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Messages - uniquorn

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1
Arctic sea ice / Re: The 2020/2021 freezing season
« on: Today at 11:29:34 AM »
iabp buoy204760-764 update, surface temperatures, oct11-28

3
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 27, 2020, 12:13:23 PM »
Big waves are again forecasted for the siberian side. Strong winds are usual at this time of the year, but the fetch should be zero or almost zero. Here, winds are blowing over open water. As a consequences, waves of 4 - 6 meters with a period of 8 - 10 seconds for Chukchi and Kara sea... A good washing again.
Hard for ice to form in seas with 4 meter waves. How deep does the mixing of water occur in such seas?

An essay from Peter Wadhams 2003  How Does Arctic Sea Ice Form and Decay?
Quote
How ice forms in rough water
If the initial ice formation occurs in rough water, for instance at the extreme ice edge in rough seas such as the Greenland or Bering Seas, then the high energy and turbulence in the wave field maintains the new ice as a dense suspension of frazil, rather than forming nilas. This suspension undergoes cyclic compression because of the particle orbits in the wave field, and during the compression phase the crystals can freeze together to form small coherent cakes of slush which grow larger by accretion from the frazil ice and more solid through continued freezing between the crystals. This becomes known as pancake ice because collisions between the cakes pump frazil ice suspension onto the edges of the cakes, then the water drains away to leave a raised rim of ice which gives each cake the appearance of a pancake. At the ice edge the pancakes are only a few cm in diameter, but they gradually grow in diameter and thickness with increasing distance from the ice edge, until they may reach 3-5 m diameter and 50-70 cm thickness. The surrounding frazil continues to grow and supply material to the growing pancakes.

At greater distances inside the ice edge, where the wave field is calmed, the pancakes may begin to freeze together in groups and eventually coalesce to form first large floes, then finally a continuous sheet of first-year ice known as consolidated pancake ice. Such ice has a different bottom morphology from normal sea ice. The pancakes at the time of consolidation are jumbled together and rafted over one another, and freeze together in this way with the frazil acting as "glue". The result is a very rough, jagged bottom, with rafted cakes doubling or tripling the normal ice thickness, and with the edges of pancakes protruding upwards to give a surface topography resembling a "stony field".

This open access article from Nature covers winter storms in much greater detail, describing both positive and negative effects on ice growth.

Winter storms accelerate the demise of sea ice in the Atlantic sector of the Arctic Ocean
Robert M. Graham, Polona Itkin, […]Mats A. Granskog    25 June 2019
Quote
Abstract
A large retreat of sea-ice in the ‘stormy’ Atlantic Sector of the Arctic Ocean has become evident through a series of record minima for the winter maximum sea-ice extent since 2015. Results from the Norwegian young sea ICE (N-ICE2015) expedition, a five-month-long (Jan-Jun) drifting ice station in first and second year pack-ice north of Svalbard, showcase how sea-ice in this region is frequently affected by passing winter storms. Here we synthesise the interdisciplinary N-ICE2015 dataset, including independent observations of the atmosphere, snow, sea-ice, ocean, and ecosystem. We build upon recent results and illustrate the different mechanisms through which winter storms impact the coupled Arctic sea-ice system. These short-lived and episodic synoptic-scale events transport pulses of heat and moisture into the Arctic, which temporarily reduce radiative cooling and henceforth ice growth. Cumulative snowfall from each sequential storm deepens the snow pack and insulates the sea-ice, further inhibiting ice growth throughout the remaining winter season. Strong winds fracture the ice cover, enhance ocean-ice-atmosphere heat fluxes, and make the ice more susceptible to lateral melt. In conclusion, the legacy of Arctic winter storms for sea-ice and the ice-associated ecosystem in the Atlantic Sector lasts far beyond their short lifespan.

<>

Winter storms enhance ocean mixing, heat fluxes, and ice melt
Sea ice dampens energy transfers between the atmosphere and ocean, and therefore the Arctic Ocean is traditionally considered to be energetically ‘quiet’ with weak turbulent mixing58. However, strong winds during the N-ICE2015 winter storms enhanced ice drift speeds54 (Figs 3a and 5a), which increased ocean-ice velocity shear59. These processes were found to generate mixing in the upper ocean, and led to increased transfer of ocean heat towards the ice59,60 (Fig. 5c–e). Observed winter ocean-ice heat fluxes typically more than tripled from 2 W m−2 to 7 W m−2 during storm periods (Fig. 5c, Methods), further impeding ice growth and in several cases initiating bottom melt59,60 (Fig. 3b).

Ocean mixing is particularly important in many regions of the Arctic Ocean because warm water of Atlantic origin is located below cold and fresh Polar Surface Water61. Along the continental slope north of Svalbard, warm Atlantic Water (>2 °C) is found close to the surface (Figs 1, 5e). Vertical mixing thus generates enhanced ocean heat fluxes. The magnitude of this heat flux is dependent on the mixing rate, as well as the depth and temperature of the warm water. During the N-ICE2015 winter drift over the deep Nansen Basin, Modified Atlantic Water (>0 °C) was found at approximately 100 m depth62. Under calm conditions in the deep Nansen Basin, Meyer et al.60 observed ocean heat fluxes at the pycnocline of approximately 3 W m−2 (Fig. S1). However, during storm periods, wind-driven mixing almost doubled the pycnocline heat fluxes to 5.5 W m−2 (Methods, Fig. S4a). These enhanced ocean heat fluxes are relatively small in comparison to changes in the atmospheric surface energy budget during storms37 and were insufficient to induce ice bottom melt, but nevertheless acted to further suppress ice growth (Figs 2e and 5c). Previous work using autonomous buoy measurements have inferred enhanced ice-ocean heat fluxes during winter storms in the Beaufort Sea25. It is therefore expected that these conditions in the Nansen Basin are representative of large areas of the central Arctic Ocean.

Accepted that the water has to be cold enough to form frazil ice.

Thanks for the post above A-team. I'll check out the error anomaly. That area seems already identified as possible out of range results.

4
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 25, 2020, 03:28:53 PM »
Thanks SimonF92. Animation scope widened to include the 2 newer buoys 204763 and 204764
Looking forward to your animations

5
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 25, 2020, 02:50:27 PM »
IABP buoy drift and surface temperature update.(11MB)

closer look at iabp204761 and 204762 in the Laptev (3.5MB)
click

6
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 25, 2020, 12:46:16 PM »
IABP buoy drift and surface temperature update. A steady drift along the line from Chukchi to Fram since oct6 until recently. My buoy list needs updating since it doesn't appear to include 204672 above. (12MB is a bit large) edit: updating this updated below

Unrelated but also interesting is the amount of heat escaping from the Nth Greenland Coast. https://go.nasa.gov/2HxW0GH

amsr2 awi v103, oct14-24
click for animations.

polarview S1B

7
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 24, 2020, 03:10:02 PM »
A closer look at refreeze not keeping up with dispersion in the Beaufort yesterday, amsr2 awi v103 oct12-23. Winds were not strong, just a little warmer.

Also moving the conversation about whoi itp121 from the melting season to this thread. Latest temperature/salinity profiles and drift path.
Temperature at 50m still high at over 2C.

itp121 shares a floe with ice mass balance buoy www.cryosphereinnovation.com/441910 currently maintaining thickness at ~2m.

8
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: October 23, 2020, 04:18:24 PM »
amsr2, awi dev v103 overlaid onto mercator 0m ocean temperature and salinity, sep4-oct22  (8MB)
Combined these two ani's from the freezing season thread to make it easier to compare daily changes.

9
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 23, 2020, 03:40:46 PM »
Mercator's take on SST's.
amsr2, awi dev v103 overlaid onto mercator 0m ocean temperature, sep4-oct22  (7MB)
Ok, from your animation is it correct to say all the regions susceptible to warming from Atlantic Waters are already covered by ice or about to be covered? (exception Barents and Kara but we know those two seas are already lost to climate change)
It seems to me the anomalously warm Laptev and ESS areas are basically over the shallow shelf, which will have a record heat release (consistent with the record heat income from GAAC and the season in general). So no Atlantic warmth here to speak about.

The Laptev sea extent beyond the shelf (and so the heat anomaly, by the way). Intrusion of Atlantic waters are discernible on the salinity maps of the mercator. (P.S. : And acknoledging that the heat and salinity extent beyond the Laptev into the central bassin, even under the sea ice).
Yes, SST is more useful if we also show SSS
amsr2, awi dev v103 overlaid at 75% transparent onto mercator 0m ocean salinity, sep4-oct22  (7MB)
mercator label is just visible.
edit: It has often been proposed that the Atlantic waters would meet the Pacific incoming at some point. The delay in refreeze and perhaps some mixing from recent strong winds would seem to make that prospect more likely (according to the model). The Siberian shelf and the Chukchi plateau help to prevent it. (Shown on the 92m salinity map upthread)

10
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 23, 2020, 02:35:23 PM »
Mercator's take on SST's.
amsr2, awi dev v103 overlaid onto mercator 0m ocean temperature, sep4-oct22  (7MB)

11
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 21, 2020, 11:57:41 AM »
NSIDC ease-grid ice sea age update. The nearest clear day I found on Worldview for comparison in the Beaufort was oct8. https://go.nasa.gov/2IITyxk
click for animation.
edit: 2000-2020 animation here

12
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 20, 2020, 02:20:05 PM »
https://go.nasa.gov/3m5uQpn  oct15-20 with AWI AMSR2 v103 inset. The north greenland gap still recovering from the summer, sea ice still lifting off Ellesmere Island. Some Nares export.

13
Arctic sea ice / Re: The 2020 melting season
« on: October 20, 2020, 12:50:10 AM »
itp121 has hardly moved. Temperature at 50m remains relatively high. Both temperature and salinity suggesting turbulence. Day 264-293.

14
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 19, 2020, 11:55:12 PM »
For what is worth (not much, admittedly), but the surface analysis of GFS (the GDAS) did not show a significant drop for SST during the week-end. <>
Raw surface temperatures and drift from iabp buoys over the last 5 days. Drift speed is the coloured path with scale at top left, temperature as text label. (Buoys in ice should be reporting ice surface temperatures. NA means they do not report surface temperature, some may be faulty.)
Click twice for full res. Large file.

15
Arctic sea ice / Re: The caa-greenland mega crack
« on: October 18, 2020, 12:35:06 AM »
CAA north coastal ice still restless. click for movement and full res.
https://go.nasa.gov/3lW02qZ

16
Arctic sea ice / Re: What the Buoys are telling
« on: October 16, 2020, 09:07:22 PM »
something like splitting seasons at day265. Working on that

17
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: October 15, 2020, 11:06:53 PM »
CAB extent update

18
Arctic sea ice / Re: What the Buoys are telling
« on: October 15, 2020, 10:48:20 PM »
A closer look at the Atlantic side temperatures at 80m depth. Max temp has been capped at -0.8C to show detail along the transpolar drift line. This means that some data is not shown fully at the Yermak plateau. I plan to look at that in more detail later.

19
Arctic sea ice / Re: The 2020 melting season
« on: October 14, 2020, 11:01:49 PM »
Beaufort 50m temperatures from whoi itp buoys, 2006-2020
edit: adjusted buoy sizes so newer year overlay is easier to identify
edit2: mp4 is smaller

20
Arctic sea ice / Re: What the Buoys are telling
« on: October 14, 2020, 10:12:41 PM »
overview of 50m temperature from whoi itp buoys, 2006-2020.

21
Arctic sea ice / Re: MOSAiC news
« on: October 14, 2020, 01:28:33 PM »
T78 and T81 update.
T81 taking a long time to cool(thicken). There are some deployment notes for T78 but nothing for T81.

22
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 13, 2020, 11:31:10 PM »
It's time to go to night vision using worldview terra modis viirs brightness temperature band 15 (night or day) https://go.nasa.gov/2FpoLVd
Today's image showing the effect of wind driven drift on the Atlantic front (awi amsr2 v103 from yesterday inset)

Quote
The VIIRS Brightness Temperature, Band I5 Night layer is the brightness temperature, measured in Kelvin (K), calculated from the top-of-the-atmosphere radiances. It does not provide an accurate temperature of either clouds nor the land surface, but it does show relative temperature differences which can be used to distinguish features both in clouds and over clear land. It can be used to distinguish land, sea ice, and open water over the polar regions during winter (in cloudless areas).

The VIIRS Brightness Temperature layer is calculated from VIIRS Calibrated Radiances (VNP02) and is available from the joint NASA/NOAA Suomi National Polar orbiting Partnership (Suomi NPP) satellite. The sensor resolution is 375m, the imagery resolution is 250m, and the temporal resolution is daily.

Only one Polarview S1B of the area today.

It's also worth looking at relatively cloud free sea ice north of the CAA today. High winds are forecast for this area too over the next couple of days.      https://go.nasa.gov/3dAMzSN

23
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: October 11, 2020, 08:23:00 PM »
No data for 2012 but 2020 is about to test the boundary set by 2018 for slow refreeze in the CAB.

24
Arctic sea ice / Re: The 2020 melting season
« on: October 08, 2020, 12:34:38 PM »
Nice, the DOS or (power)shell solution is quick if you don't need to bind the lat/lon to the list. It's interesting that 2020 salinity, which may be a signature of pacific water, is a closest match with 2012. It could just be coincidence.

Rough location overlay

25
Arctic sea ice / Re: MOSAiC news
« on: October 07, 2020, 11:32:37 PM »
from https://twitter.com/seaice_de



Quote
Lead openings and deformation caused by the wind shear are rather abrupt events than continuous processes.

26
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: October 07, 2020, 12:12:59 PM »
A quick look in more detail at refreeze in the Beaufort/southern CAB. The v103 presentation shows some nice detail suggesting a weather front passing over the area.
v103, sep30-oct6

comparison of UHH and v103, oct4 (click for correct resolution)

polarview S1A of the same area, oct6 (click twice for full res)

27
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 07, 2020, 12:48:31 AM »
There is still a massive amount of oceanic heat
Agreed.
amsr2, awi dev v103 overlaid onto mercator 0m ocean temperature, sep4-oct5

28
Developers Corner / Re: Test space
« on: October 05, 2020, 09:49:40 PM »
buoys, april-oct. Ignore the deployment straight lines.

29
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: October 01, 2020, 01:59:18 PM »
daily ImageJ pixel count on v103, sep4-30. Might be interesting to run it on Beaufort tail only

30
Arctic sea ice / Re: The 2020 melting season
« on: September 29, 2020, 12:15:08 PM »
It's a fair question but for me also it is too early to come to a conclusion. Too much movement and not enough data. Next analysis will be yearly paths with 50m temperature to see what that shows. It's likely to be warm pacific incoming from the Chukchi plateau as there is no rough topography at ~78N-140. Maybe the buoys will show us how 'wide' the warmer area is. Mercator at 34m and 92m depth misses the peak. Maybe Aslan can help with that.

OTG has plenty of suggestions ;)

edit: latest data from itp121 is a bit cooler at 50m

%ITP 121, profile 18: year day longitude(E+) latitude(N+) ndepths
2020  273.25141  -138.1066  77.2762  375
2020  273.25303   44   -0.0354   30.0949
2020  273.25311   46    0.3879   30.2224
2020  273.25319   48    0.4206   30.3668
2020  273.25328   50    0.4183   30.5225
2020  273.25336   52    0.2941   30.6820
2020  273.25345   54    0.5035   30.8875
2020  273.25353   56    0.5986   31.0057
2020  273.25361   58    0.5534   31.1116
2020  273.25369   60    0.6788   31.2080
2020  273.25377   62    0.7504   31.2909
2020  273.25385   64    0.9152   31.3495
2020  273.25394   66    0.8092   31.3845
2020  273.25403   68    0.6351   31.4414
2020  273.25411   70    0.3613   31.5064
2020  273.25419   72    0.2022   31.5450
2020  273.25427   74    0.0279   31.5973
2020  273.25435   76   -0.0417   31.6361

31
Arctic sea ice / Re: The 2020 melting season
« on: September 28, 2020, 09:44:17 PM »
2020, 2018, 2015, 2012, and 2009. Roughly the same days, similar location.

32
Arctic sea ice / Re: The 2020 melting season
« on: September 28, 2020, 12:08:30 PM »
whoi itp33 was deployed in 2009 in a similar location to itp121 but 15 days later. The animation compares the first 16 profiles.
In that location the salinity gradient was steeper in 2009, temperature was clearly much, much lower.
Depending on itp121's future drift path, this could be a combination to follow further.

33
Arctic sea ice / Re: MOSAiC news
« on: September 24, 2020, 12:51:30 PM »
@interstitial - Many of the new buoys have thickness and some additional information like 'placed on ridge' listed under buoy info here

34
Arctic sea ice / Re: MOSAiC news
« on: September 23, 2020, 11:51:29 PM »
I think you mean just north of 86 north old boy?
aye aye capn, merci
Should have mentioned wind at 75km/hr
86.1N   88.0 20-09-23 00:00   21(m/s)

35
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 23, 2020, 02:38:54 PM »
v103  daily pixel count shows the return of the possible harmonic at 50% concentration. 0% tending to agree with the jaxa minimum extent.

I wonder if seaice.de might comment on amsr2 representation of the Beaufort Sea recently. Was it perhaps freezing rain showing up more noticably over open water? Air temps of ~-2C on sep17 according to nullschool gfs

Worldview terra modis with amsr2-uhh inset, sep17
Beaufort, v103, sep4-22

36
Arctic sea ice / Re: MOSAiC news
« on: September 23, 2020, 11:28:22 AM »
No interest in snow then ;)

PS just north of 80N 86N on Polarview S1B at 03:19 this morning, track history from sailwx
weather at the moment
24 -- freezing rain
-0.2C
ice:
5 -- Very close pack ice 7/8 to < 8/8 concentration
5 -- All thin first-year ice (30-70 cm thick)
yesterday's fomo pic.

37
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: September 22, 2020, 02:23:37 PM »
Overview of available iabp buoys north of Greenland and a closer animation of 300234065497190, 300234068810610 and 300234068027940.
csv data attached as text.

https://betterexplained.com/articles/an-interactive-guide-to-the-fourier-transform/

38
Arctic sea ice / Re: The 2020 melting season
« on: September 22, 2020, 02:12:06 PM »
Quote
Arctic sea ice decline stalls out at second lowest minimum

Strange title.

39
Arctic sea ice / Re: MOSAiC news
« on: September 22, 2020, 10:45:22 AM »
Any volunteers to keep an eye on a new snow buoy, 2020S98, close the the pole?

Also 2020S106, 2020S107 and Also 2020S108
The ever improving meereisportal makes it visually simple.

For latest lat/lon it is still necessary to look at the data tables.
meereisportal here

or the iabp daily table here
though you need to know the buoyID
for example
  300234066087160   NA   2020   Snow_Buoy   AWI
   MOSAiC   09/21/2020   89.16   109.45

40
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: September 21, 2020, 08:46:01 PM »
Thanks to u300673 for this great article from 2012
Sea ice inertial oscillations in the Arctic Basin
F. Gimbert, D. Marsan, J. Weiss, N. C. Jourdain, and B. Barnier
https://tc.copernicus.org/articles/6/1187/2012/tc-6-1187-2012.pdf
Quote
As observed from buoy drift data, the sea ice  mean  speed  over  the  Arctic  increased  at  a  rate  of  9% per decade from 1979 to 2007, whereas the mean deformation rate increased by more than 50 % per decade over the same period (Rampal et al.,2009). These two aspects of recent sea ice evolution, i.e. strong decline in terms of ice extent and thickness, and accelerated kinematics, are strongly coupled within the albedo feedback loop. Increasing deformation means increasing fracturing, hence more lead opening and a decreasing albedo (Zhang et al.,2000). As a result, ocean warming, in turn, favours sea ice thinning in summer  and  delays  refreezing  in  early  winter,  i.e.  strengthens sea ice decline. This thinning should decrease the mechanical strength, therefore allowing even more fracturing, hence larger speed and deformation. A consequence is the acceleration of the export of sea ice through Fram Strait, with a significant impact on sea ice mass balance (Rampal et al.,2009,2011; Haas et al.,2008), and ice age (Nghiem et al.,2007). Moreover, sea ice mechanical weakening decreases the likelihood of arch formation along Nares Strait, therefore allowing old, thick ice to be exported through this strait (Kwok et al.,2010).

41
Arctic sea ice / Re: MOSAiC news
« on: September 21, 2020, 08:17:44 PM »
<>has uniqorn been showing us animations of tidal oscillation or inertial oscillation? And does that mean that there is no (or at the very most negligible) tidal movement in the Arctic?
You may be right binntho. The drift paths from the F Gimbert paper look very similar to the buoy animations except for a larger possible component of inertial oscillation this year. The maths is above my pay grade also but I may work up to it in time. I think tides have a part to play in the arctic, more importantly at the shelf breaks. An increase in inertial oscillation due to thinning and fractured ice cover adds another (previously unknown to me) feedback loop that deserves more consideration from the forum.

Also shown is P163 drift speed. Calculating the time between 12 peaks in the centre gave an average of 23.29hrs/peak which is too short for a lunar cycle so I'm open to other explanations.
P163
09 06 2200 to 09 12 1330
279.5hours, 12peaks = 23.29hrs/peak

I may take a look at north Atlantic buoys on another thread though a comparison of some in the central arctic from previous years would be more interesting. Meanwhile here are some of the remaining Mosaic buoys in the Greenland Sea. awi amsr2 inset to show rough ice location. (graticule belongs to the animation)


42
Arctic sea ice / Re: MOSAiC news
« on: September 20, 2020, 09:11:14 PM »
drift update from P176.
2 submarine landslides a day seems unlikely. I think I'll stick with tides.
Absolutely (grrmble grrmble) and the gif is fantastic, almost like a Micky Mouse picture.<snippage>
No update from meereisportal buoys today.
Now, how to identify an inertial oscillation ice drift component, a tidal ice drift component and a wind driven ice drift component?
Note that the more northerly mickey mouse is flatter than the others.
For each buoy, You could use a plane x,y (coordinates in your plot for instance) instead of lat lon to avoid arctifacts for being so close to the pole, then FFT the x and y components, get amplitude and phase for different frequencies and isolate translation and different modes of oscillation (x and y in phase or 180) or rotation (x and y in +/- 90 deg phase) in the 2D plane.
The wind drift won’t have a frequency in resonance with Earth rotation frequency (day)
ok. You seem to know how to do it. Here is gif of latest movement with data as txt. x and y are lon.utm and lat.utm. Let me know if you need anything else.

43
Arctic sea ice / Re: MOSAiC news
« on: September 19, 2020, 03:35:13 PM »
drift update from P176.
2 submarine landslides a day seems unlikely. I think I'll stick with tides.

44
Arctic sea ice / Re: The 2020 melting season
« on: September 18, 2020, 01:09:19 AM »
I see it differently, I think both years were eventually quite similar, when using generalizations:
2012 was sunny and warm and then windy and very stormy. It had some extra fluffy ice in the ESS but eventually it melted that ice and was left with a compact pack (and an extent record).
2020 too was sunny and warm and then very windy and somewhat stormy. It had some extra fluffy ice in the Chukchi and Siberian facing sections of CAB,  but eventually most of it melted and it was left with a mostly compact pack - except in the CA and the Beaufort arm (and a 2nd place extent finish).
I agree, only to stress that 2012 was an outlier and 2020 is almost normal as the global warming goes on.
Also I don’t see a paradigm shift at all, just a continuation of a warmer planet due to CO2. The ice is basically the same, only a lot less.
I agree too and would add that, with less ice, the arctic ocean is beginning to show itself more. Last year the CAA crack and this year the Greenland gap.

45
Arctic sea ice / Re: The 2020 melting season
« on: September 17, 2020, 01:01:16 PM »
AMSR2: Some recent days of 2020 compared to 2012
Rough overlay of 2012 vs 2020 using awi amsr2 v103, aug20-sep15 (am/pm)

gimp grain extract, the years were slightly different sizes so there is a small scaling error

46
Arctic sea ice / Re: The 2020 melting season
« on: September 16, 2020, 11:12:06 PM »
Wipneus' regional extent chart for the CAB suggests there has been a physical limit for latest refreeze set by 2012. 2018 and 2019 tending to confirm that limit. 2020 is close to testing it.

47
Arctic sea ice / Re: MOSAiC news
« on: September 16, 2020, 10:05:08 PM »
A lot of good videos on https://twitter.com/seaice_de

Quote
The Polarstern is represented by the gray ball; it is moored with its starboard bow against the ice
Quote
Lars Kaleschke@seaice_de
12 Sep  Too much tension? Be careful with the anchor line. A very dangerous environment. @MOSAiCArctic  - April 28



48
Arctic sea ice / Re: MOSAiC news
« on: September 15, 2020, 09:32:47 PM »
That 25km2 of bow radar might overlay nicely onto buoy drift now that it is relatively static. A shame it's not hourly.
This is a wider view of the previous animation here with the tight cluster at the centre.

intermittent light snow


  Lat  Long  YY-MM-DD  UTC     Wind       T(C)  N  h  VV  wwWW  ICE  Pnn(hPa)
  89.1  108.3 20-09-15 20:00    4  230     -4.6  /  /  //  //// ///// 1005.2
  89.1  108.1 20-09-15 19:00    5  210     -4.9  /  /  //  //// ///// 1005.2
  89.1  107.9 20-09-15 18:00    5  200     -4.7  /  /  //  //// ///// 1004.9
  89.1  107.6 20-09-15 17:00    4  220     -4.7  /  /  //  //// ///// 1004.8
  89.1  107.3 20-09-15 16:00    4  230     -4.9  /  /  //  //// ///// 1004.8
  89.1  107.1 20-09-15 15:00    4  200     -4.9  8  2  98  7082 49/9/ 1004.7

49
Arctic sea ice / Re: MOSAiC news
« on: September 15, 2020, 07:54:21 PM »
drift speed increased during sep13-14. click for motion

50
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 14, 2020, 09:20:26 PM »
Last four years.
You have a reasonable point that the ice age product shows a possible increase in 4+ year ice.
A technical graphics question. What made you choose to insert a transition that ignores the other 51 weeks into that animation? It makes no sense (and increases the file size).

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