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Messages - subgeometer

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Arctic sea ice / Re: The 2019 melting season
« on: Today at 03:22:31 AM »
The GFS gets really ugly from about 150hrs with a massive dipole developing which, if it eventuates, will pump rubble out into the Barents Sea and Atlantic for the rest of the run,  fed by a pair of lows sucking heat plumes from Siberia and the Mackenzie valley. Ice to 84N north of the Laptev is showing signs of staring to melt out already - the area at 84N between 105 and 120 will be one of the first patches to go.

Bringing up the rear, a third low(triplets!) sucks in moisture, loaded with latent heat, coming north from the NW Pacific monsoon.

The only cold is in areas with doomed ice, perhaps the cold indicates extra melt going on?

This is still way off, so treat with caution, but it would be diabolical if it works out, I've attached wind and surface pressure, surface temperature and precipitable moisture maps from a whopping 189hr out,

Arctic sea ice / Re: The 2019 melting season
« on: Today at 02:35:49 AM »
Hrm that solid infiltration through  the bearing straight is also concerning, if that in the chukchi shallow shelf starts to fill up with saltier water and a big storm hits, the potential for some mixing out into the freshwater could be devastating to... hrm... well on the "plus" side there's not much ice left there to melt... but  if it can start a mixing processing and salt water keeps flowing in from the pacific.... anyone know a real time   source for currents and temperature / salinity depth profiles for the bearing straight? I've poked around google with no luck...

In my mind, the danger is not that warm, saline water infiltrating the Chukchi from the Pacific will melt ice currently in the Chukchi. Because there's really barely any ice currently in the Chukchi to melt.

On the other hand, a real concern is that this continues the process of converting Chukchi hydrology to more closely resemble Bering (or Pacific!) hydrology. That's actually more dangerous to the cryosphere in general than Atlantification because of the bathymetry involved; the risk is a long-term state change for a basin rather than just a slow(-ish) advance of conditions along the Arctic/Atlantic boundary.

The Chukchi is perhaps uniquely vulnerable in this regard, being both comparatively shallow and directly adjacent to a more traditionally "oceanic"-behaving ocean.

Parts of the southern Chukchi sea are already melting out in winter the past few years when warm air intrudes, while the Bering Sea barely ever has any sea ice at all, so I think that Pacification process you describe is underway. SST anomalies are off the chart across both seas, the climatology of the region has changed. So much heat has been added there this season so the delay before refreeze will further extend

Arctic sea ice / Re: The 2019 melting season
« on: July 18, 2019, 06:24:28 AM »

The 18z GFS is back to the idea of another surge of Pacific heat and moisture, starting about 5 days out and intensifying to the end of the run.

Windy/EC is in general agreement. Lows over Chukotka and the ESS act like cogs to draw a stream from way south, while northern Alaska bakes again. Clear skies over the Chukchi sea under the warm breeze will boost SSTs further. Dew point of 2C over the ice. Clouds form once the humid ocean air has travelled a certain distance over the ice, for a good longwave irradiation. This will hasten the doom of the huge area of visibly thinning ice north of the Chukchi sea

Arctic sea ice / Re: The 2019 melting season
« on: July 18, 2019, 05:10:30 AM »
The DMI volume chart is hopeless, at best a week or 2 out of date. It's showing a ice over half a meter in open water in the Laptev bite today, and great swathes of ice in Baffin Bay in these 2 maps dated 16 July from Bremen and DMI - though what date the DMI really refers to, who knows

I've attached the comparison as both a gif(click to and an mp4. The MP4 plays fine locally but its been a bit of a lottery trying to get them to play on the forum, at least in my browser

Arctic sea ice / Re: The 2019 melting season
« on: July 18, 2019, 04:06:59 AM »
What Friv says. The ice was very thin in large regions of the Arctic when the GAC came. It finished all this thin ice, and extent plummeted. Had it not appeared on the scene, most of that thin ice would have melted anyway until mid-September. The GAC did make a significant contribution, but not as significant as the extent numbers show.

I'm not very familiar with the weather history of 2012. There was clearly plenty of momentum by this stage. JAXA shows a big week  from July 23-30 with a 7 day loss of 810000 km2, then a lag eg losing only 20K on 1/8(these lags often seem to presage a big fall to follow- was there some general spreading of the fringes through a low pressure setup?), but maintaining its lead over 2007, before plummetting again August 3 loss was 120K. Losses accelerated thru the the GAC,, peaking at 190K on August 8 and then 'easing' to 70-80000km2/day for the weeks following.

by the end of July  2012 was heading for the record. The GAC did push the melt edge much forward,, so the inner CAB ice was exposed earlier, so I suspect that enhanced the melt friendly conditions somewhat from then on

My condolescences to Neven and your family at losing your dad. Judging by his son he must have been quite a fellow

Arctic sea ice / Re: The 2019 melting season
« on: July 17, 2019, 09:57:57 AM »
A lot of the cloud on Worldview today is thin enough to peer through, and wherever you look ,from the Pacific to the Atlantic across half the basin, is dispersed ice,and  in many areas showing telltale signs of melt

I've attached images of 2 areas, colour coded 2 match  with the squares at 77 and 81 N in todays Bremen extent map

Edit: I forgot to add that the images have had the contrast enhanced by monkeying around with levels in Gimp

Arctic sea ice / Re: The 2019 melting season
« on: July 17, 2019, 02:30:30 AM »
Holes are developing all over on the Eurasian and Pacific sides as dispersion takes its toll and areas of FYI start to melt out.

The area shown is about 84-85N, north of the Laptev Sea, and a few hundred km from the Atlantic Front. If I can find time I'll have a closer look with Sentinel as things progress

Arctic sea ice / Re: The 2019 melting season
« on: July 16, 2019, 02:43:20 AM »
July 10-14.


That's a good example of Coriolis forces at work as the pack pushes out in almost all directions, with export to Barents, Kara, Laptev ESS and Beaufort.

The pack's illusion of elasticity, expanding to fill the space when "stretched", is starting to fray, especially in thde Pacific and Euasian sector, with holes appearing everywhere. On Worldview, peering thru thin cloud, there's a huge area that looks like it will be nothing but goodbye waves in 2 weeks, perhaps as far as 80N

Arctic sea ice / Re: The 2019 melting season
« on: July 16, 2019, 02:24:21 AM »
Looking at the 3,5 and 10 day GFS forecast, it looks like melting momentum is going to get a big test.

Average atmospheric temperatures away from the coast in the Chuchki, ESS and Laptev are heading to ~ zero C according to the forecast while we get some warmth in the CAA and CAB in the coming days.
Are you sure?

I checked again and it still looks the same. Lotta pale blue in those 3 seas.

The cool temps may retard things a bit but Ice in those seas is toast already. The Chukchi is almost ice free, and about half has SSTs over 10C. (How warm will it be in another month, 15C? That's going to seriously retard refreeze in that region, and is a lot of potential energy for late summer/autumn storms)The EC on Windy also thinks the the Laptev Sea will get a moderate torching(compared to June) from Saturday to Monday to finish off the coastal ice, and then a small but fairly intense cyclone in the ESS will complete the destruction of its ice.

The heat on the other side (20.5C at Resolute!) is a worry. Area seems to be going down fast still despite extent bounces in many of the regions. CAB and ESS went up a bit yesterday, Laptev sideways. I;ve attached the Norwegian Arctic ROOS area graph which shows 2019 pulling a bit ahead of 2012, and maintaining a crushing momentum, while 2012 eases off a little

Arctic Roos has a coarse SSMI resolution. Does anyone know if JAXA or Bremen etc publish an area graph?or Wipneus etc from their data? I've drawn a blank trying to locate anything giving global area, even raw numbers, apart from Arctic ROOS on the excellent ASIG pages, but I'm probably missing something

Arctic sea ice / Re: The 2019 melting season
« on: July 15, 2019, 02:03:36 AM »
Agree 100% with Friv about the BOE. It is not going to happen.

2012 is on everyones lips here but most people forget that 2012 not only had extremely good preconditioning and melting momentum but also two "prepper" years as both 2011 and 2010 was.

Personally, I think 2019 will end up at place 2-5 depending on the weather conditions during the next month.

I agree on BOE. But I also think this may be a prepper year for it.

In preparation for this year, the arctic has had poor winters since 2016. Last year it was a bit colder, but the extra ice went to the Atlantic Front, and it only took a bad May and June to bring volume back to a record low.  Area is still going down fast, and extent is keeping just ahead of 2016,  2012, and 2007. So A record can't be ruled out. The next PIOMAS update in a week will be very interesting

Arctic sea ice / Re: The 2019 melting season
« on: July 15, 2019, 01:16:05 AM »
The Lincoln Sea is pretty warm the next couple of days as winds blow up Nares strait and off Greenland etc. Those  huge areas of bare rock must drive a lot of thermals, adding turbulence, as well as more heat to the foehn wind this area is subject to?

I've added the Windy forecast for about now, as well as a Worldview image of the area yesterday

Arctic sea ice / Re: The 2019 melting season
« on: July 13, 2019, 05:32:31 AM »
Laptev bite has reached 80°N now.

Well...the bite ate 80 a week ago. It is now at 80.5!

Along with the temperature drop, the main effect of this cyclone will be to push some sacrificial ice south into the Laptev bite, which will temper its advance north for now, and maybe lower SSTs a bit

While its a big improvement on recent days, temperatures are still at or mostly a bit above average except a small area of the southern Beaufort according to GFS 5 day anomaly forecast today on Climate Reanalyser, and the warmest region with sea ice is the CAA and CAB north of it and Greenland,. Maybe not warm enough, but it keeps things interesting. With strong winds at times coming off areas of the coasts there, the pack might lift off in places

And there's a lot of heat in western Siberia available if some system develops to draw it further north

Arctic sea ice / Re: The 2019 melting season
« on: July 12, 2019, 03:26:22 AM »
It's just a huge task.

Here is 2012 on September 14th.

There's not much more 100% concentration ice on today's map than in 2012 after the massive compression against Greenland and CAA that ended the 2012 season and made its minimum so strikingly low. And a lot of this years high concentration ice is in areas that are likely to melt out or go close, north of the Laptev and ESS, or on the Atlantic front. There's a persistenr region showing lower concentration close to the pole, though its difficult to know for sure, that area has been constantly cloudy. But the holes are not difficult to find on worldview in the pack north of the Beaufort sea, and rest of Pacific and Siberian sectors. The pack could look very ragged and ugly come September, even (particularly?) if there's no new record

Arctic sea ice / Re: The 2019 melting season
« on: July 12, 2019, 02:45:47 AM »
Perhaps the CAB has copped less sunshine than in 2012, but DMI 80N temps have been warmer so far this melt season than 2012, despite the Atlantic front being further south. We had record melt fractions on the ice in June. And there's the insane SSTs, still increasing, providing energy for storminess (Substantial areas of the Chukchi are now  10-11C on Windy TV, has that ever been seen before?). And there's a lot of FYI all the way to the pole. We are currently record low by extent area and volume, and there is substantial momentum, at least for the next while.

I wasn't paying attention in 2012 so I don't have a feel for it like some others here. But I don't think a record can be discounted as yet, and I'm pretty sure we'll still be well ahead of 2012 when it takes its next big plunge in about 2 weeks

I've attached DMI charts for 2012 and 2019 so far

Arctic sea ice / Re: The 2019 melting season
« on: July 12, 2019, 02:19:16 AM »
July 6-10.


Your gifs are awesome Aluminum. Thank you.

It'd be great to see a longer period, like say the past 2 weeks, as an MP4 or other movie format, which are much more memory efficient

Arctic sea ice / Re: The 2019 melting season
« on: July 10, 2019, 03:02:22 AM »
Oh and I haven't really seen anyone talking about the MASSIVE PUSH OF HEAT the next few days that settles into the CAB.

The surface maximums aren't so dramatic as along the Siberian shore but the CAA has been under the hammer through July so far, and that;s only going to continue

Over the next few days as half the basin is covered by Russian heat and humidity, warmth also starts advanced from the CAA to the pole, and gets there about day 5.

I've attached the GFS 3 day average forecast, as well as 105 hrs into the 18z run, to show the advance of warmth from Canada, along with 900hPa (ie at around 900m altitude) temperatures from Windy TV for about now, and in 5 days.

That's not cool. 8)

Arctic sea ice / Re: The 2019 melting season
« on: July 10, 2019, 02:14:45 AM »
PS what was the source by chance?
I really like the source - pogodaiklimat - because it has graphs of the past and not just a forecast like most weather sites. It compares with daily climatology. It shows a whole month at a time. And archives the graphs of past months and years that you can access at the bottom of the page.
Downsides are that it's in Russian (Google translate to the rescue), and only covers Russia and ex-soviet states, world big cities and the USA (but not Northern Canada or Greenland).

Here are my bookmarks plus a few others I managed to find now thanks to your question.   Kotelny Island  Tiksi  Pevek  Barrow  Wrangel Island  Vize island (Kara/CAB/Barents border)  Heiss Island (Franz Josef Land)

Windy  TV also includes weather stations on its map,and you can bring up a graph of observations that scroll back quite a way(but you can't display more than a few days),  its in English, includes Canadian posts and uses the same station ID numbers as listed in your post.

You can search for stations by name and number, and if you bring up the forecast for some location, at the end it might list the nearest weather station, if you're lucky. Weather stations are sparse in the Arctic, and only at the margins

I've included a screengrab of recent observations from Resolute (which like the rest of  CAA and adjacent CAB is forecast to remain "warm" for the next week , despite all this talk of cooler conditions)

Arctic sea ice / Re: The 2019 melting season
« on: July 09, 2019, 01:59:33 PM »
380K drop in the past 3 days on JAXA, and that trajectory will continue for a bit as the Pacific and Eurasian fronts rapidly retreat and Hudson Bay and the Kara Sea expire. 2012 and 2016 both lag a bit over the next week or 2 so 2019 might be 300K or more if things go bad ahead in 2 weeks.

On JAXA in a fortnight on 22/7 the leader of the pack is 2007 on 7.02 )million km2, only 1.12 million ahead of today(or 81K per day - 2007 itself dropped 1.5 million km2  during this period) . Momentum and the next few days weather will keep 2019 well in front, at least for now

Edit - 2007 dropped 1.5 million km2 in the next 14 days, not 1.4

Arctic sea ice / Re: The 2019 melting season
« on: July 09, 2019, 12:55:40 PM »
July 4-8.


Momentum across the board at the moment. We'll see if the forecasted cool weather can put the brakes on it.

Its not really that cool on the current GFS on Climate Reanalyser, Alaska and eastern Chukotka and the Pacific sector  have no reprieve, the CAA stays warm, and massive heat build in Siberia ready to blast through the Laptev sea, if we're unlucky. And the storms will struggle to drop the surface to 0, its the warmest part of the year in the high arctic

Arctic sea ice / Re: The 2019 melting season
« on: July 09, 2019, 03:28:48 AM »

I'm not real knowledgable about this, but I'm assuming negative height anomaly over the Laptev increases likelihood and strength of surface lows and storms there, like the D9-10 cyclone in the EC. Terrible timing coming just as direct insolation starts to  drop off.

Turn on the washing machine?

Arctic sea ice / Re: The 2019 melting season
« on: July 08, 2019, 07:15:10 AM »
More greying ice in the ESS

I copied the cloud free area in the square in gimp, resized the image to one pixel, then looked at the level, which is 107.

In 8 bit graphics mid-grey is 127 or 128 (0 is black and white 255), so this ice is closer to black than white.

Naively dividing 107 by 255 to get a value in the range from 0 to 1, that comes out to an 'albedo' around 0.42 That ice is pretty good at collecting light energy, Given the ice darkens as it deteriorates, it's going to accelerate the final meltout of that and similar areas.

The pack is nowhere as grey as this coastal stuff, a, but its visible greying after melt onset gives an extra kick to insolation potential(moreso in bad years), and there is a long stretch of seas off the Russian coast that can collect continental dust etc

Arctic sea ice / Re: The 2019 melting season
« on: July 07, 2019, 09:24:59 AM »
After its ill treatment, all the coastal ice along the Russian coast is about to expire(that which hasn't already)

I've included a pic of the southern Laptev Sea today, with a gif of a section showing yesterday and today

Arctic sea ice / Re: The 2019 melting season
« on: July 07, 2019, 04:49:25 AM »
RE: hot Chukchi and Bering Seas

I wonder whether this means that the freezing season will be even more amazing than the melt season - meaning that these "hot" seas could take ages to refreeze come autumn...

The Bering has struggled in recent years to freeze at all, and melts out at the hint of warm weather, even in late winter. The Chukchi is also freezing later, and melting earlier. This year will be the same even if the SSTs don't go up some more (unlikely!). A winter with constant northerlies might turn back the trend for a bit, but who knows at what expense to say, the Atlantic side

The freezing season is bound to be fascinating, perhaps more than 2016-7, with a combination 0f 2012's low minimum and really high SSTs

Arctic sea ice / Re: The 2019 melting season
« on: July 07, 2019, 04:23:10 AM »
Wrangel Island is not going under 10C through day 10 of the Windy/ECMWF forecast today, lowest min next 5 days is 13C, with only wednesday not getting over 20C, it only makes it to 19, after some rain at 16C in the morning

Pevek a couple of hours ago was 17C, with dewpoint at 8 (Edit: fixed dewpoint, not 11C, 8C)

(The maps behind are dewpoint forecasts)

The CAA also continues to be warm. This is shaping up to be a historic week of a historic summer. I think in 2-3 weeks 2019 will have stolen a march on 2012 area and extent.

The end of the forecast hints at deepening lows stirring up the Laptev bite. As the continents start to cool in August storms are going to be attracted by potentially 10C SSTs over large areas, like flies to $hit

Arctic sea ice / Re: Latest PIOMAS update (July 2019)
« on: July 06, 2019, 04:43:57 PM »
Updated volume and volume-anomaly graphs.

Click for larger pictures, helps reading the tiny fonts.

Thanks for the amazing work.

The data is stark - it looks like 2019  is 200 km3 ahead of 2012 at this point. That doesn't leave a lot of margin, given the weather and momentum

Edit: OOps, my bad, misread the graph. upped the difference 10X

Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 07:49:36 AM »
The ESS former fast ice ice is in no shape for the blowtorch its about to go under. Nor is the Laptev ice which is extremely grey, and collapsing now. A lot less cloud on worldview today

Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 06:54:21 AM »
Currently it's 21C at the weather station at Niuqsuk Airport, just east of Barrow,  with the dewpoint at 11C, with the breeze blowing straight out onto the sea
Those dewpoints mean the ice will be literally sweating the moisture out of the air even without rainfall, with the attendant transfer of heat.  Same applies to any open water as well, assuming SSTs of around zero.

Windy says that, right now temps are up to 25C on Wrangel Island, with similar maximums each day.

(Like the temperature) the dew point drops once the air gets over the ice(3C at the surface, it rises to 6C at 950hPa and 8C at 925, at the pt indicated), but a large and increasing area will experience dew points of 2-4C in the days(and days) to come.

I've attached bunch of screenshots from Windy to illustrate, of surface dewpoint, temperature and humidity. as well as clouds for daytime on the 8th(ie 2 days out). 3C dewpoint, 4C temp and 98% humidity, which as it turns out is predicted to mark the edge of clouds - a lot of ESS ice will be undrr full sun as well. This is going to be interesting to watch

Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 04:49:38 AM »
Laptev fast ice breaking up with great rapidity in the region of the Lena Delta.

The fast ice nearer the delta broke up extensively about a week ago (it disappeared long ago right next to the delta).  The ice now breaking up in the image was spotted by grixm yesterday.  Today, there are many more cracks in this area, which to me indicates ice that has passed a certain threshold of integrity and thinness.  Melting may be rapid from here.
July 8 Nullschool forecast, surface winds and temps.

Looking somewhat toasty for the ESS...

For both reasons, I think that the Northern Sea Route will open earlier this year. End of July? On the middle of july (10th. to 20th.)? Beginning of August? Any bets?

The strait from the Kara to Laptev appears to be open already. I think there will be open water through the ESS by the end of the month, given the heat over the next week

Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 04:39:06 AM »
independent of the exact extent and area numbers, i start to think that the shape of the remaining ice in the CAB will be eye-catching as well. as i said earlier, i expect an ice free pole (not just a few hundred meter polnya) and the volume will most probably hit new record lows for the rest of the year. very interesting to watch and i think it won't take so much time anymore until we shall get a view answers to year-old questions.
I actually am not so sure the pole goes ice-free. It is simply SO hard to make it happen because the vicinity is already refreezing by September. I think a record minimum is now 50%+ likely. But I don't know if that is necessarily accompanied by ^, and if it is, I think it will be "barely".

The Slater model's appearance for 8/23-24 is what I would expect at that time. It is finally picking up on the fact that the entire PAC front is going to collapse. This gives us an easy path to a 2-2.5MKM^2 area and ~3M KM^2 extent minimum, the question is whether we go any lower.

TEALIGHT: Do you have updated forecast maps based on your albedo model? Would love to see!

The more open water near tor above 80N the more the refreeze lags in autumn (especially if the SSTs have timre to increase).  The recent cooler weather in Laptev sea may just save us this year from open water extending  to the pole, though at least according to DMI the ice is all <=1.5m in thickness from the Laptev bite to the pole. That chart isn't considered that good, has PIOMAS spoken?

The heat accumulating on the Pacific side is a worry though. The Chukchi sea struggled to refreeze last year, the Bering barely managed to at all. The adjacent parts of the CAB lacked a cold bulwark on that side in autumn and early winter. I fear that it will be worse this year

Right now the front is retreating fast in the sector, clouds cleared today around Wrangel Island and the Chukchi ice edge as the next round of heat moves in, I've attached a worldview image

Arctic sea ice / Re: The 2019 melting season
« on: July 05, 2019, 05:30:59 AM »
The Chukchi ESS and western Beaufort are a killing zone right now. The ice edge is being pushed back, a lot, and melting as it goes. That's clear from the Bremen AMSR2 maps. There's a rainband dropping 20mm along the margin between open water and ice today. When the cloud clears enough to see(and they may not for a week) I think it will look very bad. At least it's not accumulating insolation, but there's enough warmth under the clouds to do plenty of damage.

AS an aside the surface pressure map is odd the next few days, with lows and highs all around the same pressure , just either side of ~1020hPa. A few runs ago GFS had a marked low with central pressure of 1025, I've never seen a low that high

Arctic sea ice / Re: The 2019 melting season
« on: July 05, 2019, 03:15:14 AM »
Currently it's 21C at the weather station at Niuqsuk Airport, just east of Barrow,  with the dewpoint at 11C, with the breeze blowing straight out onto the sea

Arctic sea ice / Re: The 2019 melting season
« on: July 05, 2019, 02:43:42 AM »
For the next few days, at least, high pressure and warmth dominate from Kara through the central CAB to the CAA/eastern Beaufort. These are the parts of the Arctic that have been relatively protected so far, and now they will be exposed to surface melt/melt ponding and high insolation.

I think this pattern will be bad for the ice. The southern Laptev and ESS are already in such bad shape that they will melt out anyway over the next few weeks, particularly with the help of warmish river water, while Chuckchi and the western Beaufort have the high SSTs and southerlies through Bering to contend with. Add in continuing Fram export...

Beyond this, the models seems a bit unsure whether high pressure will dominate the whole central Arctic or whether the high pressure will drift across to the Eurasian side, allowing a low to develop over Beaufort, creating a reverse dipole.

Based on the emerging pattern, I expect high losses for the next 2-3 weeks, but I wouldn't dare to predict whether they will be steady or occur in fits and starts.

Its not just the rivers. The areas under cloud may be protected from sun, but temperatures are high, and the precipitable moisture levels are nuts - not much of an arctic desert this week coming. One huge blob of moisture is being pushed from Eurasia via the Kara to rotate north of Svalbard, with surface temps around 2C, while the Alaska and Chukotka heatwave pushes warmer air and more moisture in from the Pacific. The melt over the past few days has been very aggressive on that side as we see in the Bremen animation, and that's only going to continue, if not worsen. (Warm?) rain and a lot of longwave radiation, as well as very high SSTs close by

I've attached 5 day GFS forecasts for NH max(cor blimey, that's a lot of red) and avg temperatures, as well as precipitable moisture and rainfall(precipitation, ~20mm in places, but not much will be snow).

Arctic sea ice / Re: The 2019 melting season
« on: July 03, 2019, 03:22:34 AM »
NSIDC concentration map for today. erm, "dispersion"

Not much 100% ice according to this

Arctic sea ice / Re: The 2019 melting season
« on: July 03, 2019, 01:32:54 AM »
The dispersion used here means "dispersion of the pack in floes separating to each other". The examples we have today is Beaufort and somehow Kara. Caused by storms, usually.
Many examples you bring are called Trasport, or export, ect

Dispersal and Ice transport aren't mutually exclusive(any more than transport and compaction are). Recent Ice transport from the CAB into Beaufort, Barents and Greenland seas (all export)have seen their extent cease declining or go up while the CAB hasn't shown losses in return. That's why I used them as examples to counter what I saw as misrepresentation of data and the 'outlook'. Not to prove that "dispersion" was some really important Thing

Edit: There is a measure for dispersion: extent vs area as in the compactness charts Neven publishes(The problem is that they're too noisy for day to day comparison - the area and extent are on too coarse a grid maybe). But eg what's happening under the cloud north of the Chukchi sea is a lot more interesting right now, surely

Arctic sea ice / Re: The 2019 melting season
« on: July 02, 2019, 08:25:13 AM »
I've included a couple of archived Bremen concentration maps (earliest I could get for July was the 23rd), and as you can see, 2012 and 2016 don't appear definitively "holier" than 2019; at least from what I can tell. (edit - though 2019 has a lot more purely open water.)
Here's the Bremen map for the 3rd July 2012.
Brilliant!  Thank you!

I think it does bear me out; I don't think either year was particularly more dispersed than we are currently; the tight races in Area/Extent would also tend to confirm that as well.

I'm going to be very interested in about 72 hours to see what havoc the rainfall has caused.  A lot is about to land on some of the most vulnerable ice in the Beaufort, and the Kara/Barentz is already slush.

today's Bremen map shows damage from the last rain band a couple of days ago, the open water connection between Beaufort and Chykchihas grown considerably(the face's nose is almost gone, lips receding)

Arctic sea ice / Re: The 2019 melting season
« on: July 02, 2019, 02:49:19 AM »
Recent lack of dispersion Michael Hauber?

Excuse me, but What?

What is the stream of CAB ice being pumped into the Beaufort Sea? That's just one example. ESS extent bouncing, dead cat style, as the fast ice disiintegrates. A reversal of wind pushing ice into the Laptev Bite

And the elephant in the room, Atlantic export. As the WeatherDude so acutely observed, the CAB extent is high. Why?, the Atlantic exits are loaded with thick ice. The Barents Sea is very high, having been fed by that full, dispersing, CAB. The Greenland Sea is also high, it jumped ~100k this week, also from the CAB. That's a pyrrhic "gain" in extent.

Nevertheless extent dropped 400K on JAXA over the past 4 days, remaining close to record low, area is record low, we await the volume numbers

Arctic sea ice / Re: The 2019 melting season
« on: July 02, 2019, 02:18:32 AM »
Wouldn't cheer yet.  There is 2-3cm of rain forecast to fall under a bunch of these clouds on the Pacific side.

In the second half of the GFS runs today, the amount of precipitable moisture circulating in the Pacific half without much rain that blows me out, it's like a humid week in the subtropics

Arctic sea ice / Re: The 2019 melting season
« on: July 02, 2019, 02:14:29 AM »
It may not change anything but the gfs forecast has Ellesmere island over !6'C today and above 12'C seemingly constantly for the next 7 days . Next door the N. of Greenland is enjoying a balmy 8'C for the week .
Meanwhile the lowest 850hpa temps in the N.hemisphere are over the Faroes and Shetland ( where my auntie Maureen will be 90 tomorrow :)  ). There is no cold air in the Arctic or over Greenland ! .. b.c.
Warmth has spread across the CAA over the past few days and all without a cloud in the sky. And with no snow left except on the heights, so all the land between the channels can warm up considerably

This is contrary to EC/ Windy, which still has most lower areas of Ellesmere etc snowy, as well as the largest island in the Laptev, which lost all its snow a couple of weeks ago, but Windy still shows it covered in 4.74m of deep snow - odd, as it seems quite reliable otherwise, maybe there's no physical data to update the model for these spots, though in the Laptev (most of) the adjacent islands are correctly shown snowfree, so there's a bit of a bug. How much effect this has locally on the forecast I don't know, the spot with 4.68m in Ellesmere sits around 5-10C all week yet actually increases fakesnow depth by week's end after initially losing a few cm

Arctic sea ice / Re: The 2019 melting season
« on: July 01, 2019, 09:24:23 AM »
Current through the Bering Strait ~0.5 kt and swell at ice edge up to ~1.3 m.

Thank you for posting this !!

1.3 m ~ 4.4 feet. I took a lot of grief last night for suggesting the "surge" through the Strait would be maintained to the ice front.

I confess to being uncertain as to what happens dynamically at the water / ice interface but I'm not confident that anyone here thus far has the answer to that.

I'm sticking with my gut here and suggesting that there is a real possibility that a LOT of (warm) water goes over the top.of the ice edge.

You really have no idea what you are talking about Rich. This is not at all the surge you were talking about, only normal ocean swells in moderately high winds, and fairly modest swells at that. And there is absolutely no change of any warm water going over the top of the ice edge.

8 C water will work away at the ice without any help from big swells. That area is about to get another 25mm of rain after the last bout a couple of days ago. As temps start to drop in August, big swells are all too likely, with long fetches to develop in.

The latest GFS forecast on Climate Reanalyser (1 july, 00z)has taken a turn for the worst, with an obscene intrusion of heat and moisture from the pacific, and heat everywhere in 2nd half of forecast. hopefully its wrong, but a bit scary

Arctic sea ice / Re: The 2019 melting season
« on: July 01, 2019, 06:50:36 AM »
The darkening of the pack thru June is pretty stark in this movie. of worldview images. I've also attached the June 1 and June 30 for comparison.

We need a lot of bright white cloud

Edit: replaced the movie with one half the size to see if it displays the Atlantic side on the page

Arctic sea ice / Re: The 2019 melting season
« on: June 30, 2019, 03:25:02 AM »
Talking of longwave radiation and latent heat: there is a 30kg/m2 river of moisture flowing in through the Bering Strait all week, and the air column will be warm, freezing altitude varying from ~2000-3500 m over the Chukchi sea according to Windy( the freezing altitude map is nuts right now). The clouds thicken and cloudbase drops as the air hits the ice edge.

Surface temps at the spot indicated stay around 6-7C (dropping to 2C over ice) through the forecast, and the air above is about the same temp or slightly warmer up to around 900hPA and about 2C at 800hPA. Wind from the south, a 15knot breeze at the surface, about double that aloft

Does anyone have an idea how much of that moisture is arriving at the ice edge as vapour? How much latent heat is being transferred to the ice?

Arctic sea ice / Re: The 2019 melting season
« on: June 30, 2019, 02:40:55 AM »
A quick and dirty insolation calculation could made by making a grayscale version of Worldview's truecolor image for the date, ...

It would definitely be quick and dirty.  Gerontocrat was not kidding when he talked about the cost of developing a model that would accurately account for the cloud effects on albedo. 

Clouds are very, very, very complicated.  They are all different.  Different clouds let in different wavelengths of light that have different energy.  Different clouds also block upwelling wavelengths of light and reflect them back to the surface.

There are many papers on this topic.  The take home message is that it is not a simple matter of saying it’s cloudy so the Ice is protected.  Sometimes the clouds make things worse.

Sure, clouds are complicated, hence the desire to not have to handle them

My suggestion is for a method to calculate raw insolation, not longwave and other processes. Quick and dirty, but also simple. My thought is that the whiter clouds are, the more sunlight they reflect,

Arctic sea ice / Re: The 2019 melting season
« on: June 29, 2019, 04:08:11 AM »
A quick and dirty insolation calculation could made by making a grayscale version of Worldview's truecolor image for the date, then iterating over the pixels inside a mask(that excludes areas outside the sea ice area, or area of interest), and multiplying their albedo/darkness by insolation at that date and latitude.

Edit:  Then you don't have to handle clouds explicitly. Fixed a few typos

Arctic sea ice / Re: The 2019 melting season
« on: June 29, 2019, 03:41:50 AM »
Jim Hunt: see post my #2369 from June 23 where I posted the link from Zack Labe wrt SIPN prediction. Of course, I should have mentioned that one of the posts was wrt to SIPN.

With warm southerlies entering from Pacific the question is hiw much damage the ice will take? Especially the weak "arm" in western CAB will be of particular interest.

That wind from the Pacific brings a LOT of precipitable moisture, the air column over open water area of the Chukchi will be dripping with20-30kg/m2 of water, that's the average over the next 5days according to GFS. And a lot of it will be dumped as rain on the ice front, including that weak arm.

I've attached 5 day precipitation and precipitable water forecasts from GFS/Climate Reanalyser

Arctic sea ice / Re: The 2019 melting season
« on: June 29, 2019, 03:32:42 AM »
All of a sudden, everybody rushes for the exit door

Today's ECMWF forecast on WindyTV is worse than the last re export, with constant brisk northerlies blowing through Fram Straitevery day except(haha) D10

I noticed that too. At various times, it will be pulling ice from the CAB area in almost a full semi-circle, 90 degrees each way from middle at Fram with the centre of the circle at the pole. The first few days concentrate on the west side and then it will be clearing out the ice south of the Svalbard to FJL line and beyond. The winds are most intense in the first 3 days but it is a steady 16 kt (30 km/h) for about a week.

This combined with warm winds coming in from the Bering Sea means that the ice will look very different a week from now.

To me that sounds more like yesterday's forecast. There are more period of 20+ kt wind on today's with 2-stepping lows between Svalbard and Scandinavia revving it up a bit more. Otherwise its as you descibe

Arctic sea ice / Re: The 2019 melting season
« on: June 29, 2019, 03:10:33 AM »
How is that insolation anomaly created.

Are we using something to determine if there was clear skies or not

It didn't in 2016 when this thread was created by Tealight,1749.0.html

Edit: It seems it basically calculates the open water areas for each day(or at least did then, I haven't time to read through the thread right now) and multiplies that by the incoming insolation for the date. Leaving out cloud cover makes it an imperfect tool. if the Laptev Sea had been cloudy over the past week, it wouldn't be close to the temperature it is now. Maybe there's a band on worldview where pixel counting could give a value for cloud cover, I'm not sure

Arctic sea ice / Re: The 2019 melting season
« on: June 29, 2019, 02:53:56 AM »
All of a sudden, everybody rushes for the exit door

Today's ECMWF forecast on WindyTV is worse than the last re export, with constant brisk northerlies blowing through Fram Straitevery day except(haha) D10

Arctic sea ice / Re: The 2019 melting season
« on: June 28, 2019, 04:25:19 AM »
It is mostly algae causing the discoloration of ice.  At least, I'm pretty sure of it.

This may well be correct, but it still begs the question as to why such algal growth would be so prominent in the Chukchi as opposed to elsewhere. 

Perhaps it is temperature related.  However, in my experience, the presence of nutrients is often more key to algal growth.  So I think the sediment hypothesis, providing extra nutrients to the ice, should be considered at least as part of the phenomenon.

Thinner ice is one reason.

Wind blown dust and ash provides nutients too. The algae are very brown/grey, if indeed they are the primary cause of the colouration

Arctic sea ice / Re: The 2019 melting season
« on: June 28, 2019, 04:06:33 AM »
Laptev SSTs are now up to 10C in the bite according to WindyTV/EC. Most of the open water is between 6-9C. (Around the Lena delta water is an insane 17C). Have SSTS ever been this high there? Let alone on 27 June? For the next few days winds turn around and start blowing ice from the north into those warm waters, while the Chukchi will warm up some more as Alaska heats up.

Meanwhile half the basin is above freezing at the 800hPa level, all week long(The CAA, and adjacent areas of CAB, as well as the Kara Sea, the Atlantic front all take a clobbering) Even where the lows are its barely freezing at this height(2000m)

My personal not really scientific(though testable) theorem is that when a sea ice region starts looking like a head, its the beginning of the end for it, soon to distort, fall apart , and ultimately melt. We've all seen the baby elephant head that forms in the Chukchi sea the past few years. The mouth widens, the trunk narrows, and then, ... poof. The southern Beaufort starts out with more human features. So it's been with growing alarm that I've watched the whole Pacific sector take on the appearance of a bearded face in recent days.

Arctic sea ice / Re: The 2019 melting season
« on: June 26, 2019, 07:05:15 AM »
Volume is key for us here maybe, but I wouldn't write off 2D measurements as necessarily secondary for everything. Eg in its effects on the the weather and climate, extent/area measures  (where ice is) are the key thing. That sets the albedo, in part determines location of the jetstream, etc

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