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werther

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Re: The 2020 melting season
« Reply #4000 on: July 28, 2020, 11:24:44 PM »
Freegrass, hi,
those were the years of still thick pack ice and not the energy exchange that defines the last 13 years of heavy summer melt...this might help you to hold on to some earned ego, because in my opinion the present spike is really interesting.

BTW thanks Aslan, for your post on wave activity flux. It is a mechanism worth to be studied. And yes, I think the strong, warm anticyclone was something special. But similar features have happened FI the 'Kara Bulge' in '13 (IIRC). Anomalous and lasting geopotential aberrations. FOOW often refers to these processes...

Rod, g'evening to you...As far as the sillyness refers to me, I'm just registering in awe....

Jim Hunt

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Re: The 2020 melting season
« Reply #4001 on: July 28, 2020, 11:53:16 PM »
Jim .. could you please explain the value of your WV 3-6-7 image and perhaps a link to wv so those like me can go look ourselves ? Cheers ! b.c.

Bit busy on non Arctic stuff as well just at the minute b.c:

https://twitter.com/V2gUK/status/1287876064388083712

If you clicked through a couple of links at the link I helpfully provided above you'd get to the right bit of Worldview in the end, but since its you, here you go: https://go.nasa.gov/2P2Fw9R

In the left panel click the "i" buttons to discover what the various band combinations do.

In this case I simply wanted to differentiate between ice and cloud for the benefit of the Twatterati
« Last Edit: July 29, 2020, 12:08:57 AM by Jim Hunt »
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Freegrass

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Re: The 2020 melting season
« Reply #4002 on: July 29, 2020, 12:00:54 AM »
Hi Werther. You always remind me of candy.  ;D

If I understand you correctly, you're saying that a solid ice pack can't exchange heat as efficiently as wet ice? That makes sense. I was thinking that measurements back then weren't as good as they are now.

Learning every day.  :)




Edit: But then why wouldn't temps go up this high early in the melting season when the ice is still solid as it was back then?  :-\
« Last Edit: July 29, 2020, 12:08:56 AM by Freegrass »
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Re: The 2020 melting season
« Reply #4003 on: July 29, 2020, 12:06:37 AM »
Edit: windy shows almost 2m waves with 6s period hitting barrow and 2.6m with 7s period further north hitting the ice. That should give a proper stir.

20 seconds is required for a proper stir!

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werther

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Re: The 2020 melting season
« Reply #4004 on: July 29, 2020, 12:12:38 AM »
Freegrass, g'night,
At the moment I prefer black pepper peanuts over sweet candy. Yes, I suggest that thin, wetter ice has a stronger effect to keep temps lower to about 2 m while melting in the summer months. In the ninetees, thick, dry ice covered by snow gave another response when warmth was advected North. It showed in more temp spikes in the DMI graphs.
Wayne Davidson (EH2R) knows a lot more of the heat exchange through the ice (and snow)...

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Re: The 2020 melting season
« Reply #4005 on: July 29, 2020, 12:20:14 AM »
You are correct.   I think Penguin accidentally linked to the wrong graph.

The 2020 is below.  I’m still pulling for the kids! Go Sanwa Elementary School!

Rod - Thank you for your 'forgiving' explanation but I'm afraid that I was 'careless' in my reading of the years and the link was an error and not an accident :-\

So, I have to go with GFDL/NOAA projection for the September low median figure for the reasons stated in my previous posting.

To the kids at Sanwa Elementart School...yeah, Go...GO...GO. You are doing great and right there in the mix with the 'Top Scientists' :)

Remember...it's all about the Jet Stream you dummy...just a personal reminder!

Freegrass

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Re: The 2020 melting season
« Reply #4006 on: July 29, 2020, 12:21:57 AM »
Freegrass, g'night,
At the moment I prefer black pepper peanuts over sweet candy. Yes, I suggest that thin, wetter ice has a stronger effect to keep temps lower to about 2 m while melting in the summer months. In the ninetees, thick, dry ice covered by snow gave another response when warmth was advected North. It showed in more temp spikes in the DMI graphs.
Wayne Davidson (EH2R) knows a lot more of the heat exchange through the ice (and snow)...
Ok. We're getting into melting physics now. Something I haven't been studying yet and is off topic here. I'll read up on that next season. Right now I'm gonna bask in pride for a while.  8)
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Re: The 2020 melting season
« Reply #4007 on: July 29, 2020, 12:36:37 AM »

Rod, g'evening to you...As far as the sillyness refers to me, I'm just registering in awe....

Good evening to you too werther! I am sorry if I came across as rude. That was certainly not my intention.

We are all getting excited because what is happening right now is unprecedented. The DMI graph has its place, but I don’t think it is very valuable right now. That is why MOSAIC provided the temperature they recorded at 300m above the ice. That gives a better understanding of the tremendous heat currently blowing into the CAB.

I certainly did not intend to be rude to you or anyone else, and I apologize if anyone took my comments that way.

This is an extraordinary melt season! We will see where it winds up in September. 

JayW

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Re: The 2020 melting season
« Reply #4008 on: July 29, 2020, 01:17:18 AM »
Quick look between rain bands in the Beaufort.
Click to run.
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Re: The 2020 melting season
« Reply #4009 on: July 29, 2020, 01:21:51 AM »
By the way, the waves in 2012 in Barrow were much smaller.

In depth analysis at "Snow White's" web site:

https://GreatWhiteCon.info/2015/03/sea-ice-and-swells-in-the-beaufort-sea-in-the-summer-of-2014/
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Re: The 2020 melting season
« Reply #4010 on: July 29, 2020, 02:18:57 AM »
This was posted by MOSAIC today. Uniquorn has more information available on the MOSAIC thread and the buoy thread.

DMI uses a model that is heavily weighted towards the pole and tends to keep the temperature pegged close to 0C over the ice.  The heat flowing over the North Pole right now is incredible!

The weather forecasts are showing lots of WAA from areas that have seen record high temperatures, including Svalbard which is having a historic heat wave.

Oh wow, if that’s what the ice looks like deep inside the pack, I’m going to say that there’s going to be a lot of bottom melt going on for quite a few weeks past insolation. I know the suns angle is a lot lower now, so a lot more of that energy is going to be reflected off the surface of all those leads and ponds, but I think there’s still a lot of energy going into the water around and under the ice. If August has any wind events to churn things up the resulting melt could be really be significant.

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Re: The 2020 melting season
« Reply #4011 on: July 29, 2020, 02:52:18 AM »
Some changes near the Alaska coast. Top is July 28, bottom is July 25


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Re: The 2020 melting season
« Reply #4012 on: July 29, 2020, 03:36:38 AM »
Sorry I haven't posted or replied to any PMs but ive been busy with real life work.

Check out the DMI 80N graphic I've never seen it like this.

Like HOLY COW!!

If anyone has seen it this high before at anytime please post it, thank you
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D-Penguin

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Re: The 2020 melting season
« Reply #4013 on: July 29, 2020, 03:58:27 AM »
Sorry I haven't posted or replied to any PMs but ive been busy with real life work.

Check out the DMI 80N graphic I've never seen it like this.

Like HOLY COW!!

If anyone has seen it this high before at anytime please post it, thank you

See posting « Reply #3982 on: July 28, 2020, 09:47:18 PM » from gerontocrat
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Csnavywx

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Re: The 2020 melting season
« Reply #4014 on: July 29, 2020, 04:21:06 AM »
We have got to stop using that old DMI chart. There are better available now. Moyhu, for instance has a better one.

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Re: The 2020 melting season
« Reply #4015 on: July 29, 2020, 04:30:23 AM »
NSIDC extent comparisons with previous low years. 2020 is becoming more and more similar to 2012 on the Atlantic/Laptev side. Surprisingly it leads over 2012 in the southern CAA, and of course in the ESS, while lagging in M'Clure Strait and of course the Beaufort.

My take away from these images is this:  To catch 2012, the CAA & Beaufort must disintegrate this year the way the ESS, Laptev and Chukchi did in 2012, 2016 & 2019.

And so, what do we have now?  A 969 millibar storm in the Beaufort, & matching high pressure over the Kara.

Potential is very high for the Beaufort to be torn to shreds, and a lot of CAB ice to be thrown into the Laptev "pyre".


I think it is almost a certainty.  I don't think it will happen as fast as it did in 2012.

So expect a lot of posts saying 2020 has no chance.

The big factor will be what happens on the Atlantic side.

How much of the Eastern CAB will collapse??  How far will the ice line retreat?

How much will the CAA lose??
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Frivolousz21

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Re: The 2020 melting season
« Reply #4016 on: July 29, 2020, 04:46:45 AM »
Bremen concentration nose dived. While jaxa says vigorous melt all over the Pacific side
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jdallen

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Re: The 2020 melting season
« Reply #4017 on: July 29, 2020, 05:22:35 AM »
Bremen concentration nose dived. While jaxa says vigorous melt all over the Pacific side
The upper "yellow" spot in the Beaufort/Chukchi margin is just about exactly where the center of the storm lies.

Keep also in mind... 1cm of rain at current temps should produce 2-3cm of top melt.

You are going to see the "rubble" emerge from the background all across the Pacific side of the basin.

(Edit/P.S. - Southern leg of the NW passage should be open in about 10 days)
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Re: The 2020 melting season
« Reply #4018 on: July 29, 2020, 05:33:28 AM »
How much will the CAA lose??

Based on this image from yesterday and the predicted continuation of above average temps in most of the CAA for the next week, plus all the preconditioning there, I'd say complete breakup in next two weeks. How long it takes for the thicker floes to disappear is tougher to say, but I say as complete a meltout of CAA as we have seen before, not including inestimable import from CAB/Beaufort.
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jdallen

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Re: The 2020 melting season
« Reply #4019 on: July 29, 2020, 05:34:41 AM »
Additional bit... while we are focusing on the storm on the Pacific side, there are storms churning up the west side of the Atlantic that are going to clobber the Greenland Sea with rain and wind.  It bottoms out at around 985hpa on Aug. 2 just north of Iceland.

With export from the Fram cut off, expect Greenland Sea extent and area numbers to drop sharply as a consequence.
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Re: The 2020 melting season
« Reply #4020 on: July 29, 2020, 06:01:49 AM »
My prediction of a remarkable slow down in ice extent reduction didn't seem very popular here.

Average ice extent reduction from 28th June to 22 July was 127,657 per day.  Compares to previous losses over that exact date range:

2013 113,572 (I'm surprised)
2007 113,189
2019 101,859
...
2012 93,371

Average extent reduction from 22 July to 28 July was 38,380 per day.  Compares to:

2001 58,103
2013 58,897
2014 59,432
...
2012 124,874

While these dates have been effectively cherry picked to maximise the slow down shown, I still think it is still a remarkable statistic.  Extent reduction over the last 6 days has been over 30% lower than the previous slowest period for the same date range.
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bill kapra

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Re: The 2020 melting season
« Reply #4021 on: July 29, 2020, 06:14:18 AM »
with respect, reversion to the mean isnt remarkable. And the selection of time slices is one of the most seductive analytical fallacies.

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Re: The 2020 melting season
« Reply #4022 on: July 29, 2020, 06:20:45 AM »
While these dates have been effectively cherry picked to maximise the slow down shown, I still think it is still a remarkable statistic.  Extent reduction over the last 6 days has been over 30% lower than the previous slowest period for the same date range.

It is true, when we talk about ASI extent. But there is still 45 days left in this melting season and Beaufort doesn't look as it was 3 or 5 days ago. Surely, there is a decrease in area.

Also, the Northern Sea Route continues to be wide open, the seas north of Russia are getting warmer, as it happens with the Atlantic and Pacific fronts.

Finally, there is also heat on the Canadian Archipelago. I still think that the Northwest route will open on the first half of August.

When you talk about above 4M km2, are you thinking on the NSIDC September average? Or it is also about any (NSIDC or JAXA) extent daily value?

Edit: I asked because I think that it could be possible to have a little more of 4M km2 on NSIDC September average, if a freeze starts strong in September and there is not a strong melt on the final melting season. I normaly think more on the ADS JAXA daily value and at this moment, I think that 3.3 +/- 0.5M km2 could be the best bet.
« Last Edit: July 29, 2020, 06:55:01 AM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Jim Hunt

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Re: The 2020 melting season
« Reply #4023 on: July 29, 2020, 06:31:20 AM »
We have got to stop using that old DMI chart.

Perhaps we should start to roll our own? NRT and reanalysed?

https://GreatWhiteCon.info/2017/07/reanalysis-of-arctic-climate/
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Jim Hunt

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Re: The 2020 melting season
« Reply #4024 on: July 29, 2020, 06:33:33 AM »
(Edit/P.S. - Southern leg of the NW passage should be open in about 10 days)

Have you voted yet JD? Which route are you favouring?

https://forum.arctic-sea-ice.net/index.php/topic,3208
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Re: The 2020 melting season
« Reply #4025 on: July 29, 2020, 06:36:58 AM »
The cyclone is beginning to slowly fill in now.

Up to 977 hPa at 0Z according to the CMC.

The matching high has dropped 1 hPa as well!
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Re: The 2020 melting season
« Reply #4026 on: July 29, 2020, 06:50:35 AM »
For what's it's worth, HYCOM shows an interesting forecast for north of Greenland in early August - a large gap opening up, larger than anything I've seen there before.

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

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

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Re: The 2020 melting season
« Reply #4027 on: July 29, 2020, 07:02:33 AM »

When you talk about above 4M km2, are you thinking on the NSIDC September average? Or it is also about any (NSIDC or JAXA) extent daily value?


I think the chance of above 4M km2 is low, but not very low.  More likely we will go 3.5-4M km2.  This is minimum daily Jaxa extent.
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Re: The 2020 melting season
« Reply #4028 on: July 29, 2020, 07:03:49 AM »
For what's it's worth, HYCOM shows an interesting forecast for north of Greenland in early August - a large gap opening up, larger than anything I've seen there before.
Also interesting to see how the "bulwark" of old and thick ice has shifted westwards, towards the Beaufort.

Accepted wisdom has been that the last of the thick ice would be somehow anchored to the coast at and to each side of the Lincoln Sea, something I've never been quite conviced of, and the current setup certainly does not seem to support the accepted view.
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Re: The 2020 melting season
« Reply #4029 on: July 29, 2020, 07:06:06 AM »
How much will the CAA lose??

Based on this image from yesterday and the predicted continuation of above average temps in most of the CAA for the next week, plus all the preconditioning there, I'd say complete breakup in next two weeks. How long it takes for the thicker floes to disappear is tougher to say, but I say as complete a meltout of CAA as we have seen before, not including inestimable import from CAB/Beaufort.
I agree. The CAA has been sweltering in heat and the main channel is already broken up. Here's a look at what happened in Queen Maud Gulf (bottom left corner of AMSR animation). On July 13th AMSR showed nearly full ice cover, on the 16th it was still the same but concentration dropped. Worldview still showed a good ice cover, though broken up a bit.
Only 9 amazing days later, on the 25th, AMSR shows fully open water, corroborated by Worldview on the 27th.
So with the right weather and preconditioning seemingly good CAA ice can go poof in much less than 2 weeks. It is still July with over a month of melting, temps are high, and now the whole CAA shows dropped concentration, check out the last AMSR frame.
Click to animate and zoom AMSR and Worldview.



p.s. Case in point, this is how diverging volume and extent trends suddenly converge.

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Re: The 2020 melting season
« Reply #4030 on: July 29, 2020, 07:51:56 AM »
The Beaufort low is clearly visible on Worldview today. Unusually clear spiral pattern.
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Re: The 2020 melting season
« Reply #4031 on: July 29, 2020, 08:08:20 AM »
The gap increases the ice pack's mobility potential as the weak and freely floating ice cannot contain it to the extent coastal margins and their thick ice packs do. More turning of the pack is a possibility too.
For what's it's worth, HYCOM shows an interesting forecast for north of Greenland in early August - a large gap opening up, larger than anything I've seen there before. <snip> Source: https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticictn_nowcast_anim30d.gif
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Re: The 2020 melting season
« Reply #4032 on: July 29, 2020, 08:15:49 AM »
The Beaufort low is clearly visible on Worldview today. Unusually clear spiral pattern.
So far up north the Coriolis forces are pretty small. There could be some theoretical background for the exceptionally clear spirals. Not that I would know about this. There are pretty pure spirals in tropical storms too so latitude alone cannot be a defining factor for weather to construct pure spirals. The GAC-12 was also pretty huge spiralform, on occasion if I remember correctly.

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Re: The 2020 melting season
« Reply #4033 on: July 29, 2020, 08:18:50 AM »
The Beaufort low is clearly visible on Worldview today. Unusually clear spiral pattern.
So far up north the Coriolis forces are pretty small.
The storm forms further south, and besides I'd think the Coriolis plenty strong enough to create a revolving pattern at that latitude. But I'd guess that how "clear" the spiral is when seen from above is more to do with happenstance than theory. Not that I would know.
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Freegrass

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Re: The 2020 melting season
« Reply #4034 on: July 29, 2020, 08:34:11 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GIF!
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Re: The 2020 melting season
« Reply #4035 on: July 29, 2020, 08:46:03 AM »
Oops binntho, I meant the Coriolis forces are not very different in various parts of the low pressure system. Sorry.

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Re: The 2020 melting season
« Reply #4036 on: July 29, 2020, 08:48:10 AM »
The Beaufort low is clearly visible on Worldview today. Unusually clear spiral pattern.
So far up north the Coriolis forces are pretty small.
The storm forms further south, and besides I'd think the Coriolis plenty strong enough to create a revolving pattern at that latitude. But I'd guess that how "clear" the spiral is when seen from above is more to do with happenstance than theory. Not that I would know.
Or it might be an indicator of an arctic cyclone reaching mature stage: coupling with the stratosphere, accompanied downdraft at the lower stratosphere, resulting in extremely clear conditions around the (very peculiarly shaped) tropopause. See https://www.sciencedirect.com/science/article/pii/S1873965216300056 . BTW Coriolis effect (force) is max at pole.

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Re: The 2020 melting season
« Reply #4037 on: July 29, 2020, 09:22:30 AM »
The Beaufort low is clearly visible on Worldview today. Unusually clear spiral pattern.
So far up north the Coriolis forces are pretty small.
The storm forms further south, and besides I'd think the Coriolis plenty strong enough to create a revolving pattern at that latitude. But I'd guess that how "clear" the spiral is when seen from above is more to do with happenstance than theory. Not that I would know.
Or it might be an indicator of an arctic cyclone reaching mature stage: coupling with the stratosphere, accompanied downdraft at the lower stratosphere, resulting in extremely clear conditions around the (very peculiarly shaped) tropopause. See https://www.sciencedirect.com/science/article/pii/S1873965216300056 . BTW Coriolis effect (force) is max at pole.
Coriolis force is at max, yes, but evenly affecting the whole system, my mistake. But, could it so keep the spiral arms separated for longer?

ArcTickTock

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Re: The 2020 melting season
« Reply #4038 on: July 29, 2020, 09:27:25 AM »
Sorry I haven't posted or replied to any PMs but ive been busy with real life work.

Check out the DMI 80N graphic I've never seen it like this.

Like HOLY COW!!

If anyone has seen it this high before at anytime please post it, thank you

Apparently Friv you and I are the only ones shocked by this which surprises me!  Yes it is DMI, the data has some issues, what dataset does not, all that notwithstanding it is a long running series.  That up tick is a BIG DEAL and I do no recall seeing anything like that!  I see it as a very bad sign as the old maxim that DMI 80N temps are parked in a narrow summer band may be coming to an end.

binntho

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Re: The 2020 melting season
« Reply #4039 on: July 29, 2020, 09:34:56 AM »
Apparently Friv you and I are the only ones shocked by this which surprises me! 
Perhaps the rest of us have seen Freegrass's post which shows that this is not at all an uncommon occurrence.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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Aluminium

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Re: The 2020 melting season
« Reply #4040 on: July 29, 2020, 09:43:48 AM »
July 24-28.

2019.

ArcTickTock

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Re: The 2020 melting season
« Reply #4041 on: July 29, 2020, 09:44:13 AM »
The Beaufort low is clearly visible on Worldview today. Unusually clear spiral pattern.

Stunning!  And it looks like that on Bremen which “suggests” the ice is feeling it to me.  I mean it looks like an image from 20N not 75N.  This is just a crazy year, with the Laptev implosion and all the crazy sunny hot weather up till now gotta say I was still thinking melt would slow way down and we would see a second lowest year or so but not a new record, now who knows?!?  This year feels different, it is really starting to feel like the Arctic system is decoupling a bit now from all its stabilizing mechanisms and turning into something new.

ArcTickTock

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Re: The 2020 melting season
« Reply #4042 on: July 29, 2020, 09:57:06 AM »
Apparently Friv you and I are the only ones shocked by this which surprises me! 
Perhaps the rest of us have seen Freegrass's post which shows that this is not at all an uncommon occurrence.

I have just looked at the data again, odd things popped up in the pre 2000 era data (including 2000) for certain but nothing like it in the last 20 years so see it how you will, it is a pattern break to me.

glennbuck

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Re: The 2020 melting season
« Reply #4043 on: July 29, 2020, 10:33:41 AM »
 8)

Freegrass

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Re: The 2020 melting season
« Reply #4044 on: July 29, 2020, 10:36:23 AM »
Apparently Friv you and I are the only ones shocked by this which surprises me! 
Perhaps the rest of us have seen Freegrass's post which shows that this is not at all an uncommon occurrence.
I'm ready. GO!

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Tom

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Re: The 2020 melting season
« Reply #4045 on: July 29, 2020, 10:45:07 AM »
I have just looked at the data again, odd things popped up in the pre 2000 era data (including 2000) for certain but nothing like it in the last 20 years so see it how you will, it is a pattern break to me.

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

Edit: replaced image with version with arrows indicating other excursions

BornFromTheVoid

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Re: The 2020 melting season
« Reply #4046 on: July 29, 2020, 10:51:38 AM »
A side by side animation of the Arctic storm from MODIS worldview (mosaic for the 29th) with sea ice concentration. No concentration data yet for today, hence the blank right panel at the end.

I posted a higher res version on twitter too: https://twitter.com/Icy_Samuel/status/1288395604805267456

(Large file still, click to play)

I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Aluminium

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Re: The 2020 melting season
« Reply #4047 on: July 29, 2020, 10:55:15 AM »
Image attached for comparison.  It certainly looks to me like it's the highest it's been, but there are similar excursions above the mean at this time of year in 2016 and 2008, as I think others have mentioned upthread.

Edit: replaced image with version with arrows indicating other excursions

Nice comparison. 2008 and 2016 had above average extent losses for the rest of season. Coincidence?

D-Penguin

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Re: The 2020 melting season
« Reply #4048 on: July 29, 2020, 11:00:16 AM »
Apparently Friv you and I are the only ones shocked by this which surprises me! 
...it is a pattern break to me.

The melting season has provided many 'pattern breaks' has it not? The 'real' surprise would be if this season started to show an element of 'normality'. :)
Remember...it's all about the Jet Stream you dummy...just a personal reminder!

Tom

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Re: The 2020 melting season
« Reply #4049 on: July 29, 2020, 11:01:41 AM »
We have got to stop using that old DMI chart. There are better available now. Moyhu, for instance has a better one.

Since this was mentioned in passing I thought people might like to look at it https://moyhu.blogspot.com/p/latest-ice-and-temperature-data.html#arctic

It's not available for other years  :(.