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Messages - anaphylaxia

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Arctic sea ice / Re: The 2020/2021 freezing season
« on: September 18, 2020, 04:42:19 PM »
Wow, excellent representation of the whole season!

Arctic sea ice / Re: Latest PIOMAS update (September 2020)
« on: September 07, 2020, 07:43:28 PM »
Monthly update from the Polar Science Center:
August 2020 Monthly Update

 The drift anomaly shows a counter clock wise pattern compared to the normal counter clockwise pattern of sea ice drift. 

So the ice spins the way it should?

Also, the whole Spaltegletcher part calved on in July, so the sunwarmed water got like 30 km closer to the ice tongue of 79N.

My bets are on 79N. There is a considerable area for which the only catchment is Blaso lake, located at the grounding point of the 79N glacier, that is reciving an awful lot of warm meltwater, and the water level is rising day by day. It is also above sea level, with the glacier acting as a dam. Also the bedrock topography behind the grounding point is below sea level, facilitating fast slippage if the grounding zone gives way. I believe a Vavilov style ice stream could start after that.

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: August 07, 2020, 10:08:09 AM »

Interesting to see, how the 2015 collapse of the Vavilov ice cap creates a cold finger at SZ, leading to remnants of sea ice in the vicinity of +4 C waters.
*messed up the quotation*

That is the floating part of the glacier. The grounding is way up, at the west outlet of lake Blaso. There is a 900! m trench below it, and the ice tongue we se from lake Blaso to the sea outlet is tapering from 500 m to 50 m at the end. There is a very good discussion of the underwater topography in this book.

This is the main reason why i fear for an ice stream starting here. The 79N is held back by the island chain and it rests on some 100 m thick ice. But the calving of the Splaltegletscher brougth the sun warmed sea water front 20 km closer to the back end of the 79N main stream, that is only 50 m thick. There is documented history of the gletscher surging, when it calves back behind the NOIB. See fig 4.16 in the link.

The whole north leg of the glacier seems to detach. The 79N glacier is said to be anchored at Lynn O, and the small islands that stretch from north to south. If the Spaltegletscher part detaches, the sun-warmed seawater can attack the anchorpoint from the back. We might see a Vavilov ice cap like collapse on an enormous scale.

Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: April 07, 2020, 09:35:17 PM »
I think it has to do with the persistant Nares outflow, prime 5m thick ice is coming from North of Greenland

Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: July 02, 2019, 09:36:37 PM »
How did you determine that the grey zone that shows "all but the highest and lowest daily records of 1981-2010 data" (per Gerontocrat's June 29 post) is approximately 2SD? Is there a 'rule of thumb' involved here?  You said it was so on June 30.
I think the trick is with the mathematical properties of normal distribution, and the number of years available for observation. A 2-3 sigma event represents 4.2 % of all in a normal distribution, and there are ~40 years of data available, thus discarding one maxima and minima gets rid of the 5 % of the observations, corresponding to roughly the probability of them occuring.

Greenland and Arctic Circle / Re: The Nares Strait thread
« on: July 01, 2019, 05:20:51 PM »
Well, i just meant that practically the whole Kennedy Channel is full of flowing debris. The event started at June 22, when a small blockade burst in Hall Basin and its been interrupted by Hans Island just on the 28 th, until then it was flowing at the maximum speed, not hindered by obstacles, so it should be near the theoretical maximum ice carrying capacity of the current. I was interested in if anyone has crunched the numbers on this.

Greenland and Arctic Circle / Re: The Nares Strait thread
« on: July 01, 2019, 05:08:21 PM »
Nares Strait export now chugging along its theoretical maximum, with the whole Kennedy Channel filled with rounded rubble from Lincoln. And the big chunk is right about to enter the strait. Any chance of a guesstimate on area or volume export?

Arctic sea ice / Re: The 2019 melting season
« on: June 28, 2019, 06:23:58 PM »
Whats up with the weird dark structures in the laptev fast ice? If I didn't know better, it would look like land masses showing through. What actually causes this?

Thats precisely that, landfast ice. ESS is very shallow on the shelf, less than 10 m at parts. You can see smaller landfast ice fragments, blocking the way of floating ice further down New Siberian Island, like at this point,MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2019-06-25-T00%3A00%3A00Z&z=3&v=-671680.3170317126,1506201.7460831201,-425920.3170317126,1627545.7460831201

Arctic sea ice / Re: The 2019 melting season
« on: June 04, 2019, 09:09:24 PM »
July 24 th and showing almost 80% on Hudson bay? Historically its below 40% by the start of July...

Arctic sea ice / Re: The 2019 melting season
« on: May 15, 2019, 08:24:24 PM »
Minor correction, the water vapour is always in the air absorbing long wave radiation. At the dew point it condenses, and makes mist, that is absorbent to the visible spectra, insulating against short wave radiation.

Arctic sea ice / Re: 2018 sea ice area and extent data
« on: October 10, 2018, 07:26:48 PM »
Nice table and graph. Really shows how extraordinary the beginning of the 2018 melting season is.

I agree it's a nice graph, but there is the issue that it kind of conflates "rate of refreezing" with "date of the minimum".  A year with an early minimum will have had more days to refreeze by now, vs a year with a late minimum. 

Here's an alternate version -- instead of looking at extent gain at a given date, it's extent gain during the first X days after whenever the minimum was:

2018 is still in the slower-freezing half, but it's not an outlier.

Which of these is a "better" way to look at it?  Not sure.  Probably good to consider both.

Maybe if we would normalize for the extent minimum then the percentage gain since minimum would be a better measure?

Arctic sea ice / Re: 2018 sea ice area and extent data
« on: July 30, 2018, 07:44:54 PM »
Has the Greenland Sea been ice free before ?

Not in the NSIDC record.  Here's a plot showing 2018 vs the (pre-2018) lowest value on each date (Min_1979_2017), and also the 2007-2017 average extent.

Are you sure about this? 1979 to 2017 ave a good 100 k lower than 2007 to 2017? Maybe some mixup in the legends.

Arctic sea ice / Re: The 2018 melting season
« on: July 18, 2018, 05:01:19 PM »
I think someone said earlier, that the sub meter sea ice doesnt have enough insulating ability, thus the water under it cools substantially during winter. Didnt run any calculations on that, but this could explain some "missing" heat.

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