Svalbard, Yermak Plateau, and Severnya Zemlya out to Oct 14th. Shows extent, thickness, snow, and air temperatures -- winter is closing in, only the area above Svalbard is staying open.
« Last Edit: October 06, 2017, 03:39:16 AM by A-Team »

Thomas Barlow

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Re: The 2017/2018 freezing season
« Reply #164 on: October 06, 2017, 04:34:07 AM »
This freezing season is off to a horrendously bad start - see below. Add to that, the latest assessments are that globally, September shattered records.

Pavel

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Re: The 2017/2018 freezing season
« Reply #165 on: October 06, 2017, 08:28:59 AM »
It tracks colder than last year. Also the freezing of the Laptev sea happens two weeks earlier than 2016. So I wouldn't say this years' start is a horrendously bad start

Neven

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Re: The 2017/2018 freezing season
« Reply #166 on: October 06, 2017, 12:40:42 PM »
The 2017 global sea ice extent trend line is at a point where it has to decide whether it will join the pack of trend lines, or tag along with the 2016 trend line:
Compare, compare, compare

Niall Dollard

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Re: The 2017/2018 freezing season
« Reply #167 on: October 06, 2017, 04:31:12 PM »
A section of the Laptev Sea (Russian coast to the south) showing how quickly ice can advance in only one day.


Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #168 on: October 06, 2017, 04:32:34 PM »
It tracks colder than last year. Also the freezing of the Laptev sea happens two weeks earlier than 2016. So I wouldn't say this years' start is a horrendously bad start

2016 was the warmest Arctic winter on record and finished with record low volume at the end of the freeze. The chart shows this winter close to and trending similarly to 2016.

Depends on what we consider horrendous, I suppose.

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #169 on: October 06, 2017, 04:35:53 PM »
The 2017 global sea ice extent trend line is at a point where it has to decide whether it will join the pack of trend lines, or tag along with the 2016 trend line:

It has trended persistently lower this year when compared to last. Hope this trend does not continue.

Thomas Barlow

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Re: The 2017/2018 freezing season
« Reply #170 on: October 06, 2017, 06:15:13 PM »
It tracks colder than last year. Also the freezing of the Laptev sea happens two weeks earlier than 2016. So I wouldn't say this years' start is a horrendously bad start

 Last year WAS horrendous, and local conditions are NOT the whole Arctic Ocean.
« Last Edit: October 06, 2017, 06:20:58 PM by Thomas Barlow »

Pavel

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Re: The 2017/2018 freezing season
« Reply #171 on: October 06, 2017, 07:02:47 PM »
Of course it depends on how one considers horrendous. If I clearly understand what does mean "horrendous", it doesn't looks horrendous for me. We have already experienced the bullet and the cannonball by the end of the freezing season, so horrendous should be something more :) The thing that one should be concerned about is the pacific side.It still looks warm and iceless, I'm curious to see how the Chuckchi/Beaufort/ESS will track further in the season
« Last Edit: October 06, 2017, 07:39:10 PM by Pavel »

Daniel B.

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Re: The 2017/2018 freezing season
« Reply #172 on: October 06, 2017, 07:41:10 PM »
Of course it depends on how one considers horrendous. If I clearly understand what does mean "horrendous", it doesn't looks horrendous for me. The thing that one should be concerned about is the Pacific side. It still looks warm and iceless, I'm curious to see how Chuckchi/Beaufort/ESS will track further in the season

I have to agree with you on that.  Compared to recent years, it was not so bad.  Looking at the previous decade, only three had a higher minimum extent.  The low maximum last winter was a little concerning, but the 2017 melt season was fairly average.  The total melt for the year (max - min) was rather unspectacular, 9.78 compare to an average 0f 9.58, and the lowest total melt since 2006.  We will see what happens during the freezing season. 

dosibl

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Re: The 2017/2018 freezing season
« Reply #173 on: October 06, 2017, 08:09:48 PM »
FDD trends might be lining up with 2016, but its too early to tell. The big story last year was the extremely warm moments in the fall, that + the global area/extent graphs generated enough buzz that the media reported on it (and I suspect resulted in a bunch of new readers on this forum, including myself), I'll be curious to see if we get anything similar this year.

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #174 on: October 06, 2017, 10:23:14 PM »
I'm curious to see how the Chuckchi/Beaufort/ESS will track further in the season

Further in the season the Chuckchi, Beaufort and ESS will freeze as seawater wants to do and, no doubt, you will herald this as further evidence of the benign nature of our condition.

Pavel

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Re: The 2017/2018 freezing season
« Reply #175 on: October 06, 2017, 11:08:37 PM »
In the melting season I was expecting a disaster, but now I try be realistic and to avoid exaggerated defenitions. Pacific side is warm, it was clear since July. GFS forecasted more heat advection from the Pacific ocean in a week. In generall could be slighly colder than 2016, something between the cannonball and the bullet. But the season is long and each month is important

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Re: The 2017/2018 freezing season
« Reply #176 on: October 07, 2017, 11:28:32 AM »
If you compare post 2000 Arctic with 1980s and 1990s http://ocean.dmi.dk/arctic/meant80n.uk.php there is a definite trend to warm autumn, winter, spring, cool summer. Whether that means a couple of cool summers would decimate the icepack or whether there is a connection between the cool summers and the other three seasons being warm who knows?

Dharma Rupa

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Re: The 2017/2018 freezing season
« Reply #177 on: October 07, 2017, 03:05:42 PM »
Temperatures at night tend to fall to the dew point.  The major factor determining the dew point is the presence or absence of nearby open water.  The largest recent change in the Arctic climate has been the significant increase in open water.

Temperatures during the day tend to rise as sunlight hits the surface.  The major factor preventing sunlight from reaching the surface is clouds.  Clouds tend to increase in the presence of open water.  The largest recent change in the Arctic climate has been the significant increase in open water.

Thomas Barlow

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Re: The 2017/2018 freezing season
« Reply #178 on: October 07, 2017, 05:15:50 PM »
Of course it depends on how one considers horrendous. If I clearly understand what does mean "horrendous", it doesn't looks horrendous for me. We have already experienced the bullet and the cannonball by the end of the freezing season, so horrendous should be something more :) The thing that one should be concerned about is the pacific side.It still looks warm and iceless, I'm curious to see how the Chuckchi/Beaufort/ESS will track further in the season
Fair enough. I tend to look at recent years as all in the same boat. Until I see it all jump back up to pre-1990 levels, I won't consider it positive news. Maybe because I was promoting renewable energy in the early 1980s, and dedicated my life's work to warning of the dangers ahead, and finding solutions. To me, a slightly better "bad year" this year is not "dodging a bullet", as some call it. I think that's newcomers to the pollution disaster (ie. 10-15 years only) saying that kind of thing.
« Last Edit: October 08, 2017, 12:34:43 AM by Thomas Barlow »

Thomas Barlow

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Re: The 2017/2018 freezing season
« Reply #179 on: October 07, 2017, 05:59:39 PM »
but the 2017 melt season was fairly average.  The total melt for the year (max - min) was rather unspectacular, 9.78 compare to an average 0f 9.58, and the lowest total melt since 2006.
I think that is incorrect. You forget that the 'average' on the extent graphs descends each year due to recent lows. If the 'average' was left at say, pre-1999 level, then the difference would seem much greater. It is like the drought in California. The average on graphs and charts now include a 5 year period of the worst drought on record, so the 'average' is now much lower than it was 7-10 years ago. There is nothing 'fairly average' going on with the Arctic Ocean ice right now. When you see it jump back to pre-1990 levels, you can say 'we dodged a bullet'. Let me know when that happens.
Just sayin'

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #180 on: October 07, 2017, 06:58:42 PM »
If you compare post 2000 Arctic with 1980s and 1990s http://ocean.dmi.dk/arctic/meant80n.uk.php there is a definite trend to warm autumn, winter, spring, cool summer. Whether that means a couple of cool summers would decimate the icepack or whether there is a connection between the cool summers and the other three seasons being warm who knows?

Increased atmospheric moisture load, a cloudy Arctic with increased precipitation which previously was a cloudless, if cold, desert. The clouds in the winter block heat from radiating into space. The clouds in the summer, protect the ice from the sun and keep temperatures cool.

Dharma Rupa

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Re: The 2017/2018 freezing season
« Reply #181 on: October 07, 2017, 08:05:55 PM »
The clouds in the winter block heat from radiating into space.
That brings up some interesting questions about the relative importance of the different greenhouse effects of H2O, re-radiation and enthalopy; which I think I shall bring up in the Stupid Questions thread.

A-Team

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Re: The 2017/2018 freezing season
« Reply #182 on: October 08, 2017, 12:35:12 AM »
Here are the 2m air and snow/ice surface temperatures forecast out to Oct 14th, both as zonal graphs (averaged by latitude, land masked out) and as 2D maps, along with Hycom ice thickness, ice velocity vectors, and summary statistics by time stamp. Gimp layer assembly of Panoply 4.8.4 processing of REB.2017-10-04.nc

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #183 on: October 08, 2017, 03:13:29 PM »
Nice. A lot of info in such a small space.

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #184 on: October 08, 2017, 07:56:37 PM »
Too early to spot any clear deviations from the previous 5 years with a couple of exceptions. The Laptev is seeing early onset of freezing while the Greenland Sea is lagging slightly.

A-Team

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Re: The 2017/2018 freezing season
« Reply #185 on: October 11, 2017, 04:49:48 PM »
Quote
sidd: winter cloudiness at the pole is very important. that's something i would watch closely, since winter cloud is a huge brake on winter cool-down. ttown: water vapor in the clouds prevents long wave radiation from escaping from the surface and reflects it back downward.
Right, right again. But if we want to move beyond 'a snow blanket and clouds have (have not) been keeping the heat in' thus slowing (speeding) winter growth of ice extent and its thickness, thus preconditioning the 2018 melt season, ESRL offers various quantitative energy flux products as well as snow depth and rain monitoring.

The time series below shows four of the flux widgets from early Sept to mid Oct. These are a collection of initial states (ie bottom frame) taken off their daily forecast animation. Three of them use the same palette (upper left); SW stands for shortwave (visible light). The forecast extending out from the 10th to the 17th is provided at the ESRL web page in a larger format.

ESRL does not provide multi-year comparison data but that can be found in three cloud and radiation satellites that we do not follow.

Here are a few academic overviews of seasonal radiation balance and a trend graphic for extent, downwelling radiation, and clouds in September, from Lisan Lu.

https://www.whoi.edu/fileserver.do?id=164384&pt=2&p=58549
http://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0002.1
http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0238.1
https://www.nature.com/articles/srep38287
« Last Edit: October 17, 2017, 03:17:46 AM by A-Team »

A-Team

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Re: The 2017/2018 freezing season
« Reply #186 on: October 11, 2017, 09:27:53 PM »
Just testing whether the template we are aiming for over at Dev Corner -- ESRL 7-day forecast taking over from a post-minimum initial state time series -- is "too big to load" in which case some days or forecast hours will unfortunately have to be skipped over. However it seems to work ok, 9.4 MB in 57 frames.

Hopefully ESRL will switch this product (Arctic11.gif) over to whole-Arctic Ocean in the near future. However, there's something to be said for an emphasis on the Chukchi-Beaufort as that's been the last to freeze over (mid-December). That's perhaps unsurprising as the Bering Strait is much further south than Svalbard on the other side, 65.9º vs 77.9º latitudes or 12x111 km/deg = 1332 km.
« Last Edit: October 11, 2017, 10:33:09 PM by A-Team »

Pavel

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Re: The 2017/2018 freezing season
« Reply #187 on: October 12, 2017, 11:49:34 AM »
Cryosat have resumed. I don't see any 3m or thicker ice and there's very little of thicker than 2,5m ice

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Re: The 2017/2018 freezing season
« Reply #188 on: October 13, 2017, 06:30:27 PM »
NSIDC shows an impressive gain of 1 million km2 in arctic sea ice extent since 1 Oct 2017, with 800,000 km2 more ice extent on 12 Oct 2017 compared to 12 Oct 2016.

That coupled with an unusual regrowth of Antarctic sea ice to reach a season max 9 Oct 2017 (so far) rather than earlier means the overall global ice extent has recovered quite nicely compared to its state a year ago when both arctic and Antarctic ice were miserably low at the same time.
Feel The Burn!

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Re: The 2017/2018 freezing season
« Reply #189 on: October 14, 2017, 03:32:44 PM »
NSIDC shows an impressive gain of 1 million km2 in arctic sea ice extent since 1 Oct 2017, with 800,000 km2 more ice extent on 12 Oct 2017 compared to 12 Oct 2016.

That coupled with an unusual regrowth of Antarctic sea ice to reach a season max 9 Oct 2017 (so far) rather than earlier means the overall global ice extent has recovered quite nicely compared to its state a year ago when both arctic and Antarctic ice were miserably low at the same time.

Yes, there is substantially more Arctic sea ice extent now than there was on this same day last year. But it should be noted that the NSIDC ASIE increase of 1.038 km2 since October 1 is less than that measured in 2015, 2014, 2013, 2012, or 2010. Month-to-date, NSIDC SIE is still running below the ten-year average, and year-to-date, 2017 extent is deeply entrenched in second place. Bottom line, then: I'm not sure how "nicely" once can say it's recovering.

A-Team

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Re: The 2017/2018 freezing season
« Reply #190 on: October 14, 2017, 05:11:00 PM »
The time series below shows sea ice thickness from Oct 1st to the 13th followed by the ESRL forecast to the 18th. Ice 1.6m and thicker is not distinguished (shown with the same color). New ice is seen forming and thickening on the periphery but little growth occurs on ice that was already present at the seasonal minimum (as cold air can only freeze bottom water indirectly via heat equation conduction). The day 5 ice thickness graphic shows significant thinning anticipated north of Svalbard region by the 18th, not from melt so much as ice pack movement.

The Chukchi-Bering walrus population is no closer than ever, ~350 km, to sea ice lying over continental shelf, ie where food is within diving depth with ice haul-outs at hand. Consequently they have to rest on land haul-outs where juvenile walruses are at great risk from stampedes, killed by the thousand in documented events. There are two known walrus haul-outs on the south side of Wrangel Island; some ~230 similarly stranded polar bears on the north side of Wrangel were recently seen feeding on a beached bowhead whale.

Technical note: the D0 frames are taken from icethicknessday0.gif up until the 13th, at which point D5's are taken from icethicknessday5.gif with the 9th supplying the 14th, the 10th the 15th and so on. ESRL still has not fixed the sizing bug that makes these slightly different in proportion, though the palette has finally stabilized. It would have been better to combine these with the intermediate days in a small gif so that the final day could supply the forecast days.
« Last Edit: October 14, 2017, 06:55:49 PM by A-Team »

Sterks

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Re: The 2017/2018 freezing season
« Reply #191 on: October 14, 2017, 08:25:53 PM »
Therefore, expect a normal or above-normal ice extent growth.

A-Team

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Re: The 2017/2018 freezing season
« Reply #192 on: October 14, 2017, 10:07:47 PM »
Here is a comparison of the month of Oct for 2017 (upper) vs 2016 (lower). This being only mid-Oct of 2017 and two weeks being beyond the reach of any prediction system, animation forecast components stall out, frames become static as they reach their limits.

We've had posts this last month asserting the weather is not only a sure thing this fall, but even next spring, indeed the 2018 melt season is a done deal, and one person wrote off the 2018 freeze season already. There's a difference between knowledge and nonsense. D5, D7, maybe some value in D10, but even D15 appears completely out of reach. Meaningful seasonal forecast skill is still a pipe dream: the only site that got the last ENSO right was the Old Farmer's Almanac.

Some threshold got re-set way too high on attachment security after the hack scare, hopefully our admin can dial that back a bit. These gifs have had zero contact with any Adobe product and have nothing whatsoever to do with "gif89a format.aip" of Adobe Illustrator.
« Last Edit: October 15, 2017, 12:27:06 AM by A-Team »

LRC1962

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Re: The 2017/2018 freezing season
« Reply #193 on: October 15, 2017, 12:36:18 AM »
Maybe should start different post, but will ask anyway. Based on projected current path of Hurricane Ophelia:http://www.nhc.noaa.gov/storm_graphics/AT17/refresh/AL172017_5day_cone_no_line_and_wind+png/205031_5day_cone_no_line_and_wind.png
What is the possible impact on the ESS as to wind/moisture levels on ice formation, or is it possible the dissipation and earlier freezing season will mean little?
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Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #194 on: October 15, 2017, 12:41:06 AM »
The early freeze is outperforming last years freeze throughout the Arctic with the Greenland Sea being the sole exception with regards to SIE.

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #195 on: October 15, 2017, 12:44:21 AM »
True for area as well.

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #196 on: October 15, 2017, 02:27:32 PM »
JAXA DATA
Although JAXA is having a Sunday off, herewith a table and graph up to 13th October. The table shows the large variation in remaining extent gain that happened in recent years.

The graph does show that on average daily extent gain is at maximum at this time, and later settles back a bit. Methinks this is simply a matter of geography, not climate variation. As ice extent reaches more of the Russian shore further extent gain there is impossible.

The graph also shows that for an individual year (e.g. 2016) the average is irrelevant not just for the season but also any day, week or month. Oneself can but watch record and wonder and hope A-Team and his ilk come up with the goods.
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A-Team

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Re: The 2017/2018 freezing season
« Reply #197 on: October 15, 2017, 03:22:53 PM »
Quote
Pavel notes on #187: Cryosat has resumed. don't see any 3m or thicker ice and there's very little of thicker than 2.5m ice
This is a difficult data set to work with; taking a quick look at netCDF file offered on the CPOM web page (1st image below), the data was there but not in a form (Geo2D) that would allow redrawing the ice thickness map at a larger scale without the lat lon overlays.

Panoply was able to draw out the thickness observations (which seem to be head-to-tail abutted swaths over a month of orbits) and the standard deviations (2nd image). It would be possible to export the thickness numbers to excel to plot the thickness distribution (but what to do about negative ice thicknesses?). Other forums provide very knowledgable posts on Cryosat data and how to compare it to model data such as Piomas.

As the satellite completes a full cycle of its near-polar orbits, the swaths overlap in some places but don't quite come together elsewhere. I looked at several methods of filling in the gaps in ice thickness that would utilize nearby measured thicknesses before settling on D Tschumperlé's graphical algorithm in the Repair section of online G'mic, an amazing French site that allows visitors to conduct a full range of graphical manipulations over the web.

The infill came out rather nice, though it's hard to say how it would compare to kriging or other numeric estimations, much less to the real situation on the ice (which we will never know as this time frame has passed on by).

http://www.cpom.ucl.ac.uk/csopr/seaice.html
https://gmicol.greyc.fr

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Re: The 2017/2018 freezing season
« Reply #198 on: October 15, 2017, 10:22:42 PM »
Some threshold got re-set way too high on attachment security after the hack scare, hopefully our admin can dial that back a bit. These gifs have had zero contact with any Adobe product and have nothing whatsoever to do with "gif89a format.aip" of Adobe Illustrator.

I don't know if anything got re-set, but here are the attachment settings I can adjust as admin:
Compare, compare, compare

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Re: The 2017/2018 freezing season
« Reply #199 on: October 15, 2017, 11:56:23 PM »
The Arctic atmosphere tries to cool but it fails. According to the weather forecasts no significant coldness will come or even things may get warmer