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Messages - Glen Koehler

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1
Re dispersion, I agree with Binntho (becoming a habit ;) )
Re Slater. There is often an arm of thin ice close to SZ at minimum due to drift rather than refreeze. Maybe the model takes that into account?

2
Arctic sea ice / Re: The 2020 melting season
« on: Today at 11:11:09 AM »
That's easily 1m km2 about to go disappear!

3
Arctic sea ice / Re: The 2020 melting season
« on: Today at 11:05:36 AM »
Animation of the Beaufort sea over the last 12 days.

4
Arctic sea ice / Re: HYCOM
« on: Today at 06:57:08 AM »
Rod:
It is ok to doubt the model. I do not I doubt the model I doubt your melt assumptions. I have seen melt numbers estimating 5cm a day this season but that seems extremely high to me. At that rate 2 m melts in 40 days. I think we can agree when thick ice gets transported out of the region melt rates are higher than melting in place but we can mostly ignore that.
Looking at piomas model I see ice thinning by 1 m between 4/15 and 7/15. In less central locations the ice thins 1.25 m while in more central locations the ice thins by 0.75m. That is a melt rate of 8mm to 14mm per day. I also looked at Hycom on the same dates and came up with similar numbers. 7/15 includes about 4 weeks after the solstice. We are now almost three weeks beyond that. We are getting close to the time when the CAB normally starts to refreeze. The Beufort will probably melt to the end.
It has been said in past melt seasons that there is enough heat in arctic ocean to melt all of the ice if it mixed thoroughly. The melting along the Greenland CAA coast seems to be from Eckmen pumping of heat from lower down. The right storm could also do it. One of the buoys shows freshwater protection breaking down. This may or may not be happening elsewhere. There was a lot of heat in the ocean in 2019 that did not do much at the end of last season. It could have gone the other way.
I don’t think we are getting a boe this year but looking at that thickness map and saying it will result in a boe is your interpretation and not mine. By the numbers the CAB loses another 400k km^2 of area unless something unusual happens. Even so If all the other seas melts out completely, which has not happened before, the central arctic would still need to lose another 1.6 million km^2 of area in addition to the 400k km^2. The region in which the ice is in makes a huge difference. By the numbers I would expect the Beufort to end with 500k km^2 but due to its location and thickness and concentration 250k km^2 seems likely.
By the way I am using 3.75km area numbers, which I think come from NSIDC, for my estimates. They will be different for other measurements. The more seasons I participate in the more nuances I see in the data. 

5
Arctic sea ice / Re: The 2020 melting season
« on: Today at 06:07:43 AM »
This.

This is what I was getting at with the comparison post (of ice quality) I was getting at a few days ago.

I think the purple areas are a good preview of what our end of season extent will look like.

Extent will make a run at 2012, but not make it.

Area may quite likely drop below 2012, 16 & 19.

(Edit: I expect volume to drop in the tank, becoming lowest on record).

6
Arctic sea ice / Re: HYCOM
« on: Today at 01:23:53 AM »
Here is the current August 3rd run from Hycom.  The first pic is the current state of the ice.  The next one is their forecast for the ice on August 11th.  Also attached links for people to navigate there themselves.

https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticict/nowcast/ict2020080312_2020080400_930_arcticict.001.gif

https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticict/nowcast/ict2020080312_2020081100_930_arcticict.001.gif




7
Arctic sea ice / Re: The 2020 melting season
« on: August 05, 2020, 06:48:27 AM »
I'm reluctant to say this since I cannot prove it, but I REALLY am starting to wonder if we're witnessing a somewhat paradigm shift in the Atlantic currents to cause the breakup above Greenland/Lincoln Sea. I realize it's been quite warm in that entire region, but I do not think surface melt alone is enough to facilitate so much action and change.

There may well be a pardigm shift in currents as you say. But a more likely explanation comes to mind, although I could be wrong, but here goes: Off the north-east corner of Greenland you will find a very persistent and large polynia every single year. I don't think it is the one prosaically called the North East Water polynia (NEW), the description does not really fit. There is another Sirius Water Polonya as well, but that is considerably further south.

The polynia in question seems to be in the first stages of opening up in the image below. The grey blotch in the middle is what I take to be fast ice that has formed during the winter months and is here seen melting rapidly from below. The surrounding ice was not really moving this early in spring but once general ice movement gets closer to Greenland, this polynia can be more or less obscured by inflowing ice and is rarely "clean".

As I say, this seems to repeat every year that I have followed the Arctic and I seem to remember that there was a general consensus that this was caused by upwelling of warm waters that most likely had somehow escaped from the Spitzbergen current on the other side of the Fram strait, dippeed under the East Greenland Current, to resurface here at the coast of Greenland.

And it has of course occurred to me that the current opening up of ice further north of Greenland was somehow linked to this polynia and the warm upwelling. So not a paradigm change, no, but perhaps a change in magnitude - at least in temperature but perhaps also in the amount of water involved.

Or perhaps the combination of an existing current and persistent warm southerly winds were enough? And not to forget that winds over open ocean can strengthen surface currents, pulling them further and increasing their flow.

Both images benefit from a click.

8
Arctic sea ice / Re: Latest PIOMAS update (August 2020)
« on: August 04, 2020, 11:27:40 AM »
A focus on July and the larger picture.

Gap to lowest on record down to just 150 km3

9
Arctic sea ice / Re: The 2020 melting season
« on: August 03, 2020, 04:27:05 PM »
The Danes predict that by August 8, warm water will reach the North Pole.

10
Arctic sea ice / Re: The 2020 melting season
« on: August 01, 2020, 10:32:43 AM »
Beaufort Sea via RAMMB-SLIDER extremely fast playing to obscure the clouds.

Click to play. Trigger warning: Strobe effect!

11
Arctic sea ice / Re: The 2020 melting season
« on: August 01, 2020, 10:05:47 AM »
In physical reality, what matters most is thickness distribution (and volume), then area, then extent. If the ice is driven in a compacting transport, extent will plummet with not much physical impact, while the reverse is also true under a divergence regime. What we can see unfortunately with the satellites and models is the opposite, extent in high accuracy, area in medium accuracy, thickness distribution and volume with low accuracy and delays.
This allows both parties to have numbers and data on their side, which is fine, just has to be interpreted according to physics and not just visible numbers on a chart.
The sunny July did huge damage to the CAB in terms of volume, and the open Siberian seas are a disaster waiting for imports, while the Atlantic front has huge amounts of open water as in 2012 and 2016, very unlike 2019. OTOH the Beaufort is full of ice and the CAA and Greenland Sea are still holding up. The question we do not know is how much of the remaining ice is in marginal conditions - still whole for now but will melt out by mid-Sept. This is what will dictate the area numbers, and partially the volume numbers as well, as volume calculation is tied to measured area changes. The extent numbers will be dictated by area numbers, but very highly affected by compaction or divergence - very visible, much less important IMHO. 2016 was almost as low as 2012 in terms of area, but very high up in terms of extent.
My take on things is that the ice is thinner than appears, due to the impact of July insolation and due to very high movements in the last few weeks, which induced faster bottom melt. I have never seen so many days where the CAB was entirely visible, and this while the ice was doing a crazy dance around the basin. Then came the cyclone with movements induced in the other direction. The CAA has been sweltering in heat and the ice is all broken up. So I expect a some point a lot of the ice which originated with a standard FYI thickness will melt out, and so will some of the thinner MYI. This will probably leave us with a total area record or near-record, even though the Beaufort may not be in record territory at all. Oh yeah, I also expect a volume record. I can't say the same for extent, which might be far away from 2012's record, though surely below 2019. This depends on random September factors so can beat the seasoned forecasters easily.
August is upon us, the answers will be clear in a few weeks time, not much longer to wait.

12
Arctic sea ice / Re: The 2020 melting season
« on: August 01, 2020, 05:49:15 AM »
A lot changes in a week. A week ago a record year looked very possible but now the slowdown and dispersion have made a top 3 place seem likely. Even the thin ice takes a while to melt and as nights get darker peak melting has passed now.

Still a lot of things happened in the Arctic in 2020 that never happened before so 2030 free of sea ice in Summer is very possible.

Every year the Arctic makes us think it is all going to melt out only to surprise us in another way. Slowdown is well under way now but there will be further big drops bringing final Jaxa extent to just under 4m like 2019 but let's wait and see.

I was just thinking, "there are still 6 or 7 weeks left of melting, wonder how excited people can get based on one week of anticyclonic dispersion". Then I read the beginning of your comment, and thought, "here we go!" - but then I read the rest and was majorally mollified.

One week ago I escaped from a three-week Internet blackout only to see that I'd completely missed out on the July hammering. A new minimin seemed to be the generally accepted version of the future, anybody predicting anything else was quickly hammered down. Then a few days of blow from a short-lived cyclone and the previously repressed prognasticators rise to the surface, while even Friv seems to have lost steam.

I guess it is all part of the rich tapestry that is life. My two cents worth is that we will land in the middle of the fourth million, with a slim but real change of a new minimin. But what do I know?

13
Arctic sea ice / Re: What's new in the Arctic ?
« on: August 01, 2020, 05:35:00 AM »
Article in Scientific American about the current state of affairs and some tentative predictions:

Quote
On the other hand, strong storms can substantially break up the ice, potentially leaving it more vulnerable to higher temperatures and faster melting later in the season. And they can churn up the ocean, as well, allowing warmer waters to rise to the surface.

Quote
It’s all part of the vicious cycle of Arctic climate change. Within just a few decades, scientists predict the Arctic could be seeing totally ice-free summers.

14
Arctic sea ice / Re: The 2020 melting season
« on: August 01, 2020, 04:59:42 AM »
2020 has no chance to finish above 2019.  August would have to be one of the coldest in the modern record.

It's very unlikely.  Melt momentum is way worse in 2020 because of the laws of physics.

It's what happens when your entire summer torches.

What did people expect to happen???  2020 to keep losing ice at breakneck speeds until the end??

Without a "slowdown" 2020 would have crushed even 2012 by a ton.  No one expects that because the science says that wasn't likely. That kind of energy just hasnt been available this summer or any summer so far.

2019 had a warm summer 2020 had an epic summer

But we all have different opinions that's the fun of it.






15
Arctic sea ice / Re: The 2020 melting season
« on: July 31, 2020, 08:01:53 PM »
2019 vs. 2020
I was intrigued by how, on your gif, the 2019 ice looked in a worse condition is some respects, particularly in looking more scattered and therefore more vulnerable, blumenkraft. 


It is also important to note that according to the data from the neighboring topic, now the Аrea sea ice in the Central Arctic equaled the September 2019 minimum.

16
Arctic sea ice / Re: The 2020 melting season
« on: July 31, 2020, 07:52:27 PM »
2019 vs. 2020
I was intrigued by how, on your gif, blumenkraft, the 2019 ice looked in a worse condition in some respects, particularly in looking more scattered and therefore more vulnerable. 

So I made a corresponding AMSR 2 gif, again 2019 vs 2020, July 30.  I am undecided -- any analysis needs more expertise than I possess.

Warning: Large(ish) gif.    Click to animate

17
Arctic sea ice / Re: The 2020 melting season
« on: July 31, 2020, 07:10:47 PM »
2019 vs. 2020

18
Arctic sea ice / Re: The 2020 melting season
« on: July 31, 2020, 07:32:08 AM »
For anyone interested here is 2020 versus 2019, 2016, 2012....


19
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 01:10:08 PM »
But whatever the outcome might be, the gravest damage is already partly avoided: The open waters would not serve as giant collectors of solar energy, as strong insolation is already coming to an end in August.
I think you are wrong - the storm now is probably the worst that could happen, and if more storms arrive in the next weeks the situation will be even worse.

Insolation is falling very rapidly, albeit still strong, but the current cloudiness in the Arctic is probably working as an amplifier - the thin, practically see-through, clouds we have now are great for reflecting infrared radiation back to the surface, while letting a surprising amount of sunlight through.

Dispersion of the current icepack through repeated storms with light clouds inbetween is probablyby far the most efficient method of melting in the second half of the melting season. And one should avoid the trap of judging the health of the ice from above. We have no way of "seeing" thickness, and much of the dispersed ice is probably only half a meter or less. With melt from above and particularly bottom melt easily ranging in several cms per day, the rest of the ice could very well melt.

Which is not to say that a new minmin will be reached - 2012 had strong compaction towards the end, which can easily subtract 100k or more from extent.

20
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 30, 2020, 12:40:09 PM »
Two active ITP buoys 113 & 114 in the Beaufort sea are worth watching during the storm, both showing a massive mixing event in the form of a decreasing salinity gradient, down to a few hundred meters below sea level. It's destroying the freshwater lens while temps in the upper layers have been increasing. I expect rapid melt out of what's left in Beaufort and Chuckci seas in the coming days.



21
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 04:19:36 AM »
Sorry to ruin the party again but Hycom is thickness is not comparable between these years, the model has been changed several times since then, and 2012 has not been back-calculated.
BTW, DMI thickness is also not considered very reliable, again I would appreciate decreasing the frequency of posting it to the main thread.

Ah ok thanks for the info found a 2015 Hycom seems more compatible now they have fixed it, still a sucky year 2020. I Prefer data from small democratic socialist countries like Denmark and Finland, large democratic countries data is manipulated in a lot of cases it seems.

It could be argued that in a fast changing arctic, Its the models that are not updated that provide the poorest comparisons with past years. 2012 cleared out most of the years old hardened Ice. The sort capable of forming large pressure ridged fields. Unseasoned young ice, or waterlogged the previous summer is as little as ten percent as strong as fully brine excluded ice. The very rare legacy floe Mosaic used could be considered best case. May have spent many years hardning as fast Ice in the outer Siberian islands, yet the core of Its 7 m pressure ridge failed to fully freeze all winter.
On  about the best drift path it could have had.
 When they first picked it up it was waterlogged from base near to sealevel.
DMI is another example which seems to drift further from reality every year. Now showing up to three meter ice when the nearest has been slush hundreds of km further out to sea for weeks.

22
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 04:00:26 AM »
Sorry if this is ubiquitous and I just missed the boat, but is there one or a handful of consensus best thickness models/data and image sets to pay attention to in the summer? Hycom seems pretty decent intra-year unless I'm wrong there, but I was wondering if there is anything comparable or better out there to watch as well.

Off the top of my head - but this is a very difficult subject:

* Hycom seems to have quite improved recently, there is a thread started by interstitial that contains discussion of Hycom and comparisons to other thickness products. But because of model changes over time the comparison to the past is problematic, hopefully this has now been fixed going forward. My current working assumption is that Hycom is a viable thickness model. I am not aware of an accompanying volume chart or a numerical product, just the animated map and 7-day forecast.
* PIOMAS was usually considered the standard since I came to the ASIF, the model is more transparent with various numerical outputs (analyzed by Wipneus and others in the PIOMAS thread) and has good comparison between years. However it is especially painful because it is only updated twice a month. OTOH, it used to be once a month, so life is good. Like all models, it has its own problems and artifacts, some driven from NSIDC artifacts, and has an over-focus or maybe over-abundance of pressure ridges that may or may not be justified. It was validated against real-life thickness measurements back in the 2000s, but impossible to know if the calibration is still correct.
* Cryosat/SMOS is considered the standard for a measured thickness product, but is only published until mid-April. If I am not mistaken it makes some assumptions about snow thickness, surface wetness and ice salinity but is quite reliable.
* NASA's Operation IceBridge measures the ice by radar from an airplane. Naturally limited in time and space.
* The new IceSat2 should be the new gold standard of measured thickness products, but I haven't seen the data coming out of the project. See long quote below.
* DMI thickness and volume are quite colorful but not considered very reliable, for example due to weird behavior around the minimum.
* AMSR2 JAXA has a measured thickness product and volume, not reliable at all in summer.

Bottom line, in the context of this thread, of the summertime volume charts available:
DMI is not good but could be useful for comparisons from time to time.
AMSR2 is almost meaningless.
PIOMAS considered reliable.

I have quoted the below link in full, this is best discussed elsewhere but is good for the education of the readers here.

https://www.nasa.gov/feature/goddard/2020/icesat-2-measures-arctic-sea-ice-thickness-snow-cover

Quote
NASA’s ICESat-2 Measures Arctic Ocean’s Sea Ice Thickness, Snow Cover
Arctic sea ice helps keep Earth cool, as its bright surface reflects the Sun’s energy back into space. Each year scientists use multiple satellites and data sets to track how much of the Arctic Ocean is covered in sea ice, but its thickness is harder to gauge. Initial results from NASA’s new Ice Cloud and land Elevation Satellite-2 (ICESat-2) suggest that the sea ice has thinned by as much as 20% since the end of the first ICESat mission (2003-2009), contrary to existing studies that find sea ice thickness has remained relatively constant in the last decade.

ICESat-2 has a laser altimeter, which uses pulses of light to precisely measure height down to about an inch. Each second, the instrument sends out 10,000 pulses of light that bounce off the surface of Earth and return to the satellite and records the length of time it takes to make that round trip. The light reflects off the first substance it hits, whether that’s open water, bare sea ice or snow that has accumulated on top of the ice, so scientists use a combination of ICESat-2 measurements and other data to calculate sea ice thickness.

By comparing ICESat-2 data with measurements from another satellite, researchers have also created the first satellite-based maps of the amount of snow that has accumulated on top of Arctic sea ice, tracking this insulating material.

“The Arctic sea ice pack has changed dramatically since monitoring from satellites began more than four decades ago,” said Nathan Kurtz, ICESat-2 deputy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The extraordinary accuracy and year-round measurement capability of ICESat-2 provides an exciting new tool to allow us to better understand the mechanisms leading to these changes, and what this means for the future.”

Arctic sea ice thickness dropped drastically in the first decade of the 21st Century, as measured by the first ICESat mission from 2003 to 2009 and other methods. The European Space Agency’s CryoSat-2, launched in 2010, has measured a relatively consistent thickness in Arctic sea ice since then. With the launch of ICESat-2 in 2018, researchers looked to this new way of measuring sea ice thickness to advance the study of this data record.

“We can’t get thickness just from ICESat-2 itself, but we can use other data to derive the measurement,” said Alek Petty, a sea ice scientist at NASA Goddard. For example, the researchers subtract out the height of snow on top of the sea ice by using computer models that estimate snowfall. “The first results were very encouraging.”

In their study, published recently in the Journal of Geophysical Research: Oceans, Petty and his colleagues generated maps of Arctic sea ice thickness from October 2018 to April 2019 and saw the ice thickening through the winter as expected.

Overall, however, calculations using ICESat-2 found that the ice was thinner during that time period than what researchers have found using CryoSat-2 data. Petty’s group also found that small but significant 20% decline in sea ice thickness by comparing February/March 2019 ICESat-2 measurements with those calculated using ICESat in February/March 2008 – a decline that the CryoSat-2 researchers don’t see in their data.

These are two very different approaches to measuring sea ice, Petty said, each with its own limitations and benefits. CryoSat-2 carries a radar to measure height, as opposed to ICESat-2’s lidar, and radar mostly passes through snow to measure the top of the ice. Radar measurements like the ones from CryoSat-2 could be thrown off by seawater flooding the ice, he noted. In addition, ICESat-2 is still a young mission and the computer algorithms are still being refined, he said, which could ultimately change the thickness findings.

“I think we’re going to learn a lot from having these two approaches to measuring ice thickness. They might be giving us an upper and lower bound on the sea ice thickness, and the right answer is probably somewhere in between,” Petty said. “There are reasons why ICESat-2 estimates could be low, and reasons why CryoSat-2 could be high, and we need to do more work to understand and bring these measurements in line with each other.”

With ICESat-2 and CryoSat-2 using two different methods to measure ice thickness – one measuring the top of the snow, the other the boundary between the bottom of the snow layer and the top of the ice layer – but researchers realized they could combine the two to calculate the snow depth.

“This is the first time ever that we can get snow depth across the entire Arctic Ocean’s sea ice cover,” said Ron Kwok, a sea ice scientist at NASA’s Jet Propulsion Laboratory in Southern California and author of another study in JGR Oceans. “The Arctic region is a desert – but what snow we do get is very important in terms of the climate and insulating sea ice.”

The study found that snow starts building up slowly in October, when newly formed ice has an average of about 2 inches (5 centimeters) of snow on it and multiyear ice has an average of 5.5 inches (14 cm) of snow. Snowfall picks up later in the winter in December and January and reaches its maximum depth in April, when the relatively new ice has an average of 6.7 inches (17 cm) and the older ice has an average of 10.6 inches (27 cm) of snow.

When the snow melts in the spring, it can pool up on the sea ice – those melt ponds absorb heat from the Sun and can warm up the ice faster, just one of the impacts of snow on ice.

For more information on ICESat-2, visit www.nasa.gov/icesat-2 or icesat-2.gsfc.nasa.gov

23
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 03:10:48 AM »
Sorry to ruin the party again but Hycom thickness is not comparable between these years, the model has been changed several times since then, and 2012 has not been back-calculated.
BTW, DMI thickness is also not considered very reliable, again I would appreciate decreasing the frequency of posting it to the main thread.

24
Arctic sea ice / Re: The 2020 melting season
« on: July 29, 2020, 10:45:07 AM »
I have just looked at the data again, odd things popped up in the pre 2000 era data (including 2000) for certain but nothing like it in the last 20 years so see it how you will, it is a pattern break to me.

Image attached for comparison.  It certainly looks to me like it's the highest it's been, but there are similar excursions above the mean at this time of year in 2016 and 2008, as I think others have mentioned upthread.

Edit: replaced image with version with arrows indicating other excursions

25
Arctic sea ice / Re: The 2020 melting season
« on: July 29, 2020, 09:34:56 AM »
Apparently Friv you and I are the only ones shocked by this which surprises me! 
Perhaps the rest of us have seen Freegrass's post which shows that this is not at all an uncommon occurrence.

26
Arctic sea ice / Re: The 2020 melting season
« on: July 29, 2020, 06:50:35 AM »
For what's it's worth, HYCOM shows an interesting forecast for north of Greenland in early August - a large gap opening up, larger than anything I've seen there before.

Bear in mind, though, HYCOM does tend to be a bit enthusiastic at times. It remains to be seen whether its forecast comes off!

Source: https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticictn_nowcast_anim30d.gif

27
Arctic sea ice / Re: The 2020 melting season
« on: July 28, 2020, 02:17:58 PM »
Another quite large daily drop in area. We are now below 4 million km^2.

28
Arctic sea ice / Re: The 2020 melting season
« on: July 28, 2020, 11:49:26 AM »
Concentration for the 26th, 27th and both combined.

29
Arctic sea ice / Re: The 2020 melting season
« on: July 28, 2020, 01:43:57 AM »
So a cyclone starts laying waste to one third of the Arctic while the rest of the ice is bathed in direct sunshine while being caressed by warming winds...

What twisted mind thought up this scenario?

(image tweaked heavily for contrast on Photoshop)

30
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 10:52:34 PM »
Big heatwave in Svalbard ... three out of the four warmest days ever recorded are the last three days!

https://twitter.com/mikarantane/status/1287828295980113923?s=21

The reverse dipole is blowing all of that exceptionally warm air to the North Pole.

Even if we don’t set the record this year for extent, the central CAB is going to get hammered on volume.

31
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 10:47:14 PM »
    It would be interesting if an ASIF consenus for <3.5M km2 (with not a small chance of <3) (if there is any such consenus) is more accurate than almost all these offical expert estimates which cluster near or above 4M km2.  At this point I'd put my money on ASIF.
There are different metrics. September mean extent above 4M is quite possible. At least more likely than below 3M. This year has great potential to surprise but also some obstacles.
    Guilty as charged for conflating Sept avg with Sept min.  Still, those SIPN estimates look high.  but the truth will soon be known!
IF 2020 remaining melt to minimum (and sea ice gain in late September) is at the average of the last 10 years, the September NSIDC Extent average would be 3.68 million km2. Just, but only just, above 2012.

32
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 10:24:17 PM »
The SIPN median from the July report was 4.36 million km2.

Lowest NSIDC average for September was 3.57 in 2012.

For the ASIF, the most relevant poll is Juan's poll here :

https://forum.arctic-sea-ice.net/index.php/topic,3154.0.html

The mean of the ASIF predictions is 3.67.

So ASIF prediction is approximately 0.7 below the SIPN.

33
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 05:15:46 PM »
Binntho, good afternoon,

I was considering an answer, but you expressed it quite punctuated. Over the years, I often felt struck by the similarity in form of bathymetry and remaining ice at the end of the melt season. But I never struck upon an explanation that convincingly tied the two.
The sink of saline waters N of the Svalbard-Frantsa Yosefa continental shelf, sure. But the year over year quite constant ice pack front over there is partly based on the formerly well structured 'safe haven' of 1,8 Mkm2 N of Greenland. Wind moved ice usually formed a dense belt, not free to move further N.
Now that the whole pack is more mobile than ever, it 'll be interesting to see what the 5-8 Bft southerly winds are capable of (ECMWF +96-+240h).

A causal link between bathymetry and patterns of remaining ice at the end of the melt season is almost certainly the case!  The oft mentioned stratification of the Arctic cannot properly occur in the shallow ~50m waters of the continental shelf particularly on the Russian side.  The shallow seas combined are only around 2% of Arctic water volume and on the Russian side is where most of the large rivers empty into the Arctic.  Inflowing rivers are I believe about 2% of annual Arctic inflow which would have a negligible effect on the deep arctic but could be expected to be significant to the shallow coastal seas much smaller volume.  The deep arctic is subject to different conditions than the shallow seas and would be expected to behave differently.

34
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 03:03:59 PM »
To put matters to rest, nobody called other posters' analysis crazy. The notion was the outcome was crazy, to which I agree wholeheartedly. And indeed with the passing years what used to be crazy is becoming commonplace, and this trend is the really crazy thing.

35
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 09:54:15 AM »
Thankfully these crazy predictions of 2.5million are now gone. Looks like a stall will mean we finish in the pack. Though probably whether we come 2nd or 3rd will be the only question. Think 2019 and 2020 will be very close at the end despite everything. Hopefully August will be a boring month for the ice.

We have not yet seen what the impact of the cyclone will be. 

Area is still dropping significantly, and I consider that to be a more important metric than extent.

Again, 2.5 million is still on the table.  There is a huge energy budget for bottom melt and a lot of ice under 1 meter out there.  That's before we consider what the storm and continuing insolation will do - it's still over 300 watts/m2 currently when ice is exposed.

In general, I concur with Oren - I don't yet see a scenario where we don't reach at least 2nd.

36
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 09:52:30 AM »
... I think I will read posts in future and not write.

Sometimes Friv might be a trifle 'trigger happy' with all those guns he is touting but his postings make interesting and informative reading.

We cannot all be so knowledgeable as Friv and sometimes just feel the need to express our 'opinions', so keep posting  :)

37
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 09:23:07 AM »
Here's a comparison of the concentration averaged over the 23rd to the 25th, vs the concentration from the 26th.

38
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 09:06:30 AM »
July 22-26.

2019.

I was looking at nullschool this morning and thinking that the entire pack was going to drift away from the Greenland - CAA coast and towards Siberia over the coming week. Aluminium's excellet gif seems to show that process starting up!

39
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 07:13:08 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

July 26th, 2020:
     5,962,825 km2, a drop of -31,737 km2.
     2020 is the lowest on record.
     Source: https://ads.nipr.ac.jp/vishop/#/extent

Maybe today news is only this image and what it represents...


It's pretty amazing that just about anywhere the clouds thin out Concentration plummets.

I expect losses to be steady through August   2012 and 2020 will likely end up essentially tied by the middle of the second week of August unless this vortex rips up a big area of ice on the quick.

Thats impossible to know at this point how fast things will collapse.

Collapse they will

40
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 05:26:55 AM »


Slaters model predicts well behind 1st place, and serious risk of falling outside the top 2.

Current conditions and forecast have a significant amount of cold covering most of the ice that has big influence on the final extent minimum - the arc from Beaufort through ESS and to Laptev.  Beaufort has the forecast of a strong low to deal with, but I think this will be above average melt rather than apocaylpse.  Beaufort has been disperse for quite a long time now, plenty of time for the ocean to absorb heat energy to be stirred up by the storm.  But it has been the cool cloudy corner of the Arctic and the thickest multi-year ice has been pushed towards this sector a fair bit.

Big heat forecast is for north of Greenland on ice that has never melted out before.  Sooner or later there will be a first, but I see no obvious signs of it being this year.  This heat will move into the Laptev later in the forecast period where it will be able to have an impact on ice that is borderline - that is neither guaranteed to survive (barring something extraordinary), or guaranteed to melt out.  There is some heat on the ESS side as well but that only reaches a short way from coast onto ice that is almost all but guaranteed of melting anyway.

Current conditions according to EC 12Z 00hr lead  link.  Forecast has heat circulating further towards Laptev and eventually ESS at longer range.


41
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 05:08:21 AM »
Cyclone damage forecast for ice.

https://psl.noaa.gov/forecasts/seaice/

To me that looks less like a prediction for cyclone damage and more like a prediction for a complete stall in extent loss.

42
Arctic sea ice / Re: Arctic Image of the Day
« on: July 27, 2020, 02:29:19 AM »
Shoot tonight between 23:30 and 01:30 at Årvikstrand, Northern Norway. Last day with midnight sun at this spot.

43
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 11:56:29 PM »
Cyclone damage forecast for ice.

https://psl.noaa.gov/forecasts/seaice/

44
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 11:38:25 PM »
There is a noticeable increase in surf on the Barrow webcam.

45
Glen, that is pretty straight forward. Just click the 'Attachment and other options' below the input window. There you can choose a file from your computer to upload.

Generally, i would say it should be compressed (i.e. JPEG format).

A good way to compress images is to upload them to a website like lunapic.com. There you can compress/convert to JPEG/scale/crop/etc.

If you have an image that is 500 pixels or below of canvas size, it will be displayed by the forum software as it is. If it's bigger, the forum software would shrink it and only show the full resolution if you click on it.

There is also a posibility to load pictures from an external source. In this case, you copy&paste the image link, select the link, and click the 'Insert Image' button (above the input window).

Hope that answers your question. :)

46
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 10:37:10 AM »
Here is my current prediction for the sea ice min.

I'd love to see everyone's thoughts.



The region you indicated in that map is about 2.0 million km2 (based on pixel count).  I would be very surprised if the minimum extent is that low.

47
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 07:44:25 AM »
Going back to some of the comments up thread, one of the disturbing things I see in the weather over the next 5 days is the precipitation - up to 5cm in some parts of the Beaufort and Chukchi - falling as rain.

That's a huge heat input and will devastate the thinner ice.  Won't particularly help the thicker either.  It will help with the general weakening of the pack.

A lot of rain will also wash over the CAA.  Not as much, but enough.

48
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 01:33:01 AM »
A look at one small part of the CAA, south of King William Island, over the last week. This is one of the southern most parts of the CAA.

July 18 - July 25. Click to play.

49
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 10:17:47 AM »
First, Resolutes all-time-high is 20.1° from July 2 by 2012.

Second, Friv, I think your map over the minimum is somewhat pessimistic. I don't think that the Laptev bite will make it all the way to the pole. It should be close though and only depend on that time is running out. A bite reaching to 88-89°N seems very realistic given that HYCOM is right. A minimum around 3MN km2 is right now a likely outcome.

Third, the latest forecast from EC is very problematic. The Beaufort should get seriously hammered by the sub 980-cyclone. And the extent losses will likely be slow or very slow for the rest of July.

Fourth, another thing of concern is how much ESS and Chukchi will warm up until fall and cooling will start. Kara, Laptev and Baffin are supercharged with heat and will take time to cool down.

And finally, fifth, a new record low extent is not the worst thing to happen. A new records low volume is. And especially if we are going to see the thickest ice take a huge damage the next 10 days. That should make next melting season primed for another record low. We can't hope for another winter with such a strong polar vortex.

50
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 09:49:59 AM »
Well 24 hours later and numerous changes in the forecast yesterday on GFS showing the Beaufort low weakening, the 3 day forecast now shows it is back and strengthening to a possible 976 with increased wind speeds over 50kmph. Now appearing more likely to have an impact as the forecast becomes more reliable within the 72 hour period.

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