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Messages - slow wing

Pages: [1] 2 3 ... 15
1
Arctic sea ice / Re: The 2018/2019 freezing season
« on: November 07, 2018, 09:25:10 AM »
Wow! Great spot Uniquorn at #651!

And nice context Rox at #653!

That is indeed very interesting!

2
Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 09, 2018, 09:45:56 PM »
U. Hamburg has stopped updating their daily false colour ice concentration maps, so I have been unable to make and post the gifs showing changes through the week. Presuming the satellite coverage is not good enough to make them now, moving into the dark season.

Currently 59 mb of MSLP difference Across the Arctic Basin, with a 968 storm towards the Atlantic side and 1027 mb on the Pacific side. So it will be quite windy at the moment.

3
Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 06, 2018, 05:41:37 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-10-05...

4
Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 05, 2018, 05:32:43 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-10-04...

5
Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 04, 2018, 06:52:58 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-10-03...

6
Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 03, 2018, 06:53:43 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-10-02...

7
Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 02, 2018, 05:16:34 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-10-01...

8
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: October 01, 2018, 01:26:20 PM »
Looked for an extent-vs-time graph where the extent is the average over the preceding year and found it here (nice site!): https://sites.google.com/site/marclimategraphs/_/rsrc/1536226652563/collection/G12.jpg

Interesting & looks reasonably linear.

Just eye-balling, I don't see a lot of year-to-year auto-correlation so perhaps there is just the long term trend and the ice extent does, to a good approximation, forget what happened last year.

9
Arctic sea ice / Re: The 2018/2019 freezing season
« on: October 01, 2018, 05:16:18 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-30...

10
Arctic sea ice / Re: The 2018/2019 freezing season
« on: September 30, 2018, 05:27:24 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-29...

11
Arctic sea ice / Re: The 2018/2019 freezing season
« on: September 29, 2018, 05:23:23 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-28...

12
Arctic sea ice / Re: Arctic Image of the Day
« on: September 29, 2018, 12:31:43 AM »
So that's a genuine photo?  ;D

Not sure I would trust that bear with that gear!  :P

13
Arctic sea ice / Re: The 2018/2019 freezing season
« on: September 29, 2018, 12:19:45 AM »
  One can ask why the Pacific side has started to re-freeze even though temperatures are nowhere near as low as the -10 degrees C often stated here as the rule-of-thumb temperature when refreeze starts.

  A factor I haven't seen discussed here is the clear skies on the Pacific side - as seen in the Worldview screenshot in my previous post.

  Re-freeze is due, not to low temperatures, but to loss of heat.

  A clear sky facilitates loss of heat from the water as thermal radiation. That is why ice can form on a puddle on a cloudless night even when the ground temperature is above freezing.

  In my understanding, thermal radiation is likely to be a large, perhaps dominant, contribution to the re-freeze on the Pacific side. Are the contributing components to heat loss modelled in some of the predictive models for the Arctic? If so, what average percentage is thermal radiation direct to space?

14
Arctic sea ice / Re: The 2018/2019 freezing season
« on: September 28, 2018, 11:15:31 AM »
0z EURO says this thread is fake news and the melt season is far from over. DMI confirms imminent rapid Laptev retreat and very substantial front movement elsewhere as well.

Fake news!!!
<snip>

Agree it's at least possible.

Most of the extent gain appears to have come from some of the slush regions on the Pacific side - more specifically, north of the Bering & Chukchi seas - that is now registering as ice.

It hasn't even been that cold there - just -3 or -4 degrees C - nor that still. If the wind picks up there then much of that new ice could flash back to registering as sea and the extent could potentially drop again. Conceivably even to a new minimum!

Observe the candy floss (cotton candy) that is now registering as partly ice, e.g. around 180 degrees longitude, 77N latitude:

15
Arctic sea ice / Re: The 2018/2019 freezing season
« on: September 28, 2018, 05:19:40 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-27...

16
Arctic sea ice / Re: The 2018/2019 freezing season
« on: September 28, 2018, 01:09:25 AM »
Above-freezing winds at 68 km/h now crossing 80 degrees N latitude & driving waves into the edge of the ice pack.

17
Arctic sea ice / Re: The 2018/2019 freezing season
« on: September 27, 2018, 05:45:33 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-26...

18
Arctic sea ice / Re: The 2018/2019 freezing season
« on: September 26, 2018, 05:08:13 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-25...

19
Arctic sea ice / Re: The 2018/2019 freezing season
« on: September 25, 2018, 06:21:21 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-24...

20
Arctic sea ice / Re: The 2018/2019 freezing season
« on: September 24, 2018, 07:23:55 AM »
Oooh a storm is threatening
The Arctic ice pack today
If it don't get some shelter
Oooh it's gonna fade away

Called... minimum
Might get blown away (Blown away, blown away)
Called... minimum
It might get blown away.  :D

21
Arctic sea ice / Re: The 2018 melting season
« on: September 24, 2018, 05:09:25 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-23...

22
Arctic sea ice / Re: The 2018 melting season
« on: September 23, 2018, 05:23:43 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-22...

23
Arctic sea ice / Re: The 2018 melting season
« on: September 22, 2018, 05:40:18 AM »
Interesting to see, even after the equinox, this storm predicted to bring +1.3 degrees C all the way to the North Pole.

Presumably won't be melting much. With storms at this time of year I wonder mostly about the potential effects of waves and mixing of the fresh water layer from the recently melted ice with the more saline water underneath.

It's hard to speculate on the significance without seeing the physical data or even a plausible model. Could there be significant retardation of the refreeze? And even if so, could that have significant consequences for the ice pack at the end of the freeze season? Does retardation necessarily mean thinner ice? And saltier ice so less resistant in the melt season? Or, instead, is more heat radiated out into space before the ice cover arrives and might that lead to thicker ice eventually?

The system is just too complicated and unconstrained by data. As far as I can tell, it evades simple understanding on these questions.

24
Arctic sea ice / Re: The 2018 melting season
« on: September 22, 2018, 05:18:05 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-21...

25
Arctic sea ice / Re: The 2018 melting season
« on: September 21, 2018, 05:22:38 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-20...

26
Arctic sea ice / Re: The 2018 melting season
« on: September 20, 2018, 05:19:38 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-19...

27
Arctic sea ice / Re: The 2018 melting season
« on: September 19, 2018, 07:50:04 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-18...

28
Arctic sea ice / Re: The 2018 melting season
« on: September 18, 2018, 07:02:53 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-17...

29
Arctic sea ice / Re: The 2018 melting season
« on: September 17, 2018, 05:12:33 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-16...

30
Arctic sea ice / Re: The 2018 melting season
« on: September 16, 2018, 05:39:50 AM »
Oren, yes, I think it is just the ice winking in and out.

There's a large region of slush around the ESS that must be at the edge of being called ice.

Some musing on measurements & definitions...

Presumably the definitions for extent and area won't be of any fundamental physical significance. Instead, there's an algorithm processing the input data & it has a threshold for whether to include each area element. Whether e.g. a region of wet slush is counted depends on the instruments and on the algorithm in a way that is not physically simple. That's fine, presuming the answer obtained is somewhat reasonable, and the answer is consistently applied for each new day. It then gives a somewhat reasonable measure for how the extent and area are progressing.

In contrast, it should be possible to define volume in a more physical way. For example, it could be defined in proportion to the weight of water (typically ice and snow) that extends above the water level for liquid water. The total volume is then obtained by summing up the weight-per-unit-area over the defined Arctic region. That gives a simple physical understanding. The measured value would of course still be an experimentally extracted approximation to that simple physical definition.

  With this wonderful new satellite they are about to put up, which gives very accurate height measurements, a very simple physical definition would be a sum/integral of the heights above local sea level - then converting to a volume of ice using either a single constant for ice density or else using locally estimated densities after attempting to estimate the ice/snow/melt pond mix.
Again, that's a physically simple approach to measuring the ice volume/mass.


This is not my field though. Is that fair comment? Is that how e.g. the PIOMAS definition of volume is extracted in practice?

31
Arctic sea ice / Re: The 2018 melting season
« on: September 16, 2018, 05:11:50 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-15...

32
Arctic sea ice / Re: The 2018 melting season
« on: September 16, 2018, 05:10:47 AM »
Any theories as to why the floating patch of ice remains? Was the piling up creating thicker ice?
Yes.

33
Arctic sea ice / Re: The 2018 melting season
« on: September 16, 2018, 03:06:44 AM »
Worldview captured a clear view of the remaining sea ice off the Alaskan coast.

There's not much left of the persistent ice patch that originated from ice piling up against the coast during the freezing season.

34
Arctic sea ice / Re: The 2018 melting season
« on: September 15, 2018, 12:49:18 PM »
Oren, it's around zero degrees and windy in the ESS at the moment and that is predicted to continue over at least the next couple of days. So freeze-up looks unlikely just yet in the ESS.

35
Arctic sea ice / Re: The 2018 melting season
« on: September 15, 2018, 07:30:49 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-14...

36
Arctic sea ice / Re: The 2018 melting season
« on: September 14, 2018, 05:22:16 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-13...

37
Arctic sea ice / Re: The 2018 melting season
« on: September 13, 2018, 06:25:07 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-12...

38
Arctic sea ice / Re: The 2018 melting season
« on: September 12, 2018, 05:18:47 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-11...

39
Arctic sea ice / Re: The 2018 melting season
« on: September 11, 2018, 05:23:06 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-10...

40
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: September 10, 2018, 05:52:43 AM »
Wonderful! Thanks for posting, tvansant.

A couple of snippets...


Nathan Kurtz, NASA Goddard
"What I’m really excited to see are the month-to-month changes in sea ice thickness, because we didn’t have that with the first ICESat..."

"..right now there’s a lot of assumptions made about how snow accumulates on the ice over the year. With ICESat-2, we should be able to see things like the effect of a passing storm."


Thorsten Markus, NASA Goddard
"What I’m really most excited about is seeing these data come in at such a high resolution...
Over sea ice you’ll see all these gaps and ridges, and discover just how rough that remote ice is."

41
Arctic sea ice / Re: The 2018 melting season
« on: September 10, 2018, 05:44:23 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-09...

42
Arctic sea ice / Re: The 2018 melting season
« on: September 09, 2018, 07:47:12 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-08...

43
Arctic sea ice / Re: The 2018 melting season
« on: September 08, 2018, 06:09:42 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-07...

44
Arctic sea ice / Re: The 2018 melting season
« on: September 07, 2018, 05:18:46 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-06...

45
Arctic sea ice / Re: The 2018 melting season
« on: September 06, 2018, 07:07:08 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-05...

46
Arctic sea ice / Re: The 2018 melting season
« on: September 05, 2018, 05:15:25 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-04...

47
Arctic sea ice / Re: The 2018 melting season
« on: September 04, 2018, 06:49:54 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-09-03...

48
Arctic sea ice / Re: The 2018 melting season
« on: September 01, 2018, 05:26:00 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-08-31...

49
Arctic sea ice / Re: The 2018 melting season
« on: August 31, 2018, 07:15:31 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-08-30...

50
Arctic sea ice / Re: The 2018 melting season
« on: August 30, 2018, 05:19:35 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-08-29...

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