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Messages - jdallen

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1
Arctic sea ice / Re: MOSAiC news
« on: November 20, 2020, 09:35:40 PM »
So is there a fall Siberian Side or Laptev wedge trend, what do we even mean by trend, how many years of data does it take, what does normal variation mean in a rapidly changing Arctic climate, what can be considered statistical proof of a trend, is there a plausible physical basis for the trend, is the Laptev wedge a robust or biased regional choice, and how accurate is the guidance for future (ie next) years?

Oren raises an interesting complexity in #1266. On a daily coin flip, what happened in 2018 is irrelevant to 2019 which in turn is irrelevant to 2020: sampling with replacement from a fixed and familiar probability distribution. Coin flip ensembles average 50-50 but individual runs can drift off never to reach 50-50, the counterpart to natural variation.

Now suppose the ‘head’ of the coin wears down slightly during 2018 flipping process, biasing the flip towards ‘tails’ in 2019, with even worse wear-down biasing 2020 still more.  A slow runaway situation of positive feedback with earlier years becoming increasingly unrepresentative.

That may be the case for fall Laptev ice trending if each year strongly preconditions the ice — and indeed the weather — to the next. Trends are then largely self-induced (with ‘rebound' years perhaps anti-induced) rather than driven by generic global climate change, advancing atlantification, ocean-albedo effect and so on.

The figures below greatly compress 65 days the Siberian Side (upper half the Arctic Ocean in Greenland down orientation) and the Laptev-only wedge to make visualization patterns. There do indeed to be two trends: more open water earlier and a two week later shut-down. (Numerical treatments are given in earlier posts.)

Here if each year were cut into an unlabelled strip and a viewer asked to logically order them, there being 6!=720 top to bottom arrangements, it is not plausibly coincidental that the viewer’s order would agree with observed chronological order (2017 an outlier) unless the latter had a noticeable trend.

Smos-Smap provides six years of daily data back to 2015. Smos by itself goes back to Oct 2010 at U Bremen but is archived at an sub-satisfactory resolution, 202 vs 584 pixel width for the Laptev wedge. The figure below shows 2012 to the right of 2020 in the 6-year joint  mp4 (2020 2016; 2019 2018; 2017 2016 smos-smap; 2015 omitted).

The Smos-Smap combination is better, especially nearer to the 0.5m reporting limit (however it's not used with the CryoSat2 hybrid product!). Smos-Smap is examined below with Smos held back for later (hypothetical) testing and validation in earlier years like 2012 of presumed declining applicability.

A Consistent Combination of Brightness Temperatures from SMOS and SMAP over Polar Oceans for Sea Ice Applications
AU Schmitt L Kaleschke  30 March 2018  6 cites
https://www.mdpi.com/2072-4292/10/4/553/htm free full

Combined SMAP–SMOS thin sea ice thickness retrieval
C Patilea G Heygster M Huntemann G Spreen 2019 Feb 2019 13 cites
https://tc.copernicus.org/articles/13/675/2019/ free full

Assessment with Controlled In-Situ Data of the Dependence of L-Band Radiometry on Sea-Ice Thickness
P Sánchez-Gámez C Gabarro A Turiel M  Portabella  13 Feb 2020 0 cites yet
https://www.mdpi.com/2072-4292/12/4/650/htm  free full CFDD Upward Looking Sonar tests

https://seaice.uni-bremen.de/data/smos/png/
https://seaice.uni-bremen.de/data/smos_smap/png/north/

2
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 13, 2020, 11:05:58 PM »
Following up on whoi itp121 up thread, here are the charts and drift path for itp120 which is a little further north. The warm layer here at ~50m is not so pronounced and salinity is not high enough to be atlantic water which would probably be deeper in the basin anyway.
It's likely that itp120 and itp121 may have been deployed in those locations hoping to monitor pacific incoming from the chukchi plateau, in which case someone has done their homework very well.

whoi itp120 profile and location.
mercator (model) salinity at 34m, pacific side, sep2018-nov2020
full arctic animation here


3
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 26, 2020, 12:27:57 AM »
Quote
the original C2S palette is quite unreadable
The auto-archive has been created by L Kaleschke of AWI who sometimes posts here and on twitter. The files are updated daily using the updated Smos and whatever Cryo swaths that have come in. The day to day differences are small but can be visualized either by differencing the pngs or by visualizing the (perfectly done) netCDF in Panoply.

The combining algorithm parts are complex and have been under intensive development for years. Kaleschke spent four months on the Polarstern; one of the main objectives there was to synch plane and satellite overflights with myriad ice cores to improve products such as this and AMSR2. This can't be said about Piomas.

The first quickie below is contoured for major and minor scale ticks. Note the lat lon graticule is gone and the image is in 'Greenland down' orientation. The second emphasizes the thicker ice, there is very little thicker than a 1.0m this early in the freeze season and only a tiny bit near the 2.56m maximum. The third displays thickness isopleths.

No script is needed for the volume calc in an equal area pixel projection like lambert azimuthal. It's a menu item in ImageJ. It takes another click or two in Excel to graph the distribution of ice thickness (which is likely normal about the mean but skewed against thicker ice without notable kurtosis).

The main .nc files here are a great opportunity to learn about graphical display and analysis of netCDF data using painless Panoply.

https://www.giss.nasa.gov/tools/panoply/download/   easy stable netCDF menu-driven tool
https://imagej.nih.gov/ij/download.html  free scientific graphics tool

ftp://ftp.awi.de/sea_ice/product/cryosat2_smos/v203/nh/LATEST/  home folder

ftp://ftp.awi.de/sea_ice/product/cryosat2_smos/v203/nh/LATEST/W_XX-ESA,SMOS_CS2,NH_25KM_EASE2_20201017_20201023_o_v203_01_l4sit.png

ftp://ftp.awi.de/sea_ice/product/cryosat2_smos/v203/nh/LATEST/W_XX-ESA,SMOS_CS2,NH_25KM_EASE2_20201017_20201023_o_v203_01_l4sit.nc

4
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 23, 2020, 08:41:20 AM »
What I am trying to bring up is that extent by itself is only an indication of when ice thickening can possibly begin, and with the current extreme delay in the Asian sea ice extent, the ice growth in thickness is being delayed. While historically some areas of the Asian seas have had slow growth in extent, 2020 is the first year on record (as far as I know) that will likely still have an ice free NE passage on Nov 1. (And not just dodging ice, but wide a open sea lane.) The fear is that if this continues much longer even with eventual universal 100% extent on the Asian side, that first year ice will not have a chance for a 'normal' gain in thickness. Instead of >1M ice, much of the Asian sea ice could end the freezing season in a very fragile state leading to much earlier breakup and melt in 2021. Already basically the whole of the Asian side has lost a month of thickness growth, where in previous years a fairly large percentage of those seas had already started that growth.

It is a rough estimate, but if you use the correlation of Freezing Degrees Day (FDD) with ice thickness, you need ~5500 FDD to go to 2m first year ice, and ~3500 FDD to go to 1.5 meters. October is usually worth ~300 to ~400 FDD in the Arctic, so it can make a significant dent into the ice growth.
To give some more numbers, for Ostrov kotel'nyj for example. Mean temperature from 1st of October to 30th of April over the last 10 years (2010-2019) was -20.8°C, which is about 4400 - 4500 FDD. If you count from the 1st of November, this leads to 4100 - 4200 FDD. And if you ignore November and start the ice thickening the 1st of December, it makes only 3800 - 3900 FDD. This is ignoring the risk that oceanic heat flux could be strong enough this winter to weaken this correlation. If ice growth does not start in a hurry on the Siberian side, the winter would probably not be able to fully erase the memory of this melting season. Which is a great peril, as up to the last years, winter was always cold and long enough to at least bring Arctic back to some kind of a "2m FYI" state, helping to stabilize the system.

5
Arctic sea ice / Re: The 2020 melting season
« on: September 21, 2020, 08:12:27 AM »
Btw that thick looking bit north of svalbard is a stream of icebergs from Greenland.

No.

6
Arctic sea ice / Re: The 2020 melting season
« on: September 16, 2020, 03:01:54 AM »
It's not just a SST thing in the Barents, Kara and Laptev seas. The heat goes town to 30m or more. Compare the 30 m Arctic temperatures of this year with 2019 on Mercator ocean and you will see that there's much more ocean heat on the Atlantic side this year than last. On the other hand, there's less heat on the Pacific side. Over both sides, there's much more heat this year, but there is almost always a see saw effect in the Arctic between the Atlantic and Pacific.

7
Arctic sea ice / Re: The 2020 melting season
« on: September 06, 2020, 10:01:37 AM »
The cold is coming in now. It all depends on bottom melting and what the winds will do to the ice sticking out in the Beaufort, but to me it looks like the minimum could be reached on the 9th or 10th.

8
Arctic sea ice / Re: The 2020 melting season
« on: September 03, 2020, 09:50:32 PM »
From NSIDC most recent post wrt Arctic sea ice and Atlantification: "Atlantification continues
As discussed in a recent paper in the Journal of Climate led by colleague Igor Polyakov of the University of Alaska, the process of “Atlantification” of the Arctic Ocean, first noted in the Barents Sea, is continuing, with significant effects on the sea ice cover during the winter season in the Eastern Eurasian Basin. The relatively fresh surface layer of the Arctic Ocean is underlain by warm, salty water that is imported from the northern Atlantic Ocean. The cold fresh surface layer, because of its lower density, largely prevents the warm, salty Atlantic waters from mixing upwards. However, the underlying Atlantic water appears to have moved closer to the surface in recent years, reducing the density contrast with the water above it. Recent observations show this warm water “blob,” usually found at about 150 meters (492 feet) below the surface, has shifted within 80 meters (263 feet) of the surface. This has resulted in an increase in the upward winter ocean heat flow to the underside of the ice from typical values of 3 to 4 watts per square meter in 2007 to 2008 to greater than 10 watts per square meter from 2016 to 2018. Polyakov estimates that this is equivalent to a two-fold reduction in winter ice growth."

Further reading: Polyakov, I. V., et al. 2020. Weakening of Cold Halocline Layer Exposes Sea Ice to Oceanic Heat in the Eastern Arctic Ocean. Journal of Climate, 33, 8107–8123, doi:10.1175/JCLI-D-19-0976.1.

9
Arctic sea ice / Re: The 2020 melting season
« on: August 13, 2020, 04:09:43 PM »
Juan C & Gerontocrat: seems like good odds that melting rate this month could be record low unless it doesn't speed up soon.

2020 has so far lost 0.53 M km². A little more than a third of the month has passed, and the slope of decrease decreases towards the end of the month. A place in the lower part of the ranking list seems possible.

IMHO we have now entered the phase when Heat Energy balance becomes increasingly critical and we can no longer reference previous years as predictors of even the short-term or medium term condition of the Arctic ice. The 'Puff' event will be sudden and happen at any time from 'now' and is likely to surprise many, particularly those who rely on the past trend of events to predict the future demise of the Arctic ice.

10
Arctic sea ice / Re: The 2020 melting season
« on: August 09, 2020, 09:33:10 PM »
This remarkable freeze/melt cycle has been unfortunate but perhaps inevitable, putting us literally in uncharted waters with regards to massive climate change impacts.

It’s easy to forget, as the post-BOE forum properly notes, that once upon a time the Barents, Baltic, Bering, Baffin. Chukchi, and Kara hosted millions of sq km of year-round ice. (And that not so long ago, 1000 m thick ice gouged the Lomonosov ridgetop.) On 08 Aug 2020, 38% of the remaining ice (the Arctic Ocean basin, was open water. Vast areas of tundra are free of reflecting snow as well. We’re already well into BOE in most respects.

What’s going on at the moment is baffling, notably between Greenland and the north pole. It’s clear we don’t really understand the current physical state of the ice. Thus even if surface weather were predictable three days out, where things will end up by mid-October still remains up in the air.

However we do have a good grip on some of the pre-conditioning events that have brought the ice to its current state:

-1- The melt season really began in the previous freeze season, even earlier. Vast areas of surprisingly thin 0.3m ice remained in the Laptev when the Polarstern moored on Oct 4th. That and a slow start to freeze-up are documented by thousands of km of ship thickness transects with no graduating SYI floes thick enough to stand on for Mosaic. (T Krumpen http://dx.doi.org/10.5194/tc-14-2173-2020)

-2- The TransPolar Drift over winter, as accurately imaged in Ascat time series, bore little resemblance to recent years in two key respects: months of very rapid Fram-ward displacement and extensional engagement of ice to the pole and beyond. Often the ice drift is just circumpolar.

-3- The whole icepack does not rotate CW with the TPD but rather participation is demarcated by immense  curvilinear leads, newly visualized in a dockside posting by L Kaleschke and enhanced on the Mosaic forum by directional convolution. These fracture lines, coincidentally or causally, approximately delimit the puzzling openings to the pole above Morris Jesup. A lot of MYI ice between Greenland and the pole was fractured by lead formation.

-4- Missing this year was any significant CW rotational movement of thick ice out of the western CAB. While this ice has never moved further than a half gyre in the last ten years of tracking, commonly a strip of CAB ice moves to inevitable melt in the warmer open seas of the Chukchi (which might be called internal export).

-5- Export out the Fram was robust during the TPD, pushing everything ahead of a 500 km east-west line through the initial position of the PS to oblivion in the Greenland Sea. Behind this line, newly formed Laptev ice filled the growing open water gap to shore. However, since mid-May, export out the Fram, SV-FJL gap, Bering Strait, CAA garlic press and Nares have all been inconsequential (and will remain so, too little time is left).

-6- A record heat wave off Ellesmere in mid July coupled with persistent easterly winds melted vulnerable matrix ice joining floes, enabling churning of offshore ice into residual rubble. The observed movement to the west is not unusual but it was far more narrowly restricted to the CAA coast in past events. The main CAB ice pack, being no longer attached to coastal land or ocean bottom, might be set adrift to elsewhere by persistent winds from the south. We’ve not yet seen that game-changer.

-7- The Pacific-side cyclone centered on July 27th hit like a tornado at 75º/-160º decimating the ice, on Sentinel-1 and WorldView, making clear that error-prone thickness and area/extent whole-ocean numbers don’t capture key issues such as ice mechanical strength, internal pressure or response to stress.

Both the Chukchi and slow-melting Beaufort were pre-conditioned by dispersion for flash lateral and bottom melt after the storm; note insolation today at 75º surprisingly is still 64% the strength the week centered on solstice (4th image below) but has to get through clouds and escape low angle surface reflection.

Are these independent events or somehow consequent to a single master change (such as breakdown trend of equatorial heat gradient as manifested in the jet stream)? Yes to a certain extent but this view has to be distinguished from the slot machine model put forward by Csnavywx in #4662.

That is, the multi-decadal downward trend of ice has created a set-up for which a coincidental confluence of bad weather events over a single freeze/melt cycle sequentially sum to an ice disaster. Even bland weather from here to October may suffice for a seriously below-trend outcome. Regardless of how the season turns out, as @Zlabe notes, fractional BOE has gone on all summer.

The files below expand or animate with a click. File names explain the topic addressed. I thank uniquorn for valuable discussions. Clouds are removed by setting a sequential five day AMR2 stack to 'darken only' in gimp.

11
Arctic sea ice / Re: The 2020 melting season
« on: August 08, 2020, 11:08:52 AM »
Again the actual poof event in a slightly higher resolution (I must admit that on the multicolored Bremen graph it looks even more devastating):

12
Arctic sea ice / Re: The 2020 melting season
« on: July 28, 2020, 01:05:28 PM »
NSIDC extent comparisons with previous low years. 2020 is becoming more and more similar to 2012 on the Atlantic/Laptev side. Surprisingly it leads over 2012 in the southern CAA, and of course in the ESS, while lagging in M'Clure Strait and of course the Beaufort.

13
Arctic sea ice / Re: The 2020 melting season
« on: July 21, 2020, 04:18:14 PM »
I wouldn't be so confident as some posters here that the seemingly solid pack in the CAB will hold up well this coming month.  Take a look at what one seemingly solid stretch of the pack along the Laptev front from July 16th to today (click to animate).  Note that:
1.  This was without a Great Arctic Cyclone.
2.  This is not mere dispersion.  The extent front has been marching southwards the whole time.  It's just that the ice in the middle is disintegrating faster than the extent front can catch up to it to re-compactify. 

14
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: July 19, 2020, 08:24:42 PM »
Juan C, what outcome do we get if we use the most conservative historical numbers from now and onward? Where would that minimum end up in terms of SIE?
JAXA ARCTIC SEA ICE EXTENT:  6,551,222 KM2 as at 18-Jul-2020

Projections. (Table JAXA-Arc1)

Average remaining melt (of the last 10 years) would produce a minimum in Sept 2020 of 3.35 million km2, 0.18 million km2 above the 2012 minimum of 3.18 million km2.

In every year since 2007 remaining melt results in an extent below 4 million km2.

For a record low remaining melt needs to be 5.5% or more above average, as happened with remaining melt in 2012, 2015, 2016, and 2018
Gerontocrat analyzes the years 2007-2019 on his table (the latest 13 years). According to his latest post, the maximum that we can have is 3.89M km2, if 2020 lose the same ASI than 2013/2014.

15
Arctic sea ice / Re: The 2020 melting season
« on: July 19, 2020, 07:00:43 PM »
Sea ice & bathymetry.

16
Arctic sea ice / Re: The 2020 melting season
« on: July 17, 2020, 10:53:30 AM »
Regardless of what happens from here on out, 2020 has carved out a deep new low range for Arctic sea ice for part of the year and will be one for the books.  In my appraisal this means it is already a very bad year for the ice.  Keep setting new lows for different days and sooner or later one of those days will be September 16th.  We definitely will never carve out new highs for any day of the year henceforth.
Looks like, yes. Just one little detail: September 16th is not very likely for the minimum. Rather, something like September 25th...30th, more like. The reason is all the extra heat in the system likely to extend melting season a bit. The trend of it is well obvious, if one would plot a graph of 5-year running-means from 1980s all the way to 2019. It slowly extends, obviously with lots of noise outta weather effects this or that particular season. But this one, with the GAAC and remaining effect of cleaner air due to less air travel and industries much of the spring and summer due to all the quarantines around the NH - one would expect the lengthening of the season to be especially likely to be big. Which, of course, would lead to lower minimum than would "normally" be expected - more time to melt things, more things melt out in the end.

It's melting momentum, i call it. The bigger it gets, the longer it takes to exhaust its potential with everything else being "usual". And right now, it's big.

17
Arctic sea ice / Re: The 2020 melting season
« on: July 17, 2020, 03:22:59 AM »
I think it needs to be pointed out here...

Average loss over the last 5 years between the current date and minimum works out to approximately 3.58 million km2.

That gives us a September minimum of approximately 3.4 million km2.

Emphasizing... With *Average* melt. Average.

Even the lowest of the last 20-odd (2014) would put us in spitting distance of 2nd-4th.

2nd lowest minimum is almost a certainty at this point.

If we see melt like 2012, we're looking at a September minimum of 2.5 million km2 +/- pocket change.

And quite conviniently, right after OffTheGrid mentions that (my bold):

I split the Hycom month animation of thickness and this is three weeks ago, today, and forecast in a week.
The melt last three weeks has been phenomenal. ...

Now, JDallen, here's my point: when we see phenomenal melt rates for weeks on end at the peak of a melt season - we should not anyhow expect "average loss" further into the season. It is very simple: phenomenal melt rates have consequences into nearest future. When you have them, it means you just got a ton of energy into the system - this or that way, does not matter (for this particular point i am making here). Then and only then phenomenal melt rates can actually occur.

But this same exceptional amount of energy which entered near-surface layer in Arctic during recent weeks - way above average, - is not going to "poof" right tomorrow. Phenomenal melt rates means equally phenomenal SSTs, phenomenal albedo drops, phenomenally high water heat content near surface. And those will continue to influence further melt for weeks and even months ahead, phenomenally much.

Granted, weather is always fluctuating and there is some small chance that with _phenomenally_ melt-halting weather further on, we'd indeed end up with "Average loss over the last 5 years between the current date and minimum". But it's one very small chance. With average weather, we should expect at least half-phenomenal further ice loss during this season. Not "average" at all.

It is almost a certainty, thus, that 2020 will be the new lowest of all time. To me, the only question is not "if" 2020 will beat 2012; the only question is by how much.

18
Arctic sea ice / Re: The 2020 melting season
« on: July 14, 2020, 06:34:46 AM »
Lesson from the past:  2011.

High pressure dominated early 2011 and by the 18th of July Jaxa ice extent was 377k sq km ahead of July 18th 2007, which was the record at the time.  Current conditions as at 13th July are now 420k ahead of the previous record year of 2012.  However in 2011 conditions changed dramatically and by the 22nd of July 2011 a low pressure system had taken over.  The lead by then had been cut to 206k and dropped further to be 101k behind 2007 by Aug 1, as low pressure conditions continued to dominate.  In the end 2011 narrowly failed to beat 2007 in Jaxa extent, but did roughly equal 2007 in area with one agency putting 2011 first for area and others second if I recall correctly.

Current forecasts suggest another week of high pressure domination and then a switch to low pressure which would make for a switch at roughly the same time as 2011.  However forecasts at this lead are not reliable, and I think forecasts have suggested a switch early in the second forecast week for a while now and have been delaying this switch.  On the other hand 2007 made its big surge in early July, so 2011 being ahead in later July was certainly an ominous sign.  In contrast 2012 made its big surge in early August.  If conditions do switch to low pressure dominated cloudy conditions in a week or two I'd suggest beating 2012 would become unlikely, and that strong melt conditions need to extend into maybe mid August.  On the other hand I'd say it would need nearly a miracle for melt this year to not beat 2nd position comfortably.


19
Arctic sea ice / Re: The 2020 melting season
« on: July 10, 2020, 11:16:52 PM »
I don't usually have anything relevant to add here, but this came out today and seems to be topical ...

Arctic Ocean Changes Driven by Sub-Arctic Seas
https://phys.org/news/2020-07-arctic-ocean-driven-sub-arctic-seas.html

New research explores how lower-latitude oceans drive complex changes in the Arctic Ocean, pushing the region into a new reality distinct from the 20th-century norm.



The University of Alaska Fairbanks and Finnish Meteorological Institute led the international effort, which included researchers from six countries. The first of several related papers was published this month in Frontiers in Marine Science.

The Arctic Ocean, which covers less than 3% of the Earth's surface, appears to be quite sensitive to abnormal conditions in lower-latitude oceans.

"With this in mind, the goal of our research was to illustrate the part of Arctic climate change driven by anomalous [different from the norm] influxes of oceanic water from the Atlantic Ocean and the Pacific Ocean, a process which we refer to as borealization," said lead author Igor Polyakov, an oceanographer at UAF's International Arctic Research Center and FMI


This conceptual model shows the influx of Pacific and Atlantic water into the Arctic Ocean in the past compared to recent years. Blue indicates cool water and red indicates warm water. Arrows indicate the direction of water flow.

Since the first temperature and salinity measurements taken in the late 1800s, scientists have known that cold and relatively fresh water, which is lighter than salty water, floats at the surface of the Arctic Ocean. This fresh layer blocks the warmth of the deeper water from melting sea ice.

In the Eurasian Basin, that is changing. Abnormal influx of warm, salty Atlantic water destabilizes the water column, making it more susceptible to mixing. The cool, fresh protective upper ocean layer is weakening and the ice is becoming vulnerable to heat from deeper in the ocean. As mixing and sea ice decay continues, the process accelerates. The ocean becomes more biologically productive as deeper, nutrient-rich water reaches the surface.

By contrast, increased influx of warm, relatively fresh Pacific water and local processes like sea ice melt and accumulation of river water make the separation between the surface and deep layers more pronounced on the Amerasian side of the Arctic. As the pool of fresh water grows, it limits mixing and the movement of nutrients to the surface, potentially making the region less biologically productive. ...


Vertical profiles of winter (NDJFMA) potential temperature (θ, left column, °C, A,C,E,G) and salinity (S, right column, psu, B,D,F,H) for the central points of the four selected regions of the Arctic Ocean (regions are identified in the right column, their geographical locations are shown in Figure 1) from the 1970s (blue) and 2000s-2010s (red). CHL, NSTM, PSW, and PWW identify Cold Halocline Layer, Near-Surface Temperature Maximum, Pacific Summer Water and Pacific Winter Water.

Igor V. Polyakov et al, Borealization of the Arctic Ocean in Response to Anomalous Advection From Sub-Arctic Seas, Frontiers in Marine Science (2020).
https://www.frontiersin.org/articles/10.3389/fmars.2020.00491/full




20
Arctic sea ice / Re: The 2020 melting season
« on: July 08, 2020, 03:30:43 AM »
Phoenix, you are being intentionally obtuse. Hard inversions above the ice under a subsidence high trap solar energy. Arguing the details of 850 temperatures vs surface temperatures is irrelevant because in early July the energy of insolation is dominant under clear skies.

Arctic ocean air temperature forecasts beyond a few days are unreliable.

The reason that the transition to a blue Arctic ocean is slow is that the melting season is short and thermal inertia is large. The ice is "saved by the bell".  This summer there is strong "melting momentum" which is being brought on by the build up of heat under melt ponds caused by days on end of direct insolation. This weather is not good for the ice.

21
Arctic sea ice / Re: The 2020 melting season
« on: June 20, 2020, 04:34:42 AM »
Lots and lots and lots of surface melt over the entire arctic right now.

Friv keeps trying to explain that. 

It is still very early in the season, and a lot can change.  However, right now you would be hard pressed to find any year with this much surface melting occurring over the entire arctic basin this early in the melting season.

EDIT: after reading my post, I anticipate a lot of people piling on about 2007, 2012, 2016 and 2019 and saying things were bad then too.  I don’t disagree.  However, to my eye, the surface melt seems more extreme this year than in all of those other years.  We will see how things ultimately turn out. Right now I am agreeing with Friv that this will be a top 3 and has a chance for the record.

But it is still very early!  As Neven always says, we need to keep watching and comparing.

22
Arctic sea ice / Re: The 2020 melting season
« on: June 16, 2020, 07:39:59 AM »
Sibiria has always been hot in summer and cold in winter. Temps up to 45C are not uncommon
Really? Is there a reliable data series for max temps in Siberia? I've only managed to find anecdotal evidence but anything over 30C seems to be known but certainly uncommon and I haven't yet seen any references to temps over 40C (and not even 40C).

23
Arctic sea ice / Re: The 2020 melting season
« on: June 13, 2020, 12:33:32 AM »
The 12z models and 00z EURO the 12z euro isn't out yet have backed off considerably with the dipole in the long range.

Instead of setting up a full or 3/4 dipole the models slide the Eurasian vortex over the pole/Atlantic side and merge it with the GIS vortex which won't budge.

This keeps the torching over the Pacific half.

It's not a good pattern by any means but it definitely is much better than the entire CAB getting the roast.

This kind of thing is what will keep 2020 from passing 2012 in the end.

We'll see

Yep, we've seen this time and again in the last 8-9 years. It's a pattern and I think part of the reason for this strong +PV tendency has been due to a marked increase in low-level baroclinicity and eddy kinetic energy as the mid-high lats warm faster in summer than the basin proper. It is providing a transient negative feedback by preferentially favoring storms over the basin during the summer months (on the cold side of the jet). This retards melt and slows down the year-to-year summer progression. Of course, eventually the warming signal will overwhelm this, but it may take another 20 years to do so (the occasional year like 2016 nonwithstanding). Eventually, increasing warming over land will cause the warm conveyor belts on these storms to start doing enough damage to offset the shielding effect and destroy ice cover anyways. We may end up seeing a fairly long period of not much change -- followed by a quick transient period to sea-ice free, followed by decoupling of the troposphere from the stratosphere in the autumn and subsequent large hits to winter ice volume recoveries. Nakamura et. al's BoE experiments suggested as such a few years back.

And I suspect 2007 and whatever future year(s) this happens will be seen as the turning points.

If you're looking for ocean-driven signals as well, simply look at the trend of shoaling along the Atlantic-inflow stream and heat content storage coming from the Chukchi. They're pointing to the 2040s as well. Incidentally, this is around the same time aragonite undersaturation in the Arctic begins to show up, too (aragonite undersaturation starts in the 2030s around Antarctica). Full-on ecosystem disruption seems pretty ripe around that time.

24
Arctic sea ice / Re: The 2020 melting season
« on: May 24, 2020, 09:14:14 PM »
Slater's model has picked up the current preconditioning  and thinks it is favourable for strong melting way into July.
It predicts 7.34 m km² for July 13th, currently nosediving ...

   Wow, if that forecast verifies, then 2020 would be 600K and 8% below the previous records for July 13 Extent in 2019, 2016, 2012. 

    It is useful to have Phoenix provide a skeptical check on habitual ASIF catastrophism (as in "this year is the big one!"), but it is also true that 2020 has come out of the gate strong, and that the current Extent and Volume numbers do not yet reflect the preconditioning that has occurred.  In addition, the current GFS forecast shows surface temperature for most of the Arctic Ocean above 0C from May 29 - June 3, combined with substantial areas of clear sky and what seems to be high amounts of precipitable water along the Atlantic front and north of Greenland (but I lack the historical perspective to interpret the precipitable water forecast).   

    I worship at the church of the long term linear trend, which has the 2012 volume record remaining intact for 2020 but then a ca. 50% chance of falling in 2021, and increasing each year thereafter.  For Extent, the trend estimate shows the 2012 record being safe for 5-10 years.  While it is far too early to say anything definitive about 2020, considering the recent conditioning, the current GFS forecast, that scary albedo graph posted by Sublime_Rime, and the Slater model forecast (which has been pretty accurate in recent years), 2020 seems to have a greater than 50% chance of going below the 2012 volume record.  The Extent record from 2012 was due to a freak event (the GAC) that is unlikely to be repeated in 2020, so is less likely to be surpassed.  But that is less important anyway, as I also worship at the church of Volume vs Extent with the Rev. Juan C. Garcia.

25
Arctic sea ice / Re: The 2020 melting season
« on: May 24, 2020, 03:07:34 AM »
       A while back Stephan calculated the R values for Volume and Extent at the end of each month to the following September minimum.  Accepting a few assumptions (that seem reasonable), squaring those values gives the R2, a measure of the percent of interannual variation that can be explained by knowing those values, and thus reducing the width of the confidence interval for estimating the subsequent September minimum.  https://forum.arctic-sea-ice.net/index.php/topic,2348.msg257955.html#msg257955

Improved Volume prediction accuracy as melt season observations become available. 
R-square reduction in variability derived from R values posted by Stephan at https://imgur.com/a/O82kzZZ

        Linear model estimate for 2020 September average Volume before any 2020 observations:  3.9M (1.2 – 6.6) km3, (95% of cases expected to fall within 1.2 – 6.6M km3, i.e  +/- 2.7M km3).
   
      With MARCH observation as predictor, confidence interval (CI) reduction for September average Volume estimate: 4%.  Width of 95% CI with March observation: +/- 2.6M km3.
      With APRIL Volume observation, confidence interval reduction: 7%.  Width of 95% CI with April observation: +/- 2.5M km3.
      With MAY Volume observation, confidence interval reduction: 32%.  Width of 95% CI with May observation: +/- 1.9M km3.

      With JUNE Volume observation, confidence interval reduction: 63%.  Width of 95% CI with June observation: +/- 1.0M km3.

      With JULY Volume observation, confidence interval reduction: 83%.  Width of 95% CI with July observation: +/- 0.5M km3.

      With AUGUST Volume observation, conf. interval reduction: 94%.  Width of 95% CI with August observation: +/- 0.2M km3.

-----------------------------
      Those values indicate that until we have the end of May, and really the end of June, volume observations, prior observations don't give us much foresight about the September volume minimum.  Which in turn suggests that melt season conditions (temperature, cloudiness, and storms) that take effect in June, July, and August are the primary determinants for the September volume minimum.  (Some of those conditions, such as melt pond formation, may have been established earlier, but do not manifest as changes in volume until after May 31).  Thus, about 68% of the variation in September minimum Volume becomes apparent after May 31 (100% minus 32% = 68%).

     The same approach for Extent shows the R2 at the end of March, April and May at insignificant level, only reaching 22% by the end of June, and 56% at the end of July.  Thus, changes that manifest in July and August account for 78% of the variation in September minimum Extent (100% minus 22% = 78%).   

      An expert analysis by Walt Meier and NSIDC concluded  “Plotting the de-trended maximum versus minimum extent (Figure 2) shows a near-random distribution.”  “The seasonal maximum extent and the September minimum extent are not correlated...“  "because summer weather conditions strongly shape the September minimum.”
     

Figure 2. This plot compares de-trended maximum extent (x-axis) with minimum extent (y-axis). The yearly values shown are calculated by subtracting the linear trend value for that year from the total extent.  Credit: W. Meier, NSIDC.  From “Maximum extent is not predictive of minimum extent” https://nsidc.org/arcticseaicenews/2020/03/

26
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: May 12, 2020, 12:29:07 AM »
Ahh yes, I had to revive this thread as it's one of my favorites.

BEHOLD!!

27
Arctic sea ice / Re: Latest PIOMAS update (May 2020)
« on: May 07, 2020, 09:07:15 PM »
The somewhat surprising ice thickness and volume distribution in the Arctic seas and high Arctic is the result of the very strong polar vortex this winter which maintained strong cyclonic winds over the polar region. Despite the strong polar vortex, which kept cold air pretty well bottled up through the NH winter, polar region temperatures averaged above normal. That's solid evidence of Arctic warming. It should have been colder than normal with this winter's Arctic oscillation pattern.

The normal summer weather pattern is for Fram ice export to decline so, although an increased percentage of thicker ice is in position for export, don't expect massive export. As has been the case for the past decade, the ice extent in September will be controlled primarily by the weather. Nothing looks exceptional to me at this time except for global oceanic heat content which is at a record high. That heat is taking take its toll on the ice over the decades, but there's no sign yet in the weather & climate models of anything exceptional this summer.

28
Arctic sea ice / Re: 2020 Melting Season Predictions
« on: April 29, 2020, 08:14:52 AM »
It's so funny that the longer that I have been here, and the more I know about the arctic, the less certainty I feel like I have in terms of overall projections (each year has a seemingly new facet/implication). That said, I don't think this year will beat 2012, but this is the year I'm really going to look if there are more systematic changes.

I define systematic changes as an anomalously warm Bering Sea in conjunction with Atlantification and increased bottom melt. Beyond that, the crack above Greenland is wild; there's a lot to be said about changing ocean currents, but my studies in grad school never got to that point.

Overall, I find it oddly strange it has been so clear in certain areas of the arctic for so long. I just don't recall it on WorldView being like that. I feel like the changing arctic is more cloudy. I don't think 2020 will break 2012, but if there are more signs of significant, more common patterns my interest will be piqued 

29
Arctic sea ice / Re: Arctic Image of the Day
« on: April 18, 2020, 12:23:30 AM »
The Polar Vortex Looks Happy...

30
Arctic sea ice / Re: The 2020 melting season
« on: April 17, 2020, 01:06:32 PM »

31
Arctic sea ice / Re: The 2020 melting season
« on: April 12, 2020, 02:06:47 PM »
More than 2°C yesterday in the laptev sea.

https://earth.nullschool.net/#2020/04/09/2100Z/wind/surface/level/overlay=temp/orthographic=-44.76,105.99,3000/loc=130.078,71.852
That is air temperature.
Yes, but it means heat is flowing the wrong way, earlier than it should be (no freezing).

It also means top melt of the covering snow pack, potential formation of sub-snow cover melt ponding, and a general reduction in albedo.

It all adds up.
That heat was actually very weirdly narrow and local. I guess that has to do with the mountains there and the Lena river valley that channels the wind?  If you go through the different heights on Nullschool on that day, a lot of that heat comes in on the 850 hPa level, and then weirdly appeared on the Laptev at the surface level.

https://earth.nullschool.net/#2020/04/09/2100Z/wind/isobaric/1000hPa/overlay=temp/orthographic=-44.76,105.99,1500/loc=130.078,71.852

32
Arctic sea ice / Re: The 2019/2020 freezing season
« on: March 13, 2020, 09:08:53 PM »
Do we dare to say BOE?

I'm going to go out on a limb and say no. A BOE would require extent to be ~4Msqkm below the new normal come September, which I don't see happening even if we have a brutal melt season. Variability caused by weather is usually on the order of <1Msqkm.
Attached is a graph of the JAXA Arctic Sea Ice Monthly Averages since 1979 and the deviations from the linear trend.

You will see that the maximum -ve departure from the trend was in 2012 at just over 1.5 million KM2. 2nd was 2007 with an anomaly of -1.2 million km2.

A BOE (using BOE defined as sea ice extent of 1 million km2) would require melting of about 3 million km2 below the trend value for 2020 of about 4 million Km2, double the previous maximum deviation.

Data is such a bummer

34
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: January 22, 2020, 05:06:03 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

January 21st, 2020:
     13,332,633 km2, an increase of 40,141 km2.
     2020 is 11th lowest on record.
     In the graph are the today's 15 lowest years.
     Highlighted the 4 years with September lowest min (2012, 2019, 2016, 2007) & 2020.

35
Arctic sea ice / Re: 365 day average extent poll
« on: January 19, 2020, 07:40:49 AM »
I'm going to call it - the majority of us, myself included, were probably wrong. I think there's too much ground to make up in the next two months with recent gains.

36
Arctic sea ice / Re: The 2019/2020 freezing season
« on: December 22, 2019, 01:00:39 PM »
Very readable overview of open ocean tides here:

http://oceanmotion.org/html/background/tides-ocean.htm

37
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 07, 2019, 12:50:22 AM »
Apologies for taking so long to reply... I'll spare you my usual excuses, though I don't doubt they would impress you with their earnest sincerity and momentous import of the ways I manage to waste time ...

   Here is the reasoning why I proposed that the last 1 meter of ASI from 1m average thickness would melt to 0m faster than from 2m to 1m average thickness:
    -- As we lose the older thicker MYI, the remaining ice has higher percentage of younger, and thus saltier and easier to melt FYI.  Everybody seems to agree on that.

e.g. As interstitial noted at
https://forum.arctic-sea-ice.net/index.php/topic,2709.msg201895.html#msg201895
       Thinner ice, presumably with higher portion of First year Ice...
"has pockets with high salt concentrations in it. Some of the pockets even most may not of frozen solid.
   ...When the temperature climbs above -21C the pockets of high salt concentration melt first. The temperature is still too low to melt the pure ice.
   ... This is how multiyear ice is formed each freeze and thaw cycle of salty water can more and more salts out until it is pure ice with no salts. That makes the multiyear ice fresher and more melt resistant."

   -- But here is the main reason - the Thorndike (1975?) chart showing the differential rate at which ice of different thicknesses increases thickness, that Chris Reynolds posted to explain the Slow Transition hypothesis.  To me it says that unless there is some hysteresis effect, then that curve in reverse shows that thin ice also melts MUCH faster for the same amount of heat input.  For a given amount of heating energy, e.g. melting degree days in summer, more ice is lost per unit of energy in summer by thin vs. thick ice, just as more ice is gained by thinner ice for the same amount of freezing degree days during the winter.

      Here is the Thorndike chart

(And you know its good because it is Neven's account icon!)

     Here is my reversed version, with zoom into the last 2 meters.


     Seems to me that the Thorndike chart, when reversed, shows the amount of ice lost for the same amount of heat added to ice of different thicknesses.  Just as the original chart shows the amount of ice gained for the same amount of heat lost from ice of different thicknesses. 

     Thus, I am using Chris Reynolds' Slow Transition evidence to reach an opposite conclusion.

     This is a simple case of Teslacle's Deviant ("What comes in, must go out") to Fudd's First Law of Opposition ("If you push something hard enough, it will fall over") -- for you Firesign Theatre fans.  Seriously though, as a thermodynamic equation, what works in one direction should work in the reverse unless there is some hysteric effect at work.  (e.g. Teslacle was right!  This could be Vulvaire's Correlate to Teslacle - "What went out, comes back in.")

     Another chart adapted from an ASIF post by Jim Hunt
https://forum.arctic-sea-ice.net/index.php/topic,2709.msg201631.html#msg201631
shows the same phenomenon. I didn't reverse this one, but you can do that in your head.

   
     The only argument against a quicker final meter melt notion is that the because the CAB is at higher latitude, the melting process will stall as the Arctic ice melt reaches the high latitude end game.  And I might buy that idea if humanity was intelligent enough to stop pumping greenhouse gases into the atmosphere at an increasing rate, but not seeing evidence that we will, one can only suppose that warming will continue, and in fact that the rate of warming is increasing.

     I admit that gerontocrat's open water chart (up thread at https://forum.arctic-sea-ice.net/index.php/topic,2348.msg235525.html#msg235525) requires a huge rate increase in CAB September open water to have a BOE anytime soon.

      But the cumulative evidence argues that that is indeed what will happen.  While gerontocrat's CAB volume trend chart shows it reaches zero a few years later (ca. 2040?) than the whole-Arctic Wipneus volume chart (2032), it is not that much later.  That suggests that the CAB does not have enough extra resistance against melt to combat the inexorable warming and Arctic amplification underway. 

   As Tor Bejnar noted at
https://forum.arctic-sea-ice.net/index.php/topic,933.msg113144.html#msg113144
"I have also long considered the 'quick' loss of summer ice in the non-CAB regions over the past 30 years (e.g., the Beaufort going, in August, from 2/5th coverage to none between 2013 and 2016) not to be predictive of how fast CAB ice will be lost.  I think this discussion of bathymetry adds some geophysical creds to Chris's theses.  This doesn't mean, however, that I'm 'now' convinced Chris is right.  I think other issues like CO2-equivalent, mobility and storminess (emphasis added GK) may well 'over' compensate for the bathymetry-related suppression of warm water currents remaining near the ocean surface."

     As Bruce noted at
https://forum.arctic-sea-ice.net/index.php/topic,778.msg32178.html#msg32178
"Chris, I don't see any reason for the rate of summer melt increase to flatline, slow down, or even be linear. As the ice thins, the surface/volume ratio increases, which should increase the rate of melt. The thick MYI held off major assaults in 2017 and 2012, but that ice is nearly gone. What we have now is this "mesh ice" that spreads out as the edges melt (which, though it is a negative feedback (because it keeps more of the ocean covered with ice), is a short-lived one). That spreading increases the surface (both top and bottom) that can melt."

    In a second instance of using Chris Reynolds' evidence to reach an opposite conclusion, I will reinterpret a chart he posted at at https://forum.arctic-sea-ice.net/index.php/topic,933.0.html


   Read his post to see how he uses that to argue for the slow transition.  To me it shows that  September ASI volume hits zero ca. 2027, even earlier than the Wipneus chart.

   As for the hiatus, I think we've beat that to death.  I'll just repeat that 10 yearly data points is simply not long enough to make statistically valid conclusions for data with high interannual variability.  I will go out on a limb and bet that the 2012 minimum volume record has a 50% chance of being replaced in 2020, likely won't last beyond September 2021, and almost certainly won't last  beyond Sept. 2022. 

    That said by the guy who expected the October slow refreeze to continue based on GFS forecast showing continued high Arctic temperature anomalies over the last 10 days, when just the opposite happened.  I guess I was confusing the tail and the dog - my new guess is that the air temp. anomalies were high because the water transitioning to ice was giving off heat to warm the air above it. 



38
Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 07, 2019, 07:59:52 AM »
Still trying to understand how the *warmest* August on record, according to awesome +70N 925hPa temps chart produced by Zack Labe, led to such a poor loss of ice extent. No convincing explanation so far....
I am convinced that we had normal melting conditions in 2019.

WTF? Normal melting conditions? With warmest August, 2nd warmes June and 3rd warmest July (and it was quite sunny for a good part of the summer as well)? How can you call that normal? Based on temps, ice should have crashed to nil, but it held up very well, so I have the same question as the original poster: i wonder why we did not lose more ice?

My answers are:
- the GAC of 2012 was truly a powerful and rare phenomenon and simple warm weather is not enough to repeat it
- the Central Pack is really hard to crack
- the Arctic is a mystery :)

39
Arctic sea ice / Re: The 2019 melting season
« on: September 16, 2019, 11:50:44 PM »
Over on the ASIB, I've just posted the late(st) PIOMAS update, and I just wanted to share the final half here, because it's how I view this melting season. Normally, I don't like it when people post long texts, but I'm the exception to that rule, of course.  ;)

Quote
Last month, I wrote at the end of the PIOMAS update:

Quote
From what I've seen on the Arctic Sea Ice Forum, written by commenters I've known for years and highly respect, my gut feeling says this year won't be able to break the 2012 records.

But for weeks now, I've been thinking of those prophetic words uttered by Peter Wadhams, back in 2007: 'In the end, it will just melt away quite suddenly.' I don't think all of it will melt away quite suddenly in coming weeks, but maybe more than one would expect just looking at the data.

This year is a great test that will tell us a lot about the importance of melting momentum.

To be honest, I expected a clearer melting momentum signal during this final phase of the melting season. Melting momentum took off slower than years like 2012 and 2016, but when it did take off, it was fireworks (see June 2019, one hell of a month). David Schröder's melt pond fraction maps, the SMOS pixel chart, the compactness charts, the Albedo-Warming Potential graphs, the snow cover graphs, more and more they were pointing to a massive build-up of melting momentum. On top of that, PIOMAS was showing that this year was very competitive volume-wise, and for five months in a row, 2019 was in the top 3 when it came to temperature records (August coming in lowest on record):



It was clear that the spell of extremely sunny, warm weather was ending during August. That, to me, was the great test for my melting momentum theory. Weather conditions switched, but for a week or so extent loss was keeping up with 2012's pace, despite the boost provided by the GAC. But then halfway through the month, things slowed down to a crawl after all (see red trend line):



So, what happened? Of course, there was a cyclone that was in a perfect position to disperse the ice, but there was so much weak ice that in my view, momentum should have gone on for a while longer.

There are two possibilities:

1) There wasn't as much melting momentum as I assumed.

2) Melting momentum is less important than I think it is.

As said, it took a while for melting momentum to get going. Timing is of the essence when it comes to breaking melting season records. May was actually very sunny this year, but most of the radiation coming from a Sun at a still low angle, got bounced off the pristine white ice. It may sound counterintuitive, but before the real melt ponding gets going due to open skies, cloudy weather is actually worse for the ice, because with clouds comes humidity and the clouds also block outgoing radiation. This can cause the snow on top of the ice to melt just a tiny bit, deforming the structure of the snow, making it more prone to melt when the sun starts to shine in earnest. 2019 came short in this respect, as evidenced by visual inspection of satellite images. Never mind the fact that the 2018/2019 freezing season was much less spectacular compared to the previous three winters, when it comes to temperatures and extreme weather conditions.

I'm still convinced that without a decent amount of melting momentum no records will be broken. That's why in years like 2016, 2017 and 2018 it was possible to announce at an early date that the 2012 record was safe. But conversely, a massive amount of melting momentum doesn't guarantee records either. Initial ice conditions and late stage weather obviously play important roles as well.

Maybe I'm emphasizing melting momentum too much, but I still feel kind of vindicated by recent developments on the extent front. Over the last week, just a small amount of weather conducive to melting has helped nudge 2019 below the 2007 and 2016 minimums, with quite an impressive run of daily drops. Tomorrow or the day after, the 4 million km2 mark could even be breached. I always thought that this year would come in second whatever would happen, and it looks like it has:



Either way, after almost 10 years of blogging, I'm now clearly seeing the contours of that first year when ice-free conditions will be reached (in other words, an ice cover smaller than 1 million km2, which amounts to ice-free for all practical purposes). It is preceded by a freezing season similar to that of 2015/2016, starts with the melt onset 2012 saw, builds up the massive melting momentum of 2019, and ends with the crazy weather of 2016. It makes me shudder to think what the satellite images will look like then. It may take more time than most cryospheric scientists think it will take, but unfortunately, that's not much of a comfort.

The ingredients are there, AGW is the cook.

40
Some background research on Laptev shoals from A-Team
Quote
Here is more on incredible parallel to ESS shoals but on the Laptev side of the NSI. A bit of land remains today (Yaya island, now 0.5 m above sea level). Weird to see ice/rock feature not far from islands with conventional hard rock islands. The other mystery is the length ... requires a chain of pingos. Note the 5 ESS shoals are kinda in a line which would fit with a fault line and methane pingos along it,

https://commons.wikimedia.org/wiki/File:Former_Vasilyevsky_Island,_New_Siberian_Islands,_Russia,_Sentinel-2_satellite_imagery,_2-SEP-_2016.png?

google translation from  the russian wiki:
https://ru.wikipedia.org/wiki/Васильевский_остров_(Новосибирские_острова)

"Vasilyevsky is a former island (currently Vasilyevsky Shoal, Vasilyevsky Bank) in the southwestern part of the Novosibirsk Islands (the extreme west of the Lyakhovsky Islands), in the eastern part of the Laptev Sea. Before it disappeared, it was one of the smallest islands in the archipelago. Shoal (or bank) was named after the island. To the northeast is the Semenovskaya Bank, to the east is Stolbovoy Island. In 2013, a new island (Yaya) was discovered in the area.

Since its discovery, Vasilievsky Island has rapidly declined in size, until it completely disappeared by the mid-1930s due to the melting of ice mixed with rocks. The shallowest depth in 1965 was 0.8 m. Then, the increase in shoal depths continued due to melting of icy inclusions in the rocks of the bottom, chemical processes and under the influence of sea waves."

Tass:

73.59'086 "N and 133.07'398" E. “It looks like a ridge of hummocks,” said Gukov. The results of the flight convinced the director of the reserve that "ice played a decisive role in the formation of the island, raking, like a bulldozer, in shallow sediment." “This is evidenced by the location of the hummocks,” Gukov said.

It was first noticed and mapped in 1814 by Yakut trappers who mined mammoth tusks in these places. According to the materials of the Hydrographic Expedition of the Arctic Ocean, in 1912 the length of Vasilievsky Island was  4.6 km in length, it had coasts 15-16 meters high. However, according to Gukov, even such a height of the coast did not save the island, and it was eventually washed out by the waves.

The new island is much smaller - about 150 by 150 m, and it rises above sea level by only half a meter. Vasilievsky Island belonged to the Lyakhovsky Islands archipelago, which, together with the Anjou and De Longa archipelago, are included in the large island association of the Novosibirsk Islands.

When first discovered, Vasilievsky Island was 7.4 km long and 0.5 km wide.

Semenovsky Island once joined it:

September 10, 1881 American expedition D.V. made a two-day stop De Longa, sailing after the death of her expeditionary ship "Jeannette" in the ice of the Laptev Sea to the mouth of the Lena River in three boats. In the diary of D.V. De Long recorded the island’s width of 1/8 mile and a height of 3 to 9 m and noted that the island was apparently being eroded. On the top of the hill dominating the island, he found the remains of deer horns and mammoth teeth.

August 19, 1912 icebreaker-transport  “Vaigach” anchored at a depth of 8.2 m at a distance of two miles from about. Vasilievsky.   Neupokoev noted that the islands of Semenovsky and Vasilievsky did not exceed 2.5 miles in length. He suggested that once instead of two islands there was one large island, which is confirmed by the presence of an extensive shallow extending to the east, northeast and southeast from the islands of Semenovsky and Vasilyevsky.

the Semenovsky and Vasilievsky islands consist of subsoil ice covered with a layer of silt and various kinds of tundra formations, two feet thick. The ice at the coastline is exposed and is rapidly being destroyed due to melting.

http://www.evgengusev.narod.ru/laptev/kluev-1981.html

example of coastal ice/dirt decay
Worldview, ESS-1S, clear day, 2000-2018

41
Arctic sea ice / Re: Latest PIOMAS update (August 2019)
« on: August 06, 2019, 03:42:08 PM »
That highly anomalous steepening of the volume curve in mid-August 2012 is best explained, in my opinion, by Ekman pumping of heat from the Atlantic water layer into the surface ocean. Normal storms can't do this because they don't persist long enough to break up the strong density inversions. The GAC lasted ten days and was very intense at its peak. It was strong and persistent enough to break down the layering in a large volume of the Arctic ocean.

The buoy profiles were stunning. Ekman pumping by persistent high pressure areas has caused multiple episodes of upwelling along the continental shelf in the Beaufort sea, but I'm not aware of any storm other than the GAC causing a upwelling of mid-ocean water in the central Arctic ocean. There was a very large amount of energy involved in the rapid melting of ice in mid-August 2012. Because there were not large amounts of heat advected by the atmosphere, it must have come from the ocean.

This melting season atmospheric heat advection may be larger than it was in 2012, but so far storms are not persisting like the GAC, so we should perhaps expect less bottom melt from ocean heat than took place in August 2012. However, sea surface temperatures in the Arctic are very high this summer so there is a lot of ocean heat in the upper layers. Moreover, strong atmospheric heat advection has been persisting in the Arctic for months. We are going to get a chance to compare the effects of different processes on the melt minimum by comparing 2012 and 2019. The sea ice volume curves are a most important aspect of that comparison because they are a function of system enthalpy (heat).

42
Arctic sea ice / Re: The 2019 melting season
« on: August 05, 2019, 03:56:58 PM »
This thread becomes interesting. Fewer people are discussing on the state of ice right now. The greenhand may think the melt rate slows down and it will not break the record at this rate. The storm is not strong and the CAB ice seems to be pretty healthy compared with previous year(2016 and 2012). All the things seem to be predictable until mid September.

For those experienced person, they are just watching. They know the ice is not healthy as MODIS have shown. The ice is compacted but full of tiny cracks and could be completely disintegrated if strong wind comes. The high SST is the potential ice killer. They know the strong wind will not disappear in the melting season but delay because the arctic is too warm to form. The strong wind and storm really need cold air to distablize the upper troposphere. Once the thin ice meets strong wind at the end of melt season they know what it will mean to the ice with high SST surroundings(Ekman pumping). They also know the melt season will not stop as early as 2016 does because the Arctic is record breaking warm. It has the potential to extend the melt season to the mid September even the late September.

All these thinkings cause fewer people wants to discuss in this thread.

43
Arctic sea ice / Re: The 2019 melting season
« on: August 04, 2019, 02:28:43 AM »
Some further info ...

https://forum.arctic-sea-ice.net/index.php/topic,2278.msg170187.html#msg170187
https://forum.arctic-sea-ice.net/index.php/topic,2278.msg170206.html#msg170206
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Yale Researchers Find Heat Held in Arctic Ocean Doubles in 30 Years
https://nationalpost.com/pmn/news-pmn/canada-news-pmn/yale-researchers-find-heat-held-in-arctic-ocean-doubles-in-30-years/amp
https://amp.livescience.com/63462-arctic-hidden-heat.html

Newly published research suggests the amount of heat stored in a vast section of the Arctic Ocean has doubled over the last 30 years, adding another blow to sea ice that helps regulate the planet’s climate.

“The most likely outcome for this heat is that it will slow the growth of winter sea ice, which further compromises the Arctic sea ice pack,” said Mary-Louise Timmermans of Yale University.

That ocean is composed of layers divided by both salinity and temperature. One of those layers, beginning at about 50 metres of depth, is both more saline and warmer than the surface waters.

The paper calculates that sea is now absorbing five times more solar energy than it did before.

That sun-warmed water has created what Timmermans calls “archived” heat in the Canada Basin.

“That layer of water is both increasing in temperature and also increasing in thickness. Overall, it’s increasing heat content.”

The warmth under the ice hasn't dipped or varied significantly since the 1980s, she added. It's just kept marching upward "like a staircase."

Although that water has only been warmed to a maximum temperature of about 0 C, the paper calculates there is currently enough new heat stored beneath the ocean surface to thin the ice cover of the entire basin by nearly a metre. It notes the amount of such “archived” heat will continue grow as the Chukchi loses more ice.

... The study shows that climate change doesn't only threaten the Arctic through the direct melting of ice along the northern ice cap's edges, Timmermans said. Instead, all the extra heat now present in our planet presents a long-term threat to the northern ice, independent of year-to-year shifts in weather patterns. Over time, she said, that heat will break through the insulating fresh water above it and eat away at the planet's remaining northern sea ice from within.

What’s happening in the Canada Basin is an example of how losing sea ice in one area can contribute to further sea ice losses in areas hundreds of kilometres away, the paper says.

44
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 29, 2019, 01:23:18 PM »
Not free. I followed your link, had to log in ( give information) and then directly request access to the paper. Haven't received it yet.

Here is the abstract of the paper:
Quote
During recent decades, there has been dramatic Arctic sea ice retreat. This has reduced the top‐of‐atmosphere albedo, adding more solar energy to the climate system. There is substantial uncertainty regarding how much ice retreat and associated solar heating will occur in the future. This is relevant to future climate projections, including the timescale for reaching global warming stabilization targets. Here we use satellite observations to estimate the amount of solar energy that would be added in the worst‐case scenario of a complete disappearance of Arctic sea ice throughout the sunlit part of the year. Assuming constant cloudiness, we calculate a global radiative heating of 0.71 W/m2 relative to the 1979 baseline state. This is equivalent to the effect of one trillion tons of CO2 emissions. These results suggest that the additional heating due to complete Arctic sea ice loss would hasten global warming by an estimated 25 years.

From here:

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL082914

... or just use Sci-Hub to find papers <cough>

Looking at it...  this is a self evidently ridiculous paper.  It's a simple albedo calculation, based on the complete absence of ice from March through to September.

From their methods:
Quote
In the calculations of albedo and radiative heating presented here, we use data from the National Aeronautics and Space Administration's CERES Terra SSF Edition 4 monthly averaged 1 × 1-degree product, between March 2000 and October 2016, available online (https://ceres.larc.nasa.gov/order_data.php). The Arctic Ocean is defined here as the land-free area poleward of 60◦N. Due to issues concerning polar night, we only consider the months of March to September of each year.

i.e. they account for extra incoming energy during an ice-free summer, but do not account for any extra outgoing energy during the winter.  This is effectively equivalent to assuming that the Arctic freezes over as normal each winter (i.e. insulating the surface and restricting heat loss) and then the ice magically disappears overnight some time in March.

It's completely unphysical and the only utility it has is giving a ballpark figure for HALF the energy equation resulting from an ice-free Arctic. Don't waste any time trying to interpret this one any further than that.

45
Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 04:08:00 AM »
Last of 3 posts (and a half dozen updates to fix glitches).
   Yearly average ratios across Extent-Area-Volume-Thickness
...and the winner (so far) is.... (but you already knew)

 
Observations/Speculation: 
   -- 2012 stands alone as the lowest overall with two 1st place and two 2nd place rankings among the four categories.
   -- 2019 is second to lowest, with two 1st, one 2nd, and one 3rd place rankings.  2019 would require a lot of catching up in Extent and Area in the remaining weeks of melt season to take 1st place away from 2012.
   -- 2016 and 2011 are close to each other for 3nd lowest overall ranking, followed by 2017 and 2010 in a virtual tie. 
   -- The sequential rankings of 2010 (#6), 2011 (#4), and 2012 (#1) suggest that the 2012 minimum record was the culmination of a three year sequence of predisposing bad melt years vs. being entirely due to conditions in 2012 alone.
   -- Volume rankings are closely correlated with Extent and Area.  Thickness rankings less so.
   -- Nine of the 10 lowest ranking years have been in the last decade (all except 2007 at #9). 

Definition of terms, caveats, top 20 rankings for each category, and a few other things in the full PDF. Including a still photo from great video of what ice looks like at the edge of the Extent line.
Figure 2.  Ice condition near edge of the Extent limit.  Photo taken at 75N, 150W on October 29, 2016.  Credit: “Waves propagating through Arctic sea ice.”  By IBWOvids. 





Lots of calcs involved and done in a hurry, so errors possible.  Corrections and suggestions appreciated.  Now that the spreadsheet is set up, occasional updates should be pretty easy if folks are interested.


46
Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 03:55:56 AM »
4 more screenshots - Area, Concentration (opposite of Dispersion), Volume, Thickness


 




47
Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 03:41:39 AM »
Screenshots from
"Arctic Sea Ice Score Card: Extent, Area, Concentration, Volume, & Thickness - 2019 vs. 2012"
17-page PDF at http://204.197.0.54/MEmodel/NSIDC-PIOMAS2012vs2019-July26.pdf
(but that server is misbehaving 7/27/2019, should be fixed by Monday).





2012vs2019 NSIDC concentration images

48
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 24, 2019, 06:37:52 PM »
Here's a link to a review article (an article that examines recent studies and summarizes them) published in the journal "Climate Change Reports" in December 2018. The article examines whether an ice-free Arctic leads to "tipping point" behavior and concludes that it doesn't.

https://link.springer.com/article/10.1007/s40641-018-0113-2

Actually, it doesn’t. The limitations of the study are bounded by the conditions it studied. These include limitations to a data set of only variably ice covered Arctic, linearity in response in that regime, and omission of other factors not studied that might cause non-linearities and tipping points. They did go beyond those bounds in projecting an ice free arctic from July to December at +4C. But that projection too must be taken in the context of the studies limitations. In other words, that is a lower bound. Feedbacks and inputs leading to nonlinear behavior were excluded.

Said differently, the study creates a linear model based on the observational period. Arguments beyond the observational period conditions are at best speculative. To use the model to argue that tipping point behavior won’t occur falls victim of a self referential error in logic of the type: “We made a model. The model only includes linear response. The model doesn’t predict nonlinear response. Therefore nonlinear response is not possible.” Gack! 

Sadly, this sort of error is common, as is the error of extrapolating beyond the bounds of the data set and trying to apply the data set to regimes where it may not and likely does not apply.

Sam

49
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 24, 2019, 03:05:54 PM »
I think that we could avoid a lot of unnecessary disputes over something many "somehow" agree, if we would invent (ADD) an additional term to our vocabulary:

We are now talking about "Blue Ocean Events" = BOE

I suggest to add the term "Seasonal Blue Ocean State" = either BOS or SBOS

what do other think about that, as mentioned i think by distinguishing single BOEs and
a general new state that will repeat each or almost each summer, many heated debates
could be avoided and at the same time we would be more precise for "noobs" about what is meant.

50
Arctic sea ice / Re: FireStorm in Siberia
« on: July 24, 2019, 08:40:24 AM »
The low was already predicted three days ago by ECMWF, see chart, weak low south of Kara. No way they predicted the fires, even I doubt they take into account all the physics needed to predict a fire-caused cyclone.
This is smoke caught by a normal atmospheric low. A lot of smoke yes, but it is not causing the low.

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