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subgeometer

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Re: The 2018 melting season
« Reply #600 on: May 08, 2018, 01:45:32 AM »
This amount of heat at the pole in early May is unprecedented, period. I looked back to 1958. There was a pretty good spike in 2006 but there's nothing as warm as this so early.

The DMI chart is calculated from ECMWF which currently  at initialisation/000 hrs shows temps just below freezing over the pack north of Svalbard to the pole and beyond, rather than just above as per GFS. Unprecedented warmth either way.

I think it's safe to say that the Svalbard bite won't close before summer, as ATeam predicted. It looks to have become a permanent feature. The past few days the ice edge hasbeen pushed back almost 50km, and melt is evident at its edge. Looking through Bremen thin ice charts, their has been a 50km wide band of thin ice at the pack edge nort of Svalbard going back as far as I looked(feb), testament to the energy available there for melt. And it will be open for the 3 next months of serious insolation, so it will be interesting to see how warm the water gets

subgeometer

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Re: The 2018 melting season
« Reply #601 on: May 08, 2018, 02:15:31 AM »
I, for one, am glad that the snow depth forecast graphic was posted and, if Vargent hadn't done it, I was going to do it myself.  While Vargent points out the large Pacific snow melt out what struck me was that Scandinavia was modeled to be snow free in 10 days and that the land areas around Kara that have 3 to 4 feet of snow was going to see significant melt as well.  Finally, on the Kara Sea itself there was going to be significant snow melt as well that would likely cause the infamous melt ponds.

But to magnamentis' point, I don't have enough context on this melt.  Yes, it's May and it should be expected to have the snow melt.  But the degree of melt within the next 10 days seems rather large but is there enough institutional knowledge here to understand if this is well beyond standard melt?

Further, if it is a large melt, what does a significant in rush of 33 degree F water do to the melt of sea ice in the Kara or the Laptev?  More questions than answers but to see Alaska, except the North Slope, be predicted to be essentially snow free and to see the same in Scandinavia by mid-May seems like a fairly big deal.  But is there a website that can put this melt in context?

GFS is generally way too aggressive in its snow melt predictions.

jdallen

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Re: The 2018 melting season
« Reply #602 on: May 08, 2018, 02:16:22 AM »
Anomalously thick ice in the Laptev Sea, May4

How do you determine the thickness of the ice from the images?
I think uniquorn's comment was somewhat tongue-in-cheek, considering how fractured the ice appears.

If it is anomalously thick, it's not by much, and not sufficient to protect the ice from forces which attack it structurally.
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slow wing

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Re: The 2018 melting season
« Reply #603 on: May 08, 2018, 02:31:57 AM »
Clouds or melt ponds?

Looking at Worldview visible, North of Svalbard (details in image names) & the ice looks qualitatively different than it was previously.

It could just be cloud formations but, if so, these would have to be strange given what I would describe as a 'grooves & angles' appearance.

It was above freezing in the region displayed, around approximately 83.63N, 4.17E, on 2018-05-06 at 1200 UTC. (It's colder there now, ~-10 degrees C.)

So could the Worldview experts comment on whether large scale melt ponds could be an alternative possible explanation, even early in May?
« Last Edit: May 08, 2018, 02:41:48 AM by slow wing »

oren

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Re: The 2018 melting season
« Reply #604 on: May 08, 2018, 02:44:38 AM »
At this time I would say artifact/cloud, due to the sudden appearance over a largish area, lack of bluish tinge, and seeming lack of correlation to floe delineations. But another day or two could flip the verdict.
« Last Edit: May 08, 2018, 04:41:28 AM by oren »

FishOutofWater

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Re: The 2018 melting season
« Reply #605 on: May 08, 2018, 03:31:55 AM »
Anomalously thick ice in the Laptev Sea, May4

How do you determine the thickness of the ice from the images?

By going to the PIOMAS thread.

slow wing

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Re: The 2018 melting season
« Reply #606 on: May 08, 2018, 04:22:20 AM »
Thanks Oren, yes I took a closer look and agree it's probably strange clouds rather than melt ponds.

It was too cloudy on the day before, 2018-05-06, for all three satellites, and mostly too cloudy for the other satellites on the same day, 2018-05-07. (Already suggesting a lot of cloud about.)

But I was able to scan around the TERRA view and see a progression to other structures that tended to look more cloud-like.

Also, there was a small gap in the AQUA cloud cover showing white ice in the same identifiable ice position where the TERRA view showed those structures - at around 81.81N, 5.44E - compare the attached images.

So yes, the structure seems to be cloud &/or artifacts rather than melt ponds.

uniquorn

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Re: The 2018 melting season
« Reply #607 on: May 08, 2018, 10:21:53 AM »
Anomalously thick ice in the Laptev Sea, May4

How do you determine the thickness of the ice from the images?
I think uniquorn's comment was somewhat tongue-in-cheek, considering how fractured the ice appears.

If it is anomalously thick, it's not by much, and not sufficient to protect the ice from forces which attack it structurally.

Sorry. I should have referenced the PIOMAS and Cryosat anomalies.
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JayW

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Re: The 2018 melting season
« Reply #608 on: May 08, 2018, 12:25:18 PM »
Looking at the tightly packed isobars, there should be some strong easterly winds over the Beaufort beginning in a couple days, if the ECMWF is to be believed.  Unlike last week, the winds are progged to be warmer, so I wouldn't expect the leads to freeze over this time.  While there appears to be some thicker multi year ice in the Beaufort Sea, there is also a fair amount of ice that is only weeks old that formed in leads opened by previous wind events. Could be an interesting week.

https://www.tropicaltidbits.com/analysis/models/?model=ecmwf&region=ak&pkg=z500_mslp&runtime=2018050800&fh=72
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Neven

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Re: The 2018 melting season
« Reply #609 on: May 08, 2018, 12:27:48 PM »
The NSIDC has posted the correct ice age figure:
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Neven

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Re: The 2018 melting season
« Reply #610 on: May 08, 2018, 12:46:20 PM »
Looking at the tightly packed isobars, there should be some strong easterly winds over the Beaufort beginning in a couple days, if the ECMWF is to be believed.  Unlike last week, the winds are progged to be warmer, so I wouldn't expect the leads to freeze over this time.  While there appears to be some thicker multi year ice in the Beaufort Sea, there is also a fair amount of ice that is only weeks old that formed in leads opened by previous wind events. Could be an interesting week.

Indeed, Jay, the ECMWF SLP forecast for the coming six day, is a serious affair (especially combined with the anomalous heat). 1025-1035 hPa, all over the Central Arctic. This kind of weather in June or July would be a disaster for the ice, but it's not so great now either. Beaufort Gyre, here we come.
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VeliAlbertKallio

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Re: The 2018 melting season
« Reply #611 on: May 08, 2018, 12:50:38 PM »
Already back in 1950's Maurice Ewing and William Donn of Columbia University's then Lamont Geological Observatory, Palisades, New York extrapolated from the Great Lakes area lake-snow effect a similar effect for the Arctic Ocean. They proposed that global warming (aka: entry to the Interglacial) would first drive the Arctic Ocean to melt and loose its ice cover. Then the dark and exposed Polar water surface would build up so much heat in the summer that the resulting snowfall during the winter would become so big that it just could not melt away. This then tips the system (due to albedo change) to a cooling regime and the onset of the next Ice Age. This explanation for the ice ages failed due to sediment cores on the ocean beds not supporting it. Recently it has become blatantly obvious that if ocean warms, the permafrost also warms leading to high microbial activity beneath fallen snow cover, absorbtion of heat by deep soil layers that form pingos that then collapse as methane craters. In addition to albedo the rising methane, carbon dioxide, nitrous oxide, and water vapour - all conspire against the Ewing-Donn Lake Snow Effect from the Arctic Ocean with more snowfall becoming a runaway effect (a tight feedback loop). It doesn't. This brought Milutin Milanković back from the graveyard of abandoned theories. Thus, despite we see an intensifying Ewing-Donn Lake Snow Effect from the Arctic Ocean with more snowfall it will not lead to any substantial negative feedback in snowmelt. Obviously, thicker snow can take longer if weather conspires by cold temperatures and/or shielding cloud cover (a respondent negative feedback effect). 2018 looks bad already.

....what is crossing my mind, is it that hard to predict huge snow melt in may once a lot of snow is around by then? .....sorry if i sound negative.....
Actually, you sound like you believe in AGW. Tho AGW scientists predict increases in precipitation(snow, fer sure), it is also construed that global AGW excess heat will not let extra snow become extra long term snow to necessarily become excess ice.
« Last Edit: May 08, 2018, 12:58:52 PM by VeliAlbertKallio »

numerobis

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Re: The 2018 melting season
« Reply #612 on: May 08, 2018, 05:00:48 PM »
It was a warm April but so far a cold May on Frobisher Bay.

Rumour is the ice is worse than usual near the floe edge. It's still solid as far as you can see from town, no melt ponds yet (if there were, it would be crazy early), but satellite photos of the polynya looks bigger than usual.

jdallen

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Re: The 2018 melting season
« Reply #613 on: May 08, 2018, 06:53:10 PM »
Looking at the tightly packed isobars, there should be some strong easterly winds over the Beaufort beginning in a couple days, if the ECMWF is to be believed.  Unlike last week, the winds are progged to be warmer, so I wouldn't expect the leads to freeze over this time.  While there appears to be some thicker multi year ice in the Beaufort Sea, there is also a fair amount of ice that is only weeks old that formed in leads opened by previous wind events. Could be an interesting week.

Indeed, Jay, the ECMWF SLP forecast for the coming six day, is a serious affair (especially combined with the anomalous heat). 1025-1035 hPa, all over the Central Arctic. This kind of weather in June or July would be a disaster for the ice, but it's not so great now either. Beaufort Gyre, here we come.
We should see significant lift off from the Alaskan coast and significant increases in open water in the Chukchi.
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romett1

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Re: The 2018 melting season
« Reply #614 on: May 08, 2018, 07:44:53 PM »
Small update about FDD (Freezing Degree Days) anomaly north of 80 °N. Not surprisingly May has been warm (north of 80 °N) and still trying to chase 2016 as well (since start of the year). Image: https://sites.google.com/site/cryospherecomputing/fdd

FishOutofWater

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Re: The 2018 melting season
« Reply #615 on: May 08, 2018, 09:26:12 PM »
If there's a worse NH atmospheric circulation pattern than this European model ensemble forecast for Arctic sea ice, I don't know what it is, and I certainly don't want to see it.

This is the worst time of the year for excess Arctic heat because the decreased albedo will enhance melting through the whole melt season.

jdallen

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Re: The 2018 melting season
« Reply #616 on: May 08, 2018, 10:14:54 PM »
If there's a worse NH atmospheric circulation pattern than this European model ensemble forecast for Arctic sea ice, I don't know what it is, and I certainly don't want to see it.

This is the worst time of the year for excess Arctic heat because the decreased albedo will enhance melting through the whole melt season.

That forecast is a long way out (May 18), but even if not accurate, does suggest the trend.

I agree, if this plays out it suggests serious trouble.
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numerobis

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Re: The 2018 melting season
« Reply #617 on: May 08, 2018, 11:11:54 PM »
Nice big blue spot over my head on that map ;)

uniquorn

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Re: The 2018 melting season
« Reply #618 on: May 08, 2018, 11:18:59 PM »
It looks like we just started exporting MYI on the Pacific side.
Ascat mar21-may7

imagej brightness/contrast 43,255 (some loss), CLAHE 63,256,2.2
2 frames deleted due to very poor data, some parts grey filled to reduce distraction

uniquorn

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Re: The 2018 melting season
« Reply #619 on: May 09, 2018, 12:07:13 AM »
I tried to confirm this using Worldview but I could only find a couple of floes. Taking a wider view in the second animation, thicker ice often shows brighter on VIIRS band15 when the weather is clear.
I think the forecast is for winds in the same direction. Will have to watch for a few days.

Telihod

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Re: The 2018 melting season
« Reply #620 on: May 09, 2018, 11:17:42 AM »
10 day forecast. (Max temperature.)


El Cid

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Re: The 2018 melting season
« Reply #621 on: May 09, 2018, 01:48:13 PM »
10 day forecast. (Max temperature.)

Maybe (IMO) even more important than temperature is that huge high pressure zone, right where it shouln't be: the attack is coming from the already weakened Pacific side and could gain traction very fast.

uniquorn

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Re: The 2018 melting season
« Reply #622 on: May 09, 2018, 02:44:19 PM »
Beaufort MYI string export on ascat apr22-may8
Worldview may8. Significant refreeze on previously open water, or is it snow? There has been a lot of cloud there over the last few days.

The ascat animation is significantly enhanced.
imagej: brightness/contrast 41,255 CLAHE 63,256,2.2 scale x2. unsharp mask 1,0.6

numerobis

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Re: The 2018 melting season
« Reply #623 on: May 09, 2018, 07:23:18 PM »
10 day forecast. (Max temperature.)

Personally I'd be happier if we kept this thread closer to the observations. I can wait ten days to see what happened, whereas looking forward ten days from now is a total crapshoot (especially with GFS).

gerontocrat

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Re: The 2018 melting season
« Reply #624 on: May 09, 2018, 08:04:44 PM »
10 day forecast. (Max temperature.)

Personally I'd be happier if we kept this thread closer to the observations. I can wait ten days to see what happened, whereas looking forward ten days from now is a total crapshoot (especially with GFS).

Is GFS totally at fault ? I've just scrolled through cci-reanalyzer using the hourly forecast slider and I have seen nothing to match the image posted by Telihod. It all looked very ordinary to me - warmth and cold moving anti-clockwise around and no massive anomalies.
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Greenbelt

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Re: The 2018 melting season
« Reply #625 on: May 09, 2018, 08:25:37 PM »
The operational GFS and ECMWF seem in quite good agreement on a big surface high pressure over the central arctic around 1030mb over at least the next five days.  While the 10-day projections might be fanciful, the 5-7day outlooks have tended to be decent on broad features when there's model consensus, at least at lower latitudes, and I suspect the predictions are improving up north too. Will be interesting to see if we can spot melt pond formation signals after this big high (presumably) sets up, or if that's still too early season for that at the highest latitudes.


« Last Edit: May 09, 2018, 08:47:55 PM by Greenbelt »

numerobis

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Re: The 2018 melting season
« Reply #626 on: May 09, 2018, 09:04:49 PM »
gerontocrat: weather forecasting is hard. I don't exactly blame GFS. They've not kept up with the quality that ECMWF manages, but both are pretty random at 10 days out. Both are much better at 5 days and in most places excellent at 2 days.

I notice that GFS almost always predicts lower winds than actually happen here in Iqaluit, whereas ECMWF is much closer. But I don't know that it's a broad trend rather than just being different resolution. Wind speeds are often very different on the bay versus inland; if GFS has us in a grid square that averages to being a couple km inland it would explain the issue.

gerontocrat

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Re: The 2018 melting season
« Reply #627 on: May 09, 2018, 09:38:57 PM »
Things are cooling down North of 80
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marcel_g

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Re: The 2018 melting season
« Reply #628 on: May 09, 2018, 09:48:26 PM »
10 day forecast. (Max temperature.)

Personally I'd be happier if we kept this thread closer to the observations. I can wait ten days to see what happened, whereas looking forward ten days from now is a total crapshoot (especially with GFS).

Personally, I always find the "oh shit, look what's coming for the Arctic" forecasts that are a big part of the melting season threads to be valuable. Granted, the <5 day forecasts are a lot better than the 5-10 day forecasts. I guess I'm here because I want to have some clue as to what's going to happen. There is also a lot of discussion about what actually happened, and why, but the forecasts really get my curiousity going.

Neven

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Re: The 2018 melting season
« Reply #629 on: May 09, 2018, 10:17:00 PM »
Oh shit, look what's coming for the Arctic in the <5 day forecast.

1025-1030 hPa is bad enough, but it rises to 1039 hPa on day 6, and stays that way until day 10, which would be OH SHIT. It's the worst possible weather for the ice, and we're lucky that it's only mid-May. If we see this kind of weather in June, it will take some seriously cold and cloudy weather in July and August to cut the momentum short. And I will be using larger fonts for the OH SHIT.

But this is definitely oh shit.  ;)
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Neven

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Re: The 2018 melting season
« Reply #630 on: May 09, 2018, 10:22:56 PM »
As expected, Barentsz is dropping off a cliff. CAB is also showing a drop, but it will probably go up again. Eyes should be kept on the Beaufort. It has been lagging a bit, but given the current forecasts the Beaufort Gyre should really start pulling the ice away from the coasts any day now.
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bbr2314

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Re: The 2018 melting season
« Reply #631 on: May 09, 2018, 10:59:24 PM »
As expected, Barentsz is dropping off a cliff. CAB is also showing a drop, but it will probably go up again. Eyes should be kept on the Beaufort. It has been lagging a bit, but given the current forecasts the Beaufort Gyre should really start pulling the ice away from the coasts any day now.
Yikes. I think the problem this year is the ATL front close to the CAB is just so open that once momentum gets going (as is now happening), we may not have enough import from the grye to negate open water reaching.... extremely.... far past 80N by 9/1.

The next week+ of weather is going to put an enormous bullseye into the heart of the pack. But on the plus side, perhaps we see more of a CAB/CAA-esque situation along the Siberian shorelines this year? The amount of ice there is quite impressive, however, it normally melts out entirely.


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Re: The 2018 melting season
« Reply #632 on: May 09, 2018, 11:27:49 PM »
10 day forecast. (Max temperature.)

Personally I'd be happier if we kept this thread closer to the observations. I can wait ten days to see what happened, whereas looking forward ten days from now is a total crapshoot (especially with GFS).

I agree...the short-term forecasts are of some interest in terms of figuring out what is going on at the moment and guesstimating the future, but the longer term forecasts are simply noise.

numerobis

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Re: The 2018 melting season
« Reply #633 on: May 09, 2018, 11:50:54 PM »
970 mb storm flitting by the Baffin sea on Saturday. There go my weekend plans to go skiing.

JayW

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Re: The 2018 melting season
« Reply #634 on: May 10, 2018, 12:02:26 AM »
May 5-9 Beaufort and some Chukchi, 101 hour loop.  Easterly winds north of Alaska are beginning to ramp up, and are progged to increase over the next 24 hours, persistenting for several days.  We'll see soon if anything freezes.

Contrast slightly increased for detail.  Imagery courtesy of the University of Alaska at Fairbanks.
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http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images?search%5Bfeeds%5D%5B5%5D=1&search%5Bsensors%5D%5B3%5D=1
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Michael Hauber

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Re: The 2018 melting season
« Reply #635 on: May 10, 2018, 12:29:20 AM »
The forecast is for a big high, but for the most part it is surrounded by low pressure/troughing.  So not a lot of warm air coming from the south into the Arctic to go with all the sunshine and warming of air in place as it descends.
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Shared Humanity

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Re: The 2018 melting season
« Reply #636 on: May 10, 2018, 02:41:43 AM »
10 day forecast. (Max temperature.)

Personally I'd be happier if we kept this thread closer to the observations. I can wait ten days to see what happened, whereas looking forward ten days from now is a total crapshoot (especially with GFS).

Is GFS totally at fault ? I've just scrolled through cci-reanalyzer using the hourly forecast slider and I have seen nothing to match the image posted by Telihod. It all looked very ordinary to me - warmth and cold moving anti-clockwise around and no massive anomalies.

What does 10 day forecast max temperature mean anyway? Is this the max temperature reached over the 10 day period for a specific point on the map? If that is so, it's meaningless.

Bob Wallace

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Re: The 2018 melting season
« Reply #637 on: May 10, 2018, 02:42:49 AM »
The NSIDC has posted the correct ice age figure:



How one plots their data can change the impact on the viewer.




The message I would like to see made obvious is that the Arctic is running out of older ice. 

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Re: The 2018 melting season
« Reply #638 on: May 10, 2018, 08:14:25 AM »
The NSIDC has posted the correct ice age figure:



How one plots their data can change the impact on the viewer.




The message I would like to see made obvious is that the Arctic is running out of older ice.
Further thought... the total thickness should be reduced by the change over time of maximum extent.  For example, while the percentage of 2nd year ice has remained more steady than the other ages, its absolute coverage has declined by between 30-40% since the start of the time period in question.

I'm looking for numbers....
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Bob Wallace

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Re: The 2018 melting season
« Reply #639 on: May 10, 2018, 08:55:33 AM »
So we need a widening band of white along the top.

"In Memory of Ice That Used To Be"

If you don't find numbers I can create a version where the color part gets squeezed down 30% to 40% from left to right.  It wouldn't be as accurate as year to year but it would make conditions more apparent.

Dave C

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Re: The 2018 melting season
« Reply #640 on: May 10, 2018, 09:23:58 AM »
Can the Bremen map possibly be accurate?

The ice has never melted by the pole. I can't remember it even being that thin before, let alone in May.


oren

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Re: The 2018 melting season
« Reply #641 on: May 10, 2018, 10:26:52 AM »
]
Further thought... the total thickness should be reduced by the change over time of maximum extent.  For example, while the percentage of 2nd year ice has remained more steady than the other ages, its absolute coverage has declined by between 30-40% since the start of the time period in question.

I'm looking for numbers....
If you're looking for thickness distribution over time, Wipneus posted just such a chart in the PIOMAS thread a few days ago. Ice age is more difficult, but one could take NSIDC ice area on the ninth week every year, and use that as a scaling factor over the NSIDC graph.

Steven

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Re: The 2018 melting season
« Reply #642 on: May 10, 2018, 11:34:55 AM »
the total thickness should be reduced by the change over time of maximum extent.  For example, while the percentage of 2nd year ice has remained more steady than the other ages, its absolute coverage has declined by between 30-40% since the start of the time period in question.

Maximum sea ice extent has decreased by about 10% since the early 1980s:

http://nsidc.org/arcticseaicenews/files/2018/04/Figure3.png

Moreover, the NSIDC ice age graph uses an Arctic Ocean domain that excludes regions like Bering, Okhotsk, Baffin, Greenland Sea, etc.  The decrease in maximum sea ice extent for that domain is about 5% rather than 10%.

Vergent

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Re: The 2018 melting season
« Reply #643 on: May 10, 2018, 11:58:01 AM »
Long range GFS will keep bouncing around, it keeps showing similar potentialities.



Verg

edit: I think it has something to do with the second law of thermodynamics.

Neven

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Re: The 2018 melting season
« Reply #644 on: May 10, 2018, 01:39:47 PM »
Can the Bremen map possibly be accurate?

The ice has never melted by the pole. I can't remember it even being that thin before, let alone in May.

These are usually artifacts caused by clouds or melt ponds or glitches or whatever. My rule of thumb is: The yellow/green colours need to persist in the same place for at least three days. If that's the case, it may be that there is ice divergence there due to melting and/or winds.

BTW, if you want to see if something happened before, or when, you can compare concentration maps on this special page on the Arctic Sea Ice Graphs page (pick a date): Concentration Maps.
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meddoc

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Re: The 2018 melting season
« Reply #645 on: May 10, 2018, 01:53:54 PM »
Long range GFS will keep bouncing around, it keeps showing similar potentialities.

edit: I think it has something to do with the second law of thermodynamics.

Oh, You don't say.
The whole Heat Transport and GHG- Effect and in Reality, everything is governed by the I & II Laws of Thermodynamics. We know where we are headed. Only the Time left is the Question. But, surely no turning around.

Everything else is just Politics.

friedmators

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Re: The 2018 melting season
« Reply #646 on: May 10, 2018, 02:03:55 PM »
10 day forecast. (Max temperature.)

Personally I'd be happier if we kept this thread closer to the observations. I can wait ten days to see what happened, whereas looking forward ten days from now is a total crapshoot (especially with GFS).

Is GFS totally at fault ? I've just scrolled through cci-reanalyzer using the hourly forecast slider and I have seen nothing to match the image posted by Telihod. It all looked very ordinary to me - warmth and cold moving anti-clockwise around and no massive anomalies.

Slightly OT, but the GFS has a hurricane in the Gulf of Mexico in about 12 days...Not sure how the verification scores line up in the Arctic versus globally, but that model has issues.

Vergent

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Re: The 2018 melting season
« Reply #647 on: May 10, 2018, 03:32:44 PM »
10 day forecast. (Max temperature.)

Personally I'd be happier if we kept this thread closer to the observations. I can wait ten days to see what happened, whereas looking forward ten days from now is a total crapshoot (especially with GFS).
Is GFS totally at fault ? I've just scrolled through cci-reanalyzer using the hourly forecast slider and I have seen nothing to match the image posted by Telihod. It all looked very ordinary to me - warmth and cold moving anti-clockwise around and no massive anomalies.

Slightly OT, but the GFS has a hurricane in the Gulf of Mexico in about 12 days...Not sure how the verification scores line up in the Arctic versus globally, but that model has issues.

You have to read the caption "10 day max temperature". It can be found in the outlook section

http://cci-reanalyzer.org/wx/fcst_outlook/

Verg

edit: placement

Shared Humanity

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Re: The 2018 melting season
« Reply #648 on: May 10, 2018, 03:43:22 PM »
So we need a widening band of white along the top.

"In Memory of Ice That Used To Be"

If you don't find numbers I can create a version where the color part gets squeezed down 30% to 40% from left to right.  It wouldn't be as accurate as year to year but it would make conditions more apparent.

That chart would be powerful.

jdallen

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Re: The 2018 melting season
« Reply #649 on: May 10, 2018, 03:43:39 PM »
the total thickness should be reduced by the change over time of maximum extent.  For example, while the percentage of 2nd year ice has remained more steady than the other ages, its absolute coverage has declined by between 30-40% since the start of the time period in question.

Maximum sea ice extent has decreased by about 10% since the early 1980s:

http://nsidc.org/arcticseaicenews/files/2018/04/Figure3.png

Moreover, the NSIDC ice age graph uses an Arctic Ocean domain that excludes regions like Bering, Okhotsk, Baffin, Greenland Sea, etc.  The decrease in maximum sea ice extent for that domain is about 5% rather than 10%.
Excellent points. Makes the need for my adjustment less necessary.
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