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uniquorn

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Re: The 2020 melting season
« Reply #2200 on: July 04, 2020, 11:38:43 PM »
There are a few mosaic buoys that can show fram export over the next couple of weeks.

gerontocrat

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Re: The 2020 melting season
« Reply #2201 on: July 04, 2020, 11:58:37 PM »

On a separate note....w/ PIOMAS numbers in....the 3 regions which are most likely to retain material volumes of ice at the minimum are clearly now CAB, Beaufort Sea and Greenland Sea. On a combined basis, these three seas have over 1,000 km3 more ice through this June vs. last year.

How much of that difference will 2020 make up over the rest of the summer ?
Ice that ends up in the Greenland Sea is doomed to die - if not this year then next year.
It has been, is, and will be really warm off the east coast of Greenland. That ice volume is so high reflects very large export via the Fram overwhelming high rates of melting. This is probably bad news for ice in the Central Arctic Ocean.

I attach the Greenalnd melt graph from DMI for the 3rd July. We are not supposed to see such high melt in the NE of Greenland - which has been the case for the last 10 days or so. If there is high melt on the land, then you can be sure the offshore sea ice is getting hammered as well.
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Re: The 2020 melting season
« Reply #2202 on: July 05, 2020, 12:28:06 AM »
Am I correct in remembering that this kind of sunshine can cause up to 5cm/day of top melt? So this week long HP could melt 30cm off of wide swaths of the ASI?

If the water under the ice warms up, how much ice starts melting per day? 0.5cm? 1cm? Do we know how fast bottom melt was going in other years, when there were still buoys in the ice measuring such things?

See for example this 2011 paper from Don Perovich:

https://tos.org/oceanography/assets/docs/24-3_perovich.pdf

Quote
Surface melt in 2007 was typical for the Beaufort Sea, with melt starting in early June and a total of 0.7 m of surface melt. The difference in 2007 was the extremely large 2.1 m of bottom melting. There was a gradual buildup of heat in the upper ocean in July and August. Bottom melt rates increased throughout the summer, reaching peak values of 0.1 m d–1 in late August.
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uniquorn

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Re: The 2020 melting season
« Reply #2203 on: July 05, 2020, 12:31:43 AM »
Ascat struggling somewhat with the summer weather, day82-185 (180-182 not available) but still good for an overview of the melting season so far.
compressed to 2.2MB.  Greenland does look different on the last few frames.
Located day180-182. Animation updated downthread.
« Last Edit: July 05, 2020, 10:55:27 PM by uniquorn »

Pagophilus

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Re: The 2020 melting season
« Reply #2204 on: July 05, 2020, 12:37:07 AM »
Thank you for your replies, gandul and Phoenix.  It is great to learn from you. 

Worldview image showing just how sad the condition of ice is in the Chukchi right now...
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Rod

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Re: The 2020 melting season
« Reply #2205 on: July 05, 2020, 01:26:17 AM »

Ice is generally pushed inwards under anticyclones (clockwise rotation). This is because the wind pushing on the ice actually makes the ice move at an angle further to the right than would be expected, because of the Coriolis effect. Here is a basic diagram on how the ice would move with this setup (probably a bit exaggerated). Of course this is approximate, and also doesn't account for ocean currents, collisions with other ice or land, etc.

Do you have a citation for this grixm? I’m not saying you are wrong, but your red arrows are pointing in the opposite direction of what I would have expected based on what I have learned from A-Team and Fishoutofwater over the years.

I did a quick literature search and could not find anything. Based upon Ekman pumping, I would have expected these winds to be pushing the ice at a 90 degree angle out the Fram and into the Atlantic. Uniquorn’s buoys data would seem to support that. I don’t claim to have any expertise on this matter and I am probably wrong.

I agree that in the western arctic basin the winds are likely driving the ice further north. But along the Atlantic side, I think the winds are driving the ice out the Fram. 

If you can point me to a scientific journal article that supports your conclusion I would love to read it. 

Again, I’m not trying to be difficult, and you might be correct.  But, I would love to see a journal article that addresses this issue. 
« Last Edit: July 05, 2020, 01:54:40 AM by Rod »

Ice Shieldz

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Re: The 2020 melting season
« Reply #2206 on: July 05, 2020, 01:32:02 AM »
AMSR2 sea ice concentration – 2020 May14th to July3rd

click to play

OffTheGrid

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Re: The 2020 melting season
« Reply #2207 on: July 05, 2020, 01:56:29 AM »
The subpolar heatwaves in eurasian and nth american sector have made tatters and rags
 of subpolar jet. At top of turbosphere, 250hpa, is reverse jet from east to west blow as air moves south , even passing equator in 90% of circumference, except for small  cell propped up by la nina walker cell in central pacific. Strong global Low altitude backflow IS sweep southern tropical heat and moisture nth, cause records floods in stheasf asia, AND hot air punch through to feed strong north pole ridge as ramp up over seaice cooled surface air. Temp above zero from surface to 3km altitude above pole is ongoing.
Hadley cell are demolish. Ferrel cell circulate planet, owning turbosphere from 60 nth to 20 sth. Polar cell maintain, while sea ice melt cool arctic basin. Very much room for polar cell eaten by ferrel system in next few months. Stereographic projection in nullschool images to best display full hemisphere dynamics.
« Last Edit: July 05, 2020, 02:02:01 AM by OffTheGrid »

gandul

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Re: The 2020 melting season
« Reply #2208 on: July 05, 2020, 02:07:46 AM »

Ice is generally pushed inwards under anticyclones (clockwise rotation). This is because the wind pushing on the ice actually makes the ice move at an angle further to the right than would be expected, because of the Coriolis effect. Here is a basic diagram on how the ice would move with this setup (probably a bit exaggerated). Of course this is approximate, and also doesn't account for ocean currents, collisions with other ice or land, etc.

Do you have a citation for this grixm? I’m not saying you are wrong, but your red arrows are pointing in the opposite direction of what I would have expected based on what I have learned from A-Team and Fishoutofwater over the years.

I did a quick literature search and could not find anything. Based upon Ekman pumping, I would have expected these winds to be pushing the ice at a 90 degree angle out the Fram and into the Atlantic. Uniquorn’s buoys data would seem to support that. I don’t claim to have any expertise on this matter and I am probably wrong.

I agree that in the western arctic basin the winds are likely driving the ice further north. But along the Atlantic side, I think the winds are driving the ice out the Fram. 

If you can point me to a scientific journal article that supports your conclusion I would love to read it. 

Again, I’m not trying to be difficult, and you might be correct.  But, I would love to see a journal article that addresses this issue.
The ice is pulled by the wind, but always has a perpendicular drift component noticeably to the right toward the high pressure side of the isobars (NH). Thus an anticyclone tends to bring the ice together while a cyclone creates dispersion.
The same reason why garbage tends to concentrate at the center of the ocean gyres, who take their rotational mechanical energy from predominant anticyclones (for instance Sargazos sea under the Azores/Bermudas High)
Also dispersion in storm explains why Tom Hanks lose Dr Wilson in the middle of a storm.
2016 was super dispersion year, just the opposite to this one so far. I suspect both extremes can be very as detrimental to the Arctic. 2016 ended with a super low volume in December, nothing ever seen after or before.
« Last Edit: July 05, 2020, 02:14:03 AM by gandul »

Rod

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Re: The 2020 melting season
« Reply #2209 on: July 05, 2020, 02:18:26 AM »
I don’t disagree with the general proposition. But with respect to Fram export and the currents involved in ice export, I question whether the red arrows on the Atlantic side of grixm’s map are correct.

From what I see, the ice is going out not in.  Uniquorn’s data showed that.

It is a minor point, but important. Is the ice that PIOMAS predicted as thick going to the Atlantic or going north to be preserved?


Freegrass

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Re: The 2020 melting season
« Reply #2210 on: July 05, 2020, 02:29:30 AM »
It looks like this 'stirring' should result in a lot of of Fram export

I don't see much Fram export in that forecast.  Due to Coriolis force there's an angle of about 30 degrees between wind direction and sea ice drift, with the drift deviating toward the high pressure area, see the references here.  In the forecast posted above there won't be much ice crossing the boundary between CAB and Greenland Sea.
If I understand you correctly, what you are saying is that this July Arctic High will compact the ice so much that there won't be enough ice left to be exported through Fram. If that's true, that would mean that we would see a tremendous amount of extent loss through compaction. I'm not sure the ice is dispersed enough for that much compaction, but I'm willing to be surprised by the hand of God...  ::)
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Rod

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Re: The 2020 melting season
« Reply #2211 on: July 05, 2020, 04:02:40 AM »
Thank you Phoenix, but you miss my point.

I was looking for a peer reviewed study that addresses the current situation. Maybe there isn’t one. Grixm spoke with authority. I was hoping he had something. If A-Team or FOW were still around they could probably help.

Wikipedia is junk. Anyone can post anything to that.  And, the Beaufort Gyre is on the opposite side of the CAB from what I’m focused on anyway.

If anyone knows of scientific studies on Fram export under the current conditions we are seeing, please send me a link. 

In any event, we will all keep watching and waiting to see what happens.

The next few days look interesting!
« Last Edit: July 05, 2020, 04:11:07 AM by Rod »

Tor Bejnar

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Re: The 2020 melting season
« Reply #2212 on: July 05, 2020, 04:08:52 AM »
...
The Central Arctic Sea ice area has plummeted in the last 2-3 days. Note that this is NOT reflected in any loss of sea ice EXTENT. Seems to be all about low concentration. But if this continues questions on the resilience of the Central Arctic Sea's ice might surface (again).
...
Isn't loss of SIA, with no loss of SIE traditionally a sign of growing melt ponds 'confusing' the sensors?

Of course, extensive melt ponds across the CAB during the peak of summer would be disastrous for that bastion of stable ice.
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Pagophilus

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Re: The 2020 melting season
« Reply #2213 on: July 05, 2020, 06:23:20 AM »
...
The Central Arctic Sea ice area has plummeted in the last 2-3 days. Note that this is NOT reflected in any loss of sea ice EXTENT. Seems to be all about low concentration. But if this continues questions on the resilience of the Central Arctic Sea's ice might surface (again).
...
Isn't loss of SIA, with no loss of SIE traditionally a sign of growing melt ponds 'confusing' the sensors?

Of course, extensive melt ponds across the CAB during the peak of summer would be disastrous for that bastion of stable ice.

But if there are growing meltponds, where would they be?  The black 'dots' of low concentration on the AMRSR2 images have been skipping merrily around the Central Arctic Sea ice for the past week, as they so often do.  Consistent low concentration has been showing up where there IS low concentration... the rapidly failing Chukchi, the ESS, the margins of the Laptev...  Again (sigh} I am probably missing something...  Maybe the effect is too subtle to register on the map?
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ajouis

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Re: The 2020 melting season
« Reply #2214 on: July 05, 2020, 06:30:02 AM »
After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

ajouis

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Re: The 2020 melting season
« Reply #2215 on: July 05, 2020, 06:55:20 AM »
I think today’s amsr 2 image of the arctic shows a few interesting things. There is a serious melting event in the chuchki, which is not surprising given how much the water heats up in the Bering strait, similarly all the coastal ess ice either has disappeared or is disappearing, and in general the aspect of the northwest quadrant shows fair amounts of melt (melt ponds?), so I don’t think it will be our saving grace. The CAA has some big leads from earlier meltponding but we will have to see how it clears up the channels, especially the western ones and the ones at the border of the cab. Hudson is starting to drop like a stone in aspect, as expected. Finally on the atlantic side, the laptev bite is getting bigger, and with room to grow (ending up detaching the kara ice?), and the rest of the more southern atlantic front shows excess ice and slow melt, maybe the gulf stream will be enough to avoid those positive anomalies carrying over to the minimum. Also the Fram aspect seems to indicate that free flow is allowed, which goes in the same direction as the last images uploaded on the rammb thread, there is, albeit limited movement.

 For now it comforts me in my personal prediction of a below 3 cubic millions piomas minimum.
After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

interstitial

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Re: The 2020 melting season
« Reply #2216 on: July 05, 2020, 07:49:50 AM »
On one of the islands between the kara and laptev the ice caps do not look like they are in great shape.

grixm

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Re: The 2020 melting season
« Reply #2217 on: July 05, 2020, 08:04:54 AM »
Thank you Phoenix, but you miss my point.

I was looking for a peer reviewed study that addresses the current situation. Maybe there isn’t one. Grixm spoke with authority. I was hoping he had something. If A-Team or FOW were still around they could probably help.

Wikipedia is junk. Anyone can post anything to that.  And, the Beaufort Gyre is on the opposite side of the CAB from what I’m focused on anyway.

If anyone knows of scientific studies on Fram export under the current conditions we are seeing, please send me a link. 

In any event, we will all keep watching and waiting to see what happens.

The next few days look interesting!

I don't know about Fram export specifically, if it doesn't line up with the expected forces from the wind then there can be multiple explanations, like I mentioned in my post: Ocean currents, being forced in a different direction due to pressure from surrounding ice and land, etc.

The core message of my post was merely that the force from the wind on ice is at an angle to the right from the actual wind direction. A source for this, as well as possible conflicting forces in the Fram, can be seen here for example: https://nsidc.org/cryosphere/seaice/processes/dynamics.html

oren

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Re: The 2020 melting season
« Reply #2218 on: July 05, 2020, 08:17:33 AM »
High pressure dome=compaction, low pressure storm=dispersion, ice moves somewhat to the right of the wind, all this is well known in the context of this thread. The scientific citations can be discussed at length in a different thread.
However, the Fram (and Nares) case is indeed special, the current supports export, and the land mass of Greenland (and Ellesmere) helps steer the ice away from the Arctic, though it still hugs the coast to its right due to Coriolis.
From my limited experience, a setup of wind from the general north into and along the strait (as expected for the coming days) will indeed result in export. However, it is best to wait for said export and see for oneself if it materializes or not.

blumenkraft

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Re: The 2020 melting season
« Reply #2219 on: July 05, 2020, 09:02:16 AM »

Aluminium

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Re: The 2020 melting season
« Reply #2220 on: July 05, 2020, 10:15:24 AM »
June 30 - July 4.

2019.

uniquorn

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Re: The 2020 melting season
« Reply #2221 on: July 05, 2020, 10:24:40 AM »
Looking closer at the Beaufort Sea using uni-hamburg amsr2-uhh, jun1-jul4. The small cyclone over the Mackenzie Bay area having an effect. click to run
I've been helpfully pointed to the missing ascat files above. Will fill in the gap later.

oren

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Re: The 2020 melting season
« Reply #2222 on: July 05, 2020, 10:57:28 AM »
June 30 - July 4.

2019.
Interesting developments all around. Ice is being decimated south of Wrangel Island, and on a smaller scale northwest of Point Barrow. A lot of movement in the ESS towards the west.
Also for those who ask from time to time if Kara ice is relevant to the High Arctic melting season, the animation shows nicely the import of ice from the Kara to the CAB east of FJL. The less ice there is in the Kara, the less this can happen (not to mention that warm air off the continent can cool over ice in the Kara, if it exists, before it can reach the CAB).
Some small export seems to be starting in the Fram. And the Nares ice started running for the exit as expected.

ArcticMelt2

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Re: The 2020 melting season
« Reply #2223 on: July 05, 2020, 11:38:42 AM »
June 30 - July 4.

The Northeast passage is close to early open. When is the earliest opening of this passage?

ArcticMelt2

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Re: The 2020 melting season
« Reply #2224 on: July 05, 2020, 11:45:53 AM »
Melting is increasingly shifting to the Atlantic side. As shown in the topic about SMOS yesterday. This is not surprising because apparently the main heat transfers in the spring were north of the Kara Sea.

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Re: The 2020 melting season
« Reply #2225 on: July 05, 2020, 11:46:22 AM »
June 30 - July 4.


The Laptev/CAB is blowing up. No ice within 5-6 degrees latitude of the Taymyr Peninsula can survive the Siberian heat onslaught of 2020.

ArcticMelt2

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Re: The 2020 melting season
« Reply #2226 on: July 05, 2020, 11:51:35 AM »
June 30 - July 4.

The Northeast passage is close to early open. When is the earliest opening of this passage?

One of the last ice barriers in the Kara Sea is practically open.

Image from today:
« Last Edit: July 05, 2020, 12:17:51 PM by ArcticMelt2 »

JamesW

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Re: The 2020 melting season
« Reply #2227 on: July 05, 2020, 12:04:47 PM »
High pressure dome=compaction, low pressure storm=dispersion, ice moves somewhat to the right of the wind, all this is well known in the context of this thread. The scientific citations can be discussed at length in a different thread.
However, the Fram (and Nares) case is indeed special, the current supports export, and the land mass of Greenland (and Ellesmere) helps steer the ice away from the Arctic, though it still hugs the coast to its right due to Coriolis.
From my limited experience, a setup of wind from the general north into and along the strait (as expected for the coming days) will indeed result in export. However, it is best to wait for said export and see for oneself if it materializes or not.

Correct: High pressure dome=compaction.

This is why I asked for the compaction/dispersion charts which gerontocrat kindly posted up as the high pressure dome got started. I would expect while the anomolous high is in place we will see compaction and larger drops in area/extent along with the increase in insolation for melt rate in the central seas.

So far its ringing true with JAXA and NSIDC and information in the 2020 Sea ice area and extent data thread. Therefore we should expect some high decreases for the next few days with a good chunk of it being down to compaction from the high pressure dome in the central artic seas.

Once the high is over or moved out after a couple of days. I will kindly ask gerontocrat to re post up the compaction/dispersion chart to see how this high has affected everything. So we can understand better at this time in the season the overall effect, on how it has or possibly not compacted the ice centrally and its overall impact.


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Re: The 2020 melting season
« Reply #2228 on: July 05, 2020, 12:28:27 PM »
3-day forecasted average 10m wind speed (GFS) - today's forecast vs Saturday's forecast.

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Re: The 2020 melting season
« Reply #2229 on: July 05, 2020, 12:53:23 PM »
Сan see how quickly the large ice floe of fast ice 30 km in size disappears into the Laptev Sea.

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Re: The 2020 melting season
« Reply #2230 on: July 05, 2020, 01:45:36 PM »

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Re: The 2020 melting season
« Reply #2231 on: July 05, 2020, 02:36:07 PM »
The black line severs white space.

Pagophilus

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Re: The 2020 melting season
« Reply #2232 on: July 05, 2020, 02:50:55 PM »
Looking at Aluminium's invaluable animation playing over a few times, it looks like the clockwise rotation of the ice pack, perhaps resulting from the nascent anticyclone, and the consequent Coriolis-Effect-driven compaction of the ice pack may already be taking place.  So, props to grixm, gandul etc.

Along with general melting, this would help explain the recent dramatic drops in extent in the Central Arctic Sea.  Not so sure how it explains the drop in area though...  And again, if there is significant meltponding in the central ice, wouldn't that show up as consistent patches?

June 30 - July 4.

2019.
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ArcticMelt2

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Re: The 2020 melting season
« Reply #2233 on: July 05, 2020, 03:01:05 PM »
Looking at Aluminium's invaluable animation playing over a few times, it looks like the clockwise rotation of the ice pack, perhaps resulting from the nascent anticyclone, and the consequent Coriolis-Effect-driven compaction of the ice pack may already be taking place.  So, props to grixm, gandul etc.

Along with general melting, this would help explain the recent dramatic drops in extent in the Central Arctic Sea.  Not so sure how it explains the drop in area though...  And again, if there is significant meltponding in the central ice, wouldn't that show up as consistent patches?

You can also see the average ice drift pattern over the past three days. Well see how the ice moves around the incipient anticyclone.

The most significant effect is that the warm air masses from the Kara Sea penetrate north, and expand the depression in the ice. As can be seen in the animation of Aluminum, this recess has greatly expanded over the past and now has reached 82.5 degrees north latitude.

So I was wrong when I said that the Kara Sea is of little importance for summer melting. In fact, it strengthens the warm masses moving towards the Central Arctic from the Atlantic.
« Last Edit: July 05, 2020, 03:45:18 PM by ArcticMelt2 »

Pagophilus

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Re: The 2020 melting season
« Reply #2234 on: July 05, 2020, 03:46:06 PM »
The black line severs white space.

Holy... guacamole.  I feel as if a giant engine is revving up and the rubber is about to hit the road.

Part of the CAB is very clear this morning.  I took screenshots on Worldview, cranked the contrast waaaay up, and I think it helps to distinguish the continuous ice of the CAB from the broken up ice area that is approaching the pole and causing concern.  I drew a red line representing my visual perception of the approximate boundary between the two.

AMSR2 does not make this distinction, so I thought this worthwhile.  Hope I am seeing things correctly... these are subjective visual evaluations

Northern Laptev is at top left/center, 'Zemlya top right and then further down is FJL.
« Last Edit: July 05, 2020, 05:07:07 PM by Pagophilus »
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GoSouthYoungins

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Re: The 2020 melting season
« Reply #2235 on: July 05, 2020, 03:48:01 PM »
<Removed, improper here. O>
« Last Edit: July 05, 2020, 05:20:00 PM by oren »
big time oops

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Re: The 2020 melting season
« Reply #2236 on: July 05, 2020, 05:23:51 PM »
Nullschool forecast July 7.  Two days from now, two weather systems, anticyclone over pole, cyclone centered near Svalbard, look set to cooperate, like a pair of gears, on getting ice through the Fram.  And much of that ice may be fragmented to with 5 degrees of the pole.  I know it takes time to move that much ice, but just sayin'....
« Last Edit: July 05, 2020, 05:38:06 PM by Pagophilus »
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ArcticMelt2

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Re: The 2020 melting season
« Reply #2237 on: July 05, 2020, 05:30:51 PM »
It is alleged that the the earliest opening Northeast Passage of the sea route off the coast of Siberia happened in 2012. How true is this?

https://www.sciencedirect.com/science/article/abs/pii/S0165232X15001743

Quote
Changes in sea ice conditions along the Arctic Northeast Passage from 1979 to 2012

As a result of decreasing multiyear sea ice, thinning ice and delayed freeze-up, the spatially averaged length of open period (ice concentration < 50%) increased from 84 days in the 1980s to 114 days in the 2000s and reached 146 days in 2012.

https://global.weathernews.com/news/12647/



Distribution of sea ice in the Arctic Ocean (as of June 28th, 2019) and past open periods of shipping passages (green) and predicted open periods for 2019 (red/yellow)

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Re: The 2020 melting season
« Reply #2238 on: July 05, 2020, 06:22:46 PM »
https://twitter.com/ZLabe/status/1279777745208143872

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#Arctic air temperature rank by month over the satellite era - 2020 is the 2nd highest June on record in this analysis


ArcticMelt2

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Re: The 2020 melting season
« Reply #2239 on: July 05, 2020, 06:47:39 PM »
https://twitter.com/AlaskaWx/status/1279818749621624832

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Sea ice extent in the Chukchi Sea remains near the 1981-2010 average in @NSIDC  data but fell quite a bit the past week. Open water now along the Alaska coast all the way to Pt. Barrow. Ice loss in the Beaufort Sea progressing but slow.


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Re: The 2020 melting season
« Reply #2240 on: July 05, 2020, 06:53:29 PM »
https://twitter.com/ZLabe/status/1279777745208143872

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#Arctic air temperature rank by month over the satellite era - 2020 is the 2nd highest June on record in this analysis


I love that chart. It highlights the long ~ 3 year periods of consistency leading up to the record minimums in 2007 and 2012.

It's scary to think about what a melt season like the current one is going to do after a winter on the warm side. It seems like russian roulette with a loaded gun at this point.

FishOutofWater

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Re: The 2020 melting season
« Reply #2241 on: July 05, 2020, 07:47:47 PM »
I'm here. I learned from A-Team that, because sea ice is a deformable medium, the best thing to do is to look at markers of where it is moving. There's no disagreement that high pressure over the pole leads to compaction around the pole and low pressure leads to dispersion. That said, the Arctic has many obstacles that cause sea ice to pile up, rotate and thin. Moreover, high pressure causes easterly winds along the shelf margins which induce upwelling. Persistent winds of 10 days or more can cause strong coastal upwelling events which may bring up stored heat from subsurface layers.

The worst set up for sea ice is low pressure over the pole in the winter and high pressure in midsummer. Guess what? That exactly what's happened this year.


Frivolousz21

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Re: The 2020 melting season
« Reply #2242 on: July 05, 2020, 08:07:28 PM »
Looking at Aluminium's invaluable animation playing over a few times, it looks like the clockwise rotation of the ice pack, perhaps resulting from the nascent anticyclone, and the consequent Coriolis-Effect-driven compaction of the ice pack may already be taking place.  So, props to grixm, gandul etc.

Along with general melting, this would help explain the recent dramatic drops in extent in the Central Arctic Sea.  Not so sure how it explains the drop in area though...  And again, if there is significant meltponding in the central ice, wouldn't that show up as consistent patches?

June 30 - July 4.

2019.

The Bremen sic comes from channel 89ghz on the AMSR2 instrument

Which cannot see through clouds and fog

A huge area of FOG blew up thanks to very warm and relatively moist LOW LEVEL WARM ADVECTION....

concentration will drop as things clear out the next few days.  The beginning of the clearing has started on the Atlantic side.

The RIDGE of HIGH PRESSURE is still DEVELOPING and is also ARRANGING itself to become more vertically stacked.  Which will uniform the descending air and aid in drying out the atmosphere and vanished the clouds and fog with it.



HOWEVER THE FOG IN SHORT DOSES WHEN THE LPWE ATMOSPHERE IS A PRIMED WITH HEAT AS IT HAS BEEN PROBABLY HAS HELD THE SURFACE TEMPS UNDER THE CANOPY OF FOG IN THE 0.5-2C RANGE.

JUST FREAKING BRUTAL.  AND NOW WE ARE UNDERGOING A QUICK ASCENSION INTO WIDESPREAD SUN.

Potential solar INSOLATION is still above 500W/M2 until the 12th of July or so.

And above 475W/M2 until the 20th over the CAB.

2020 is really making it's case to finish lowest in volume, area, and extent.



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Re: The 2020 melting season
« Reply #2243 on: July 05, 2020, 08:44:15 PM »
...
The Central Arctic Sea ice area has plummeted in the last 2-3 days. Note that this is NOT reflected in any loss of sea ice EXTENT. Seems to be all about low concentration. But if this continues questions on the resilience of the Central Arctic Sea's ice might surface (again).
...
Isn't loss of SIA, with no loss of SIE traditionally a sign of growing melt ponds 'confusing' the sensors?

Of course, extensive melt ponds across the CAB during the peak of summer would be disastrous for that bastion of stable ice.

But if there are growing meltponds, where would they be?  The black 'dots' of low concentration on the AMRSR2 images have been skipping merrily around the Central Arctic Sea ice for the past week, as they so often do.  Consistent low concentration has been showing up where there IS low concentration... the rapidly failing Chukchi, the ESS, the margins of the Laptev...  Again (sigh} I am probably missing something...  Maybe the effect is too subtle to register on the map?


Wouldn't the Polarstern follow the exact thickness as well as concentration in their vicinity so that we could compare their measured data with all the models like piomas, hycom, extend and especially meltponding versus "really" low concentration.


If wie had access to such real-life data we could save ourselves many discussions about model flaws and model accuracies. Not 100% but at least strong hints, supported by facts, even though from a limited region?

ArcticMelt2

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Re: The 2020 melting season
« Reply #2244 on: July 05, 2020, 08:56:51 PM »
https://twitter.com/AlaskaWx/status/1279831110608842753/photo/1

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Great view Saturday afternoon from NOAA-20, image courtesy @uafgina. Unusually clear skies over NW Alaska show dramatic but typical diffs in #seaice around Utqiaġvik: ice remains east of Pt. Barrow. Inland, ice remains on lakes north of 70.5N.


Frivolousz21

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Re: The 2020 melting season
« Reply #2245 on: July 05, 2020, 08:57:02 PM »
...
The Central Arctic Sea ice area has plummeted in the last 2-3 days. Note that this is NOT reflected in any loss of sea ice EXTENT. Seems to be all about low concentration. But if this continues questions on the resilience of the Central Arctic Sea's ice might surface (again).
...
Isn't loss of SIA, with no loss of SIE traditionally a sign of growing melt ponds 'confusing' the sensors?

Of course, extensive melt ponds across the CAB during the peak of summer would be disastrous for that bastion of stable ice.

But if there are growing meltponds, where would they be?  The black 'dots' of low concentration on the AMRSR2 images have been skipping merrily around the Central Arctic Sea ice for the past week, as they so often do.  Consistent low concentration has been showing up where there IS low concentration... the rapidly failing Chukchi, the ESS, the margins of the Laptev...  Again (sigh} I am probably missing something...  Maybe the effect is too subtle to register on the map?

The 89ghz channel on the AMSR2 can't see through clouds/fog.  When obscure by these things it registers as near 100 percent concentration.

Jaxa uses channel 36 GHz and channel 18ghz as a filter.  I don't believe jaxa uses channel 89ghz but they might for coastal edges.  But I am unsure it's been a long time since I've read about the algorithms.

NSIDC keeps two long term data sets or at least one long term data set using the lower frequency channels on the ssmis instrument so the data is compatible with the ssmi data that iirc ran from late 78 to 88.  And the data on the sat before that from 72-78.

However for their real time graphics they use channel 91 GHz I believe on the ssmis.

So the lower frequency channels like 18/36 GHz on the AMSR2 instrument can differentiate between between clouds, fog, water vapor, and cloud ice with open ocean, sea ice, snow, and wet ice.

The drawback is the resolution is like 3x worse than the channel 89ghz which is like 3-5km resolution.


This is why looking at the BREMEN OR HAMBURG HIGH A RES CONCENTRATION WONT ALWAYS MESH WITH NSIDC OUTPUT.

The TWO IMAGES BELOW ARE FROM JUNE 30TH AND JULY 4TH.

ON JUNE 30TH THE SOUTHERN CAB WAS CLEAR AND SUNNY.

ON JULY 4TH IT WAS INUNDATED BY DENSE FOG.

YOU CAN SEE THE LOWER CONCENTRATION THAT APPEARED MOSTLY DUE TO MAJOR MELTPONDING JUST VANISHED.

BUT IN REALITY IT'S STILL THERE.



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Re: The 2020 melting season
« Reply #2246 on: July 05, 2020, 09:02:40 PM »
Optimizing workflow. All Sunday movies in one post.

7-day hindsight mean temperature anomalies, Arctic ice drift map, and Fram ice drift via SAR. Click to play.

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Re: The 2020 melting season
« Reply #2247 on: July 05, 2020, 09:09:06 PM »
12Z GFS - So the big high is going to establish itself over Beaufort after finishing North Pole? This is forecast for July 15th. Still far away, but worth looking at.

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Re: The 2020 melting season
« Reply #2248 on: July 05, 2020, 09:22:31 PM »
https://twitter.com/ZLabe/status/1279777745208143872

Quote
#Arctic air temperature rank by month over the satellite era - 2020 is the 2nd highest June on record in this analysis



So far May/June of 2020 is the warmest on record between 70-90N.

And even tho we are only 3 days into July.  The start is a straight MEGA TORCH.

AND THE FORECAST CALLS FOR THE MEGA TORCH TO PERSIST THROUGH THE 11/12TH WHEN WE DROP BACK TO WELL ABOVE NORMAL..

It's not a wonder why area and extent have dive bombed.  And this is without a dipole.
I got a nickname for all my guns
a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

ArcticMelt2

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Re: The 2020 melting season
« Reply #2249 on: July 05, 2020, 09:38:15 PM »
So far May/June of 2020 is the warmest on record between 70-90N.

And even tho we are only 3 days into July.  The start is a straight MEGA TORCH.

AND THE FORECAST CALLS FOR THE MEGA TORCH TO PERSIST THROUGH THE 11/12TH WHEN WE DROP BACK TO WELL ABOVE NORMAL..

It's not a wonder why area and extent have dive bombed.  And this is without a dipole.

According to these data, in reality, 2020 is warmer than 2012 in the Central Arctic in the first half of summer. Why, then SMOS shows more melting in 2012?