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Messages - jdallen

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Arctic sea ice / Re: The 2020/2021 freezing season
« on: January 20, 2021, 11:13:52 AM »
So basically we have thicker ice on the Pacific side and thinner ice on the Atlantic side this year compared to last.  Overall, there does not appear to be a big difference.

Overall, the damage to the refreeze has already been done.  We are now one month past the solstice, and the energy budget is rapidly moving away from building thick ice.

I am doubtful the peripheral seas will see much at all in the way of significant ice building.  The thickness numbers for the CAB and adjacent seas are sickening to look at. It is hard to imagine large stretches of the CAB being able to make it past 3M thickness.  If the polar vortex continues to be disrupted, we might be lucky to make it much past 2.5m for much of the pack.

I'm feeling rather pessimistic.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: January 04, 2021, 01:01:33 AM »
...whoi itp120
That temperature profile is very, very strange, and quite disturbing.  Upwelling or intrusion from elsewhere, but strange, if not local, that a layer like that would slide along just under the top 25m of cold near-surface water.

The implied availability of local heat is significant.

Arctic sea ice / Re: MOSAiC news
« on: December 06, 2020, 06:21:48 AM »
<lots of snippage>

The following drawbacks should be noted:

-4 -The new product does not provides ocean current, temperature or salinity.
-5- The Canadian Archipelago, Baffin Bay and Hudson Bay are not modeled.
-6- Sea ice thickness and sea ice drift observations are not assimilated (as with Hycom) leading to understated summer Fram Strait export.
-7- There is no reanalysis product for 1993–2019 despite coverage by this product
[-8- Wave interaction with the MIZ is not included though written up separate preprint]
That's a lot of limitations.  I hope they can do some reanalysis with the '93-'19 data.  That would be pretty critical to understanding the limitations of the model, and help assess its accuracy and utility.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 19, 2020, 07:03:13 AM »
what a retreat on the kara sea!

I think we are going to see that as long as the hurricane season continue spawning storms.  After they break up, they still carry a huge amount of energy which consistently is being thrust north along the NAM eastern seaboard to blow into the Barents and Kara, with the last remnants being spun into the central basin proper.

This is the same rough pattern that first evolved in 2016 and has to a greater or lesser degree been continuing the last 4 years, and suggests a possible new weather regime.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 15, 2020, 11:03:50 PM »
Today's a warm day on the Atlantic Front
This has been a consistent pattern since the start of the refreeze.  It's been book-ended by cold air being flushed out of the Arctic, breaking south across the Canadian shield into the US great plains.

Here's the September anomaly map from Climate Reanalyzer.  I'll be interested to see Octobers when it turns up, and Nov. after that to see if my hunch is borne out.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 12, 2020, 08:18:51 AM »
       +2.7C per decade is Monstrous.
Going out on the limb of my ignorance, I'll hazard a guess that for the near term at least, the recent above-average increases in Extent and Area could lose some momentum.  If that DMI anomaly does not fall, it is easy to imagine a new record low maximum in spring 2021.
You and I have similar hobbies, but I think yours is further evolved and more detailed.

Oh, without question 2.7c is monstrous, and I'm very much of the opinion we are in the middle of a "tip over" into a new climate regime.

As to the recent century and multiple century extent and area increases - they neither surprised me nor reassured me.  Quite the contrary, they represent heat getting locked in, and the exchange of ocean heat with atmosphere slowing down.

They will without question slow down - as the areas of "hot" open water become farther removed from areas with persistent low temperatures.  By the end of the season, most of these will still freeze - the Chukchi, & Kara for example, and probably the Okhotsk - but the Bering and Barents will likely remain significantly ice free for the duration.

Mostly I think this will be driven primarily from the fact we will have little or no circulation which isolates the Arctic from inflows from lower latitude.  I think we are set up currently to it set up much like 2016, and the recent flows from tropical storms have persistently carried moisture and heat across the Barents into the Kara and then around into the Laptev and central basin.  (see my previous post with a capture from Climate Reanalyzer).

There are similar but less talked about intrusions of heat on the Pacific side, which are blowing across Kamchatka and into the Bering and Chukchi.  I don't see these patterns breaking down soon.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 10, 2020, 06:58:31 AM »
Guys could we please end this off-topic for this thread?
Oren, Gandul, JD, Aslan, etc. please let's keep the focus on the 2020 freezing season.
Gandul, you couldn't shup up could you? Valuable contrubutors are leaveing the thread, again.
With respect, my content *is* in relation and relevant to the current refreeze.

To Oren - salinity differences are going to result in a freezing temperature increase of only about 0.5c at most, and that will only be fairly close to the continental margins where ice is already forming.  The loss required for a phase change to take place remains the same.  Similarly, the increased distribution of heat to higher levels in the water column remains an obstacle.

Heat, both that being imported from further south - as very nicely illustrated by some of the weather posts I've seen - and what was picked up this summer are the key obstacles the freeze needs to overcome.

As an additional example underscoring my point, here's a frame grab 3 days out showing a major intrusion of moisture into the Atlantic side of the basin.  The effect of this is two fold; 1st, it seriously throttles out-going heat that needs to leave the atmosphere.  That's actually the biggest direct effect, in my estimation.  2nd, the phase change of that moisture from vapor to liquid to ice will replace some non-trivial fraction of the heat that would otherwise come out of the ocean, slowing the freeze.  The more of these plumes we see blowing into the basin, the bigger the challenge there will be to getting thicker ice.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 09, 2020, 11:00:31 AM »
I'll try to put my thoughts together in something more coherent, but let me put it this way, at the most elemental level:

It's all about Enthalpy.

Increased capture, reduced outgoing radiation mean the total heat present in the Arctic ocean has greatly increased.  (restricted by increased water vapor content in the atmosphere, along with additional CH4 and the increases in CO2... remember just how powerful a green house case H20 is...)

Ice can't form until sufficient heat has left the ocean surface to permit phase change to take place.  We already know that the water column has been disrupted, and that Atlantic water (and heat carried with it) is much closer to the surface and more accessible than the past.

Simply put, with the current energy balance, the Arctic can't dump the heat fast enough.

Even without the present throttling effects of weather (higher atmospheric temperatures and increased humidity, among other factors), the typical export of heat out of the atmosphere is not going to be able to dissipate the additional heat captured during the melt season. Heat simply won't get radiated out of the top of the atmosphere fast enough.

So, the bigger pile means there is that much more heat present which must get moved *somewhere* before the physics of phase change will permit the ice to form, over very large areas of the Arctic.

Unfortunately I don't have quantitative values to present here on this, but I think the qualitative argument should still be compelling.  As a rough estimate, the Arctic picked up something like 30% more energy this year during the melt season, *before* we factor in intrusion of Atlantic heat.

It can't get dumped fast enough.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 09, 2020, 10:43:16 AM »
    And now we can add warm Siberian river drainage into the Arctic Ocean as another factor (article posted upthread).  Given the record breaking high Siberian temperatures over land in summer 2020, the river water draining those areas must have been especially warm.
Yes, but in context, not a major player in the total energy equation currently playing out.  The impact of circum-arctic drainage is much more important early in the melt season.  Once albedo drops and insolation rises, the effect of a few thousand km3 of warmer water becomes less significant.  At this point in the year, it is of far less import than continuing inflow from Atlantic currents and atmospheric circulation where the remnants of tropical storms drag huge influxes of moisture into the Arctic.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 26, 2020, 11:36:04 PM »
Yes Milwen. This evening's ECMWF op run has substantial warmth flooding the eastern half of the Arctic at the end of the run. Still 10 days away so at the end of the medium range.

Negative Arctic dipole.
... and the same level of astounding temperature anomalies we saw in 2016, and to a lesser degree later, except, perhaps, worse.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 26, 2020, 06:30:54 AM »
I don't understand physical oceanography very well, but this is very simple geochemistry. High salinity is a dead give away that the water is of Atlantic origin.
Salinity is a key indicator, along with the documented invasion of Atlantic fauna and algae northwards and eastwards out of the Norwegian sea.

It is happening now, probably has been for over a decade.  I don't think it's theoretical any more.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 26, 2020, 02:10:51 AM »
the original C2S palette is quite unreadable
The quickie below is contoured for major and minor scale ticks. Note the lat lon graticule is gone and it is in 'Greenland down' orientation. The second emphasizes the very thickest ice, there is a tiny bit at 2.56m.
This may be the most depressing image I've ever seen on these forums.

It suggests all the land fast ice is gone, for practical purposes.

It suggests all of the 3m+ ice is gone, similarly.

The pack is completely unhinged and at the full mercy of the weather.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 25, 2020, 08:25:25 AM »
      The Panoply map is very interesting.  What are typical cooling rates for November, December, and January?  In other words, what does a current temperature of 273-275K in most of the ESS and Laptev, and much of the Kara, suggest for when those waters are likely to freeze?
It's not what they suggest now.

It's what they augur for spring that is significant.

There is no ice.  There will likely be no ice over large stretches of that open water for weeks.

Right now, it looks like we'll be flying under 2016's numbers by close to half a million km2 for most of the refreeze season.  Come March, that will potentially be half a million km2 of exposed ocean sucking up heat and not reflecting it back out of the atmosphere as the sun returns.

Even when enough heat has been dumped for that water to freeze, with the coverage we'll get, those higher temperatures will mean thinner ice, by 10's of centimeters, which will be more vulnerable and melt out faster when the sun starts to return.

I'm expecting an early max, and a return of May melt ponds next spring, is the take-away I have of these numbers.

Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: October 20, 2020, 06:53:11 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.
This is truly uncharted territory!
900K+ km2 versus 2007 & 2016; 1+ million km2 versus 2012.
Words aren't adequate.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 19, 2020, 02:37:06 AM »
Gandul, I haven't read the paper itself yet but I get the feeling you are misreading this paragraph. While the positive feedback (reduced sea ice => higher mixing rates => reduced sea ice) is a (very reasonable) hypothesis, the increased coupling of AW heat and the sea ice is not, if I read this correctly.
I accept it, but as a hypothesis, not a fact. This forum is an echo chamber and pretty soon everyone will be accepting the Atlantification of Laptev sea as a fact.

Don't take our word for it.

You can listen to the mute testimony of Emiliania Huxleyi (EHux).

It is coming, in fact, in progress.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 18, 2020, 10:12:02 AM »
There's a reason scientists studying climate change use complex models not tea cups
Worst freeze season ever underway ...
Concur.  As I observed in the extent and area thread, the numbers on the eastern side of the basin - Kara, Barents, ESS and Laptev - are terrifying.

As FooW observes, this is already having an impact on northern hemisphere circulation and weather.

While the Beaufort and Chukchi numbers are not at record breaking levels, they are not good, and the sea surface temperatures are very much so.

Looking back at another question up thread about the influence of this all... you touch on it by way of stating the heat to melt the ice year round is already present in the Arctic, it just isn't accessible... the net enthalpy in the Arctic is rising almost exponentially, and combined with the observed destruction of the haloclines in the Atlantic side of the Arctic is a dire portent for the very near future. 

The buffers which used to keep a lid on that heat are gone.  Lack of ice growth will merely be a symptom.  The real story will play out in the changes we are going to see in winter weather in the northern hemisphere.

What happens with the weather next spring will be definitive in ways humanity has not experienced in over 10,000 years.  There is simply too much heat loose in the northern hemisphere.

The analogy I think of is one which actually came from my study of geology/vulcanology.  It ties back to the observation of events prior to a phreatic explosion at the rim of a atoll volcano.  Prior to the explosion, there were major jets of steam venting from the area which would later explode.  Someone asked if that would be sufficient for the energy to dissipate.  The point made then was that the steam jets were akin to a giant sticking his finger through the hole in the roof of a hut.  There was no way the giant was going to climb through it, nor would the roof of the hut be enough to contain him.

So it is with the increase in enthalpy in the Arctic.  What we are seeing now in fact is the culmination of years of build up and Atlantification, probably starting before 2012, probably before 2007. 

The last few years, we've watched the giant sticking his finger through a hole in the roof.  I think we are about to see him emerge.

Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: October 18, 2020, 09:49:05 AM »
NSIDC Area Graphs

The Russian Shore

Barents. Kara, Laptev, ESS - how late will the freeze be? How fast when it does happen?
The ESS, Laptev and Kara numbers are staggering.  Barents numbers are bad, but not so much by comparison.

This is no doubt already seriously throwing off northern hemisphere weather.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 16, 2020, 07:50:35 AM »
The Copernicus CMEMS viewer by Lobelia Earth is really something. There's a learning curve but it's fast and stable. The pop-up even graphs the whole history of all the variable layers chosen! Hopefully more people here will look into this tool.
I agree... just started playing with it and already impressed.

Arctic sea ice / Re: 2020/21 Freezing Season Predictions
« on: October 10, 2020, 03:24:01 AM »
I predict volume to be 20,000km3 at maximum.
On reflection, and seeing how the refreeze is starting, I think I need to revise my estimate down as well. 

I think even at 20,000, we may be high this season.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 10, 2020, 03:12:19 AM »
FWIW, the "open water heading into the arctic night = GOOD" argument has always struck me as a violation of Occam's Razor: Less ice, more open water, later and later into the fall just does not seem "good" to me.
It’s not that it is good. It is that there are physical reasons (Stefan-Boltzmann Law) to expect that the more energy you make available now, the more energy will radiate out to space during the NH night.

The net effect is energy loss and therefore another factor to moderate, rather than precipitate, the decline of sea ice in the years to come.

A-Team is conflating this negative feedback effect that he, as scientist, knows well, with other atmospheric effects which are less clear and of more conjectural nature, to produce an overtly alarming picture.
I'll disagree mildly with the last and bolded, and to a lesser degree with how you characterize A-Team's method.

I really can't remember in 7 years where he's seriously overstated an effect or mechanism.

Or even modestly for that matter.

Frankly, I think it is hard to understate the likely impact of warming of the Laptev, ESS, Barents and Kara in particular that took place during the melting season.

I think it's hard to understate the impact of the breakdown of stratification in the peripheral seas on the Atlantic side, along with the enormous influx of heat that's being pulled along by "Atlantification".

Other posters have correctly pointed out that outgoing black body radiation will not be able to dump the heat that's been accumulated, and is *still* being imported by southerlies pulling storms, heat and moisture into the basin from further south.

I think it bears serious watching, as my "hunch" at this point is we will see an extremely anemic refreeze, with a significant reduction in end of refreeze volume, even if those peripheral seas appear to refreeze robustly.  I think the portents for next year are very serious indeed.

Edit:  What we need, desperately, this winter:

- A strong polar vortex
- Crystal clear skies
- Minimal snow on the pack

I'm pessimistic about the probability of any of them.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 09, 2020, 08:04:22 AM »
It's an interesting point: Is ever-slower refreeze a big negative feedback on planetary warming in general and Arctic warming in particular? <snip>

I'd say no.  The slow refreeze is happening exactly because there is so much heat in the system, outgoing radiation can't cool things off fast to drop it to where the sea surface freezes.

Secondary effects from this are going to be general disruption of northern hemisphere atmospheric circulation, with massive break outs of cold air from the polar regions, and massive inflows of heat and moisture out of the similarly but not as severely overheated tropics.  The Enthalpy bucket is overflowed faster and more voluminously than the drain can carry away the extra.

Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: October 09, 2020, 07:58:10 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

October 8th, 2020:
     4,404,243 km2, an increase of 44,616 km2.
     2020 is 2nd lowest on record on this date.
     Highlighted 2020 & the 4 years with a daily lowest min in Sept. (2012, 2019, 2016 & 2007).
     In the graph are today's 10 lowest years.
I'm pretty certain - 2020 passes 2012 as lowest year in all metrics over the next week.

Not quite as fast as I thought, but close.

Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: October 04, 2020, 08:28:15 PM »
Sea ice area gain on this day 35 k, 11 k less than the 2010's average gain of 46 k         
I anticipate 2020 will cross over 2012 to become lowest in both extent and area in about two weeks time, +/- a few.

Arctic sea ice / Re: 2020/21 Freezing Season Predictions
« on: September 29, 2020, 05:35:09 AM »
Knowing how the season has started, I think we'll likely see a record low maximum, but not by much.

Somewhere around 13.7±0.3sqMm extent seems like a good ball park estimate for me.
A hair low, but close I think.

My prediction is three fold:
High probability      - 14.0-14.5, shaded towards the low end.
Medium probability - 13.75-14.25, shaded towards the middle.
Very high probability 13.75-14.5, of course.

It depends if the refreeze is more like 2019/2020 or 2017/2018.

Looking at the NOAA data there seems to be a natural limit driven by geography which I suspect lies between 14.0 and 14.5 million km2, which may be the range our winter max falls in for a while.

Annual minimum will continue to decline along with volume, and be driven more by how soon the melt season starts and how hot Siberia gets, and how early.

There also I'll predict, volume at max for sometime is going to plateau at around 20,000-23,000 km3 similarly, drifting down slowly to the high teens.  This year I'll place my bet on 21,000km3 +/- 250.

However, if we get the inflow from cyclones I'm half expecting, my estimate could be high by over 1000km3.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: September 22, 2020, 04:38:35 PM »
A little unusual thing is happening. Hurricane Teddy is heading towards Canada and according to forecast it will reach Greenland as Tropical/Subtropical storm. It is too soon to tell if it will affect Arctic in some way but worth to mention it.

That's a HUGE tropical storm force wind field.  That's going to drag a huge plume of moisture and heat along with it all the way to the high Arctic.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: September 22, 2020, 04:34:49 PM »
Considering the current SST situation, I expect there to be an unusually long lasting polynya in the ice in the ESS until a record late date, perhaps mid-November or so.
Not so much polynya as just simply the seas not refreezing.

With so much insolation taken up this summer, combined with influxes of advected heat through intrusion of warmer southerly water on both sides of the Arctic, along with continued massive plumes of sensible and latent atmospheric heat (warm air, high moisture content), I'm expecting a refreeze along the lines of 2016/17, and a possible new low maximum.

Over the coming weeks, Siberia and eastern Europe will chill dramatically while the Arctic seas will remain quite warm.  There will be coastal freezing, but I expect the present heat and incoming storms through the fall will keep the ice at bay for a very long time, particularly in the Barents and Laptev.

On the Pacific side, I'm anticipating a late refreeze of the Chukchi, Okhotsk and Bering for much the same reasons, continuing and building on the trend we've seen the last few years in those regions.

I suspect the Beaufort, coastal Laptev and much of the ESS will freeze up fairly fast, again starting at existing ice edges or the coast, and leaving a warm gap between for some time.

The Kara I think is a wild card.  While it is shallow and close to the "cold continent", I think we're going to see a lot of flow into it from continuing tropical storms that will then sweep around counter-clockwise from it into the Arctic basin proper.  That may keep it open and the Atlantic side warmer for longer and generally reduce the desperately needed FDD's required for a strong refreeze and good volume production.

Not willing to speculate quantitatively on "Max" numbers yet even remotely, but both interested and concerned about what lies ahead.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: September 19, 2020, 03:11:05 AM »
I do wonder if atmospheric aerosol levels have begun to rebound somewhat, since global traffic has picked up massively since mid-March.<snip>

I also think it is also worth noting that Antarctica and the Arctic are two different animals
Aerosol levels may have helped the melt by slightly increasing available insolation, their absence won't necessarily help the refreeze.  What has really affected that is the availability of moisture in the atmosphere, and advection (or the absence thereof) from lower latitudes.  It is hard to understate the importance of H2O as a greenhouse gas, and it's increase is a positive feedback of warming caused by increased CO2.

And yes, the northern and southern hemispheres are profoundly different.  The Antarctic suffers from nothing like the pollution issues the Arctic has, and as a "cold continent" the ice it has locked in is much better protected from heat.

There will probably be retreats by the Antarctic ice caps over the next few centuries, but unless CO2 spirals totally out of control (> 1000PPM), they will probably persist long after the Arctic ice and Greenland ice cap are memories.

Because of that, atmospheric circulation in the southern hemisphere will probably remain broken into three circulation cells.  It would be fascinating to see, but, none of us will live that long I expect.

Arctic sea ice / Re: The 2020 melting season
« on: September 17, 2020, 10:22:29 PM »
     Nice graphic uniquorn.
     FWIW - Perhaps the difference between 2020 and 2012 can be summarized as:<snip>
Does anyone doubt that 2020 was a paradigm shift?
This ain't your grandma's arctic anymore!

Actually, I'd say the "flip" happened between 2007 & 2012.  Since then, I think we've just been working through latency in the system.

Arctic sea ice / Re: The 2020 melting season
« on: September 17, 2020, 08:05:06 AM »
Thanks FG, let the thread stand but I prefer posts go into the melting season thread for the next couple of days. NSIDC area is still making new lows for the year, and I'd rather wait for the mid-Sep PIOMAS update on the 19th.
Agree.  Don't think it's quite done yet.

Don't think it will challenge 2012, but, I think the fact it is still "uncertain" is important and relevant.

That we *don't* have a definitive switch over to a refreeze I think is very significant.

Arctic sea ice / Re: The 2020 melting season
« on: September 16, 2020, 04:07:53 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.
I think what is happening on the Atlantic side is far more dangerous.

It translates into later refreeze, thinner ice at max volume in March/April, and faster melt out, much as we saw this season.

The open water and heat will also be magnets for storm systems coming up from along the eastern seaboard of NAM.  And considering all the damn hurricanes, tropical storms and depressions that are active, that threatens to seriously slow down the freezing season, much as it did in 2016.

Only we're a lot worse off than we were in 2016 I think, in terms of heat balance.

Arctic sea ice / Re: Arctic Image of the Day
« on: September 15, 2020, 05:01:52 AM »
I can’t end my fascination of the Queen Elizabeth Islands! With the fresh snow and fall sun angle I had to spend some time making a new wallpaper from today’s satellite imagery. I cleaned up the photos to really enhance the terrain.
Amazing places, which are going to be totally transformed over the next century.  I suspect the Northern Boreal forest will return there, possibly assisted by us in an attempt to stabilize climate in some sort of sustainable fashion.

Arctic sea ice / Re: The 2020 melting season
« on: September 14, 2020, 08:20:39 PM »
It wouldn't be much of a rebound anyways when you consider how thin all of the ice is.

What good is 4 year old ice that's under a meter thick
It’s more resilient than FYI under a meter.
<mass snippage>

Weather will be the determinant of the pack's survival, not the existing ice.

As for this year, as some posters mentioned above, we have very warm SSTs in the Arctic. I don't even exclude a possibility for a late-season GAC doing much damage in a week or two. Not likely, of course, but if it happens - resulting further ice loss may be easily able to drop 2020 well below 2012.
I expect a "late" minimum, but mostly because the metrics will be stepping back and forth around the current value, with net losses taking it down perhaps another 50k or so at most.

For a storm to affect that significantly it would need to be very intense, advect a great deal of heat with it, and very specifically target the weakest parts of the current pack.  That's a lot of qualifiers which as you suggest, make it unlikely.

Arctic sea ice / Re: Arctic Image of the Day
« on: September 14, 2020, 09:02:58 AM »
My perambulations through EOSDIS brought me this today - a cyclonic weather structure in the Chukchi.

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 14, 2020, 12:24:42 AM »
It wouldn't be much of a rebound anyways when you consider how thin all of the ice is.

What good is 4 year old ice that's under a meter thick
It’s more resilient than FYI under a meter.
<mass snippage>

Weather will be the determinant of the pack's survival, not the existing ice.

jdallen pretty convincing. I agree with almost everything you explain. Still that does not negate that, if we have that 7% of ice that has become older in the Western CAB post-2016, let’s count with its existence for future years. My belief is that it does matter, it is one of few negative feedbacks that the Arctic ice has to avoid imminent oblivion, that is: some regeneration of old ice if several years seasons do not push it away one direction or another.

I just happen to believe we are in for a gradual decline, which I know is not a popular opinion here. Yet some folks are noting that “this year would be creating big news if it wasn’t because of 2012”, yes, and that’s because of the current gradual decline of which 2012 was the exception.

I Used to believe 2030 was a good BOE prediction, but I am not so sure when one counts some negative feedbacks: extended falls after bad seasons lead to enormous late heat release, increased snowing, later springs, rebound years; years in a row with low or moderate CAB ice export lead to MYI rebound; warm ocean currents not easily reaching the western CAB ice...
mind you, I agree that a very bad year before 2030 might come and ice extent can go down even 1 m km2 but that would probably be exceptional, followed by rebounds, back to the gradual downhill track as it has happened post 2012, clearly.
Anyway, this is all speculation, reason why I post it here.
Thanks for shifting the discussion here.

I still think 2030-ish is the way to bet as far as a BoE is concerned, and agree that we'll get years if not decades of "dead cat bounces" while the Arctic as a system languishes in a marginal condition between the previous and next "stable" state.

I think my primary criticism about the value of MYI is more nuanced than may have come across in my OP.

There is no question that MYI was key to buffering and balancing the Arctic as a system, especially pre-2007.  The key function it served really didn't have to do with the implied latent energy uptake it represented.  MYI doesn't absorb more energy that FYI when melting.  The heat budget for phase change remains the same.  Rather, it was it's mechanical strength, across vast stretches of the pack which helped stabilize the system as a whole.

Part of that strength depended seriously the temperature of the ice as much as it did on its salt content - ice at -20c is almost as hard as bedrock - and has nearly the same mechanical strength.  So, pre-"modern" era conditions with millions of KM2 MYI and sub -10c temperatures meant that wind and other kinetic forces could be spread across very large areas with relatively little damage, and, that there would be little movement or disintegration of the ice outside of the pack margins.  This has made the system  more or less stable since the last of the Laurentide ice sheet vanished over 4500 years bce. (Prior to this, it was probably stronger.)

It's thickness ->at scale<- was important as well, as it meant year over year, it could lose 2+m of thickness, still remain in place, and provide a similarly broad-scale platform for re-deposition of new ice from below and new fresher ice refrozen from melt above.  It tended to stay in place.  It tended to keep albedo high, and by nature of strength and coverage, limit seasonal uptake of heat.  These last were as if not more important than the thermal inertia the ice itself provides.

Scroll forward now to the modern era, particularly at key junctures like 2007, 2010 (an underrated melt year), 2011 and 2012.  I'm adding a link to one of my favorite graphics by Jim Pettit here to help illustrate:

Those years mentioned are key in they are points in which the melt season destroyed large areas of MYI.  2010 in particular is notable for that, as even though extent and area did not drop to record levels, it was the first year we observed volume drop below 5,000 km3.  2007 was the first below - WAY below - approximately 9000km3 (2006 was 8993km3).  2011 and 2012 were years that continued the trend, dropping volume under 5000km3 and progressively chipping away at what some of used to call "matrix pack"; called such because of the very regular way it would fracture, essentially creating what could be considered fault lines in the ice while mostly retaining strength and coherence.

Those losses of volume and by extension MYI are critical to set the stage for what we see starting most dramatically in 2016.  The winter pack now fractures and recombines at much lower scales, eliminating the resistance it used to have to mechanical forces, and making the entire pack as a whole far more mobile.  Combine this with increasing advection of heat from southerly seas, and you have the new seasonal regime we now see. 

The result is, we have nothing like the larger expanses of MYI we used to see, which unbroken might cover 10's of thousands of km2. We are lucky if we see blocks of more than about 2500.  And because of warmer temperatures overall, for longer periods of both the melt and refreeze seasons, that relict ice has nothing like the mechanical strength of the old pack.

So, to finish my thought for the moment and conclude, MYI was far more important for the structure and mechanical characteristics it provided than it was for any sort of thermal component.  So while it exists now, it has nothing like the structure it had in the past, and because of that is only marginally less vulnerable than FYI when exposed to the conditions we now see during the melt season.  Without that structure, it doesn't really provide a buffer against loss as it used to.

Arctic sea ice / Re: The 2020 melting season
« on: September 13, 2020, 09:15:50 AM »
It wouldn't be much of a rebound anyways when you consider how thin all of the ice is.

What good is 4 year old ice that's under a meter thick
It’s more resilient than FYI under a meter.

That difference is more academic than practical, at 1m.

Anyway, the notion that Western CAB ice is homogeneously under a meter thick is misleading.
I can imagine a field of mixed floes of different thickness, surviving tall  ridges, ... the closer to CAA the thicker and older in average.

*Mostly* true, I'll agree, but I think you are overstating  how much of that melange is actually MYI and of significant thickness.

The region between the NP and the Beaufort sea has suffered surface melting but has stayed relatively protected compared to the other side of the NP. It stayed substantially colder during July even when it was 24/7 under the sun.
Now this 1 millon km2 of extent has several years of being stretched, exported to Beaufort sea or the CAA channels until it completely melts. It is a region of slow turnover time compared to the Gyre or the ice on the transpolar drift. It is a buffer against abrupt apocalypse scenarios.
You are making an awful lot of assumptions there, in the face of evidence - like the melt out of thick, MYI north of Greenland this year - which don't support your rosy interpretation of the ice's survivability.

Other posters have pointed out that Transpolar drift is broken.  The Gyre is broken.  Pretty much every mechanism we are used to watching and basing assumptions on, is broken.

And then there is the raw question of how much what we see in models is diverging from what's actually visible where we have "feet on the ground".

The only buffer we have against "sudden apocalypse" scenarios is the weather. 1 million km2 of 1m thick MYI or the equivalent simply doesn't have the thermal inertia to stop an apocalypse if the weather isn't cooperative.

The net enthalpy in the system has exploded, between additional solar uptake, and the huge inputs implied by the salinity data we see around Atlantification, as well as less dramatic inputs through the Bering strait on the Pacific side.

At this point, it really all hinges on seasonal uptake and existing heat.  Not extent.  Not area.  Not thickness.

We burned through ~15,000 km3 worth of ice this season already.  The ice you are citing (1,000,000 km2 of more or less 1m thick MYI) would represent less than 7% of that.

Even if I'm generous, and assume say, an average of 3m thickness, (which is VERY generous), we are talking about less than 20% of what has been lost this season already (PIOMAS figures).

It's not a bastion.  It's barely a cushion.  At best, averaged out, it's about 4 weeks of melt.  That's how thin a margin the Arctic pack's survival hinges on.

So back to my point... even if you are correct about quantity, at this stage in the evolution of the Arctic, it is weather, not ice volume which will determine any given year if we can avoid a BoE. 

That's been true pretty much since 2012.  Many of us have been holding our breath every year since 2012 in fear of a BoE.  So far, we've lucked out.  Increasingly, the deck is being stacked against us.

Some years ago, during one or another poll, I indicated that I thought there wouldn't be a BoE until sometime after 2029, and probably not before 2050.  At this point, I'll be surprised if we make it to 2029 *without* a BoE.  MYI won't help prevent it.

Weather will be the determinant of the pack's survival, not the existing ice.

Arctic sea ice / Re: MOSAiC news
« on: September 11, 2020, 07:46:46 PM »
Cold at the Polarstern, balmy in the Beaufort, Chukchi, ESS, Laptev, Kara and Barents.

The two adventurers had internet/sat phone the whole time and expert tech team support for it. Enough to send those pictures, receive weather forecasts and ice maps, have GPS lat lon and communicate with the rescue team on the rented icebreaker about the hopeless ice on the Svalbard side.
Suggests to me the ice is in worse shape even than what the expedition team leadership has already shown us.

It will be interesting to see what some of those researchers say and publish when they return.

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 10, 2020, 06:40:57 PM »
I think it's real. Noaa-20
Oh, there isn't any doubt.

It really confirms what A-Team and others have been saying about the ice this season.

It also highlights the disconnect between actual conditions an the models we are relying on.  It illustrates that fundamental changes have taken place in the Arctic as a system, and similar fundamental assumptions made by the models - in particular volume - need to be reevaluated.  In previous years, certainly pre-2012, possibly as late as 2016, a modest cyclonic feature - not even a storm - like that would not have shattered the main pack across such a wide area.

We desperately need more and different data.

Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: September 10, 2020, 09:15:10 AM »
For those who can't wait:

3,586,426 09 sept   -3k
The difference between 2020 and 2012 is mostly academic at this point.

Arctic sea ice / Re: The 2020 melting season
« on: September 08, 2020, 10:24:40 PM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Large GiF!

Probably belongs in the stupid question thread but...

I've been clicking on these animations for weeks. Is it normal to have all of these lows rolling up through the Barents and into the Arctic? I remember a few years ago when someone labeled this behavior as a cyclone cannon. Is there a stuck weather pattern that is causing this?

I think the short answer is, sort of, and it didn't use to be.  IIRC the "Cyclone Cannon" descriptor started being used in 2016 with the storms charging from the tropics along the NAM eastern seaboard all the way to 80N.  I know I started using it to describe the strings of storms we were seeing.  Whether I was first, I don't recall.

It hasn't been so much that this year, as from what I could see, a lot of the storms have spawned further north from moisture and heat carried north by the remains of other systems that lost coherence.  Not quite the same.  In 2016 the storms were retaining structure from start to end.

I think the underlying mechanism is similar - a breakdown of the Hadley/Ferrel/Polar cell circulation in the northern hemisphere - permitting direct transfer of air masses from equator to pole.  That weather tends to follow the NAM and Asian eastern seaboards I think because both ocean margins provide a handy energy source to power and gradient to steer the air masses consistently.

Arctic sea ice / Re: The 2020 melting season
« on: September 08, 2020, 08:23:20 PM »
As you frame it, 4 year old MYI which is only 1-2m thick is of equal value to what 4 year old MYI *used* to be - 3m thick or more for the most part, and far more robust than the scattering of dots the current maps present. 
When MYI is that thin, can it survive another year of melt? Because when ice gets thicker, it freezes at the bottom
It all very much depends on the melt conditions the ice is exposed too.

It can survive, but will be much different in nature - "Hybrid" if you will - than older, thicker MYI was in the past.

MYI which is seriously degraded (down to under 2M in thickness) will not be as robust even if it manages to gain thickness during the refreeze.  New ice will not be as consolidated - of the same quality, hardness and physical structure - as the surviving older ice.  There's fertile ground for a doctoral thesis there, assuming the ice survives long enough for research to capture what it looks like and how it behaves.

For me, it helps to understand what is going on by approaching the overall outcome season over season as a sum of probabilities.  For example,  some small fraction of it may actually be thicker and miraculously thicken further over the refreeze, but key there is the "bell curve" for thickness distribution is shifting badly against thicker older ice.

The distribution of the mechanisms generating those probabilities - insolation, cloudiness, wind, melt ponds and more - hasn't really altered that much, exceptions being increased WAA and indirectly things like lower albedo.

But to some degree they are not structural changes in the original system dynamics as the are derivative modifications of it, produced by increased overal enthalpy in Arctic and northern hemisphere climate systems. 

As a metaphor - consider the Arctic's heat reservoir as a bucket with strategically drilled holes in it, and it's heat budget as a hose playing water into it.  The system in balance will have the water level rise and fall predictably based on relative inputs.  Add another small hose or just increase the flow slightly (WAA, Atlantification, increased spring continental run-off, etc.) and change the size of the holes (decreased albedo for example, or stronger greenhouse blocking of outgoing radiation), and eventually the water will rise until it finds a new balance. 

Key dynamics of the system - phase change physical chemistry, insolation, black body radiation, greenhouse physics, et. al. remain mostly the same. 

What they are playing out on has not.

This of course is a tremendous simplification but I found it useful as a mental exercise to help understand and put in context the dynamics of what we see playing out before us.

That's well illustrated by what's happening this year.  While warm, melt conditions haven't been nearly as extraordinary as they were in 2012.  Yet, here we are at 2nd lowest in most metrics, with a slim chance still of catching 2012.  We got here because of a cascade; the same inputs, but the shift in probable outcomes for each event means less ice and increased capture of heat in the system.  I think we all know how it will eventually play out.  Most of our arguments about it are over timing.

Arctic sea ice / Re: MOSAiC news
« on: September 08, 2020, 09:55:07 AM »
Could a higher loss in ice volume result in lower salinity due to more fresh water or is this irrelevant in such depths? (Please delete, if this question is too obviously stupid ;) )
Reasonable and not Stupid.

In previous melt seasons possibly, but one challenge the Arctic faces is increasing intrusion of more saline Atlantic and Pacific water, at steadily decreasing depths.  This makes the additional melt less relevant.

What also makes it less relevant is the general decrease in the "lens" of somewhat fresher water that used to persist year over year in the central Arctic and to some degree the Beaufort.  If it contributed to that, additional melt would help slow down the year over year decline in ice.  However under the rapidly evolving conditions we've seen over the last 10-15 years, it is not as helpful a factor as it might have been.  Far better would be for it to have remained ice instead.

Arctic sea ice / Re: The 2020 melting season
« on: September 08, 2020, 09:43:32 AM »
Longish meta discussion, perhaps crossing off topic, but hopefully useful exposition.

@jdallen Relax, ...<snip>...
It seems I ruffled some feathers.
My only personal criticism is the one you resolved. More on feather ruffling down post.
- I am not sure if there is any implication for future seasons ... <snip> ... But per Piomas, there is a lot of 1 to 2 meter ice in a region overlapping the NASA 4+y regiin.
This speaks to discussions both here and on other threads about ice quality and and how products we currently are relying on for data seem increasingly less accurate in how they characterize the state of the ice.

I would also hazard to say "a lot" is very much qualitative rather than quantitative, less scalar and more binary.
- <snip> the parochy has been cherishing this product <snip> it looks pretty convincing, <snip> I personally trust this product <snip>
I find "cherish" an odd word to apply here, as it suggests an attachment that really doesn't exist. "Looks convincing" is similarly perilous as it asks us make value judgments rather than evaluate what is presented critically.

Similarly, "trust" is really not relevant.  What is relevant, is how closely the model output matches what is actually present in the Arctic.  The Polarstern expedition even without presenting much of its detail, has already highlighted the fact that there is an increasing gap between what the models produce and what is actually present, and that not in a favorable direction.

Since joining the forum in 2013, I've become both much more conservative in my declarations, and less likely to draw conclusions from the output of a single data source.  To this point, any model I evaluate is being examined in context with others like it, which use different algorithms and frequently completely different sets of data.  For the most part, it is only when I see broad agreement across them that I will make strongly worded statements.  And recently, I've relied far more on what is directly observable (EOSDIS for example) rather than modeled information.

I'm not yet seeing how your assertion is borne out in that context, aside from the specific, narrow definition you are using to support your suggestion that ice may somehow be recovering.

"Recovery" is a provocative and very strong word to use, in the context of the discussions taking place here, and in view of other information sources that would not support its use.  What is also worth reflecting on is just how narrowly you are having to set your definitions to justify it.  As you frame it, 4 year old MYI which is only 1-2m thick is of equal value to what 4 year old MYI *used* to be - 3m thick or more for the most part, and far more robust than the scattering of dots the current maps present.  That in itself is what I suspect is provoking more than a few readers here.

I think that's a serious mistake in analysis, and very much overlooks context.  There are many explanations for what we are seeing in those graphics, but very few of them would justify the use of "Recovery" as a relevant and useful characterization.  It strikes me as being akin to sending out a press release when a fire has been put out on one wall of a building, while the blaze continues to intensify elsewhere.

Better would be to examine the model in context, and ask yourself or others a few more questions about it.  You may be able to avoid getting your ears boxed as thoroughly as mine were. 

Arctic sea ice / Re: The 2020 melting season
« on: September 07, 2020, 11:48:53 PM »
In what region would you expect that rebound, gandul?
Check it out yourself above
Not his job to prove your point, please.

You made the assertion, your job to lay it out and describe your evidence for it.

Arctic sea ice / Re: September predictions challenge 2020
« on: September 06, 2020, 10:28:02 PM »
This is a big dice roll so early in the season, but I'll throw my hat in.

JAXA: 3.75-4.25     High
NSIDC: 4.0-4.5      High
PIOMAS: 3.75-4.25 Medium

I am surprised, that my estimates may actually turn out to be too *high*.

NSIDC is below 4.0 million km2
Jaxa may pass 3.75 shortly.
I may still be in play with PIOMAS.

I'm pretty shocked.

Arctic sea ice / Re: The 2020 melting season
« on: September 05, 2020, 08:39:04 AM »
The extended models are beginning to show the most impressive GAAC of the season forming.
CMC on potential GAAC....!


<snip> Real danger for the ice that heat will transfer to the cooler Beaufort and yet again the whole basin is ridiculously above average for September.

Actually, the real danger is... Dipole.

That's what the models are hinting at (but is far from certain), from what I see in the un-snipped image I left.

At this stage, even "blistering" heat isn't going to advect enough heat to seriously affect the pack.  That's going to have to come from the ocean.

A strong dipole down the Atlantic front and back towards the ESS across the pack could disrupt it, cause compaction and damage, pulling more heat up from depth and continuing bottom melt by providing a source of heat greater than the out-going heat loss.

If it were not for the wind, at this stage of the season, a strong high pressure system would be a godsend as it could bring clear skies and nothing to impede outgoing heat.

We will have to see how things play out.

Arctic sea ice / Re: The 2020 melting season
« on: September 04, 2020, 09:24:13 PM »
NSIDC Daily extent below 4 000 000 km^2! Yay!

Another century drop of 112 and only 599 away from the 2012 minimum.
I wouldn't say "Yay!" though.
I'll forgive the "Yay!".

It has nothing to do with the ice.

It's the excitement and satisfaction of people, who've been denied credibility for years when speaking to the climate catastrophe we face, seeing tangible validation of what they've been screaming about for decades.

I can assure you, and I think I speak for many here, it is a very grim satisfaction.

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 04, 2020, 05:49:30 AM »
The new AMSR2_AWI is up to version 102 today and has the early Sept dates but slightly changed per swath hour as noted in the new ReadMe.

So you demonstrate the HYCOM model to be complete crap in one thread and use it to illustrate the ice pack edge displacement in another, even when:
Thank you for stepping in Oren.

Now, to put some context into this, models can still be useful even if flawed, if they are consistent.  HYCOM I think fits into this category.  Seeing directly how they depart from direct observation is useful, and I think A-Team has been pretty clear about that. It's not an either/or proposition.  One can be critical on one hand about it's overall accuracy and still find information it provides useful.  The two things are not mutually exclusive.

Second, since 2013, the Arctic has pretty much been reduced to a bowl of ice cubes (MYI) surrounded by slush (interstitial lead ice that forms between MYI fragments).  It is utterly unsurprising that Polarstern could find a chunk of relatively "thick" MYI in the middle of this.  This doesn't make the HYCOM model more or less relevant.

When you are dealing with models and sensors that are working in multi-kilometer resolution, it is not just easy, but pretty much *certain* that you will find serious localized exceptions to what a model might be reporting... unless you are talking about 100% open water.

Arctic sea ice / Re: The 2020 melting season
« on: September 01, 2020, 05:09:09 AM »
whoi itp114 in the Beaufort. Microcat1 is mounted at 5m depth. Peaked at -0.665C today, avg closer to -0.75. Position is roughly centre of the worldview image.

Last buoy status on 2020/8/31 113047 UTC : temperature = -0.8125 °C, battery = 10.423 V

Still seeing bottom melt.  That could easily be 1-1.5C a day pending on how well mixed the top 5-10M of water are.
You beat me to it.  I'd put it at about 1 cm/day.

The Beaufort & CAA are far enough south that they'll still have decent insolation for a few days as well.

2nd is looking very certain at this point, probably with room to spare.

Arctic sea ice / Re: The 2020 melting season
« on: August 31, 2020, 07:01:02 PM »
Latest projection... all of the previous 20 years are now going for the 2nd lowest again.
To equal 2012, losses would need to average 54,100 km² per day from now until September 16th (2012 minimum date). The previous record large loss for this period was 27,900 km² per day in 2010.
My hunch right now is, that we'll see a late minimum - at or after the equinox.

The combination of fragmented ice, vastly increased solar capture earlier in the season, bottom melt, vulnerable extent south of 80N and upcoming potential for rough weather leads me in this direction.  This would also be in keeping with the "extension" (earlier start, later end) of the melt seasons we've been seeing progressively for possibly as long as a decade or more.

While there's still a chance we could make it to 2012, I think it will end up a 'near miss'.

The difference between the two (2020/2012) may more semantic than concrete, considering the overall current ice quality.

It will be interesting to see how close my assessment is to reality.

And to echo Neven - it's all about the melting momentum now.

Arctic sea ice / Re: The 2020 melting season
« on: August 29, 2020, 11:00:58 PM »
Never mind 'not dropping' , the dmi80+ temp. has risen again . Yesterday it was sharing it's exceptional height with 2016 , today it is out on it's own . Open water , meltponds and warm winds are all working to extend the season . ECM's forecast keeps temps above or close to 0'C for the next week . b.c.
Hopefully, the WAA stops soon, but the temp stays high - so somehow that heat gets dumped out of the system.

Over large sections of the Arctic we have an extra 4 weeks (or more) of captured insolation added to the heat budget.  It's been stacking up seriously since 2016, though that may only signify when we started paying serious attention to it.

About the worst thing I can think of happening now would be calm clear skies that permit a quick surface re-freeze, locking a lot of that heat into the system.

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