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Messages - grixm

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1
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: August 05, 2020, 04:48:33 PM »
In the mean time, while I don't know how to find exact area numbers, Nico's graph for the last two days suggest an averaged drop not much different from the past week, in other words around -60k km^2 per day.

2
Arctic sea ice / Re: The 2020 melting season
« on: August 04, 2020, 10:22:06 AM »
July 30 - August 3.


Looks like the entire pack is slowly being pulled apart down the middle. You can see it on the drift chart too.

3
Greenland and Arctic Circle / Re: Greenland 2020 Melting Season
« on: August 01, 2020, 07:44:12 PM »
What is the large black splotches on the webcam ice? Rock/dirt on the bottom of the glacier? In that case I didn't realize the valley was so shallow. Or is it just a dirty ice layer of the glacier?

4
Greenland and Arctic Circle / Re: Greenland 2020 Melting Season
« on: August 01, 2020, 05:08:43 PM »
I have a question regarding how this mass gain/loss is calculated. Is this a model based upon precipitation? Or is this using date from GRACE data?

How much of this precipitation is falling as rain? If you look a lot of the mass gain is right on the edge of the ice sheet. Isn’t it possible that a lot of moisture in the summer months is rain and that it may not actually add to the mass of the ice sheet long term? Is this taken into account when the calculate the yearly gain/loss?

Also is it possible that some of the mass gain on the outside of the ice sheet is due to the glacier slumping slightly? For example if the glacier sped up slightly and caused the area nearest the sea to rise by say 5 meters would that not show up on GRACE?

Maybe these are separate topics but I’ve been wondering about them for a few years.

TIA

It is a model based on lots of input, including precipitation. You can read all about it in this paper: https://www.frontiersin.org/articles/10.3389/feart.2016.00110/full

But GRACE data is not used. It does not update fast enough and is probably not good enough resolution for a near-real-time product.

5
Arctic sea ice / Re: The 2020 melting season
« on: July 28, 2020, 02:17:58 PM »
Another quite large daily drop in area. We are now below 4 million km^2.

6
Arctic sea ice / Re: The 2020 melting season
« on: July 28, 2020, 07:55:48 AM »
Both 0z GFS and ECMWF initialized with the storm at 968 hPa

7
Consequences / Re: Heatwaves
« on: July 27, 2020, 07:03:28 PM »
Extremely hot weather is forecast in the middle east over the next few days. Over 53 C several places in Iraq and near Kuwait and Iran.

For reference the all-time record for Iraq is 53.8 C. Iran 54 C and Kuwait 53.9 C.

8
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 08:17:03 AM »
The anomalously thick ice that we had earlier this season along the Atlantic front has been destroyed.


1. The Atlantic  side where it says had ice 1-1.5M above normal(the recent normal,  not the 1970s-90s) has melted out.

It must be mentioned that this ice has been pushed away from land by the compacting winds. I don't how thick it still is and it certainly has melted some, but your posts make it seem like just because there were ice touching the island shores a month ago and now there isn't, means that it all has vanished. No, much of the same ice is still there, just a few hundred km further to the north. So it is possible that the high thickness anomaly from before was reasonably accurate.

9
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 01:50:47 PM »
How is this ice here being so robust? It's very warm in the water and air, there's little other ice around to buffer the heat, and last PIOMAS update the 15th said that the ice was quite thin at that time. Yet it is still there in significant amounts, it almost doesn't look like it has melted much at all in the past week or two.

10
Arctic sea ice / Re: The 2020 melting season
« on: July 23, 2020, 02:33:47 PM »
Daily NSIDC area value went back to record low today.

11
Arctic sea ice / Re: The 2020 melting season
« on: July 23, 2020, 11:15:10 AM »
Just wondering, when will the ice in CAA start to give in. It seems like for much of CAA islands temperatures will remain nicely near +10C until the end of July.

It has already started to give in. The southernmost channel is already at least halfway open water, and the innermost large channel is cracking and disintegrating more day by day. This will just slowly spread more and more inwards over the next couple of months. It won't happen all at once though, the CAA ice is resilient.

12
Arctic sea ice / Re: The 2020 melting season
« on: July 23, 2020, 08:06:29 AM »
The ice is compact, I don't understand how that's a controversial statement at all. Like it has been said before, compactness is just area divided by extent. And that figure is very high, as is to be expected after the central basins have experienced compacting winds for weeks on end.

13
Following a discussion from another thread, here is the promised chart of PIOMAS volume divided by UH area, a measure of average thickness.
Please note that due to the wide distribution of ice thicknesses, and by the definition of the measure, average thickness will often rise (or slow down its drop) in times of accelerated area loss, and will drop sharply during initial ice regrowth.
Click each chart to enlarge and zoom.

Notes: Thanks to Wipneus for both sets of data. Some missing UH values were interpolated manually.

Hmm, I thought the PIOMAS raw output was a thickness map, and this had to be masked with an area map to produce a volume figure. And this mask is normally NSIDC area, so I wanted to see what the volume would be if the thickness was masked with the AMSR2 area instead, that's what I meant in the other thread.
In your charts however, it goes the other way: The PIOMAS volume from Wipneus is used as is, and divided by the AMSR2 area, to give a different thickness than PIOMAS originally produced. But this means that the PIOMAS volume input for your equation is already masked with the NSIDC area, no? Or am I misunderstanding something?

14
Has anyone combined the PIMOAS thickness data with AMSR2 area to create a better volume measurement then?

15
Arctic sea ice / Re: HYCOM
« on: July 19, 2020, 10:43:53 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.



PIOMAS does not try to accurately model the ice edges, only the average thickness of an area *if* there is ice there. To calculate the volume it uses external data for area and thus it doesn't count ice in locations that the area data says there is no ice in, even if PIOMAS has modeled a thickness above 0 there.

16
Consequences / Re: Global Surface Air Temperatures
« on: July 19, 2020, 08:02:58 PM »
NASA GISS For June 2020

June: 0.92C above 1951-1980 average (1.18C above preindustrial; 1.38C above 1750)

First 6 months 2020: 1.11C: degrees above 1951-1980 average (1.37 above preindustrial; 1.57C above 1750)

https://data.giss.nasa.gov/gistemp/maps/index_v4.html

As far as I can tell, this is tied with 2019 for hottest month for June ever recorded. Again.

17
Arctic sea ice / Re: The 2020 melting season
« on: July 19, 2020, 07:43:10 AM »
The animation below is from the laptev and near ESS.

The last 4 days.

We can see major melt out in PLACE...

Now that is pretty interesting. With the constant compacting winds one would expect such gaps to be quickly filled by the ice around it, rather than expand because they melt even faster than new ice can fill them.

18
The forum / Re: Forum Decorum
« on: July 18, 2020, 10:30:26 PM »
I must ask why in the world blumenkraft's comment accusing GSY of making a racial slur was left in the melting thread. It is 1) completely off-topic and derailing, and 2) an unfounded and outrageous attack on his character, at least it looks that way from the outside. It deserved to be deleted as much as any of GSY's posts as it was the root cause of the entire drama. Fellow moderators cannot be given special treatment.

19
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: July 18, 2020, 06:02:08 PM »
I don't think NSIDC area will ever reach zero unless they apply a mask in the Gulf of Ob and the Yenisey Gulf. The NSIDC algorithm thinks ice is present there year-round.

Of course it will if things continue as they are, just maybe not in your lifetime.

He means that it is literally impossible for the NSIDC area to reach zero because the model erroneously but consistently reports ice in areas where there is none, such as the gulf of Ob.

20
Arctic sea ice / Re: The 2020 melting season
« on: July 17, 2020, 03:37:08 PM »
The rate of area loss in the respective seas suggests that Hudson, Baffin, Laptev and Kara all will be empty of ice within 10 days.

21
Arctic sea ice / Re: The 2020 melting season
« on: July 16, 2020, 07:42:27 PM »
The evolution of some dark stains 86N in the CAB. Big gif.

22
Arctic sea ice / Re: The 2020 melting season
« on: July 15, 2020, 08:03:23 PM »
2.  The conclusion that the ice is currently compact is utter rubbish.

There is open water all over the ice pack and huge melt lakes and ponds.


Melt ponds, sure. But open water? I don't really see it. The resolution on sat pics is not great, but still..

23
The fast ice in the fjord is cracking and also draining fast. This is today vs yesterday.

24
Arctic sea ice / Re: MOSAiC news
« on: July 13, 2020, 08:44:23 AM »
Has anyone been able to spot the floe and Polarstern on sentinel sat images? There's a cloud free view on the 7th and it should be near this spot according to the coordinates on their blog. But I can't quite seem to see anything.

https://apps.sentinel-hub.com/eo-browser/?zoom=12&lat=81.39204&lng=4.42371&themeId=DEFAULT-THEME&datasetId=S2L1C&fromTime=2020-07-07T00%3A00%3A00.000Z&toTime=2020-07-07T23%3A59%3A59.999Z&visualizationUrl=https%3A%2F%2Fservices.sentinel-hub.com%2Fogc%2Fwms%2F42924c6c-257a-4d04-9b8e-36387513a99c&evalscript=cmV0dXJuIFtCOEEqMSxCMDMqMSxCMDIqMV0%3D

25
Arctic sea ice / Re: The 2020 melting season
« on: July 13, 2020, 08:19:21 AM »
July 8-12.

2019.

It is impressive how a protruding Laptev "bite" is not stretching towards the 80N line like most years, but instead the whole width of the Laptev sea reached 80N at the same time

26
Arctic sea ice / Re: Northern Sea Route thread
« on: July 12, 2020, 10:53:24 PM »
This kind of seeking "official" agains visible, physical and mathematical  facts is part of what
kept us to react to AGW in time, even though my teachers told me it will eventually happen about 60 years ago in school.

The route is navigable, it think we're talking about the development and behaviour of the arctic ice in the first place and not about some russion civil cervants feeling fit to announce something today or tomorrow because it's i.e. Sunday.

While I understand where you are coming from, a sea route opening is not a scientific event, it is shipping-related event. The route is open when the ships can start sailing it. And this does not equate there being no ice in the route, it equates the ships having confidence that there is no ice in the route. Because without this confidence, the ships will not attempt to sail the route, even if it would have worked if they gambled and tried anyway. And such confidence requires confirmation from a better source than just hobbyists peeking at low-resolution cloudy satellite images.

27
Arctic sea ice / Re: Northern Sea Route thread
« on: July 12, 2020, 09:56:38 PM »
I guess the numbers in that Russian ice chart indicate tenth of ice coverage (e.g. 9 = 9/10 = 90%)

Yes it is annotated in the full picture in the link I posted.

28
Arctic sea ice / Re: Northern Sea Route thread
« on: July 12, 2020, 09:39:10 PM »
As far as I understand the route is not officially open until the relevant authorities issues an ice chart that shows clear passage. This has not happened yet, it still shows blockage in the Kara. And I don't think regular ships will attempt the route without this sort of confirmation. Might happen next update though. http://www.nsra.ru/en/navigatsionnaya_i_gidrometinformatsiya/chart_ice_kara_sea.html

29
Arctic sea ice / Re: The 2020 melting season
« on: July 11, 2020, 10:52:01 PM »
Fun fact: If my calculations are correct then the current rotation of the central basins sea ice due to the anticyclone carries about 2E13 joules of kinetic energy. This must be eventually converted to heat for the rotation to stop, which is enough to melt 60 000 cubic meters of ice. This might sound significant at first but actually it is just the equivalent of around 10 nanometers of ice thickness across the arctic.

30
Arctic sea ice / Re: The 2020 melting season
« on: July 09, 2020, 09:45:37 PM »
This animation seems to show a lot of transport south through the Fram being driven by the GAA.  How does this compare with satellite era averages for the summer months?

Wipneus's regular updates in the PIOMAS model thread includes a graph of fram export volume with the seasonal average: https://forum.arctic-sea-ice.net/index.php/topic,119.msg271734.html#msg271734

31
Arctic sea ice / Re: The 2020 melting season
« on: July 09, 2020, 03:51:32 PM »
While extent continues to drop, area has actually stalled for the last 4 days. More draining melt ponds?

 where is that graph from ? what is it showing? 
.. and why does it bear no relation to Gerontocrat's updates or what appears to be happening ? b.c.

It is from https://cryospherecomputing.tk/ and it shows the NSIDC daily area. It has not fully shown up in gerontocrat's charts yet because he uses 5-day averages, but it will soon. Even today will be significantly lower loss than yesterday in his data.

32
Arctic sea ice / Re: The 2020 melting season
« on: July 09, 2020, 02:10:35 PM »
While extent continues to drop, area has actually stalled for the last 4 days. More draining melt ponds?


33
Arctic sea ice / Re: The 2020 melting season
« on: July 07, 2020, 09:52:48 PM »
We haven't seen a photo of the laptev from under the clouds for a while, I really want to see how it looks by now.

34
Arctic sea ice / Re: The 2020 melting season
« on: July 05, 2020, 08:04:54 AM »
Thank you Phoenix, but you miss my point.

I was looking for a peer reviewed study that addresses the current situation. Maybe there isn’t one. Grixm spoke with authority. I was hoping he had something. If A-Team or FOW were still around they could probably help.

Wikipedia is junk. Anyone can post anything to that.  And, the Beaufort Gyre is on the opposite side of the CAB from what I’m focused on anyway.

If anyone knows of scientific studies on Fram export under the current conditions we are seeing, please send me a link. 

In any event, we will all keep watching and waiting to see what happens.

The next few days look interesting!

I don't know about Fram export specifically, if it doesn't line up with the expected forces from the wind then there can be multiple explanations, like I mentioned in my post: Ocean currents, being forced in a different direction due to pressure from surrounding ice and land, etc.

The core message of my post was merely that the force from the wind on ice is at an angle to the right from the actual wind direction. A source for this, as well as possible conflicting forces in the Fram, can be seen here for example: https://nsidc.org/cryosphere/seaice/processes/dynamics.html

35
Arctic sea ice / Re: The 2020 melting season
« on: July 04, 2020, 10:21:54 PM »
To be completely fair, the stirring should happen in the other direction to promote dispersion,. mechanical breakup of floes and bottom melt... One of the positive aspects of this setup is that it keeps ice compact...
Anyway, the 12z EC is slightly worse in strength and persistence of the 2020 GAH (Great Arctic High)

In my inexperience, I am puzzled by what you write, gandul.  Would there not be dispersion as well as compaction with this clockwise rotation?  It looks like this 'stirring' should result in a lot of of Fram export, starting some possible Nares export, and ice also being spread out into all the open water in the now-warming Laptev Sea and into what is a rapidly melting Chukchi.  I understand that ice might tend to be jammed together along the Canadian side, but wouldn't it also be dispersed further in other areas, where it may well then rapidly melt?  I may be missing something and would be glad to learn.

Ice is generally pushed inwards under anticyclones (clockwise rotation). This is because the wind pushing on the ice actually makes the ice move at an angle further to the right than would be expected, because of the Coriolis effect. Here is a basic diagram on how the ice would move with this setup (probably a bit exaggerated). Of course this is approximate, and also doesn't account for ocean currents, collisions with other ice or land, etc.


36
Arctic sea ice / Re: The 2020 melting season
« on: July 04, 2020, 05:48:33 PM »
Daily area is now lowest for the date.

37
Arctic sea ice / Re: The 2020 melting season
« on: July 03, 2020, 10:41:31 PM »
Area anomaly. Useful map that for some reason isn't posted very often.
Thank you.  As a map fiend I really like this.  Maybe it would be used more if the baseline for comparison were not 1979 to 2015 and instead were a more recent set of years??  As it is, I think it shows how different this year is with much clarity.

It is a more recent set of years. 2000-2019 according to the text on the image itself. Or was that what you meant?

38
Arctic sea ice / Re: The 2020 melting season
« on: July 03, 2020, 05:39:22 PM »
Area anomaly. Useful map that for some reason isn't posted very often.

39
Arctic sea ice / Re: The 2020 melting season
« on: July 02, 2020, 06:12:43 PM »
Maybe someone can answer this for me. With 2020 just about going lowest on record today, how come the NSIDC extent line has 2020 8th lowest? According to the NSIDC, 2020 is above 2010, 11, 12, 14, 16, 17 and 19 and whilst for some years the gap is small, in other years its quite a large difference especially with 2010 whilst JAXA has it effectively level, NSIDC has 2010 way ahead.

I know the NSIDC uses a 5 day average and the resolution is lower but we have never been above 2012 on JAXA yet the NSIDC has 2020 above 2012 for a good while now. I don't think I have seen JAXA and NSIDC looking so different before and are usually on the same page.

Well, one reason could be that NSIDC is not as good as JAXA to measure along the coast and gulfs. This is especially relevant now because many river outlets in Russia melted out record early, but the NSIDC extent does not pick up on this. You can see below one such example circled in red. This area is actually completely devoid of ice. But in some other years, like 2017, 2014, 2019, and 2011 out of the years you mentioned, there were still ice here. Yet NSIDC would report the same extent as now, unlike JAXA.

41
Arctic sea ice / Re: The 2020 melting season
« on: July 02, 2020, 02:56:42 PM »
Big daily drop in area today. Won't immediately show up on gerontocrat's 5-day average charts, but if this keeps up the area will be record daily low very soon.

42
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 21, 2020, 07:53:17 AM »
I just noticed that on Wipneus's PIOMAS maps, the map template and data seems to be drawn using a radial coordinate system since every line is slightly curved instead of straight. However, the origo does not seem to be on the geographic pole. Instead it seems to be somewhere in northern greenland. Why is this?

43
Arctic sea ice / Re: The 2020 melting season
« on: June 19, 2020, 10:22:13 AM »
June 14-18.


Looks like some serious melting in the northern Laptev. It looks like all the three pockets of open water could be connected into a single one pretty soon.

44
Arctic sea ice / Re: The 2020 melting season
« on: June 18, 2020, 09:53:26 PM »
RIP the big floe east of Greenland.

45
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 18, 2020, 02:09:00 PM »
Grixm, this looks like Natural color rendering to me. Try a custom one like

return [B8A*1,B03*1,B02*1]

Click 'custom rendering', then the '</>' button, and paste the monospaced code above. Then the 'Refresh' button.

Thanks, that gives much better contrast

46
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 18, 2020, 01:04:49 PM »
'Effects' do your search - visualisation -then 4 icons appear on the right of the dataset line zoom-pin-hide-effects.

I'm saying that I have been using these effects but they do not work anymore. The two images I posted have the same effect settings.

47
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 18, 2020, 10:06:54 AM »
Anyone know what happened with the "gain" setting on Sentinel Hub / EO browser? It used to be useful to increase contrast in ice that would otherwise just look completely white. But now it only reduces the brightness without increasing contrast/clarity at all. Is there a site with proper gain control for sentinel images?

Examples below. A picture from a month ago from another thread, and then how that same date with approximately the same gain settings looks low.


48
Arctic sea ice / Re: The 2020 melting season
« on: June 18, 2020, 09:34:45 AM »
Not to mention that wind drastically increases the thermal conductivity between the ice and air. Just like how a fan cools you down, but with the heat traveling in the opposite direction as long as the air is warmer than the ice. And it is: Even in the middle of the storm most of the surface air is forecast to be above 0C. The wind also makes the ice move faster through the sea, which has the same effect of increasing the thermal conductivity between the water and ice.

So storms melt the ice, even if they block out the sun. But does it melt it faster or slower than a sunny day without wind? I don't know.

49
Arctic sea ice / Re: The 2020 melting season
« on: June 16, 2020, 09:19:40 AM »
More fast ice breakup today. In the Laptev sea near the Lena river delta, and in the western ESS.

50
Consequences / Re: COVID-19
« on: June 13, 2020, 09:32:10 AM »
Exponential growth is definitely back. Third day in a row now with all-time high daily new confirmed infections.

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