Support the Arctic Sea Ice Forum and Blog

Author Topic: The 2018 melting season  (Read 655322 times)

Greenbelt

  • Frazil ice
  • Posts: 167
    • View Profile
  • Liked: 39
  • Likes Given: 24
Re: The 2018 melting season
« Reply #400 on: April 23, 2018, 01:22:26 AM »
Looks like the GFS favors high pressure too, well out into the extended.

S.Pansa

  • Frazil ice
  • Posts: 170
    • View Profile
  • Liked: 42
  • Likes Given: 5
Re: The 2018 melting season
« Reply #401 on: April 23, 2018, 09:27:28 AM »
Currently the newly opening areas in the Bering Strait seem to refreeze. But this ice might have a very short live span.
Latest model runs predict temps will be briefly above zero form Wednesday on. The "heat wave" is - for now - forecasted to culminate next Sunday with southerly winds. 
Even though it is still far out, GFS & ECMWF are in good agreement. For once, ECMWF seems to be more bullish while both models continue to show huge differences in snow height.

Could be interesting. Open water south to a line from Barrow to Pevec in early May? At least snow cover should get a big hit. We will see ...



oren

  • Moderator
  • First-year ice
  • Posts: 6309
    • View Profile
  • Liked: 2318
  • Likes Given: 1963
Re: The 2018 melting season
« Reply #402 on: April 23, 2018, 11:23:09 AM »
Currently the newly opening areas in the Bering Strait seem to refreeze. But this ice might have a very short live span.
The newly formed ice in the strait area and on the Alaskan side of the Chukchi is even more vulnerable than its thickness indicates, as it probably lacks any snow cover.

Daniel B.

  • Grease ice
  • Posts: 659
    • View Profile
  • Liked: 8
  • Likes Given: 29
Re: The 2018 melting season
« Reply #403 on: April 23, 2018, 05:42:39 PM »
2018 Arctic sea ice has already dropped ~ 1 million square kilometers from its maximum. Average 1980 decade Arctic sea ice didn't reach 12.89 million square kilometers till May 23, with the sun approaching highest elevation in the sky.

The ice drop over the past 30 days is fairly average.  Those years that have had higher melt through the first month have not shown a tendency towards a new minimum; 1990 being the lone exception.  Contrarily those years in which the melting season starting slowly, did not show any propensity towards higher minima.  There was a slightly greater tendency towards higher first month melt in those years with higher maxima, but even that was rather nebulous.  2012 had a relatively high maximum, and a slow first month's melt, but took a nose dive later in the summer.  So far, 2018 Arctic sea ice melt has shown nothing memorable.

FishOutofWater

  • Grease ice
  • Posts: 873
    • View Profile
  • Liked: 501
  • Likes Given: 179
Re: The 2018 melting season
« Reply #404 on: April 23, 2018, 05:56:16 PM »
What's memorable about this year is the record shattering low amount of ice in the Bering sea through the whole freezing season. There's nothing special about the first month of the melt season.

Lord M Vader

  • Nilas ice
  • Posts: 1330
    • View Profile
  • Liked: 46
  • Likes Given: 29
Re: The 2018 melting season
« Reply #405 on: April 23, 2018, 06:15:57 PM »
FOW, oh yes, it IS memorable and spectacular with the exceptionally low sea ice concentration in Bering Sea. As the waters there are open now, the ocean is now able to store all heat from the sun. And I assure you that the sun is rather strong this time at year. In fact, the sun is now above the horizon for about 15 hours per day in this area.

Instead of being reflected, the sunlight has already started to warm the ocean there. According to eart.nullschool.net the SSTs in this area is now -0,8o to -1,4o. I think we can imagine that it should be a lot harder for the sea ice to form in this area later this year, or perhaps even in January if we are going to see a repeat of stormy weather there.

Trebuchet

  • New ice
  • Posts: 22
    • View Profile
  • Liked: 10
  • Likes Given: 1
Re: The 2018 melting season
« Reply #406 on: April 23, 2018, 07:33:53 PM »
The isolation is already keeping the southern Chukchi from refreezing (Kotzebue sound) looking at the past few days on Worldview.
"Now this is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning." W.S.Churchill

oren

  • Moderator
  • First-year ice
  • Posts: 6309
    • View Profile
  • Liked: 2318
  • Likes Given: 1963
Re: The 2018 melting season
« Reply #407 on: April 23, 2018, 07:45:35 PM »
It's not just insolation, but also the effect of the warm Alaska coastal current.

Sarat

  • New ice
  • Posts: 41
    • View Profile
  • Liked: 15
  • Likes Given: 113
Re: The 2018 melting season
« Reply #408 on: April 23, 2018, 07:57:43 PM »
I assume this is a technical problem, not real extent data right?


Neven

  • Administrator
  • First-year ice
  • Posts: 7756
    • View Profile
    • Arctic Sea Ice Blog
  • Liked: 1133
  • Likes Given: 521
Re: The 2018 melting season
« Reply #409 on: April 23, 2018, 07:58:43 PM »
If you see a similar thing on the Antarctic graph, it's almost certainly technical in nature.  ;)
Il faut comparer, comparer, comparer, et cultiver notre jardin

Wherestheice

  • Frazil ice
  • Posts: 313
    • View Profile
  • Liked: 89
  • Likes Given: 19
Re: The 2018 melting season
« Reply #410 on: April 23, 2018, 08:25:13 PM »
I assume this is a technical problem, not real extent data right?

may I ask where you got that graph?
"When the ice goes..... F***

Sarat

  • New ice
  • Posts: 41
    • View Profile
  • Liked: 15
  • Likes Given: 113
Re: The 2018 melting season
« Reply #411 on: April 23, 2018, 08:37:15 PM »
(Maybe off topic to continue in this thread, apologies)

This looks like AMSR2 satellite issue hopefully not a permanent one, all AMSR2 graphs/maps are affected by large swaths of missing data.

See here:
https://seaice.uni-bremen.de/sea-ice-concentration/
« Last Edit: April 23, 2018, 08:45:45 PM by Sarat »

gerontocrat

  • First-year ice
  • Posts: 9352
    • View Profile
  • Liked: 3744
  • Likes Given: 28
Re: The 2018 melting season
« Reply #412 on: April 23, 2018, 08:54:16 PM »
(Maybe off topic to continue in this thread, apologies)

This looks like AMSR2 satellite issue hopefully not a permanent one, all AMSR2 graphs/maps are affected by large swaths of missing data.

See here:
https://seaice.uni-bremen.de/sea-ice-concentration/
I would not be surprised if JAXA has to go on holiday for a bit.
I have a horrible memory of a discussion some time back about how the satellites (AMSR2 and the USAF one feeding NSIDC) are operating well beyond their design life without replacements in the pipeline.
Ho hum.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

A-Team

  • Young ice
  • Posts: 2701
    • View Profile
  • Liked: 646
  • Likes Given: 33
Re: The 2018 melting season
« Reply #413 on: April 23, 2018, 10:12:20 PM »
I asked Dr. P Chang of NOAA today why so many swaths on ASCAT have been blacked out for 4-5 days (similar to but different than AMSR2).

He said there were no problems with the satellite nor its instrument but that "it’s a network connectivity issue between eumetsat and NOAA...instrument is still healthy.... If we have the data we can recreate the images...I asked my folks to do that".

The Eumetsat home page that operates this satellite is serving a truly crappy dumbed-down version of the data that cannot serve as replacement for NOAA's secondary version.

How long did Eumetsat plan to let the glitch run before fixing the network connectivity issue? Does Eumetsat plan to repair the damage by resending the data? How long has NOAA been aware of this problem prior to my email?

Meanwhile, all these satellite time series have glitches from time to time. I've explored various technical fixes in the past, such as layering up the defective image over the previous day, deleting the bad swaths to transparency using a color picker, capturing show-through along with the good parts of the bad image, and replacing it.

There's a cross-platform variation on this that stubs in a grayscale from another satellite for the missing pieces, say Jaxa, which so far has been unaffected. That is doable but much more complex because of scaling, swath timing and correlative tonal matching. It does put in real contemporaneous data unlike putting the previous day but then again it's not scatterometer data.

*/*/*/

Update: NOAA was able to repair days 111 and 112 but not the three previous. Day 113 is not available yet, about 6 hours late. [Update: it has appeared, about 18 hours late. Update: day 114 arrived on schedule, minor problems with it indicating the "network connectivity issue between eumetsat and NOAA" is still not repaired.]

Actually very little has happened in terms of ice movement.

Scrolling out five days in nullschool GFS pressure and wind, a slight low cuts itself off from a larger Siberian feature and drifts aimlessly across the central Arctic. Winds will be incoherent at a reglional level except westward along the Alaskan coast.

OSI-SAF has not been able to repair their 3 blanked-out days, 10-12 April 2018. This may have a different explanation.

http://osisaf.met.no/p/osisaf_hlprod_qlook.php?year=2018&month=04&day=09&action=d%2B&prod=LR-Drift&area=NH&size=100%25

Checking UH AMSR2 to see if they have significant glitches, the answer is no for the month of April. Black-out wedges do occur from time to time; the archive is never repaired by management. These are largely peripheral and not as damaging as changes in pixel dimensions.

My theory is no one but us ever looks at the data as it comes in. It is all robotic pipeline from satellite to web archive. Once in a great while, maybe a researcher goes back and uses the archived imagery for a paper. Only then are gaps noticed. By that time, repairs won't be possible any longer.

There's too much reliance on robotics; it makes no economic sense given the expense of the satellite, the cheapness of an intern or elderly volunteer, and the value of a long time series.

« Last Edit: April 25, 2018, 10:28:27 AM by A-Team »

Neven

  • Administrator
  • First-year ice
  • Posts: 7756
    • View Profile
    • Arctic Sea Ice Blog
  • Liked: 1133
  • Likes Given: 521
Re: The 2018 melting season
« Reply #414 on: April 23, 2018, 10:38:18 PM »
Thanks for asking, A-Team. I had noticed something was off with ASCAT yesterday.
Il faut comparer, comparer, comparer, et cultiver notre jardin

gerontocrat

  • First-year ice
  • Posts: 9352
    • View Profile
  • Liked: 3744
  • Likes Given: 28
Re: The 2018 melting season
« Reply #415 on: April 23, 2018, 11:16:17 PM »
I asked Dr. P Chang of NOAA today why so many swaths on ASCAT have been blacked out for 4-5 days (similar to but different than AMSR2).

He said there were no problems with the satellite nor its instrument

Always a relief to me when it is not a problem with what's up there. Or am I getting nervous unnecessarily?
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

  • First-year ice
  • Posts: 9352
    • View Profile
  • Liked: 3744
  • Likes Given: 28
Re: The 2018 melting season
« Reply #416 on: April 23, 2018, 11:29:33 PM »
I am giving my speculation of the relative importance of average temperature vs the much higher maximum daytime temperatures at high latitudes another airing.

The large contrast between the average and maximum temperatures  is illustrated in the two images below. The average image would suggest that the entire Arctic ocean is below zero.

The second image shows that maximum temperatures will be and have been well above freezing at various places on the fringes. Two places are highlighted in red, one in the middle of the Siberian Arctic coast and the other on the Alaskan side of the Chukchi.

The third image shows where there is open water - is it a coincidence that the two highlighted places on this image are the same ?

ps: with maximum temperatures like that, the snow is going to take a hammering even if it freezes at night.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

JayW

  • Grease ice
  • Posts: 604
    • View Profile
  • Liked: 223
  • Likes Given: 280
Re: The 2018 melting season
« Reply #417 on: April 24, 2018, 12:11:50 AM »
"To defy the laws of tradition, is a crusade only of the brave" - Les Claypool

FishOutofWater

  • Grease ice
  • Posts: 873
    • View Profile
  • Liked: 501
  • Likes Given: 179
Re: The 2018 melting season
« Reply #418 on: April 24, 2018, 02:10:09 AM »
The open water on the north shore of Siberia did not show signs of refreezing in today's MODIS Worldview image. The offshore southerly winds that opened the polynya had temperatures around 0 C. When you consider that days are long now in the Arctic, this is not good news for the ice and snow. The good news is that it's colder than normal in the CAA.

sedziobs

  • Frazil ice
  • Posts: 395
    • View Profile
  • Liked: 63
  • Likes Given: 12
Re: The 2018 melting season
« Reply #419 on: April 24, 2018, 02:27:52 AM »
123 hour loop Chukchi sea.
Very cool to see new ice that forms each night vanish during daylight hours.

oren

  • Moderator
  • First-year ice
  • Posts: 6309
    • View Profile
  • Liked: 2318
  • Likes Given: 1963
Re: The 2018 melting season
« Reply #420 on: April 24, 2018, 03:00:55 AM »
123 hour loop Chukchi sea.
Very cool to see new ice that forms each night vanish during daylight hours.
Yes. An animation is worth a thousand words. I noticed that the northern part managed to keep some ice cover, while the south (Kotzebue Sound) lost it completely each day. So in a few days of warming the northern part is bound to lose a chunk of extent.

Thomas Barlow

  • Guest
Re: The 2018 melting season
« Reply #421 on: April 24, 2018, 04:46:19 PM »

jdallen

  • Young ice
  • Posts: 3248
    • View Profile
  • Liked: 525
  • Likes Given: 206
Re: The 2018 melting season
« Reply #422 on: April 24, 2018, 08:12:25 PM »
It all hinges very heavily on the next 8 weeks weather.  Not sure I can emphasize that enough. I do know that each year we start in a more difficult place vis-a-vis total heat in the system. That makes the weather more critical than any year in the record previously save the possible exception of 2013, while in ways we may be more vulnerable now.
This space for Rent.

uniquorn

  • Young ice
  • Posts: 2755
    • View Profile
  • Liked: 1246
  • Likes Given: 247
Re: The 2018 melting season
« Reply #423 on: April 24, 2018, 08:44:47 PM »
With favourable weather (for viewing) north of Greenland yesterday I thought I'd try to find visible signs of thicker ice north of the 'Kara tongue' using viirs. An ascat image of the 'Kara tongue' export is shown inset on the first two frames. I've squashed the palette in each zoom of the viirs image as far as possible to show detail around the boundary while minimising artifacts.
Not very conclusive, but the area on the left of the last frame does appear to show longer cracks and less refrozen fractures. Hopefully the ice is a bit thicker there.

ascat apr23
worldview terra/modis, viirs brightness temperature band 15, progressively squashed palette apr23

dosibl

  • New ice
  • Posts: 44
    • View Profile
  • Liked: 6
  • Likes Given: 0
Re: The 2018 melting season
« Reply #424 on: April 24, 2018, 08:48:48 PM »
Jdallen (or others), with that in mind what are the key weather metrics we can keep an eye on over the next two months? Up-thread Neven and others have been noting the persistent high that is trying to set up shop, my recollection from last melting season is that a high pressure system can potentially lead to less clouds and more insolation, is that the main concern?

I know the various GACs (may not be the best term for them) from the past few years can really churn up the ice, but my understanding was that storms generally compact the ice and didn't really cause massive loss. Weaker ice may not hold up as well to storms, but from an ice-preservation standpoint I assume we'd rather have a stormy summer than a clear-sky summer. 

numerobis

  • Grease ice
  • Posts: 837
    • View Profile
  • Liked: 16
  • Likes Given: 3
Re: The 2018 melting season
« Reply #425 on: April 25, 2018, 01:29:48 AM »
Neven is impressed by some research that shows melt ponds are the devil.

The argument is that if you have ponds of water forming on top of the ice, they can gather up a lot of heat and melt the ice from the top during the early summer (until the ice cracks and the ponds drain). That means more total solar heat absorbed over the summer, and conditions the remaining ice to melt faster.

And how do you make melt ponds? By shining the sun on the snow to melt it, but not breaking up the ice too early with a storm.

So that's why high pressure on the arctic, from the end of April to early June, seems bad.

Juan C. García

  • Nilas ice
  • Posts: 2075
    • View Profile
  • Liked: 1002
  • Likes Given: 728
Re: The 2018 melting season
« Reply #426 on: April 25, 2018, 05:29:14 AM »
Jdallen (or others), with that in mind what are the key weather metrics we can keep an eye on over the next two months? Up-thread Neven and others have been noting the persistent high that is trying to set up shop, my recollection from last melting season is that a high pressure system can potentially lead to less clouds and more insolation, is that the main concern?

On 2016, the Beaufort Gyre was very strong. That is why 2016 is still the lowest on record, on this time of the year.

http://neven1.typepad.com/blog/2016/05/beaufort-under-relentless-high-pressure.html
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.

slow wing

  • Grease ice
  • Posts: 819
    • View Profile
  • Liked: 156
  • Likes Given: 498
Re: The 2018 melting season
« Reply #427 on: April 25, 2018, 06:48:04 AM »
Neven is impressed by some research that shows melt ponds are the devil.

The argument is that if you have ponds of water forming on top of the ice, they can gather up a lot of heat and melt the ice from the top during the early summer (until the ice cracks and the ponds drain). That means more total solar heat absorbed over the summer, and conditions the remaining ice to melt faster.

And how do you make melt ponds? By shining the sun on the snow to melt it, but not breaking up the ice too early with a storm.

So that's why high pressure on the arctic, from the end of April to early June, seems bad.

 Yes, it is clear to me also that melt ponds can accelerate melt, for the physical reason given above and because liquid water absorbs shortwave solar energy so much better than ice or snow.

 I think it likely that a large part of the reason 2012 set the low extent record in September was the extraordinary fraction of Arctic sea ice covered in melt ponds during May & June - as was observable even from the satellite data.

 The part of your post where I haven't seen observational evidence is that the ice pack can be broken up by storms so much, over so much of the Arctic & as early as May or June, that melt ponds can't easily form.

 Has that been established? If so, could someone point out where please?

 In the central Arctic much of the ice will have a thickness in the range of roughly 1.5 to 2.5 meters and so a free board above the water level of a couple of tens of centimeters - say 20-30 cm. Can much of the 2 meter thick ice be broken up so small - presumably no more than meters across rather than tens of meters or larger - by storms in May or June?

 I would need to see some evidence for what runs counter to my mental picture that is based in part on photos of ice breakers & their trails, where the ice can look intact even when substantially thinner than that.

 Parenthetically, I also suspect that if sea ice is broken into transverse dimensions not much larger than its thickness - and so unable to form melt ponds - then it would melt out more quickly anyway due to all the exposed leads and to bobbing and rocking around. But I've only seen lake ice, not sea ice - so that is just a guess.
« Last Edit: April 25, 2018, 07:13:37 AM by slow wing »

litesong

  • Frazil ice
  • Posts: 395
    • View Profile
  • Liked: 20
  • Likes Given: 15
Re: The 2018 melting season
« Reply #428 on: April 25, 2018, 09:45:25 AM »
I would need to see some evidence for what runs counter to my mental picture that is based in part on photos of ice breakers & their trails, where the ice can look intact even when substantially thinner than that.
NSIDC much declared the early August 2012 Arctic storm as the main contributor to 2012 minimum Arctic sea ice loss.
http://nsidc.org/arcticseaicenews/2012/08/
Follow-up information in September & October confirmed the August 2012 Arctic storm as the culprit. http://nsidc.org/arcticseaicenews/2012/09/

Neven

  • Administrator
  • First-year ice
  • Posts: 7756
    • View Profile
    • Arctic Sea Ice Blog
  • Liked: 1133
  • Likes Given: 521
Re: The 2018 melting season
« Reply #429 on: April 25, 2018, 10:32:28 AM »
NSIDC much declared the early August 2012 Arctic storm as the main contributor to 2012 minimum Arctic sea ice loss.
http://nsidc.org/arcticseaicenews/2012/08/
Follow-up information in September & October confirmed the August 2012 Arctic storm as the culprit. http://nsidc.org/arcticseaicenews/2012/09/

No, they didn't. Did you even read your own links?

Quote
While this drop coincided with an intense storm over the central Arctic Ocean, it is unclear if the storm prompted the rapid ice loss.

(...)

This could be due to mechanical break up of the ice and increased melting by strong winds and wave action during the storm. However, it may be simply a coincidence of timing, given that the low concentration ice in the region was already poised to rapidly melt out.

(...)

The most notable event was a very strong storm centered over the central Arctic Ocean in early August. It is likely that the primary reason for the large loss of ice this summer is that the ice cover has continued to thin and become more dominated by seasonal ice. This thinner ice was more prone to be broken up and melted by weather events, such as the strong low pressure system just mentioned. The storm sped up the loss of the thin ice that appears to have been already on the verge of melting completely.

If the ice hadn't been as pre-conditioned during May, June and July, the storm would have had much less of an effect. We haven't seen that level of pre-conditioning since.
Il faut comparer, comparer, comparer, et cultiver notre jardin

Neven

  • Administrator
  • First-year ice
  • Posts: 7756
    • View Profile
    • Arctic Sea Ice Blog
  • Liked: 1133
  • Likes Given: 521
Re: The 2018 melting season
« Reply #430 on: April 25, 2018, 10:48:33 AM »
NH snow cover is suddenly falling off a cliff:
Il faut comparer, comparer, comparer, et cultiver notre jardin

uniquorn

  • Young ice
  • Posts: 2755
    • View Profile
  • Liked: 1246
  • Likes Given: 247
Re: The 2018 melting season
« Reply #431 on: April 25, 2018, 04:07:48 PM »
With more warm temperature anomalies forecast over ess and laptev for the next few days, an animation of amsr2 for this melting season with today's worldview for comparison.

uni-hamburg amsr2 ice concentration for ess and laptev Mar21-Apr24.
Worldview terra/modis apr25

 

numerobis

  • Grease ice
  • Posts: 837
    • View Profile
  • Liked: 16
  • Likes Given: 3
Re: The 2018 melting season
« Reply #432 on: April 25, 2018, 05:15:58 PM »
The part of your post where I haven't seen observational evidence is that the ice pack can be broken up by storms so much, over so much of the Arctic & as early as May or June, that melt ponds can't easily form.

You're right, that part I'm speaking beyond where I should have spoken.

It's clear that when the ice cracks, the melt ponds drain out. But that spring storms would cause those cracks, I don't have the data to prove.

Maybe look at Hudson Strait and the Baffin Sea this weekend? We're about to get a nice big storm.

EDIT: just checked the forecast better; we're expecting very strong winds tomorrow in Iqaluit due to a weak storm. It's forecast to come with a fair bit of snow, but the winds aren't that big overall -- they just happen to hit us just right.

A more powerful storm is forming up Sunday over the northern end of Hudson Bay. It should shake things a bit more.

Hudson Bay isn't super relevant to the ice up North of course, it's just a microcosm to study.
« Last Edit: April 25, 2018, 05:23:02 PM by numerobis »

bbr2314

  • Nilas ice
  • Posts: 1817
    • View Profile
  • Liked: 163
  • Likes Given: 53

Andreas T

  • Nilas ice
  • Posts: 1143
    • View Profile
  • Liked: 17
  • Likes Given: 4
Re: The 2018 melting season
« Reply #434 on: April 25, 2018, 06:31:47 PM »
Neven is impressed by some research that shows melt ponds are the devil.

The argument is that if you have ponds of water forming on top of the ice, they can gather up a lot of heat and melt the ice from the top during the early summer (until the ice cracks and the ponds drain). That means more total solar heat absorbed over the summer, and conditions the remaining ice to melt faster.

And how do you make melt ponds? By shining the sun on the snow to melt it, but not breaking up the ice too early with a storm.

So that's why high pressure on the arctic, from the end of April to early June, seems bad.
repeating some stuff from previous discussions because this keeps coming up:
It is worth looking at the mechanisms by which ponds accelerate melt, rather than just repeat the shorthand "meltponds absorb"
The ponds are darker in colour because much of the light passes through the clear water in the pond and the fairly translucent ice floe into the ocean below and doesn't come back out again.
Absorption therefore takes place mostly in the ice (especially if there are algae present) and in the ocean, not so much in the water in the pond.
Snow reflects sunlight so the best way to melt it is to blow warm air over it (especially if its also moist) rain would be best.
This comes with low pressure rather than high pressure which at the lower sun angle in April looses more outgoing radiation through clear sky than it gains.

FishOutofWater

  • Grease ice
  • Posts: 873
    • View Profile
  • Liked: 501
  • Likes Given: 179
Re: The 2018 melting season
« Reply #435 on: April 25, 2018, 06:40:24 PM »
There's a big difference between the sun angle at the north shore of Alaska and at the north pole in late April. Moreover, we have seen a dipole with low pressure on the Siberian side of the Arctic ocean and high pressure on the Canadian side. Oversimplification does not make for a cogent analysis of how the weather is impacting sea ice this spring.

The blue areas north of Siberia in the imagery shown a few posts above indicate areas of possible melting. That is not a good sign for sea ice longevity on the Siberian side of the Arctic ocean.

uniquorn

  • Young ice
  • Posts: 2755
    • View Profile
  • Liked: 1246
  • Likes Given: 247
Re: The 2018 melting season
« Reply #436 on: April 25, 2018, 07:29:14 PM »
With even more warm temperature anomalies forecast over bering and chukchi for the next few days, an animation of amsr2 for this melting season.

Light blue areas normally indicate lower concentration but may also be due to cloud cover (imho).

uni-hamburg amsr2 ice concentration for bering and chukchi Mar21-Apr24.

uniquorn

  • Young ice
  • Posts: 2755
    • View Profile
  • Liked: 1246
  • Likes Given: 247
Re: The 2018 melting season
« Reply #437 on: April 25, 2018, 08:59:20 PM »
I wasn't going to post amsr2 of the atlantic side but do so in memory of the plucky floe that almost made it across the nth of Svalbard 'killing zone' earlier this month.
Worldview confirms the attempt in the second animation (marked with an X in the first frame). Interesting to see how fragile the refreeze between the floes is in this area.

uni-hamburg amsr2 ice concentration for kara and barents Mar21-Apr24
Worldview terra/modis mar28-apr9

oren

  • Moderator
  • First-year ice
  • Posts: 6309
    • View Profile
  • Liked: 2318
  • Likes Given: 1963
Re: The 2018 melting season
« Reply #438 on: April 25, 2018, 09:46:54 PM »
I wasn't going to post amsr2 of the atlantic side but do so in memory of the plucky floe that almost made it across the nth of Svalbard 'killing zone' earlier this month.
Worldview confirms the attempt in the second animation (marked with an X in the first frame). Interesting to see how fragile the refreeze between the floes is in this area.
Great animation. The heat content of that area is amazing. Latitude above 81oN in April, healthy-looking floes constantly exported into it, all melting quickly leaving no trace. Atlantification completed.

jdallen

  • Young ice
  • Posts: 3248
    • View Profile
  • Liked: 525
  • Likes Given: 206
Re: The 2018 melting season
« Reply #439 on: April 25, 2018, 10:48:34 PM »
Neven is impressed by some research that shows melt ponds are the devil.

<snippage>

So that's why high pressure on the arctic, from the end of April to early June, seems bad.
Neven is right, and high pressure and full unfiltered sunlight is unambiguously bad for the Arctic regardless of snow cover.

To an earlier question - the things to watch are albedo and SST  I think.  Those will suggest to us how much insolation is being taken up, and how much heat is available to be applied to the ice.
This space for Rent.

jdallen

  • Young ice
  • Posts: 3248
    • View Profile
  • Liked: 525
  • Likes Given: 206
Re: The 2018 melting season
« Reply #440 on: April 25, 2018, 10:55:07 PM »
With more warm temperature anomalies forecast over ess and laptev for the next few days, an animation of amsr2 for this melting season with today's worldview for comparison.

uni-hamburg amsr2 ice concentration for ess and laptev Mar21-Apr24.
Worldview terra/modis apr25

I've been distracted for a few days, but started noticing this in my semi-daily surveys of Worldview.  I'm not sure if it qualifies yet as an early start, but the timing combined with clear skies isn't helpful.
This space for Rent.

Michael Hauber

  • Grease ice
  • Posts: 900
    • View Profile
  • Liked: 77
  • Likes Given: 14
Re: The 2018 melting season
« Reply #441 on: April 26, 2018, 01:21:41 AM »

 I think it likely that a large part of the reason 2012 set the low extent record in September was the extraordinary fraction of Arctic sea ice covered in melt ponds during May & June - as was observable even from the satellite data.

 The part of your post where I haven't seen observational evidence is that the ice pack can be broken up by storms so much, over so much of the Arctic & as early as May or June, that melt ponds can't easily form.


As far as I know there is no good satellite observation of melt pond data showing the amount of surface melt ponding in May/June 2012 vs other years.  The paper on melt ponding that made a big impression in this forum was based on modelled melt pond formation, not observations.  From  a subjective eyeball assessment of the amount of red in channel 3-6-7 images on MODIS I'd say 2012 had high surface melt ponding, but not as high as 2016.

My opinion is that breaking up the ice pack with a storm does more damage than melt ponds.  In visible images melt ponds are hard to see without the 3-6-7 filters that show them up red.  But gaps between the ice are appear very much darker (but satellite viewing angle compared to solar incident angle may change the difference in darkness).  I'd suspect a lot more energy is absorbed by patches of water mixed in  with the ice following a storm than are absorbed by melt ponds, and that this energy will be transferred to the ice by melt season end.  In 2012 there was a moderate and short lived storm in late June, after which large areas of the Arctic became somewhat dispersed with patches of open water mixed in.  These areas steadily got worse throughout the season until they were very fragile prior to the early August storm which finished the job.  Constant storms such as 2013 means a disperse pack with lots of water to absorb solar energy, but a serious shortage of solar energy to be absorbed.  Short periods of storminess followed by long periods of sunny is the ideal melting recipe in my opinion.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

wallen

  • New ice
  • Posts: 78
    • View Profile
  • Liked: 40
  • Likes Given: 2
Re: The 2018 melting season
« Reply #442 on: April 26, 2018, 04:24:05 AM »
Many comments abound regarding the Fram export each year, but I have just been looking at the waters between Svalbard and Franz Josef Land. To me the ice looks in very poor state and I am wondering if it does melt out there, what possible effect it could have for the rest of the melt season.

romett1

  • Frazil ice
  • Posts: 251
    • View Profile
  • Liked: 15
  • Likes Given: 0
Re: The 2018 melting season
« Reply #443 on: April 26, 2018, 09:25:55 AM »
Models are now predicting warm weather over Northern Greenland starting around May 02 (image). Next week could be interesting. Image: https://www.tropicaltidbits.com/analysis/models/

litesong

  • Frazil ice
  • Posts: 395
    • View Profile
  • Liked: 20
  • Likes Given: 15
Re: The 2018 melting season
« Reply #444 on: April 26, 2018, 09:54:28 AM »
No, they didn't. Did you even read your own links?

Quote
While this drop coincided with an intense storm over the central Arctic Ocean, it is unclear if the storm prompted the rapid ice loss......
The most notable event was a very strong storm centered over the central Arctic Ocean in early August. It is likely that the primary reason for the large loss of ice this summer is that the ice cover has continued to thin and become more dominated by seasonal ice. This thinner ice was more prone to be broken up and melted by weather events, such as the strong low pressure system just mentioned.
I read the links when they were made in 2012, over & over.  I read the links often in succeeding years. Just before I mentioned these links, I read them over & over, again. It was the storm that busted up the thin ice & helped flush the ice to the south... with wind differently directed from the norm, also.
Not till mid to latter June did 2012 Arctic sea ice really start to drop, altho not much more than previous years. It was near August that the fame of 2012 Arctic sea ice really parted itself from all years previously AND ALL YEARS AFTER 2012.
I stand by my statement that the storm really busted the ice & believe the storm set up wind directions that easily transported busted ice out of the Arctic.
 
 


Neven

  • Administrator
  • First-year ice
  • Posts: 7756
    • View Profile
    • Arctic Sea Ice Blog
  • Liked: 1133
  • Likes Given: 521
Re: The 2018 melting season
« Reply #445 on: April 26, 2018, 10:01:47 AM »
I stand by my statement that the storm really busted the ice & believe the storm set up wind directions that easily transported busted ice out of the Arctic.

It's fine for you to stand by your statement, but don't say that the NSIDC stated the same.
Il faut comparer, comparer, comparer, et cultiver notre jardin

VeliAlbertKallio

  • Frazil ice
  • Posts: 202
  • Eheu fugaces labuntur anni
    • View Profile
    • Sea Research Society (SRS)
  • Liked: 82
  • Likes Given: 111
Re: The 2018 melting season
« Reply #446 on: April 26, 2018, 12:13:56 PM »
Citing from the Arctic News:

Sam Carana Admin · 24 April at 02:29: "Something appears to be wrong with the Arctic sea ice extent chart at the University of Bremen, Germany. The chart shows a sharp fall of extent that isn't matched by other websites that track extent."

Sam Carana: "I received a kind email from Gunnar Spreen, Ph.D., University of Bremen - Institute of Environmental Physics, who explains the glitch:"

"Dear Sam Carana,

Thank you for informing us about the problem. The anomaly you are seeing is a glitch in the processing. As you can see from the sea ice concentration map on our webpage seaice.uni-bremen.de not all data was available yesterday. This caused large gaps in the sea ice area, which caused the sea ice extent to drop artificially. We are investigating the causes and will update the graph as soon as we can. I will let you know when the problem is resolved.
I am sorry for the inconvenience and thank you for your interest in our products.

Best wishes,
Gunnar"

I assume this is a technical problem, not real extent data right?
"Setting off atomic bombs is considered socially pungent as the years are made of fleeting ice that are painted by the piling up of the rays of the sun."

Daniel B.

  • Grease ice
  • Posts: 659
    • View Profile
  • Liked: 8
  • Likes Given: 29
Re: The 2018 melting season
« Reply #447 on: April 26, 2018, 02:33:36 PM »
No, they didn't. Did you even read your own links?

Quote
While this drop coincided with an intense storm over the central Arctic Ocean, it is unclear if the storm prompted the rapid ice loss......
The most notable event was a very strong storm centered over the central Arctic Ocean in early August. It is likely that the primary reason for the large loss of ice this summer is that the ice cover has continued to thin and become more dominated by seasonal ice. This thinner ice was more prone to be broken up and melted by weather events, such as the strong low pressure system just mentioned.
I read the links when they were made in 2012, over & over.  I read the links often in succeeding years. Just before I mentioned these links, I read them over & over, again. It was the storm that busted up the thin ice & helped flush the ice to the south... with wind differently directed from the norm, also.
Not till mid to latter June did 2012 Arctic sea ice really start to drop, altho not much more than previous years. It was near August that the fame of 2012 Arctic sea ice really parted itself from all years previously AND ALL YEARS AFTER 2012.
I stand by my statement that the storm really busted the ice & believe the storm set up wind directions that easily transported busted ice out of the Arctic.

Both likely combined to result in the rapid ice loss.  Looking at the NSIDC data, the winter maximum in 2012 was the second highest since 2003 (only 2008 being higher), and remaining high until the beginning of June (passing 2008 and 2002).  Over the next two weeks, the Arctic lost an incredible amount of ice, dropping 2012 to the second lowest extent on record (2016 being lowest).  The melt from there was fairly routine, until the end of July.  Then the August storm took over, breaking up the ice, resulting in a new record low.  While the drop from the beginning of August to the September low was the largest on record, it was only 8% greater than the 2008 drop.  Indeed, had the ice began August at the same level as 2008, the ice loss would have only dropped 2012 to 4th lowest.  Hence, the combination of the two melts yielded the record low.

litesong

  • Frazil ice
  • Posts: 395
    • View Profile
  • Liked: 20
  • Likes Given: 15
Re: The 2018 melting season
« Reply #448 on: April 26, 2018, 04:36:18 PM »
I stand by my statement that the storm really busted the ice & believe the storm set up wind directions that easily transported busted ice out of the Arctic.

It's fine for you to stand by your statement, but don't say that the NSIDC stated the same.
Michael Hauber says:
......My opinion is that breaking up the ice pack with a storm does more damage than melt ponds...... I'd suspect a lot more energy is absorbed by patches of water mixed in  with the ice following a storm than are absorbed by melt ponds, and that this energy will be transferred to the ice by melt season end.  In 2012 there was a moderate and short lived storm in late June.....  These areas steadily got worse throughout the season until they were very fragile prior to the early August storm which finished the job.....Short periods of storminess followed by long periods of sunny is the ideal melting recipe in my opinion.

jdallen

  • Young ice
  • Posts: 3248
    • View Profile
  • Liked: 525
  • Likes Given: 206
Re: The 2018 melting season
« Reply #449 on: April 26, 2018, 05:12:48 PM »
I stand by my statement that the storm really busted the ice & believe the storm set up wind directions that easily transported busted ice out of the Arctic.

It's fine for you to stand by your statement, but don't say that the NSIDC stated the same.
Michael Hauber says:
......My opinion is that breaking up the ice pack with a storm does more damage than melt ponds...... I'd suspect a lot more energy is absorbed by patches of water mixed in  with the ice following a storm than are absorbed by melt ponds, and that this energy will be transferred to the ice by melt season end.  In 2012 there was a moderate and short lived storm in late June.....  These areas steadily got worse throughout the season until they were very fragile prior to the early August storm which finished the job.....Short periods of storminess followed by long periods of sunny is the ideal melting recipe in my opinion.
We should take this discussion to "chatter" as we are discussing past years and specific mechanisms.  I tend to agree with Neven.
This space for Rent.