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Messages - Tom

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Arctic sea ice / Re: The 2020 melting season
« on: July 29, 2020, 11:01:41 AM »
We have got to stop using that old DMI chart. There are better available now. Moyhu, for instance has a better one.

Since this was mentioned in passing I thought people might like to look at it

It's not available for other years  :(.

Arctic sea ice / Re: The 2020 melting season
« on: July 29, 2020, 10:45:07 AM »
I have just looked at the data again, odd things popped up in the pre 2000 era data (including 2000) for certain but nothing like it in the last 20 years so see it how you will, it is a pattern break to me.

Image attached for comparison.  It certainly looks to me like it's the highest it's been, but there are similar excursions above the mean at this time of year in 2016 and 2008, as I think others have mentioned upthread.

Edit: replaced image with version with arrows indicating other excursions

Arctic sea ice / Re: Freeform season chatter and light commentary
« on: July 19, 2020, 11:00:51 PM »
 I’ve been lurking hear for a few years, and I just wanted to say a big thank you to the whole community for the interesting and informative posts.

I also have to admit that it was only today that I realised quite how big the arctic seas are.  Someone made an offhand comment in the melting thread equating 2020’s current extent lead to the size of Germany, and for all the talk of century drops over the years I didn’t have a grasp of how big that was.

I am slightly astonished to discover the area of Wales (I am from the UK, so this is our standard large area comparator) is only 20,779 km2

This means that according to the Jaxa extent data the Arctic had been losing an area 6.5 times the size of Wales PER DAY on average for the whole of this month.  That’s 117 times the size of Wales this month alone  :o

Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: July 17, 2020, 04:13:46 PM »
Jaxa has had quite an impressive run this month:

 1st July 2020     -101,897
 2nd July 2020     -63,951
 3rd July 2020    -119,837
 4th July 2020    -126,111
 5th July 2020    -132,082
 6th July 2020    -194,704
 7th July 2020    -179,077
 8th July 2020    -138,925
 9th July 2020    -103,732
10th July 2020      -96,893
11th July 2020   -134,180
12th July 2020     -79,277
13th July 2020   -144,613
14th July 2020   -186,534
15th July 2020   -151,088
16th July 2020   -145,352

Average (Jul): -131,141
Average (last 10 days): -135,967
Average (last  5 days): -141,373

Arctic sea ice / Re: What the Buoys are telling
« on: July 14, 2020, 01:55:27 PM »
Another report from SIMB3 386840.

It looks to be on the threshold of melting out of its hole.

Plus an image of an ancient SIMB from the archives. How I imagine the scene at 74.0 N,   132.6 W as we speak!

Hi,  Thanks for posting these graphs/images, could you help confirm/correct my understanding of this data.

I think the x-axis is the vertical position on the buoy of the temp sensor (each sensor marked, 2cm apart), so taking the blue line for the 1st July, it makes sense to me that  0-63 is above ground air temps (pole is sticking ~1.2m in the air), and 145-190 is sea temp, but I am not sure how to interpret the middle section.

Maybe 64-79 is sun-warmed water (melt pond) then 79-121 is ice (so 84cm thick), with 121-145 a pool of warmed fresh melt water sitting between the ice and the colder salty sea water, or is the bottom of the ice at 145 (where temp starts dropping to -1.8 deg)?

Then trying to understand what changed between 1st and 14th July (blue line to red line), my guesses are that:

1. The air temp has dropped significantly, and is now below zero (0-65 now negative temp)
2. Assuming the water/ice boundary is at zero, the ice surface now is at 89 (red line now above blue between 79/89) - so ice has melted 20cm in 13 days
3. The melt pond has been cooled by the lower air temp?  (drop in temp between 65-79), perhaps the melt pond now has a thin ice layer on it's surface?
4. The ice from 81-121 (or 81-145) has warmed further.
5. The lower air-temps has cooled the melt-water making it harder to see where the ice layer begins?
6. How salty would the melt-pond be?  Could it be negative temp and still water?
7. Does the fact that the temp from 69-145 is no colder than -0.4 mean that it could be floating in melt water almost entirely - but then surely if this was the case it would have drained?
8. Looking at the cryosphere link at the mass-balance graph, this seems to show the "snow surface" changing from ~0cm on the 1st July to -17cm on the 14th (which does tie in roughly with my 20cm estimate above).  The bottom of the ice also gets deeper (which I assume is a mistake) The thickness is ~1.5m, which if 145 is the bottom would put the top at 70, so possibly this has been confused by the drop in temp between 70-79 of the red line.

I can see that as time progresses (green->purple->brown->blue->red) the temperature of the middle section has increased, and the data from green->blue shows consistent warming of the ice.

Sorry for all the question, this has gotten a bit longer than I anticipated:

TL/DR - is the ice bottom at 145 or 121?  Is the ice surface currently at ~89?  Does the temp of the ice being so close to zero mean it's closer to melting?

Arctic sea ice / Re: Arctic Image of the Day
« on: June 21, 2019, 05:39:09 PM »
The Freya glacier (Greenland) webcam is online again. Snow cover looks very bad compared to previous years.

Really nice webcam images - I like the temp info as well - hits 11.9C on the 16th.  Noticeable that there are lots of blue-sky days as well.

Made an animated gif for the last 30 days:

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