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Messages - Juan C. García

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1
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: Today at 12:38:12 AM »
JAXA ARCTIC EXTENT :-  9,728,067 km2(June 22, 2019)

- Extent is 5th lowest in the satellite record.
- Extent loss on this day 87 k, 13 k more than the average loss on this day of 74 k.
- Extent loss from maximum 4,543 k, 156 k (3.6 %) greater than the average of 4,387 k loss from maximum by this day,
- On average 44.4% of the melting season done, with 83 days to average date of minimum (13 September).

We are now entering the period of maximum daily extent loss that lasts until mid or late July.
Until the last 2 days, over the last 2 weeks and more extent loss has been below or well below average.

Will above average daily extent loss be sustained?
Will area loss follow suit and return to at least average daily loss levels?

Like many another, I have been wondering why extent losses have dropped so slowly.  I think much of the reason may lie in the Barentz Sea.  Two tongues of ice have been projecting into the Barentz for some time, as the ice pack rotated away from the Pacific side and towards the Atlantic side, an unusual move.  One tongue projects between Svalbard and FJL and one between FJL and SZ.

The initial reaction was that this ice had gone to 'oblivion', into the 'killing zone', and I too was of that opinion.  In fact the ice tongues have been remarkably persistent (see the first comparative NSIDC map below, comparing June 8 and 22 this year).  No doubt this is partly because new ice is entering the Barentz, but the Barentz waters are cooler this year, and I think this may be in large part because so much ice has melted into the Barentz, forming a cold freshwater layer at the top, at least in the region of the ice.  So there ice hangs around longer than expected in the Barentz, so extent declines more slowly (the Beaufort also plays its role, but others have mentioned that).

Comparisons with June 22, 2018 (second map) and with the silver-medal-holding 2016 show how unusual this situation is.  There is a LOT of ice in the Barentz.  Will the main ice pack melt as far back as in previous years, to the continental shelf to the N of FJL etc?  That might be a big determinant as to how low extent goes this year.   

2
Arctic sea ice / Re: The 2019 melting season
« on: June 23, 2019, 04:36:58 PM »
mercator(model) temperature 0m, pacific side, jun1-21 (not anomaly)

3
Arctic sea ice / Re: The 2019 melting season
« on: June 22, 2019, 05:26:54 PM »
Included is a 20 hour loop showing the impressive ridge.  As energy rotates around it, it will go through several anticyclonic wave breaks (evident already).  These often give numerical models difficulty.  As they "break" they generally result in a cyclone downstream, in this case the Beaufort/CAA region.   Again, very hard to predict, and should give anyone pause about buying model runs beyond hour 120, and temper expectations.  Just my two cents.  I'll go back to simple observations of interesting features.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=1&im=24&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_m08&x=13964.6669921875&y=16288.22265625

4
Arctic sea ice / Re: The 2019 melting season
« on: June 22, 2019, 05:09:09 PM »
The warmth on the Pacific side is extreme. And this warmth is pouring into Beaufort. Locally SSTs are up to 10 °C ! I like the smell of a water bath in the morning...

5
Arctic sea ice / Re: The 2019 melting season
« on: June 22, 2019, 04:30:06 PM »
In the light of all the recent weather predictions, for my own purposes I have to make sense of what actually happens as those predictions unfold.  So forgive me if the following seems redundant to some of you... it may not to seem so to less experienced people like myself. Lots of lacunae in my knowledge, happy to be corrected.

Images are from Worldview, unaltered.
1.  The low pressure system remains parked over Novya Zemlya and is forecast to continue to do so.  Ice will continue, presumably, to get dragged in an arc out of the Kara and towards the Barentz.
2.  For fun.  The bluest ice I can remember seeing on Worldview, fast ice in the northern Kara coast. Closeup below the first image.  I am guessing the ice here is melting like crazy and forming massive meltponds in the process.
3.  I presume this is the warm, humid ridge being drawn from Siberia by the joint action of the low on the right of picture and high on the left of picture.  Should be interesting to see how it develops and what it does.  If the clouds are telling the story, it looks like it is just in the process of forming over the Arctic ice.
4. High pressure area.  Lots of solar insolation over this summer solstice.

7
Arctic sea ice / Re: The 2019 melting season
« on: June 20, 2019, 07:03:24 AM »
The fire situation in Siberia is spiraling.
Spiraling rather literally in Alaska.

It will be somewhat uncomfortably interesting observing intensifying fires around the Arctic basin over the coming months. They don't seem currently worse than at the same date over recent years, though there's always the potential that they could only ever inevitably become much worse than they ever were.
2012 vs 2019:

8
Arctic sea ice / Re: The 2019 melting season
« on: June 20, 2019, 01:39:04 AM »
Ha, petm beat me to it.  ;)

Sea Ice Concentration, June 4 – June 18 (click to animate)

9
Arctic sea ice / Re: The 2019 melting season
« on: June 20, 2019, 01:33:55 AM »
Bremen NIC, last 4 weeks, cropped (https://seaice.uni-bremen.de/databrowser/).
5-day trailing median.

Click to animate (2.6 MB file size).

10
VOLUME:- We are told (and logic supports this) that as volume declines PIOMAS volume calculations get more prone to error - the freeboard amount, grid element by grid element, that is translated into thickness  becomes very small. This is then multiplied by a factor of around 10(?) to get the thickness of each element. The sensors have their limits.
(Warning: Layman's unverified explanation) Note that PIOMAS is not based on freeboard measurements by satellite sensors. PIOMAS is based on calculations of energy transfer (temps, winds, insolation, bottom melt) and ice movement. It's a model, not a measurement, although it is calibrated by NSIDC ice concentration data - when area disappears, so does part of the volume. PIOMAS model results have been compared to other ice thickness sources, and performed relatively well.

12
Arctic sea ice / Re: The 2019 melting season
« on: June 18, 2019, 04:51:23 AM »
Interesting fast ice destruction by what looks like river runoff on the ESS.

13
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: June 14, 2019, 08:39:32 AM »
NSIDC NT extent and area within the Arctic Basin (where most of the ice to survive the 2019 summer is now) graphs.

Extent is in nowhere land while area is nosediving about a nose ahead of the nosediving pack.

14
Arctic sea ice / Re: The 2019 melting season
« on: June 14, 2019, 12:54:59 AM »
I agree with the fact that we should not put too much emphasis in one season's melt. As others have indicated, what we are experiencing now has to be considered in light of the larger trend - the slow moving disaster of vanishing sea ice as evidenced by Brian Brettschneider's 100 year North American temperature change plot, where we can see how the Beaufort has shifted from an ice nursery into graveyard and how a melting of Greenland has created a vast cold pool.

15
Arctic sea ice / Re: The 2019 melting season
« on: June 13, 2019, 10:35:53 AM »
Click on the .gif to see an SMOS (satellite microwave measurements) map comparison for the 12 June on 2010 through this year, which is all the years in the database.

I find it easiest just to eyeball and compare the sizes of the beige area for each year, which tends to represent ice without a noticeable layer of surface water.

The size of this year's beige area is seen to be still 'within the pack' - with 2012, the year that still holds the record for lowest extent at the end of the melt season - standing out as having much less beige area than all the other years on this date, 12 June.

How much was that a coincidence for 2012; how much was it causal?  :P

16
Arctic sea ice / Re: The 2019 melting season
« on: June 12, 2019, 08:35:20 AM »
The ESS joining the Laptev, with "melt-pond blue" intensifying and spreading away from the coast in the past 3 days, and temperatures in Pevek hitting 18Co and expected to remain this abnormally high in the next few days, with southerly winds blowing offshore, and clear skies.
Click to animate.

17
    I just read about yet another feedback mechanism I was not previously aware of:
      ' Freshly melted ice ... creates a layer of cold water that protects sea ice above from more melting.   "It isolates the ice from the hot devil water sitting at the bottom waiting to come up" Wagner explains.  Less sea ice means there will be less of that protective cold layer, leading to even more melting. '
https://www.cnn.com/2019/06/08/world/arctic-beneath-ice-intl/index.html

     Which got me thinking it would be useful to have an inventory of all the significant reinforcing ("positive") and suppressive ("negative") feedbacks that affect Arctic sea ice.

    I did not find any forum title where this would fit, but this section seems to be the most closely related topic.  It could require its own thread, similar to the Glossary.

Here is the kind of list I have in mind:

Reinforcing feedbacks:
1. Melted ice creates cold layer that insulates remaining ice from warmer subsurface water.  Less ice to melt reduces this insulating layer.  Which leads to even less insulating cold layer water.

2. Less ice leaves darker ocean water with lower albedo, thus energy from solar radiation is absorbed into water instead of reflected.  Warmer water leads to less ice.

3.  Overall, fractured ice is more mobile and thus more susceptible to being exported via Fram Strait or Nares Strait.  There is chance of an ice bridge to block export via Nares Strait with fractured, reduced ice cover.  Increased export results in less multi-year thick ice, and more mobile young ice the next year.

4.  Fractured or thin sea ice floes have more surface area per unit volume and therefore melt at lower temperatures than thicker ice, or larger ice floes.  This leads to less surviving ice the summer to become thicker multi-year ice.

5.  Fractured vs. contiguous ice allows more wave action that interferes with freezing of ice and allows wave action to break ice into smaller pieces less resistant to melt.  Resulting in more fracturing of the remaining ice and even more wave action.

6.  Albedo reduction by replacing ice with dark water leads to warmer water and more energy in the Arctic Ocean system.  That in turn increases frequency, intensity, or both, of cyclones causing wave action that break up ice. Which reduces albedo even further.

7.  Weakening of the Polar Cell results in more frequent occurrence of Arctic Dipole, that increases export of ice out of the Arctic, which lowers Arctic sea ice, which leads to warm Arctic Ocean water, which leads to further weakening of the Polar Cell.  (whew, that's a long chain)

8.  Loss of ice cover weakens the polar cell which in turn allows more incursion of of warm moist air masses from the south into the Arctic, which leads to more weakening of the polar cell.

9.  Weakening of the polar cell allows more cyclonic systems to move into the Arctic.  Those cyclones disrupt the Arctic sea ice, and in doing so further weaken the polar cell.

10.  Younger, thinner ice has higher salt content and thus lower melt temperature.  Therefore it has less chance of surviving the summer melt to become more resistant, thicker multi-year ice.

11.  Reduced snow cover allows earlier spring warm up of Arctic land mass, which results in warmer air flowing onto the Arctic Ocean. This warms the system as a whole, leading to reduced snow cover and earlier snow loss the following year. 

12.  More open ocean leads to higher humidity and more extensive or thicker cloud cover over the Arctic Ocean in the fall and winter.  More extensive or thicker cloud cover in fall and winter reduces heat loss thus reduces winter refreezing.

13.  Earlier spring warm up of Arctic land mass, results in increased permafrost and land ice thaw, resulting in earlier and more melt water flowing from land into the Arctic Ocean. The meltwater warms the Arctic Ocean and reduces Arctic sea ice.  Which leads to more open water with lower albedo to absorb solar radiation in the summer, increasing summer heat content of the system  More open water allows this heat to escape to moderate winter air temperatures and earlier spring warm up.

14.  Reduction of Arctic sea ice allows increased flow of warmer Pacific or Atlantic water into the Arctic, leading to further decline of Arctic sea ice, leading to more Pacification and Atlantification of the Arctic Ocean.

***
Compensatory or Suppressive feedbacks:
1.  Ice cover insulates the Arctic Ocean in winter.  With less sea ice cover there is faster energy loss and winter cooling, and thus faster winter ice increase after a lower September minimum extent.

2.  Thin ice grows much faster than thick ice.  Thus faster winter ice increase compensates for thinner ice after a strong melt season. 

3.  More open ocean leads to higher humidity and more extensive or thicker cloud cover over the Arctic Ocean in the summer.  More extensive or thicker cloud cover in summer reflects more solar radiation and thus reduces summer ice melt.

*****************************

     My wording is no doubt less than perfect for many of these.  Some may be just plain wrong.  Some I just made up!  Maybe I should just find a good book or review article with such a list.  Any suggestions?

   If you think a proposed feedback is incorrect or wrongly stated, it would helpful to have that noted.  But I'm not looking to start multiple debates about which feedbacks are most important. 

      I don't get a commission for each new proposed feedback, so there's no need to get heated.  The planet is hot enough as it is.  These are just suggested entries.  There must be suppressive feedbacks missing from the list.

   I just thought a list would be interesting because I keep finding out about feedbacks I had not previously been aware of. 





18
Arctic sea ice / Re: The 2019 melting season
« on: June 08, 2019, 09:50:11 PM »
Good explanation of the Arctic Dipole and its interaction with Arctic Sea Ice
https://en.wikipedia.org/wiki/Arctic_dipole_anomaly

Jeff Masters - Weather Underground - the early June Arctic forecast and prospects for summer
https://www.wunderground.com/cat6/Strong-Arctic-High-Pressure-System-Bringing-Significant-Melting-Sea-Ice

19
NASA WorldView doesn't have timestamps. Neither does Sentinel Playground. Only the day and it could be taken anytime during this day.

Sites with timestamps:

Rammb Slider: http://rammb-slider.cira.colostate.edu/.

PolarView: https://www.polarview.aq/antarctic

GINA Puffin Feeder: http://feeder.gina.alaska.edu

20
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: June 07, 2019, 06:49:37 AM »
Hey all,

Zach Labe posted a graph of CAB sea ice extent that I thought looked great. I know such is already posted here by someone(s), but it's a nice graph. I inquired about updating and access so he added it to his page of graphs, says he will update a couple times a week.

Thought maybe Neven might like to use it on the graphs page...?

https://sites.uci.edu/zlabe/arctic-sea-ice-extentconcentration/

Cheers

I really like Zach's graphs, the visuals are astounding. But I'm a bit confused by the topmost graph on the site. It seems to me that the colours are wrong with regard to the green, white and brown lines, at least when comparing them with the Jaxa extent graph showing the same years.

The colours seem about right until the crossovers in july, where it seems that they have been switched: 2012 goes from white to brown, 2016 goes from green to white and 2007 seems to not only switch colours from brown to green, but also to shift years ...

Or am I missing something totally obvious? It wouldn't be the first time!

21
Arctic sea ice / Re: The 2019 melting season
« on: June 07, 2019, 04:42:40 AM »
Thanks pccp82. 
My bad.  The image I had in mind was August 6, 2012.

I guess at that point we were discussing the Great Arctic Cyclone of 2012, and I confused that with the great GIS melt day of July 11, 2012.


Looking at that same view for dates on either side of either event, or July-Aug dates in other years, gives some perspective for how out of bounds both events were.   For example the July 21, 2018 image seems to be typical for recent dates in July-August:     

Trying to save face, I went looking for the average 2meter max temp. forecast for Greenland over the next 3, 5 and 10 days https://climatereanalyzer.org/wx/fcst_outlook/, but those are now not showing anywhere near the extent of GIS surface melt shown in the 2012 images.  Update-as of June 9, GFS forecast on Climate Reanalyer shows majority of GIS above freezing on June 13, not too far behind extensive and record breaking surface melt events on July 11 and August 6, 2012.

    While the updated hourly forecasts have no shortage of positive 2M temp anomalies for Greenland over the next 10 days, the max temp hourly forecast also indicates that the area of GIS surface melt next week won't be anywhere close to the July 11 and August 6, 2012 images.  So either I just blew it with respect to Greenland surface melt coming next week, or the 10-day outlook changed.    ***My mistake in previous post was misunderstanding that the 10-day Greenland surface temp reading was not the average for a 10-day period, but the average of hourly values for the 10th day, i.e. a single day reading not a 10-day average.  As noted above, updated forecast shows that June 13 (which was the 10th day noted in original post) is forecast to have an extent of surface melt similar to record-setting events in 2012.

    That said, the current hourly forecasts still shows the high precipitable water, the persistent crazy high temp. anomalies stretching across long arc of northern Siberia, and for much of the forecast period, also on the North American side.  The forecast shows snow cover depth north of Greenland essentially gone by June 10 2019 (scale is cm).



vs. June 10 in 2018. 


It took until June 22, 2018 for snow depth image to match the June 10, 2019 forecast.  While that does not seem like a cataclysmic difference to my untrained eye, a 12 day earlier loss of snow cover with the sun at near maximum height, combined with many blue sky hours also in the forecast, does seem notable in terms of insolation.   

Enough covering my tracks.  What I definitely did get right and did not exaggerate was an Arctic weather expert ringing the alarm bell about the forecast as it appeared at that time, and the Arctic sea ice situation overall.  Vote climate.
 

22
Arctic sea ice / Re: Latest PIOMAS update (June 2019)
« on: June 05, 2019, 08:45:45 AM »
The volume and volume-anomaly graphs.

23
Consequences / Re: Worst consequence of AGW
« on: June 04, 2019, 07:39:37 PM »
  Do you think they actually have any idea what they are "protesting" or do they want to skip school? Greta Thurnberg is a tool being used by her celebrity mother to further her own image. Greta is a dolt (sorry, it's true).

You can rant and rave about "Climate change will do XYZ!" but unfortunately none of the aforementioned individuals have a basic grasp on impending changes, or anywhere near the knowledge of even the entry-level posters of this forum. 

I think you're short-changing Greta and the XR movement.  They've brought the issue of climate change to public attention more assertively than anyone since Al Gore's An Inconvenient Truth.  I think Thurnberg is a more credible and effective spokesperson than Gore, in fact.

Gore is no climate scientist either.  But what credentialled expert has had comparable impact on public awareness?

Public protests and civil disobedience are central to effecting social change.  They are, I believe, the most effective tools.

24
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: June 04, 2019, 07:46:26 AM »
Juan, I know we all appreciate how reliable you are! And I cannot replicate your graphs or tables, so will always delete if you post later.

25
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: June 04, 2019, 06:55:50 AM »
In case Juan can't make it tonight (JAXA was very late in posting):

[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

June 3rd, 2019:
     10,558,744 km2, a drop of -34,927 km2.
     2019 is 2nd lowest on record.

26
Arctic sea ice / Re: The 2019 melting season
« on: May 31, 2019, 11:55:38 PM »
ECMWF forecast shows a continuation of that huge high pressure area for at least three more days, but then things get more interesting with lows trying to butt in. I expect steady losses to continue, but we'll have to wait and see how much momentum is being built up right now. Hopefully, PIOMAS can tell us some more, and I also hope that Dr David Schroeder will be willing to share data again.

27
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: May 31, 2019, 04:04:02 PM »
How we already know 2019 will be a big melt year for Greenland


28
Arctic sea ice / Re: Global sea ice area and extent data
« on: May 31, 2019, 02:43:41 PM »
NSIDC NT global sea ice area and extent both now  4 sigma below the 1981-2010 normal.

'long' graphs => you must click.

29
Arctic sea ice / Re: The 2019 melting season
« on: May 31, 2019, 07:29:38 AM »
May, monthly mean temperatures (karstenhaustein.com).


60-90N       : + 1.848
66-90N       : + 2.046
Greenland    : + 2.715
Arctic Ocean : + 1.601

30
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: May 29, 2019, 12:47:34 PM »
Of course, Be Cause!  8)

This is a GIF showing the Kane Basin. Franklin Island upper left.

Timeframe shown: 17.05. ~14:00h UTC to 29.05. ~15:30h UTC

Notice how the surface current after Franklin is dominant only on the right side (if you go downstream) of the Strait. A standing wave in Kane Basin exports floes very quickly but only in a narrow band. The movement of floes in the rest of the basin is mainly caused by tidal waves, not the downstream current. The big floes dancing around there is fast ice originating here in the Kane Basin. Only if they somehow manage to make it fully into the narrow standing wave they will be sucked down into the Baffin Bay.

Nothing has slowed down export wise as i see it.



31
Arctic sea ice / Re: The 2019 melting season
« on: May 28, 2019, 11:04:38 PM »
The ICESat2 data is now available!

It is indeed: https://nsidc.org/data/icesat-2/products/level-3b

As far as I can tell the nearest thing to what we are after is the level 3B Gridded Monthly Sea Ice Freeboard (ATL20). However a quick scan of the site has yet to reveal a product that converts those numbers into sea ice thickness.

32
Arctic sea ice / Re: The 2019 melting season
« on: May 28, 2019, 10:11:56 PM »
The ICESat2 data is now available!

I have no idea how to get it or how to use it, but it could make this melt season very interesting if it turns out to be user friendly. 

I can't get the links to Twitter to work from my phone, but it should be pretty easy to locate with a search. 

33
Nothing to see here! Move along!


34
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 28, 2019, 03:05:17 PM »
Update of the NSIDC NT sea ice extent and area graphs for the Arctic Basin only (with the understanding that most of the ice to survive the 2019 summer melt will be found there).

Very close to 2016 in the contest for lowest values for the day of year.

35
Arctic sea ice / Re: Global sea ice area and extent data
« on: May 24, 2019, 11:17:48 AM »
Two more days and everything will be back to normal again.

Right?

36
Permafrost / Re: Permafrost general science thread
« on: May 23, 2019, 01:59:44 PM »
Widespread Permafrost Degradation Seen In High Arctic Terrain
https://phys.org/news/2019-05-widespread-permafrost-degradation-high-arctic.html

A McGill-led study published recently in Environmental Research Letters presents close to 30 years of aerial surveys and extensive ground mapping of the Eureka Sound Lowlands area of Ellesmere and Axel Heiberg Islands located at approximately 80 °N. The research focuses on a particular landform (known as a retrogressive thaw slump) that develops as the ice within the permafrost melts and the land slips down in a horseshoe-shaped feature. The presence of these landforms is well documented in the low Arctic.

... "Our study suggests that the warming climate in the high Arctic, and more specifically the increases in summer air temperatures that we have seen in recent years, are initiating widespread changes in the landscape," says Melissa Ward Jones, the study's lead author and a Ph.D. candidate in McGill's Department of Geography.



The research team noted that:

- There has been a widespread development of retrogressive thaw slumps in high Arctic polar deserts over a short period, particularly during the unusually warm summers of 2011, 2012 and 2015;

- That the absence of vegetation and layers of organic soil in these polar deserts make permafrost in the area particularly vulnerable to increases in summer air temperatures;

- Despite its relatively short duration, the thaw season (which lasts for just 3-6 weeks a year) initially drives the development of slumps and their later expansion in size, as their headwall retreats; and

- Over a period of a few years after the initiation of slumps, study results suggest various factors related to terrain (e.g. slope) become more important than air temperature in maintaining active slumps


Open Access: Melissa K Ward Jones et al, Rapid initialization of retrogressive thaw slumps in the Canadian high Arctic and their response to climate and terrain factors, Environmental Research Letters (2019)

38
Arctic sea ice / Re: The 2019 melting season
« on: May 22, 2019, 05:01:26 AM »
May 17-21.

39
Arctic sea ice / Re: The 2019 melting season
« on: May 22, 2019, 03:59:51 AM »
Quote
be cause: can only guestimate area that heads out of the basin but it is a lot
Right. Wind-driven ice motion has been extraordinary this freeze/melt season. By translocating thicker, older ice into zones that will melt out later in the summer, or exporting ice altogether out of the basin via the Fram, Nares and Svalbard-FJL chain plus blocking Kara Sea ice on the import side, wind-driven ice motion may challenge conventional bottom and top melt this year as the leading ice volume loss mechanism.

The first image below shows  on mid-basin Atlantic-side feature drift (boundary between old and new ice) over the the last 195 days using twenty-day contours.

A similar area of ice ahead of the front has been (or will be if wind patterns keeps up) irreversibly displaced out of the basin. This area can be measured, not adjusting for compression or extension, by lifting geo-referenced Ascat images onto Google Earth Pro for its ellipsoidal (WGS84) area and length calculations (2nd image shows the 7.109 million sq km polygon of relevant Arctic Ocean.

Wx predictions are the proverbial drunk looking for her car keys under the street lamp because the light is better there -- winds thousands of meters above the ice are easier to predict than the 0m winds, yet only the latter actually move the ice pack (by coupling to pressure ridges and floe edges rather than flat pan).

You can see this on any given day by comparing ice motion vectors observed by OSISAF/NSIDC to winds GFS or ECMWF are showing, before or after reanalysis (3rd image). Surface currents are negligible (or as oceanographer R Woodward notes, induced by ice keels) outside the intake funnels of the Nares and Fram and inconsistent Bering Strait flows to/from the Chukchi. Note the ice pack has a certain amount of mechanical rigidity, leading to cohesive motion despite a heterogeneous stress field.

The Arctic Ocean is seriously 'under-instrumented', meaning models have never had sufficient calibration or feedback guidance. On the rare instances an instrumented ship has been out there in May (eg N-ICE spring 2015), measurements departed markedly even from nearby land stations like Ny-Ålesund. However nobody ever fixed a weather model or reanalysis based on a basin instrument account.

Help is in sight (with a 2-3 year delay?): this Sept, AWI's Polarstern will drift for a full year on a thick Siberian-side floe (lol !) to collect "direct in-situ observations of the climate processes that couple the atmosphere, ocean, sea ice, bio-geochemistry and ecosystem ... to enhance understanding of the regional and global consequences of Arctic climate change and sea-ice loss and improve weather and climate predictions. https://www.mosaic-expedition.org

This won't be meagre point weather and ice properties because they are going out to a 50 km swath radius on both sides of the drift track. The 4th image shows a hypothetic drift trajectory. They'd have been home early this year whereas in 2017/18 the ship would hardly have moved in the hoped-for direction:

233 days of anti-transpolar drift 2017-2018.mp4
https://forum.arctic-sea-ice.net/index.php/topic,2278.msg155398.html#msg155398

The Oden made a remarkable observation of open water at the north pole on 25 Aug 18, photographing a walrus there, messing with a research sled. Ask yourself how much open water there had to be regionally for a walrus to swim to the NP on that date and when it last ate: the water is 4,087 m deep whereas the deepest walrus dive ever recorded is 500m.

This and a few little things like ice thickness went seriously under-reported (except by Jim Hunt and twitter). This has really got to change -- scientists chewing on their cud for years (buffing their journal articles) while leaving everyone else in the dark.

I had an identical experience trying to get even the most mundane CTD casts from the Polarstern when by great good fortune they were able to reach the Weddell Sea during that unprecedented reversal of the Fram in Feb 18 attributed to a sudden stratospheric warming. A cr*ppy article by another research group ensued who also couldn't get the data. Where is the public benefit in  hoarding?

40
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 21, 2019, 02:12:00 PM »
NSIDC NT sea ice extent and area in the Arctic Basin (where most of the last summer ice will be) continue to drop fast.

41
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 19, 2019, 05:47:08 AM »
May 18th, 2019:
     11,374,861 km2, a drop of -46,238 km2.
     2019 is 2nd lowest on record.

42
Arctic sea ice / Re: The 2019 melting season
« on: May 18, 2019, 12:01:27 PM »
There is max temperature in the last image.
A quibble...

I think I am right in saying that the GFS maximum (and minimum) temperature images are a bit deceiving, in that even if the forecast is 100% correct, there will not be a date/time when the image is a reality.

For the 5 day image shown, I think the image shows the maximum temperature for each element of the grid over the next 5 days. So one place might be at maximum today, another in 3 days time, and so on.  You can tell this from the image. Alaska cannot be at maximum temperature at the same time as Norway - if Alaska is basking in the late afternoon sun, Norway is freezing in the early early hours before dawn.

Thus the maximum image exaggerates the heat, the minimum image exaggerates the cold.

Mind you, it still looks like the Central Arctic sea ice is on the move and in serious grief..

43
Arctic sea ice / Re: The 2019 melting season
« on: May 17, 2019, 11:47:49 AM »
60 hour loop of the Beaufort. May 14 12Z  - May 17 0Z.
 (Requires a click)

Second attachment is the ECMWF forecast. The tight pressure gradient north of Alaska is progged to persist another 5 days or so, resulting in 20-30 knot easterly winds.

44
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 17, 2019, 09:23:59 AM »


At the moment still little reason to suppose sea ice loss will accelerate further.

So..just in the interest of keeping it fresh...what variables are you taking into consideration when you suggest that there is no reason to suppose sea ice loss will accelerate?

For clarification, I'm grateful for the effort that people like you put into providing the data that you do. Thank you!!

But I'm also coming from a perspective that we're heading for an inevitable BOE / climate apocalypse in coming decades and that most people here are just here to witness that and share the experience.

There's a balance of people who are seeing the potential for short-term demise and those like yourself who are saying...not yet.

Anyway ..I'm curious to know what variables you consider when there are differences of opinion. I sincerely want to learn.
My statement referred to current forecast period of around 10 days simply from looking at fairly low +ve temperature anomalies and current fairly strong extent loss. i think it is far too early to look at the end of season minimum with any confidence at all. Others disagree.

Thanks for the reply. As someone trying to learn, each piece helps. My inference is that you see atmospheric temperature as the dominant variable.

It would be interest to get some kind of sense of how people rank the various variables.

As a newbie, I would guess water temperature is at least up there with atmospheric temperature . Sunlight has been pointed out. The spin which brings ice to Fram seems important. Nares being open with a steady throughput. Wind. The thickness of the ice. The level of surface fracturing.

Thanks for your patience. I'm just trying to get oriented. Asking questions helps.

45
Consequences / Re: Places becoming less livable
« on: May 16, 2019, 10:04:06 PM »
The sargassum problem is way bigger than just Mexican beaches. It affects wide areas of the caribbean. I saw the problem first hand last year, and it was astonishing to see nature's capacity for disruption.

For anyone interested this website is a great resource for tracking sargassum blooms:

http://seas-forecast.com/

46
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 16, 2019, 06:31:54 AM »
Bimonthly BOE evaluation

May 15 extent was 11,568,100 km^2. With on average 121 days to go until the end of the melt season on September 13th, we now require a daily drop of -87,323 km^2 for a BOE to occur. (See Attachment 1).

There have been many days of below average melt, and several days of above average melt. Total extent loss thus far in May is -739,276 km^2. And total extent loss so far this season is -2,705,021 km^2. This has resulted in the current average daily drop of -42,266 km^2. If the month of May ended today, this would the 3rd fastest daily loss from maximum to the end of May (behind 2010 at a whopping -57,318 km^2 per day, and 2014 at -42,541 km^2 per day). (See Attachment 2).

Looking only at the month of May (so far), we have averaged -49,285 km^2 per day. This average daily drop places May 2019 as 8th out of 13 (2007-2019) in average daily May melt (See Attachment 3).
Although we still have 16 days to go this month, and many of the ASIF gods are becoming worried about the high pressure setup forecast by GFS.

No 2nd post for mid monthlies, don't have the data calculated and I am traveling so even this post was unexpected for me.

Edit: was tired and missed 2,000 km^2 so the averages will be slightly lower. My mistake.

47
Arctic sea ice / Re: The 2019 melting season
« on: May 15, 2019, 11:18:30 PM »
I have some analysis - nothing too spectacular - at the end of PIOMAS May 2019 that I've just posted on the ASIB. Two images below from that blog post, ECMWF weather forecast and Beaufort yesterday vs a week later in 2016:

48
Arctic sea ice / Re: Latest PIOMAS update (May 2019)
« on: May 15, 2019, 11:14:52 PM »
PIOMAS May 2019 is up on the ASIB. If there's a mid-month update form the PSC today or tomorrow, I'll append it to the blog post.

49
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: May 14, 2019, 08:52:40 PM »
@Tor - Thanks!  We will see.



  Consequently, he is hesitant to make any new ice-free projections.

He's hesitant to make any specific ice-free projections, but he does think that it will be sooner than 2030.

No, he never said that.  Only that it might.

Well, if you start from right here in the video - https://youtu.be/yoy4U7MGIdo?t=1103

Here's some of the dialogue -

Wiselaw:
"There are some publications now, peer-reviewed publications which are using the global climate and Earth system models and, uh, hand picked some of them for their better representation of the Arctic ice area and they provided the estimate of ice disappearance roughly between 2030 and 2040."

Guy:
"And what do you think about that?"

Wiselaw:
"I would still think that it might happen sooner than that but I would hesitate to provide a specific date basically because the system is so complex and so nonlinear."


¯\_(ツ)_/¯


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