Support the Arctic Sea Ice Forum and Blog

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - anaphylaxia

Pages: [1]
1
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: July 02, 2019, 09:36:37 PM »
Oren,
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.

2
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.

3
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?

4
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 https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),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

5
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...

6
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.

7
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?

8
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.

9
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.

Pages: [1]