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Lord M Vader

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Re: The 2019 melting season
« Reply #3250 on: July 04, 2019, 09:32:50 PM »
I do not appreciate the latest EC run! The more benign conditions that have been present from earlier runs is not as discernible in this run. Kara Sea seems to be the only region that will see "ice friendly" conditions, from D4 and onward then. First the area will be hammered over next 48 hours or so. But not much ice left there anyway.

bbr2314

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Re: The 2019 melting season
« Reply #3251 on: July 04, 2019, 09:39:36 PM »
I do not appreciate the latest EC run! The more benign conditions that have been present from earlier runs is not as discernible in this run. Kara Sea seems to be the only region that will see "ice friendly" conditions, from D4 and onward then. First the area will be hammered over next 48 hours or so. But not much ice left there anyway.
Too bad Kara is 95% ice free at this point... this is actually the theme of the summer -- whenever an area goes ice free, the weather becomes less horrible. Which is useless for retaining sea ice. All of 2019's negative anomalies are either over the continents or over recently ice-free ocean waters (i.e. bits of the Beaufort that were ice-free in June).

TeaPotty

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Re: The 2019 melting season
« Reply #3252 on: July 04, 2019, 09:46:05 PM »
Big change for the worse in latest ECMWF long range, in disagreement with GFS:

July 4th 12z:



July 4th 00z:


Sterks

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Re: The 2019 melting season
« Reply #3253 on: July 04, 2019, 10:12:01 PM »
 This is Sentinel 2 visible, over a zone of the Beaufort Sea West of Banks Island. Lucky these days was open skies (for image availability). Gif is big, I purposely made over 700, requires a click.
What I really like of these broken areas of melting floes is their multiscale character, like a fractal. The more one zooms in, the smaller floes appear is similar proportion to the bigger ones and so. It is the smallest ones that melt out in days or hours. A moderate storm accelerates this cascade from large to small floes, which finally dissipate by top, bottom, lateral melt and wave washing.
« Last Edit: July 04, 2019, 10:36:30 PM by Sterks »

Sterks

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Re: The 2019 melting season
« Reply #3254 on: July 04, 2019, 10:23:59 PM »
I do not appreciate the latest EC run! The more benign conditions that have been present from earlier runs is not as discernible in this run. Kara Sea seems to be the only region that will see "ice friendly" conditions, from D4 and onward then. First the area will be hammered over next 48 hours or so. But not much ice left there anyway.
It's quite something how the EC flip flops at times, it now looks more to what GFS was showing and to the update 24h ago. Somebody posted reliability metrics, and it's been doing good, but GFS was doing surprisingly as good or even better

jdallen

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Re: The 2019 melting season
« Reply #3255 on: July 04, 2019, 11:30:30 PM »
Rainfall earlier in the week had the predicted effect on the Kara and regions of the Barentz it hit.
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Pagophilus

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Re: The 2019 melting season
« Reply #3256 on: July 05, 2019, 01:14:01 AM »
Looks like the Laptev fast ice is finally shattering fully. On the latest worldview shot you can see massive cracks everywhere there isn't clouds

grixm, nicely spotted!  It is a significant development.  I took a screenshot and bullied it around in Photoshop to bring out the cracks and 'see' through the clouds better.  Hope you don't mind. The extensive cracking of a huge area of fast ice is, I hope, even more visible.  Unlike the recent breakup of fast ice in the ESS, where there was nowhere for the ice to go, these floes can probably easily migrate into what is now a huge Laptev bite, filled with warmer water.

BTW, the ice is not really that blue... I pushed saturation in Photoshop to make the cracks stand out.
« Last Edit: July 05, 2019, 01:23:27 AM by Pagophilus »

Paul

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Re: The 2019 melting season
« Reply #3257 on: July 05, 2019, 01:35:32 AM »
I do not appreciate the latest EC run! The more benign conditions that have been present from earlier runs is not as discernible in this run. Kara Sea seems to be the only region that will see "ice friendly" conditions, from D4 and onward then. First the area will be hammered over next 48 hours or so. But not much ice left there anyway.
It's quite something how the EC flip flops at times, it now looks more to what GFS was showing and to the update 24h ago. Somebody posted reliability metrics, and it's been doing good, but GFS was doing surprisingly as good or even better

But that is normal for medium to long range forecasting and any short term changes can make a big difference later on in the run.

It does look like in the short term there is a strong high on the Atlantic side of the basin and a ridge into the Chuckchi by day 2.

 The ridge into the chuckchi is more concerning than the high as it brings very warm air over ridiculasly high SSTS against an ice edge which has retreated quite far north. Its not July 2015 standards in terms of strength of the winds but it could well have some impacts.

Apart from that, things look quite slack on most runs with not many isobars at all and let's face it, if June has not been so warm on the Pacific side, the upcoming weather pattern may not be a big deal but you get the feeling the ice thh
is year is quite vulnable and is most definitely vulnable to bottom melt which might be explaining why the ice edge is retreating northwards fairly rapidly.

subgeometer

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Re: The 2019 melting season
« Reply #3258 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).

subgeometer

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Re: The 2019 melting season
« Reply #3259 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

Rod

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Re: The 2019 melting season
« Reply #3260 on: July 05, 2019, 03:46:52 AM »
The heat wave in Alaska has started.  It will probably be the most extreme ever recorded. 

It is not clear how that might effect the ice.  I’m still waiting to see if the Beaufort soup starts melting, but it is taking a long time.

This heat, if it moves north, may be the kicker. 

I’ll leave it to the weather experts to comment on whether they think this heat will hit the sea ice.


FishOutofWater

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Re: The 2019 melting season
« Reply #3261 on: July 05, 2019, 04:08:08 AM »
Yes, that heat in Alaska will affect the ice because the southerly winds will blow over open water that's already absurdly warm for the Arctic before it reaches the ice. The warm air blowing off Alaska will still be pretty warm when it hits the ice because it is passing over water that's anomalously warm. The ice edge will be pushed back.

oren

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Re: The 2019 melting season
« Reply #3262 on: July 05, 2019, 04:35:59 AM »
The heat wave in Alaska has started.  It will probably be the most extreme ever recorded. 

It is not clear how that might effect the ice.  I’m still waiting to see if the Beaufort soup starts melting, but it is taking a long time.

This heat, if it moves north, may be the kicker. 

I’ll leave it to the weather experts to comment on whether they think this heat will hit the sea ice.
A lot of the Beaufort soup originated as MYI from the CAB, as shown in A-Team's ASCAT animations. Small wonder it takes a long while to melt. But I don't expect a repeat of the performance of "Big Block" from 2016, that fought melting tooth and nail and went on and on and on, all the way into late September, despite the early open water that year and the resulting local heating, and despite the storms that came to be known as the 2016 GAC. I think this year's Beaufort MYI will prove much weaker, and should disappear by end-July or mid-Aug.

Check out this AMSR2 animation by Wipneus from 2016.
Also this post by slow wing documenting the initial breakup on July 16th. This monster was ~100km across and an estimated initial thickness of ~4m.
« Last Edit: July 05, 2019, 04:48:08 AM by oren »

Rod

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Re: The 2019 melting season
« Reply #3263 on: July 05, 2019, 04:44:13 AM »
Thank you Oren. 

Those are interesting images. I think we are lucky the ice in the Beaufort has hung on so long this year.

Someone called it a killing zone several weeks ago, and so far that has not been the case. However, I think things will turn soon and all of that “snow cone” ice will start disappearing. 

If/when it does, hold on to your seatbelts because extent will crash. 

subgeometer

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Re: The 2019 melting season
« Reply #3264 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

Michael Hauber

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Re: The 2019 melting season
« Reply #3265 on: July 05, 2019, 07:43:21 AM »
I've often suspected a repeat of 2007 conditions may result in near ice free conditions, considering that 2007 had to contend with a much larger proportion of thicker multi-year ice than has been around since then.

With a lot of heat in June, a strong retreat in the Pacific and with more compaction and less dispersion evident this year seems to have some similarities to 2007.  In general there is more dispersal of ice currently in the ESS region than there was same day 2007

NSIDC ice comparison shows a strong retreat in the Pacific centre.  Compared to 2007 this year is retreating faster towards Chukchi and not as fast towards ESS.  Similar speed of retreat in Laptev which suprises me due to the severity of both wind and heat in that sector this year.



Temps at 925hp show how much hotter this year is than 2007.  The strongest heat is more towards Laptev this year, but is overall noticeably warmer.





Wind driven compaction and export was an important factor in 2007.  There were some quite strong winds over the Pacific sector that drove the ice towards the Atlantic.  Keep in mind Ekman transport will push the ice to the right of the wind vector so the ice will travel much more away from the Chukchi region than the roughly right angle winds suggest.



In contrast this year winds have definitely been milder over the Pacific sector, although there have been some very strong winds towards Kara and some moderate winds near Laptev.



Overall more heat, but less help from winds than 2007.  Assuming the pattern continues, is that enough to set up a similarly devestating melt season as 2007, and what impact would that have with the multi-year ice greatly reduced?

Is the fact that ice retreat towards Laptev is only similar to 2007 and not well ahead despite apparently much hotter conditions and solid wind important?  Was the ice there thicker this year?  Or was the heat perhaps not as strong as shown in the models (I believe a lot of extrapolation is involved producing these temperature maps).




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Aluminium

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Re: The 2019 melting season
« Reply #3266 on: July 05, 2019, 08:02:47 AM »
June 30 - July 4.

2018.

oren

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Re: The 2019 melting season
« Reply #3267 on: July 05, 2019, 08:17:36 AM »
I've often suspected a repeat of 2007 conditions may result in near ice free conditions, considering that 2007 had to contend with a much larger proportion of thicker multi-year ice than has been around since then.
...
NSIDC ice comparison shows a strong retreat in the Pacific centre.  Compared to 2007 this year is retreating faster towards Chukchi and not as fast towards ESS.  Similar speed of retreat in Laptev which suprises me due to the severity of both wind and heat in that sector this year.
...
Wind driven compaction and export was an important factor in 2007.  There were some quite strong winds over the Pacific sector that drove the ice towards the Atlantic.  Keep in mind Ekman transport will push the ice to the right of the wind vector so the ice will travel much more away from the Chukchi region than the roughly right angle winds suggest.
...
Overall more heat, but less help from winds than 2007.  Assuming the pattern continues, is that enough to set up a similarly devestating melt season as 2007, and what impact would that have with the multi-year ice greatly reduced?

Is the fact that ice retreat towards Laptev is only similar to 2007 and not well ahead despite apparently much hotter conditions and solid wind important?  Was the ice there thicker this year?  Or was the heat perhaps not as strong as shown in the models (I believe a lot of extrapolation is involved producing these temperature maps).
PIOMAS says end-May thickness in the Laptev was much higher this year compared to 2007, with the missing volume elsewhere - Chukchi, Beaufort, CAB near CAA. And given the actual temperatures on Kotelny Island and in Tiksi, I doubt there were modeled temp errors in the Laptev region, though the Arctic at large is indeed sparsely covered by weather stations.

oren

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Re: The 2019 melting season
« Reply #3268 on: July 05, 2019, 08:19:11 AM »
The end-May 2019-2007 PIOMAS comparison, thanks to Wipneus. Today we should have the end-June comparison.
Edit: bear in mind 2007 was much warmer than 2019 in the Laptev region in May, which is part of the reason for the differences in volume there at the end of the month. End-April had smaller differences, and conversely smaller differences in the Beaufort as well.
« Last Edit: July 05, 2019, 08:28:37 AM by oren »

aslan

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Re: The 2019 melting season
« Reply #3269 on: July 05, 2019, 08:38:41 AM »
I do not appreciate the latest EC run! The more benign conditions that have been present from earlier runs is not as discernible in this run. Kara Sea seems to be the only region that will see "ice friendly" conditions, from D4 and onward then. First the area will be hammered over next 48 hours or so. But not much ice left there anyway.
It's quite something how the EC flip flops at times, it now looks more to what GFS was showing and to the update 24h ago. Somebody posted reliability metrics, and it's been doing good, but GFS was doing surprisingly as good or even better

But that is normal for medium to long range forecasting and any short term changes can make a big difference later on in the run.

It does look like in the short term there is a strong high on the Atlantic side of the basin and a ridge into the Chuckchi by day 2.

 The ridge into the chuckchi is more concerning than the high as it brings very warm air over ridiculasly high SSTS against an ice edge which has retreated quite far north. Its not July 2015 standards in terms of strength of the winds but it could well have some impacts.

Apart from that, things look quite slack on most runs with not many isobars at all and let's face it, if June has not been so warm on the Pacific side, the upcoming weather pattern may not be a big deal but you get the feeling the ice thh
is year is quite vulnable and is most definitely vulnable to bottom melt which might be explaining why the ice edge is retreating northwards fairly rapidly.

Yes, this morning the IFS is still really bad, but it's initialization is quite different from GFS, and seems better by the way, like yesterday:


Nightvid Cole

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Re: The 2019 melting season
« Reply #3270 on: July 05, 2019, 11:41:57 AM »
« Last Edit: July 05, 2019, 11:47:08 AM by Nightvid Cole »

petm

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Re: The 2019 melting season
« Reply #3271 on: July 05, 2019, 12:35:21 PM »
I think we are lucky the ice in the Beaufort has hung on so long this year.

The Beaufort hasn't hung on, exactly. It crashed early (export) and was then repeatedly replenished (import) from the adjacent CAB due to cyclones in May and June. It is a kill zone: open water, dispersed ice, high SST, MacKenzie inflow, etc. Just because it isn't showing up in extent doesn't mean it isn't melting at an accelerated rate, to the contrary. Wait for a few storms to hit this month (assuming they do) to see dramatic drops in extent. The entire Beaufort plus an unusually large amount of adjacent CAB (barring replenishment) will melt out completely.

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Re: The 2019 melting season
« Reply #3272 on: July 05, 2019, 12:45:09 PM »
I think we are lucky the ice in the Beaufort has hung on so long this year.

The Beaufort hasn't hung on, exactly. It crashed early (export) and was then repeatedly replenished (import) from the adjacent CAB due to cyclones in May and June. It is a kill zone: open water, dispersed ice, high SST, MacKenzie inflow, etc. Just because it isn't showing up in extent doesn't mean it isn't melting at an accelerated rate, to the contrary. Wait for a few storms to hit this month (assuming they do) to see dramatic drops in extent. The entire Beaufort plus an unusually large amount of adjacent CAB (barring replenishment) will melt out completely.
+1

petm

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Re: The 2019 melting season
« Reply #3273 on: July 05, 2019, 12:45:13 PM »
A large polynya has appeared far off the Siberian coast!

Nice find.

(If you want to make it easier, use the share link at the top right of WorldView. The polynya is here: https://go.nasa.gov/327fU0O )

The ice in this area looks considerably less healthy than a week ago, before that front came through the Chukchi: https://go.nasa.gov/329PfQR
« Last Edit: July 05, 2019, 12:56:01 PM by petm »

oren

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Re: The 2019 melting season
« Reply #3274 on: July 05, 2019, 12:51:04 PM »
 Meanwhile, somewhere in the Inner Arctic Basin  :o

Thawing Thunder

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Re: The 2019 melting season
« Reply #3275 on: July 05, 2019, 12:56:35 PM »
The Beaufort hasn't hung on, exactly. It crashed early (export) and was then repeatedly replenished (import) from the adjacent CAB due to cyclones in May and June. It is a kill zone: open water, dispersed ice, high SST, MacKenzie inflow, etc. Just because it isn't showing up in extent doesn't mean it isn't melting at an accelerated rate, to the contrary. Wait for a few storms to hit this month (assuming they do) to see dramatic drops in extent. The entire Beaufort plus an unusually large amount of adjacent CAB (barring replenishment) will melt out completely.

Not to mention the broad conditioning and thinning of the ice. The CAB is weak now because of replenishing the Beaufort and spilling the rest of its assets constantly down Fram strait. From now on IMO even average melt without spectacular storms will be enough to bring the ice to the brink of collapse. I'm eagerly awaiting the new volume data to get a better idea of how well or bad the ice really is.
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El Cid

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Re: The 2019 melting season
« Reply #3276 on: July 05, 2019, 02:41:01 PM »
Slater's model update:

Expected extent on Aug 24, 2019 : 4,32 M sq km (getting closer to 2012!).

NSIDC extent on same date of

2012: 4,18
2007: 4,91
2016: 4,97
2011-18 average: 5,10

(also take a look at the map, it shows possible disintegration close to the Pole)

iceman

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Re: The 2019 melting season
« Reply #3277 on: July 05, 2019, 03:02:58 PM »
Slater's model update:

Expected extent on Aug 24, 2019 : 4,32 M sq km (getting closer to 2012!).
   ....

Thanks for these regular updates, El Cid.

Since lately I've taken an interest in the daily Slater maps and couldn't find an archive of them, I started saving them. Here's a gif of the first 7: June 27 - July 4.
   ....

So, that's two large gaps in succession between the Slater and anomaly models. The red "observed" line will probably thread both, but I wonder whether the next week or two will be a tell on which model proves more accurate for late August.

petm

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Re: The 2019 melting season
« Reply #3278 on: July 05, 2019, 03:21:04 PM »
Slater's model update:

Expected extent on Aug 24, 2019 : 4,32 M sq km (getting closer to 2012!).
   ....

Thanks for these regular updates, El Cid.

Since lately I've taken an interest in the daily Slater maps and couldn't find an archive of them, I started saving them. Here's a gif of the first 7: June 27 - July 4.
   ....

So, that's two large gaps in succession between the Slater and anomaly models.

Do you happen to know what the anomaly forecast is? (I realize it's the light blue line on the graph, but what is it based on?)

magnamentis

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Re: The 2019 melting season
« Reply #3279 on: July 05, 2019, 03:27:10 PM »
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.

El Cid

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Re: The 2019 melting season
« Reply #3280 on: July 05, 2019, 03:30:05 PM »
"Do you happen to know what the anomaly forecast is? (I realize it's the light blue line on the graph, but what is it based on?)"

As far as I know, it is a very simple projection: taking the current anomaly and  extrapolating it to T+50. I do not think anyone should care about the light blue line. Tha dark blue, the actual model, however, has good forecasting skill

bbr2314

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Re: The 2019 melting season
« Reply #3281 on: July 05, 2019, 03:31:19 PM »
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!

petm

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Re: The 2019 melting season
« Reply #3282 on: July 05, 2019, 03:36:25 PM »
Tha dark blue, the actual model, however, has good forecasting skill
Thx.

petm

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Re: The 2019 melting season
« Reply #3283 on: July 05, 2019, 03:38:25 PM »

Niall Dollard

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Re: The 2019 melting season
« Reply #3284 on: July 05, 2019, 03:43:16 PM »
Recent tweet by Judah Cohen:

GFS predicting a possible end to streak of warm/positive polar cap geopotential heights and high latitude blocking.  This would result in more typical weather to the Arctic region including Alaska and less sea ice melt in the Arctic ocean and less land ice melt on Greenland.

Nightvid Cole

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Re: The 2019 melting season
« Reply #3285 on: July 05, 2019, 05:02:08 PM »
I'm afraid a July cooldown is too late to save the ice. Apparently the amount of solar radiation reflected from the Arctic in June is almost a decisive determination of the final September extent (r = 0.91).  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JD025819

F.Tnioli

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Re: The 2019 melting season
« Reply #3286 on: July 05, 2019, 05:06:02 PM »
... 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
...
And while those systems push warmth into the Arctic, the cold air spills out of the Arctic southwards elsewhere; in particular, Moscow (Russia) is going through a series of record low air temperatures since the end of June, some days being ~12°C tops (which normally is a kind of weather of end of September for the area, rather than end of June / beginning of July).

This is not the 1st time Arctic loses large amount of "coldness" via losing air masses to temperate belt, and every time it happens i think proportionally large extra warming hits the Arctic as well (with everything else being equal). Jet stream weakening in action...

El Cid

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Re: The 2019 melting season
« Reply #3287 on: July 05, 2019, 05:20:45 PM »
I'm afraid a July cooldown is too late to save the ice. Apparently the amount of solar radiation reflected from the Arctic in June is almost a decisive determination of the final September extent (r = 0.91).  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JD025819

Interesting study!

Sterks

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Re: The 2019 melting season
« Reply #3288 on: July 05, 2019, 05:42:35 PM »
I'm afraid a July cooldown is too late to save the ice. Apparently the amount of solar radiation reflected from the Arctic in June is almost a decisive determination of the final September extent (r = 0.91).  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JD025819
Without having entered into the study (which may indicate also the importance of early melt onset, or not) I would say July clear skies favor capture of solar heat as well, taking into account that now there’s more open water, and lowered albedo wet floes.
Also, Judah Cohen graph doesn’t imply there won’t be open skies, but certainly less movement and cooler areas. We’ll see if it verifies

Davidsf

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Re: The 2019 melting season
« Reply #3289 on: July 05, 2019, 06:04:49 PM »
Melt extent ratio -- is that what it sounds like, amount of melt compared to amount of ice at the start of the melt season? Thank you

Tor Bejnar

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Re: The 2019 melting season
« Reply #3290 on: July 05, 2019, 06:28:16 PM »
I see that we are about to be able to compare 'today' values with 2012 using JAXA AMSR2 data.
Arctic ice is healthy for children and other living things.

b_lumenkraft

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Re: The 2019 melting season
« Reply #3291 on: July 05, 2019, 06:38:24 PM »
Melt extent ratio -- is that what it sounds like, amount of melt compared to amount of ice at the start of the melt season? Thank you

It's melt extent divided by ice extent.

I assume (please correct me if i'm wrong) it's based on daily values.

bbr2314

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Re: The 2019 melting season
« Reply #3292 on: July 05, 2019, 07:11:36 PM »
The 12z GFS shows heights lowering by D10 but it is only bc there is a moderate cyclone sitting over the Arctic which is actually dumping rain. This may be evidence that the trend toward lower heights will be due to increasing basin-wide cyclonic activity versus anything beneficial to the ice.

RoxTheGeologist

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Re: The 2019 melting season
« Reply #3293 on: July 05, 2019, 07:16:46 PM »
Yes, that heat in Alaska will affect the ice because the southerly winds will blow over open water that's already absurdly warm for the Arctic before it reaches the ice. The warm air blowing off Alaska will still be pretty warm when it hits the ice because it is passing over water that's anomalously warm. The ice edge will be pushed back.

That's a great way to transfer heat from the warm water to the cold ice. Evaporation followed by condensation on the ice.

Niall Dollard

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Re: The 2019 melting season
« Reply #3294 on: July 05, 2019, 07:37:48 PM »
I'm afraid a July cooldown is too late to save the ice. Apparently the amount of solar radiation reflected from the Arctic in June is almost a decisive determination of the final September extent (r = 0.91).  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JD025819

Interesting study!

It is. It would be nice to know what the top of atmosphere Reflected Solar Radiation figure for June 2019 was and give us an idea what we might expect.

The correlation is pretty good - but some years eg 2008 and 2014 there was a considerable difference.

I was wondering if the authors (Zhan and Davies) ever contributed to the Sea Ice Prediction Network - but alas I cannot find any ref to them in 2019 or 2015 SIPN reports.


 

petm

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Re: The 2019 melting season
« Reply #3295 on: July 05, 2019, 07:39:44 PM »
Melt extent ratio -- is that what it sounds like, amount of melt compared to amount of ice at the start of the melt season? Thank you

It's melt extent divided by ice extent.

I assume (please correct me if i'm wrong) it's based on daily values.

Correct -- daily ratio of melt extent to total extent. It's not well validated, just another metric to keep an eye on. See e.g. here for more details:
https://forum.arctic-sea-ice.net/index.php/topic,382.msg162829.html#msg162829

b_lumenkraft

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Re: The 2019 melting season
« Reply #3296 on: July 05, 2019, 07:44:23 PM »
Correct -- daily ratio of melt extent to total extent. It's not well validated, just another metric to keep an eye on. See e.g. here for more details:
https://forum.arctic-sea-ice.net/index.php/topic,382.msg162829.html#msg162829

Thanks for the validation, Petm. :)

uniquorn

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Re: The 2019 melting season
« Reply #3297 on: July 05, 2019, 07:47:33 PM »
mercator (model) salinity at 34m overlaid with unihamburg amsr2-uhh at 40% transparent with light contrast to increase visibility of fractures in the overlay. amsr2 also has its open water, normally blue, set to 100% transparent. While it may arguably be more relevant to show 0m salinity the idea here is to show the underlying near surface ocean currents which tend to get obscured by low salinity melting ice.
mar21-jul4. Probably best viewed full screen (double click) No scale as the overlay obscures the salinity colours. Blue is fresher than red.

aslan

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Re: The 2019 melting season
« Reply #3298 on: July 05, 2019, 07:58:15 PM »
I'm afraid a July cooldown is too late to save the ice. Apparently the amount of solar radiation reflected from the Arctic in June is almost a decisive determination of the final September extent (r = 0.91).  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JD025819

Interesting study!

It is. It would be nice to know what the top of atmosphere Reflected Solar Radiation figure for June 2019 was and give us an idea what we might expect.

The correlation is pretty good - but some years eg 2008 and 2014 there was a considerable difference.

I was wondering if the authors (Zhan and Davies) ever contributed to the Sea Ice Prediction Network - but alas I cannot find any ref to them in 2019 or 2015 SIPN reports.

With a big bag of salt. First is downward Solar flux at surface for June 2019, second is the same for June 81-10.

P.S. : sorry I just take realized that scales are slightly différent...

aslan

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Re: The 2019 melting season
« Reply #3299 on: July 05, 2019, 08:23:31 PM »
And I think I did not exactly answer the question :s Same for upward Solar flux at TOA, with a good scale this time.