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Author Topic: What happened (or didn't) in May?  (Read 713 times)

JimboOmega

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What happened (or didn't) in May?
« on: June 02, 2017, 11:42:32 PM »
So May came, and with volume so much below normal, some people were calling for a cliff.

Instead (as extent goes) we had a pretty unimpressive month, especially compared to last year.

So... what happened - or didn't - in May?  Anybody want to take a shot at explaining it before NSIDC does?

gregcharles

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Re: What happened (or didn't) in May?
« Reply #1 on: June 03, 2017, 12:03:34 AM »
What I've gleaned, primarily from these boards, is that:

A) May temperatures were cooler than expected, at least in some areas of the Arctic, leading to less overall melt, and ...

B) The pack is more broken up than it has been in past years, which leads to more dispersal. Since extent relies on a threshold concentration percentage, which was, historically, a reasonable way to estimate the borders of extent, it doesn't really take into account this dispersal very well. 

I'm not an expert at this though. I'm sure better answers will be coming along shortly.

Cid_Yama

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Re: What happened (or didn't) in May?
« Reply #2 on: June 03, 2017, 01:06:22 AM »
LOL Yes, better answers are out there. 

Expect a huge drop in June.  Followed by nay sayers saying they knew all along, and it doesn't mean anything.   

DavidR

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Re: What happened (or didn't) in May?
« Reply #3 on: June 03, 2017, 02:37:09 AM »
The first place to look is the Pacific. The ice in the Pacific will melt out in May so the low extent in Okhotz and Bering this year accounts for most  of the variation between this year and last.

https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-extent-regional.png
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-area-regional.png

Wipneus's graphs suggest about 300K more ice last year than this year in that  area. This accounts for almost all the variation between this year and last year.
May loss
2016: 1790327   2017: 1510297.

In any year where the Pacific extent is high at the start of May we should expect high extent losses in May.

All the other areas seem to have followed a fairly normal melt path. If they started high they  ended high and if they started low they ended low.

The fact that the average thickness of the ice was low at the end of April, does not  mean there was a lot of thin ice.  Only very thin ice less than 0.6 m thick at the beginning of the melt season will have melted out so far. It is more likely that the area covered by ice 1- 3 meters thick last year was covered by thinner ice this year. Thinner ice at that thickness will be melting out over the next two months so we should expect larger than average losses over the next two months. This will probably lead to a final figure in September well below September 2012.
« Last Edit: June 03, 2017, 03:25:08 AM by DavidR »

Sterks

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Re: What happened (or didn't) in May?
« Reply #4 on: Today at 11:29:27 AM »
I think I'm going to earn a position of target of some criticism and unfriendliness, but I've got the impression that some of you people are selectively ignoring facts:
- It is true that the Pacific sector has a very bad color. Nevertheless, the Beaufort Sea (key in the destruction of ice) has only come to a modest start. More importantly, the Beaufort Sea has ended a lot colder than last spring. See how fractures are frozen as soon as they are opened and we are on May 11th. The refreezing came very late (December) with the loss of ocean heat that this entails. Not only that, the snow has generally been scarce in the area, so ice has nicely thickened reaching up to three meters (see Piomas, Cryosat).
- We are waiting for a heat wave that some members are announcing since April. Be not disappointed, if it does not come. I put the chances at 50% that heat will be maintained during the month of June, that's the key. Why? Because the deposited snow on the continents, not only in Asia but also in America, broke all sorts of records, perhaps caused by the extreme deviation of the Arctic Autumn and the Winter. Could this not cause a cooling effect in the summer weather? Seems a bouncing oscillating effect that is not nuts at all.
- The extent is in normal values ​​of the 21st century, far from the lowest data from other years. Do not forget one thing: the extent and the area are very important to give a boost to the melting season or to inhibit it, and the critical time now begins. The albedo potential maps just show that the anomalies in the Pacific (relatively unimportant) are canceled out by the anomalies in the Atlantic (relatively unimportant), with anomalies in the Arctic proper that are just irrelevant for the time being. The brief time of change must come.
- Volume also rebounds

It's still early to forecast (also on volume), I'll wait as much as possible to make a prediction for this poll, to have a clearer judgment. A very strong heatwave must come, when it comes, if it comes, or if it doesn't, I will put my vote or just comment about it if the voting is closed.
I wanted to quote the previous comment to add the context of what has happened since then with snow cover. I add a gif with May snow cover anomaly so far, from the Rutgers University Snow Lab
It is undeniable this year spring is late in many locations of the Northern Hemisphere, just as much early it was in preceding years. The wave of heat is coming north but with a delay caused by the buffer of heavy snow fallen in the winter.
This has a cooling effect, and as a consequence this will substract some of the heat reaching the Arctic via continental air acvections in the coming weeks.
However this is only a factor. Still not made up my mind. And it is true the heat at least is advancing much faster from the American side, this is truly dangerous.
In reply to recent discussions on the main melting season thread, I repost my views early on May, they turned out to be on the right track (although not all right). This is a better thread for it.
The coldness of the Northern Hemisphere due to excess snow was the answer for me and is the answer for now. Melt was slow until middle June. Volume anomaly with respect to 2012 has but virtually disappeared. I would call that a big rebound of volume from a scarily low number to something scary yet, but not as much.
But as I indicated just before June, the extraordinarily swift melt of snow in America end of May did not bring good omen and we can see now why.
« Last Edit: Today at 11:38:18 AM by Sterks »