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sark

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Re: The 2019 melting season
« Reply #5100 on: August 01, 2019, 06:45:30 AM »
The 18Z GFS run on Climate analyser sees a big storm taking over most of the basin later in the run, not quite a GAC, but lots of fairly strong wind. The EC today on Windy disagrees, so we'll have to wait and see. (both see continuing injections of heat and moisture especially over the Canadian and Pacific sectors and adjacent CAB).

If the AO turns negative now, with an increase in cloud and possible storms, just as the sun is getting low at high latitudes, especially if combined with further incoming physical or latent heat, I don't think that is the best news. The N Hem tropical cyclone season is just about to crank into action. GFS also foresees an Atlantic hurricane missing Florida, and beginning a swing north, Again a long shot, but its a sign of the dangers the cooling after summers peak may bring
 

https://en.wikipedia.org/wiki/2018_Atlantic_hurricane_season#Hurricane_Oscar

many systems are cruising straight into the polar cell.  I remember Oscar, the last named Hurricane of the 2018 Atlantic season.  Fish storm, sustained itself as a rapidly moving midlatitudes cyclone and sailed right past Britain.  The low from that tropical storm was mapped spiraling in and landing right at the North Pole November 1.

maybe I'm just seeing them more

pic not related, but i use it often.  This polar disturbance in 2019 stole the stable weather months of May & June and July has been good to us but it was 108 or 109F in France.  are we going to get at least TWO stable months of "polar cell" function in 2019 before the October outbreaks begin?

I pray this shit settles down in August
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Killian

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Re: The 2019 melting season
« Reply #5101 on: August 01, 2019, 08:42:31 AM »
<snip, this is more suited elsewhere, not here; N.>
« Last Edit: August 01, 2019, 10:40:33 AM by Neven »

sja45uk

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Re: The 2019 melting season
« Reply #5102 on: August 01, 2019, 09:18:35 AM »
BTW, is old ice more resistant to melt than young ice, i assume yes but am not sure.

Yes it's less salty.

I would have thought that most of the salt in seawater gets rejected when it freezes. Do you know how salt content varies with age of the ice and how much difference it makes to melting? [EDIT] More likely it is just MYI is much thicker so more resistant to wave action and requires more energy to melt out.
« Last Edit: August 01, 2019, 09:38:58 AM by sja45uk »

kynde

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Re: The 2019 melting season
« Reply #5103 on: August 01, 2019, 09:31:29 AM »
A friend living north of St Petersburg told me that the blueberries are ripe one month early this month .... Nobody can remember them this ready at this time.  Surely this is a natural indication of a high soil temperature. Not good for Arctic ice assuming this can be extrapolated across the edges of Laptev and Kara .

Hmm, you don't mention when exactly, but the end of July and early August is perfectly normal time for blueberries to ripen here abouts. And I know when they turned ripe near Imatra and near Hamina and it was not out of the ordinary in either location. Both cities are reasonably close to St Petersburg and at least make a case against extrapolating from said region north of St Petersburg. St Petersburg is quite far away from Eastern Siberia, local weather is perhaps in some correlation to the Barents, but not beyond it.

I live in Helsinki and am currently writing this about a 100 miles north west from St Petersburg. The blueberries weren't anomalously early, but there is hardly any of them this year. That may due to drough or bad weather during pollination. I'm not sure which it was this year, but this happens from time to time and is not exceptional either.

Sterks

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Re: The 2019 melting season
« Reply #5104 on: August 01, 2019, 09:40:38 AM »
The only thing I see from the EC is a high pressure system over the Asian/Pacific side with compacting winds on Laptev and ESS to Chukchi-CAB, not really strong but sustained from D+3 to D+7. It could negatively affect the ESS remains.
Anything beyond is very uncertain lately.

Sterks

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Re: The 2019 melting season
« Reply #5105 on: August 01, 2019, 09:50:02 AM »
(Another complaint, another change. Those of you who like these posts, better? Answer via PM *only*, please.
Those of you who don't like them: Shush. Scroll.)


<A mumbo jumbo of numbers including a cringing self-pat-in-the-back followed here>
Don't tell me or anybody else what we have to do. I don't like your posts and I won't shush.

aslan

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Re: The 2019 melting season
« Reply #5106 on: August 01, 2019, 10:17:31 AM »
The only thing I see from the EC is a high pressure system over the Asian/Pacific side with compacting winds on Laptev and ESS to Chukchi-CAB, not really strong but sustained from D+3 to D+7. It could negatively affect the ESS remains.
Anything beyond is very uncertain lately.

GFS is in agreement with IFS for a deep low around the 10th, despite usual shifts from one run to the other, shift in strenght, localization, etc... The canadian guy is also not that far away from this solution. And there is strong arguments for a deep low. I think it is time to pay attention to a possible big low.

BenB

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Re: The 2019 melting season
« Reply #5107 on: August 01, 2019, 10:22:37 AM »
The forecasts keep jumping around, with no clear pattern, but the general picture seems to be a mix of warm and cold anomalies, and of weak high and low pressure systems. In other words, neither very good nor very bad for the ice. Images attached are Euro 72-hour forecast.

The warmth over CAA over the next few days is worth watching, as is the renewed build-up of SSTs in the Laptev thanks to high pressure and clear skies.

Finally, at the speculative end of the forecasts, the Euro sees a fairly strong cyclone develop around D9, and the GFS goes Medieval on the ice over the period D8-15, with a powerful cyclone followed by a massive intrusion of heat from Siberia. Time will tell.

DrTskoul

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Re: The 2019 melting season
« Reply #5108 on: August 01, 2019, 11:32:40 AM »
BTW, is old ice more resistant to melt than young ice, i assume yes but am not sure.

Yes it's less salty.

I would have thought that most of the salt in seawater gets rejected when it freezes. Do you know how salt content varies with age of the ice and how much difference it makes to melting? [EDIT] More likely it is just MYI is much thicker so more resistant to wave action and requires more energy to melt out.

As salt gets rejected the ice is not homogeneous ( includes regions with defects and brine channels etc) and thus weaker than ice that was rejected most salt.

Sources: Met Office, Anderson DL '58 A Theoretical Analysis of Sea-Ice Strength

cognitivebias2

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Re: The 2019 melting season
« Reply #5109 on: August 01, 2019, 01:59:55 PM »

Alphabet Hotel

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Re: The 2019 melting season
« Reply #5110 on: August 01, 2019, 03:24:34 PM »
This piece that has detached from the pack near the New Siberian Islands is basically one very large floe that is slowly breaking up. There are some interesting bits of ice embedded in it. Some of them look like they came from a broken up ice shelf or something similar.

Alphabet Hotel

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Re: The 2019 melting season
« Reply #5111 on: August 01, 2019, 03:30:44 PM »
This piece that has detached from the pack near the New Siberian Islands is basically one very large floe that is slowly breaking up. There are some interesting bits of ice embedded in it. Some of them look like they came from a broken up ice shelf or something similar.
Close-up of part of the above. The largest piece is a little over 2 km wide. (Image is upside-down relative to Worldview.)

psymmo7

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Re: The 2019 melting season
« Reply #5112 on: August 01, 2019, 04:27:17 PM »
How warm is it in the CAA? At the Northern edge its quite pleasant. At the time of writing (10.30 am Nanavut time) it is already 16°C and forecast to go higher and remain anomalously high for some time as the attached graph shows

Frivolousz21

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Re: The 2019 melting season
« Reply #5113 on: August 01, 2019, 04:49:37 PM »

To me it looks like this year's falling even further behind 2012 in terms of finishing with the lowest extent on record. 

Volume may end up being the lowest on record although I believe that should go to 2011 I don't think 2011 with mottled correctly when you look at the cryostat data it shows that 2011 was pulverized.


First off I am going to attach two graphics. 

One of them is around 75 North right on the border of the Beaufort and the Canadian basin about 150KM North of the Parry Channel region.

The other it is about 73.5 North in the middle of the Beaufort sea.

They tell a story that shows why melting the Western CAB is very hard.

You can see that the further north ITP shows this recent warm spell didn't intrude there.

While just SW of there it came hard.

This has to do with the easterly wind component and the thickness of the ice that's coming out of the cab.

so at this point to me it's very clear that the Western cab is not going to be melted like 2012 was.

the Atlantic side it's also clearly not going to retreat as far as it did in 2012. 

The CAA has been getting bombarded for a while almost relentlessly warmth and yet the northern two-thirds is still full of ice.  This isn't as much due to the late start their versus say other year where it melted further.

This is likely due to their being above-normal snow cover there heading into this season.

Satellite scans show that around at at North rim the ice inside of the area towards the pole everywhere is more solid and s thicker than in 2012.

So we get into the middle and end of August melting will be stuck at the very edges and compassion will be harder to come by versus a year for the ice is thiner and can be crushed together more easily.

The only way to overcome this would be a traditional dipole that really stuck in place through the end of the melt season. 

That's not happening.


I will say on a side note that there is almost no snow right now anywhere in the northern hemisphere and it shows in the weather in the Heights in the pressures very subtle but it's very clear.

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Ossifrage

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Re: The 2019 melting season
« Reply #5114 on: August 01, 2019, 04:51:24 PM »
I'm impressed with how effective a vacuum cleaner the Crack is proving to be. The Arctic mouth of M'Clure Strait now sports a large area that is effectively ice-free, because the fragmented ice that belongs there has been pulled north, then west (and into the Beaufort) by the relentless torque being applied to the CAA/CAB boundary.

There's going to be quite a bit of ice left, and we may or may not make it to the record. But a lot of that ice is going to end the season very far from where it started the season, and even with all else being equal, I don't think that bodes well for future seasons.

RikW

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Re: The 2019 melting season
« Reply #5115 on: August 01, 2019, 04:56:55 PM »
I've just looked at the recent graphs/numbers in the data topic, and the difference between the total ice pack (record low) and the CAB (relative high compared to the last 10 year) is striking.

A quick glance on worldview tells me the ice looks fragile/almost shattered in some regions, probably much worse than earlier years, is just just dispersion what keeps the Area numbers that high?

Though als layman I'd say more dispersion while having the same amount of ice will have the area numbers the same, only extent numbers higher; Or in other words, I'd say that dispersion won't have such a striking distortion on area numbers

BenB

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Re: The 2019 melting season
« Reply #5116 on: August 01, 2019, 05:35:06 PM »
A couple of points in relation to CAB area/extent:

1. How far 2019 is behind depends on the numbers you're using. The Wipneus graphs show CAB area and extent near record low (see below). I do think we're a bit behind 2012, but not necessarily as far as the NSIDC figures suggest.

2. Normally the CAB starts melting from the Atlantic side, which is where we're behind this year. On the other hand, we're far ahead on the Pacific side. This means that the CAB will relatively soon be attacked from all sides, whereas normally it would take longer for open water to reach it on the Pacific side.

Edit: Part of the difference in the numbers is due to the difference in how the seas are defined, but that only emphasises that you can draw demarcation lines between the surrounding seas and CAB in different places in order to reach the conclusion you want to reach. I think the overall amount of ice is most relevant at this stage.
« Last Edit: August 01, 2019, 05:41:29 PM by BenB »

Vergent

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Re: The 2019 melting season
« Reply #5117 on: August 01, 2019, 05:48:45 PM »
To me it looks like this year's falling even further behind 2012 in terms of finishing with the lowest extent on record. 
Friv,
I thought you were dead. A new record, in my view, depends on the weather. GFS shows a mini cyclone torching the ESS for a few days. That 350k of slush will be gone. A compaction event (like 2007) could put 2019 over the top. I give it 50/50%. The second law is pissed off with all that hot land and warm water surrounding all that ice. Expect to be surprised.
Verg

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Re: The 2019 melting season
« Reply #5118 on: August 01, 2019, 07:07:17 PM »
A couple of points in relation to CAB area/extent:

1. How far 2019 is behind depends on the numbers you're using. The Wipneus graphs show CAB area and extent near record low (see below). I do think we're a bit behind 2012, but not necessarily as far as the NSIDC figures suggest.

2. Normally the CAB starts melting from the Atlantic side, which is where we're behind this year. On the other hand, we're far ahead on the Pacific side. This means that the CAB will relatively soon be attacked from all sides, whereas normally it would take longer for open water to reach it on the Pacific side.

Edit: Part of the difference in the numbers is due to the difference in how the seas are defined, but that only emphasises that you can draw demarcation lines between the surrounding seas and CAB in different places in order to reach the conclusion you want to reach. I think the overall amount of ice is most relevant at this stage.

If you look closely at the area graphs, every sea is toast (at zero ice or soon to be) with the exception of the CAA and the CAB. This is where 2019 will fail to keep pace with 2012 and end up in 2nd place.

Milwen

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Re: The 2019 melting season
« Reply #5119 on: August 01, 2019, 07:07:38 PM »
HYCOM - Arctic ice thickness (CICE) model - August 2 - August 8

Considering that light pink color is just a slush and looking only at thick ice. There will be not much left.

So what I've done: I've checked world view and mapped location of the slushed ice. Then I isolated colors from zones where slush is located from todays HYCOM data. Then I checked last day (August 8 ) map and removed those color values = by guessing that those values will represent slush in a next week.

Here is animation  from August 2 to August 8



Here is altered image from August 8 (slush levels removed). This would represent area of sort of solid ice.



And last image is ice thicker than 1m:

« Last Edit: August 01, 2019, 07:48:58 PM by Milwen »

BenB

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Re: The 2019 melting season
« Reply #5120 on: August 01, 2019, 07:11:31 PM »
If you look closely at the area graphs, every sea is toast (at zero ice or soon to be) with the exception of the CAA and the CAB. This is where 2019 will fail to keep pace with 2012 and end up in 2nd place.

We'll see. I think second place is most likely, but I don't rule out first place. I think that once the surrounding seas melt out, the CAB will start to decline more quickly. How quickly? As for the CAA, the forecast isn't great, so it will continue to lose ice. I doubt it will match 2012.

El Cid

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Re: The 2019 melting season
« Reply #5121 on: August 01, 2019, 08:06:04 PM »
HYCOM - Arctic ice thickness (CICE) model - August 2 - August 8

Considering that light pink color is just a slush and looking only at thick ice. There will be not much left.

So what I've done: I've checked world view and mapped location of the slushed ice. Then I isolated colors from zones where slush is located from todays HYCOM data. Then I checked last day (August 8 ) map and removed those color values = by guessing that those values will represent slush in a next week.

Here is animation  from August 2 to August 8



Here is altered image from August 8 (slush levels removed). This would represent area of sort of solid ice.



And last image is ice thicker than 1m:



milwen, have you done this for previous years and didi the result forecast the ice minimum? I guess not

philopek

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Re: The 2019 melting season
« Reply #5122 on: August 01, 2019, 08:30:00 PM »

milwen, have you done this for previous years and didi the result forecast the ice minimum? I guess not

Probably not but also often not that far from it.

I. The area with thick ice in previous years was 2-3 times larger, hence 2012 could match such a forecast quite well had it been made.

II. The ice in general in earlier years was thicker (look at the volume and wait for the new July volume for emphasizes. I predict a few "Octopus-Eyes" here once the July numbers will be out.

III. The area with thin ice in previous years was larger as well, hence attacking the inner basin
was starting later because the ice around 75-80N had to be melted before.

IV. The thin ice in previous years was mostly less thin = thicker.

I promote since long the theory that sooner or later we gonna be in for a nasty surprise because whatever remains and however large extent of it will be, we are going to reach zero thickness and if that happens over a large area with relatively similar ice-thickness, it can happen extremely fast even without a GAC, while i think if we are going to see either one big storm, lasting a week. or many slightly weaker storms over a few days until mid August we're done with the old record.

As far as the above mentioned is concerned, one would have to calculate chances for 50cm thick ice around the pole to melt during the next few weeks. I can't because i lack the skills to to that.
« Last Edit: August 01, 2019, 10:29:39 PM by philopek »

UCMiami

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Re: The 2019 melting season
« Reply #5123 on: August 01, 2019, 09:36:36 PM »

Edit: Part of the difference in the numbers is due to the difference in how the seas are defined, but that only emphasises that you can draw demarcation lines between the surrounding seas and CAB in different places in order to reach the conclusion you want to reach. I think the overall amount of ice is most relevant at this stage.
I agree - at this time of year the Wipneus further south boundaries for the non-CAB seas creates a very different picture of how people view the melt season. I don't know whether it is better or not - it creates a much larger CAB but interestingly it also creates a pretty consistent graph profile for that larger CAB. It means that there is less Atlanta/Pacific bias to the numbers - doesn't matter that this year the Pacific leads and other recent years the Atlantic has led since by early August all that is left in either case is that large CAB (and the CAA which is small and not that relevent to what is happening in the open seas.)

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Re: The 2019 melting season
« Reply #5124 on: August 01, 2019, 09:38:43 PM »

To me it looks like this year's falling even further behind 2012 in terms of finishing with the lowest extent on record. 


+1.

Average extent loss from this point forward is 2.1Mkm2. 2012 had 2.9M.

With CAB area flatlinining in the second half of July, volume probably followed suit. Anything is possible with the weather, but no records look likely at this point in light of 2012's huge finish.

VeganPeaceForAll

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Re: The 2019 melting season
« Reply #5125 on: August 01, 2019, 09:43:29 PM »
[......
Here is altered image from August 8 (slush levels removed). This would represent area of sort of solid ice.



And last image is ice thicker than 1m:



That is very helpful.
How much did the sea ice thickness reduce on average last month. I think it is hard to tell exactly,  but it looks like the thickness decreased approximately 0.5m. It would be amazing if someone could create a program measuring the average ice thickness loss based on the Hycom model and ice volume loss as well.
If this melt rate continues throughout August,  how much ice will there be left by the end of August?
The remaining ice will also be very mobile. What happens if a lot of it blows out to the ice kill zone of Beaufort?

I attach the latest 30 days map.

aslan

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Re: The 2019 melting season
« Reply #5126 on: August 01, 2019, 10:41:09 PM »

It was not fully intended, but by the way and by way of illustration, GFS has come closer to others global models, and is showing more deepening forced by diabatic heating.

And the follow-up... Sorry, but I like to understand how models works and to cook them, and why they are always in epic fail but are still incredible useful. The low is now forecasted to go down to 988 hPa -the attached image is showing 989 hPa but this is not the absolute minimum-, and this will probably be the last say. Don't be shy if you are sure that the models are shy :p So real world consequences, with a sea like rarely seen in Arctic, up to 4 m and 10 s, with Barrow and Prudhoe Bay going to be battered : https://tidesandcurrents.noaa.gov/waterlevels.html?id=9497645&units=standard&bdate=20190801&edate=20190802&timezone=GMT&datum=MLLW&interval=6&action=

petm

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Re: The 2019 melting season
« Reply #5127 on: August 01, 2019, 11:03:59 PM »
That low is already hitting the Beaufort. It will be interesting in a few days to try to assess how much damage even a small low will have done.

philopek

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Re: The 2019 melting season
« Reply #5128 on: August 01, 2019, 11:28:07 PM »
In addition I find the path of that thing interesting.

Should the forecast only be slightly too optimistic the ice will be in DEEP trouble, even more than it already is.

The lower image is from TODAY not yesterday and considering the path of this and most probably a few more storms coming along soon, I think it's safe to say that the pacific side will be well in new record territory as a whole  and the atlantic side looks quite a bit wonky when looked at the shadows thoroughly.
« Last Edit: August 01, 2019, 11:34:28 PM by philopek »

petm

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Re: The 2019 melting season
« Reply #5129 on: August 01, 2019, 11:42:34 PM »
the pacific side will be well in new record territory

Yeah, record melt anyways. Possibly some dispersed ice will continue to repopulate the area from the already highly dispersed CAB, depending on winds. Otoh, I wouldn't be surprised to see a huge extent bite taken out of the eastern Beaufort / CAB to match the area / volume bite.

Edit:
Quote
FORECAST FOR THE BEAUFORT SEA (Days 1 through 5)...Winds will be
generally easterly near the ice edge through Thursday before
switching to northerly as a system passes through. Expect the ice
edge to retreat northward 10 to 20 nm. As the northerly flow takes
hold, the pack ice should advect back southward into the warmer
waters. The net result will be an increased area of the marginal ice
zone and continued melt.
« Last Edit: August 01, 2019, 11:57:44 PM by petm »

pearscot

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Re: The 2019 melting season
« Reply #5130 on: August 02, 2019, 02:13:02 AM »
Well, this system is not particularly large, but the forecast for Barrow is quite windy for the next few days - today certainly looks the part. I just added a small screenshot from windy dot com to show what's driving the waves:

pls!

Rod

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Re: The 2019 melting season
« Reply #5131 on: August 02, 2019, 05:25:39 AM »
This was posted by Zack today.  I’m not sure what thread it belongs in, but more people will see it in this one. 

Many of you already have this data, but it is a nice little cheat sheet for those of us that don’t always remember the numbers. 

I’m saving it for a quick reference guide.  Maybe others will want to as well. 

wallen

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Re: The 2019 melting season
« Reply #5132 on: August 02, 2019, 05:52:03 AM »
With approx 40 days till the end of the melt season, all cards are still on the deck.

Aluminium

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Re: The 2019 melting season
« Reply #5133 on: August 02, 2019, 06:26:52 AM »
July 28 - August 1.

2018.

mabarnes

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Re: The 2019 melting season
« Reply #5134 on: August 02, 2019, 06:52:18 AM »
August should be a very interesting month ... insolation at the pole starts dropping like a stone.  The race is on.  Personally, I'm rooting for the ice ... but it is not looking good.

Killian

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Re: The 2019 melting season
« Reply #5135 on: August 02, 2019, 06:55:01 AM »
<snip, no meta-discussions, thanks; N.>
« Last Edit: August 02, 2019, 04:19:37 PM by Neven »

Killian

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Re: The 2019 melting season
« Reply #5136 on: August 02, 2019, 07:08:03 AM »
<snip, this is more suited elsewhere, not here; N.>

Neven, while you were away I was "strongly encouraged" to move this daily analysis of the 2019 melt season out of the Data thread. So, I only post the data there.

I moved the analysis to this location because it is about the melt season. Though this one was very short... because there just wasn't much new to say, sometimes it's paragraphs long. Now you don't want it here.

Which thread do you think it appropriate for? 2019 vs 2012?

<Yes, try there; N.>
« Last Edit: August 02, 2019, 04:20:28 PM by Neven »

subgeometer

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Re: The 2019 melting season
« Reply #5137 on: August 02, 2019, 07:19:52 AM »
If the Uni Bremen extent graph is to be believed 2012 has a lot of catching up to do, 2019 leads by a country mile. I'm not sure if its correct about this, but it goes with the map we follow.

JAXA extent losses have slowed over the past 2 days, but here 2019 still leads by 170000km2, up 10K  yesterday.

A few days slow down on extent or even the weird flatlining on area can't be read to signal anything definitive about the season or its ongoing momemtum - 2012 also went really slow about this time - at least on measures like extent, though Wipneus melt ratio graphs show a spike in melt at the same time, the prelude to the massive drop to follow with the GAC. I only hope Friv is right about the CAA and Atlantic front


Rod

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Re: The 2019 melting season
« Reply #5138 on: August 02, 2019, 07:26:12 AM »
<snip, this is more suited elsewhere, not here; N.>

Neven, while you were away I was "strongly encouraged" to move this daily analysis of the 2019 melt season out of the Data thread. So, I only post the data there.

I moved the analysis to this location because it is about the melt season. Though this one was very short... because there just wasn't much new to say, sometimes it's paragraphs long. Now you don't want it here.

Which thread do you think it appropriate for? 2019 vs 2012?

I enjoy your analysis.  I don’t care where it gets posted, but I hope you continue to post it.  I don’t know why there has been push back.  Lots of people speculate on here and it is fun to look at the guesses and see how they turn out. 

subgeometer

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Re: The 2019 melting season
« Reply #5139 on: August 02, 2019, 07:45:48 AM »
July 28 - August 1.

2018.

The pack continues to spread toward the encroaching melt edge. A lot of ice on death row, anything south of 80N on Eurasian and Pacific side, with areas to 85N soon to join it I think.

El Cid

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Re: The 2019 melting season
« Reply #5140 on: August 02, 2019, 08:05:21 AM »
petm, can you post you uni bremen median graph for today? and maybe as comparison 2012 for the same date? i find them most useful. thanks

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Re: The 2019 melting season
« Reply #5141 on: August 02, 2019, 08:29:39 AM »
July 28 - August 1.

2018.

These animations are a wonderful Rorschach Test.

It's impossible to look at that and not be drawn toward the ice blinking out in the ESS. Harder to focus on the circle N of 80N and see the relatively complete ice.

My visceral reaction to these is always to cringe. But I've kinda prepared for the easy stuff outside of 80N to go. Still think the E. Beaufort may have ice outside of 80N at the minimum.

Edit: Correction. Original version indicated W. Beaufort as place where ice was expected at year-end. That was a typo.
« Last Edit: August 02, 2019, 09:37:41 AM by Rich »

Wildcatter

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Re: The 2019 melting season
« Reply #5142 on: August 02, 2019, 09:14:22 AM »
I'm a bit surprised at the lack of attention given the ice along the southern pack, which has usually been a safe haven. Are we expecting that to change? It's progressively getting worse, it immediately jumps out to me compared to other years.

BenB

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Re: The 2019 melting season
« Reply #5143 on: August 02, 2019, 09:23:34 AM »
Still think the W. Beaufort may have ice outside of 80N at the minimum.

You mean E. Beaufort, presumably? It's possible, if more ice is transported from the CAB. I think what's already there will melt out, though. See the difference just one day makes:

Sterks

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Re: The 2019 melting season
« Reply #5144 on: August 02, 2019, 09:25:11 AM »
I'm a bit surprised at the lack of attention given the ice along the southern pack, which has usually been a safe haven. Are we expecting that to change? It's progressively getting worse, it immediately jumps out to me compared to other years.
Southern pack should be all the ice south of the NP., doesn't narrow it. You mean south where?

sja45uk

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Re: The 2019 melting season
« Reply #5145 on: August 02, 2019, 09:30:05 AM »

As salt gets rejected the ice is not homogeneous ( includes regions with defects and brine channels etc) and thus weaker than ice that was rejected most salt.

Sources: Met Office, Anderson DL '58 A Theoretical Analysis of Sea-Ice Strength

A very interesting paper on brine pockets and the tensile strength of sea ice, but I wonder how often the ice is in pure tension rather than compression or shear. It seems that the crack north of Greenland is probably caused by wind blowing off Greenland and across the ice towards the North Pole. It is also presumably relevant to ice breakers that put the ice in local tension by driving a wedge shape into the ice at the bow.

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Re: The 2019 melting season
« Reply #5146 on: August 02, 2019, 09:40:31 AM »
Still think the W. Beaufort may have ice outside of 80N at the minimum.

You mean E. Beaufort, presumably? It's possible, if more ice is transported from the CAB. I think what's already there will melt out, though. See the difference just one day makes:

Corrected. I did mean East.

binntho

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Re: The 2019 melting season
« Reply #5147 on: August 02, 2019, 09:48:45 AM »

As salt gets rejected the ice is not homogeneous ( includes regions with defects and brine channels etc) and thus weaker than ice that was rejected most salt.

Sources: Met Office, Anderson DL '58 A Theoretical Analysis of Sea-Ice Strength

A very interesting paper on brine pockets and the tensile strength of sea ice, but I wonder how often the ice is in pure tension rather than compression or shear. It seems that the crack north of Greenland is probably caused by wind blowing off Greenland and across the ice towards the North Pole. It is also presumably relevant to ice breakers that put the ice in local tension by driving a wedge shape into the ice at the bow.
I may be totally wrong here, but I've always assumed that ice breakers sailed up onto the ice and broke it by pressing downwards. Cutting with the bow, like butter with a knife, wouid presumably only work in very thin and fragile ice, or dispersed ice.
PS this discussion seems to getting a bit OT, perhaps it could be continued here https://forum.arctic-sea-ice.net/index.php/topic,854.0.html or even better here https://forum.arctic-sea-ice.net/index.php/topic,2274.0.html
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Re: The 2019 melting season
« Reply #5148 on: August 02, 2019, 11:26:15 AM »
- The current ESS ice falls into the category of "It would have melted anyway without a GAC".
My feeling is that it's going to melt out anyway without a GAC..., but with the help of a couple of storms and pressure gradients.
Same with Beaufort. One way or another it keeps getting import. At this rate, I agree some of that ice survives below 80N, but a moderate storm may erase it from the map, a la 2015.

- The Euro model predicts a pretty central moderate 975-980 hPa low by day 8, forecast will probably change. It would be bad if it happened not as central but shifted toward the ESS/Chuckchi.
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BenB

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Re: The 2019 melting season
« Reply #5149 on: August 02, 2019, 11:42:38 AM »
- The Euro model predicts a pretty central moderate 975-980 hPa low by day 8, forecast will probably change. It would be bad if it happened not as central but shifted toward the ESS/Chuckchi.

I'm attaching the Euro forecast (first image) so people can easily see what you're talking about. On the other hand, the GFS has moved away from a deep low (second image).