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Messages - Tom

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1
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 https://moyhu.blogspot.com/p/latest-ice-and-temperature-data.html#arctic

It's not available for other years  :(.

2
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

3
Voted lowest.  No confidence at all due to “weather”!

But we only need slightly above average melt to get first (2.8% - thanks gerontocrat) and this seems more likely than not given the melting momentum / heat in the system.  Also hycom showing thin ice on the pacific side.

4
Arctic sea ice / Re: The 2020 melting season
« on: July 23, 2020, 11:04:59 AM »
To my eyes it shows an expectation that area/extent losses will slow, but that thinning will still be occurring
Hycom forecasts do not show area/extent losses in their forecasts. If there was Ice in a location the forecast will show at least the thinnnest ice. Their forecasts show thin ice turning white but never melting.

Thanks for taking the time to improve my understanding.  It is much appreciated.

5
That first graph seems to show that we should expect extent/area loss to continue.

I say this because the area taken by ice <0.26m ice is larger than previous years.

6
Arctic sea ice / Re: The 2020 melting season
« on: July 22, 2020, 10:53:13 AM »
I have discovered that HYCOM ice thickness model produce a 30-day animated gif which is really nice to look at, and not that big (they do a 12-month one as well which I highly recommend - see https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/arctic.html)

The below 30-day image includes a forecast for the 20th-28th  (date at the top is the date of ice forecast, date on the map is the date the image was produced, so you will see it's a now-cast up to the 20th, then a forecast)

To my eyes it shows an expectation that area/extent losses will slow, but that thinning will still be occurring

7
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: July 19, 2020, 11:24:21 PM »
That´s a lot of drowning sheep.  :(

Absolutely  :)

8
Arctic sea ice / Re: HYCOM
« on: July 19, 2020, 11:12:53 PM »
Thanks for that info.  It’s been bugging me for a while that the images didn’t seem to reflect reality in worldview, especially since I knew it incorporated area data, but that makes much more sense if it’s using the area data as a mask to produce the volume numbers from the model output.

9
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

10
Arctic sea ice / Re: What the Buoys are telling
« on: July 19, 2020, 10:34:20 PM »
Another report from SIMB3 386840.

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

Which now appears to have happened. Perhaps as a result the thermistor string is now making better contact with the remaining ice?

Thanks for the update.  I’m finding them really interesting now I understand them a bit better.  I agree with you completely. It clearly looks like the buoy is now sitting 60cm lower since the meltout.

11
Arctic sea ice / Re: HYCOM
« on: July 19, 2020, 10:12:20 PM »
Piomas also shows ice that isn’t really there.  I noticed in particular around the islands east of Svalbard.  Attaching a mostly cloud free pic from 2 days before.  Hycom seems to match better what can be seen in worldview.


12
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

13
Arctic sea ice / Re: What the Buoys are telling
« on: July 15, 2020, 03:16:46 PM »
@Jim,  Thanks for the explanation, much appreciated.  I’ve been trying to get a better handle on what the buoys report so that I can quantify some of the weather related excitement in the main melt thread.

Looking again at the image you posted I see your point about the sensor creating a melt pit, which I guess makes this data as fuzzy and open to interpretation as everything else arctic related.

14
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?

15
Policy and solutions / Re: Electric cars
« on: December 05, 2019, 12:59:45 PM »
In the UK at least the Tesla Model 3 is available to specify with a Tow Hitch


16
I've gone with 3 to 4.5.  I was tempted to include another low bin, but since this is extent and not area I think the chances of a highly compacted finish are low, and this would be necessary for a really low extent figure.

It's also 0.75 either side of my actual jaxa Sept min prediction of 3.75 in a solid 2nd place

17
Arctic sea ice / Re: Northern Sea Route thread
« on: July 12, 2019, 12:45:54 PM »
It looks open on the Bremen concentration map, but in worldview today (12th July) there is still quite a large chunk in the ESS that stretches to the coast.  It doesn't look in great shape, so I don't think it will be that long now.



Edit: reduced image size (oops)

18
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.

https://www.foto-webcam.eu/webcam/freya1/

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:

19
Arctic sea ice / Re: Latest PIOMAS update (August)
« on: August 05, 2018, 08:42:02 PM »
Thanks both for your insights.  I'm finding the knowledge and information available from the contributors to this forum fascinating.

@gerontocrat if you have the time and inclination I'd be interested to see the piomass loss by month over time for the melting season.

20
Arctic sea ice / Re: Latest PIOMAS update (August)
« on: August 05, 2018, 02:07:03 AM »
Re my previous post.  Could this just be down to less ice being available at (presumably warmer) lower latitudes at the end of the season?

If I read correctly there was less volume loss from this point in 2012 than the 80's average, despite the final volume being so much lower.

21
Arctic sea ice / Re: Latest PIOMAS update (August)
« on: August 05, 2018, 01:59:48 AM »
EDIT: Using the decades averages on the graph seems to make it clear volume loss is accelerating.

I find it very interesting that despite the lower actual volume your decade trend figures seem to show the "melt from now to min" actually steadily decreasing decade by decade.

Any idea why this would be, or have I misunderstood the figures?

22
Changed from 4.5-5.0 to 4.25-4.75

Going purely on projections based on averages I think about 4.6ish, but have changed bin as I think recent weather means the chances of undershooting are higher than overshooting.

23
Quote
So the median prediction, after a drop of 0.99 in 2012, was to drop only a further 0.25 in 2013.

In a chaotic system, I think after such a large drop it would be unusual to expect a further drop from the new low the following year, and that the principle of "regression to the mean" would mean that you should expect an increase the following year.

24
Arctic sea ice / Re: How soon could we go ice free?
« on: June 15, 2018, 02:13:43 PM »
The problem I see with applying linear trends to estimate the "ice-free" date is that it doesn't make sense to me that the arctic will continue being able to melt xxx km3 of ice each year.

I assume that as the ice volume reduces it will retreat into the CAB, where it will be more resistant to melt (shorter melting season etc).

Currently the melting season starts first in the peripheral seas.  As warming continues in winter and max volume reduces, presumably comparatively more of the reduction in winter volume will be in the periphery than in the CAB, so it won't be there to be easily melted at the beginning of the melt season.

I'm sure this will make the ice in the CAB easier to melt, but not by enough to make up for the overall volume reduction.

In summary, I think that as the winter max volume reduces the volume of ice melted each year will decline, and there will be a slowing of the rate-of-change in volume reduction (a long-tail decline)

Having posted all this obviously I should point out that I'm just making stuff up based on opinions from this forum  :)  I also think that the system is incredibly complex and trying to predict the future is a fools errand.

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