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uniquorn

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Re: MOSAiC news
« Reply #1200 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)


A-Team

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Re: MOSAiC news
« Reply #1201 on: September 21, 2020, 10:03:15 PM »
Quote
inertial oscillations
These papers go back to the 1960's if not earlier. I added some classics over at the wave forum.
https://forum.arctic-sea-ice.net/index.php/topic,2417.msg287387.html#msg287387

The Polarstern has left its second floe for Bremerhaven, escaping the encroaching pole hole of darkness but also missing a lot of the early freezing system, not completing a full cycle which would take staying until Oct 4th.

The ship's progress can be followed by pasting lat lon data from awiMet into the excel template containing the haversine distance formula, the elapsed time between reports (hrs are commonly skipped), and a velocity column as we do for buoys.

However since the accuracy provided is poor, it is easier for eyeball estimates just to count the hours between 0.1 drops in latitude which represent 11.1 km of progress to the ice edge. Over the last 24 hours, those are 3,2,6,3,3,2,5.2,1,1,1,2,1,1 so the speed has been running at 2-11 km/hr.

In other words, there has been some 2m ice but lately favorable leads and lower compression ice where the ship can make rapid progress. The PS is rated at 28.7 km/hr for calm open seas so 11 km/hr indicates very insubstantial ice for the last 80 km despite the very high latitudes.

They are dropping longitude as opportunity presents as this gives a shorter path to the unconsolidated ice north of the the edge, as well as representing the homebound direction. The ship should emerge from the WorldView and Sentinel-1B pole holes late tomorrow.

The AMSR2_AWI shows the averaged concentration (relative to the palette) for the last 16th days. The red line shows its envelope, areas outside have been entirely open water the entire time. (This is a gimp trick to determine minimum crop boundaries for long time series.)

There's no significance to this unless the ship gets stuck or stops for a few days to observe conditions near the ice edge.
 
Update: The ship is making much faster time now, with only one hour between 88.2 and 87.5. Will they share any of the transiting data on ice thickness and condition? (No.)

Update: The Polarstern has covered 206km  in the last 24 hours ending 20-09-22 21:00 for an incredible average speed -- through 'solid ice' of 8.6 km/hr perhaps aided by a 17m/s gale force tailwind that may be diminishing ice compression. Just paste the two lat lon in the first two columns and rows of any spreadsheet and the haversine formula in R1C3...

=ACOS(COS(RADIANS(90-A1)) *COS(RADIANS(90-A2)) +SIN(RADIANS(90-A1)) *SIN(RADIANS(90-A2)) *COS(RADIANS(B1-B2))) *6357.444

   Lat  Long  YY-MM-DD  UTC     Wind       T(C)  N  h  VV  wwWW  ICE  Pnn(hPa)
  87.5    99.6 20-09-22 04:00    6   90    -15.0  /  /  //  //// ///// 1013.3
  87.6  100.8 20-09-22 03:00    6  100    -13.9  1  9  98  4011 58/98 1013.1
  87.7  100.8 20-09-22 02:00    6  110    -13.5  /  /  //  //// ///// 1013.3
  87.7  100.6 20-09-22 01:00    6  110    -12.4  /  /  //  //// ///// 1013.1
  87.8  100.1 20-09-22 00:00    6  110    -11.4  /  /  //  //// ///// 1013.0
  87.9    99.7 20-09-21 23:00    5  120    -10.9  /  /  //  //// ///// 1013.0
  88.0  100.4 20-09-21 22:00    5  130    -10.8  /  /  //  //// ///// 1012.7
  88.1  100.8 20-09-21 21:00    4  130    -10.8  /  /  //  //// ///// 1012.6
  88.2  100.6 20-09-21 20:00    4  130    -10.8  /  /  //  //// ///// 1012.5
  88.2  102.3 20-09-21 19:00    3  110    -10.9  /  /  //  //// ///// 1012.6
  88.3  103.2 20-09-21 18:00    3  120    -11.0  /  /  //  //// ///// 1012.4
  88.3  103.9 20-09-21 17:00    3  150    -11.2  /  /  //  //// ///// 1012.5
  88.3  105.7 20-09-21 16:00    3  150    -10.9  /  /  //  //// ///// 1012.4
  88.4  105.9 20-09-21 15:00    3  140    -10.6  7  7  99  0222 58/98 1012.3
  88.4  105.0 20-09-21 14:00    3  160    -10.7  /  /  //  //// ///// 1012.1
  88.5  104.8 20-09-21 13:00    3  150    -10.6  /  /  //  //// ///// 1011.8
  88.5  105.1 20-09-21 12:00    2  150    -10.9  7  2  99  4022 58/98 1011.6
  88.5  105.5 20-09-21 11:00    1  170    -11.3  /  /  //  //// ///// 1011.4
  88.5  105.7 20-09-21 10:00    3  190    -11.3  /  /  //  //// ///// 1011.3
  88.5  106.2 20-09-21 09:00    3  180    -11.2  7  2  99  4022 58/98 1011.2
  88.5  106.5 20-09-21 08:00    2  160    -11.1  /  /  //  //// ///// 1011.1
  88.6  105.5 20-09-21 05:00    1  200    -11.0  /  /  //  //// ///// 1010.8
  88.6  106.4 20-09-21 04:00    2  180    -11.0  /  /  //  //// ///// 1010.6
  88.6  106.9 20-09-21 03:00    3  180    -11.9  7  9  98  4042 58/98 1010.3
  88.7  107.5 20-09-21 02:00    3  150    -11.6  /  /  //  //// ///// 1010.3
  88.7  108.0 20-09-21 01:00    2  140    -11.9  /  /  //  //// ///// 1010.3
  88.7  108.5 20-09-21 00:00    1  140    -12.7  /  /  //  //// ///// 1010.3
  88.8  108.8 20-09-20 23:00    2   80    -11.8  /  /  //  //// ///// 1010.2
  88.8  107.8 20-09-20 22:00    1   90    -11.7  /  /  //  //// ///// 1010.2
  88.9  107.1 20-09-20 21:00    1   80    -11.6  /  /  //  //// ///// 1010.0
  88.9  105.7 20-09-20 20:00    1  350    -11.3  /  /  //  //// ///// 1009.6
  88.9  106.5 20-09-20 19:00    1  310    -11.3  /  /  //  //// ///// 1009.2
  88.9  108.2 20-09-20 18:00    1  310    -11.5  /  /  //  //// ///// 1008.8
« Last Edit: September 23, 2020, 12:47:56 AM by A-Team »

Latent

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Re: MOSAiC news
« Reply #1202 on: September 21, 2020, 10:20:53 PM »
BBC seems to have some inside info.  I have looked back on this Forum but have found no mention of this in particular. 
You need to read further down the article to see the quotes from Julienne Stroeve on her Mosaic mission:
https://www.bbc.co.uk/news/science-environment-54211760

Sorry if I have attached this incorrectly, not a techie ;)

A-Team

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Re: MOSAiC news
« Reply #1203 on: September 22, 2020, 03:42:00 AM »
Quote
news in the BBC piece?
We've been considering two new articles from J Stroeve that appeared in The Cryosphere in the the last month. This sounds like a third Mosaic-specific version is coming soon. The news (?) is that Cryosat has a significant thickness bias that cannot properly account for a snow cover.

Was 4.5 months out in the cold and dark, cut off from internet productivity, a good use of Stroeve's and other principal scientists' time? I would say it was not.

So here we go with yet another satellite (Cristal) that promises to do it better, in part using new measurements from the Mosaic year. Here it sounds like it will measure reflectance of two simultaneous microwave frequencies in the Ku and Ka bands. That is WWII terminology for 12–18 GHz and 33.4-36.0 GHz.

While ice thickness and volume have always been the Achilles heel of Arctic remote sensing, it is necessary to get at it by satellite observation because models can't do it satisfactorily and  ships cannot always be out there. Indeed even supplemented with buoys, plane overflights and touch-and-go sampling, they cannot provide comprehensive sampling.

Indeed Cryosat takes a month of orbits to get one round of swath assembly. So I would guess design of Cristal is not just accurate freeboard but equally about getting a wider swath so fewer orbits are needed to build a picture (done in part by having two satellites). 

Freeboard does not give thickness except with the assumptions of ice density and buoyant equilibrium. How well does that work with under-ice melt ponds, porous ice, incomplete brine exclusion, undrained deep melt ponds, flooded negative freeboard floes, repeatedlymelted and refrozen snow and so on?

It is still years away from launch in 2027 so the question could be raised whether the Arctic ice of its time will be a good match to the design indicated by Polarstern research of ice of last winter.

'Thickness' alone may not really characterizes critical properties of the ice even today -- there were too many surprises this melting season. Will snow depth be the focus or will we be wishing we had a rain-on-snow satellite -- or just ordinary rain gauges on a giant fleet of buoys that could be deployed any time for far less expenditure?

https://forum.arctic-sea-ice.net/index.php/topic,2906.msg287133.html#msg287133

Trends and spatial variation in rain-on-snow events over Arctic Ocean during early melt season
https://tc.copernicus.org/preprints/tc-2020-214/

"CRISTAL -- Copernicus polar ice and snow topography -- will carry a multi-frequency radar altimeter and microwave radiometer to measure and monitor sea-ice thickness and overlying snow depth. It would also measure and monitor changes in the height of ice sheets and glaciers around the world thanks to its interferometric radar mode.

IRIS will significantly improve the measurement accuracy of its predecessor SIRAL-2 (a Ku band only altimeter on board ESA’s CryoSat-2 Earth Explorer mission) thanks to the dual frequency operation and by adding the measurement of sea surface height as part of the mission objectives.

The drifting polar orbit is 760km above the Earth. Its on-board memory will be able to store up to 4 terabits of science data during its 7.5 year lifetime."
« Last Edit: September 22, 2020, 03:52:08 PM by A-Team »

binntho

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Re: MOSAiC news
« Reply #1204 on: September 22, 2020, 07:24:10 AM »
I think tides have a part to play in the arctic, more importantly at the shelf breaks.
I agree. But perhaps it is a part that is not easily visible to us.

Quote
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.

But fits well with an inertial oscillation (IO) at slightly less than 2 per day this close to the pole. From my reading I gather that the IO goes from 2/day at 90N to 0 at the equator.

Quote
Meanwhile here are some of the remaining Mosaic buoys in the Greenland Sea.
Not really possible to discern any tidal oscillation, perhaps the scale is too large. We know that there is a larger tidal effect here than in the Arctic, although not all that large (you need to go south of the Greenland-Iceland-Scotland line to get into proper tidal movement). The maximum tidal movement in Longyearbyen is around 2m, in Reykjavik it is almost 5m. Out in the open ocean, the movement is signifcantly less, perhaps 0.5m in the Greenland sea, 1 - 1.5m just south of Iceland.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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uniquorn

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Re: MOSAiC news
« Reply #1205 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
« Last Edit: September 22, 2020, 11:18:46 AM by uniquorn »

uniquorn

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Re: MOSAiC news
« Reply #1206 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.
« Last Edit: September 23, 2020, 11:47:35 PM by uniquorn »

OffTheGrid

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Re: MOSAiC news
« Reply #1207 on: September 23, 2020, 11:40:55 PM »
I think you mean just north of 86 north old boy?
That slush pic in their wake was at 88.3 just after they left on the 20th btw.
I think the Cap'n thunk the kids needed a bit of a reality check by scaring them to think they were going to run head on into a Beaufort 9 storm front with wave and swell chaos in the shelf fragments and skyscraper sized  Bergs on the edge of the ice front.
Instead he has turned ninety degrees due West to run with it.
They've copped the force nine thunderstorm hot front on the butt. But so far have no idea what force 9 sea states near coasts look like. He may blood them with that experience in the next few days.
This auld Ships Cap'n do. Me bin coastal on sail in force twelve Gustin to 180kmph. And experienced the site of 100+ ft rolling breakers from one horizon to the other coming in from the southern ocean at 60 second period all day long. Wavelength some 3km and velocity over 200kmph in the deep where they spawned, the beasties!

uniquorn

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Re: MOSAiC news
« Reply #1208 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)
« Last Edit: September 24, 2020, 12:21:39 AM by uniquorn »

A-Team

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Re: MOSAiC news
« Reply #1209 on: September 24, 2020, 10:37:04 AM »
The Polarstern continues to hug the 86th parallel for the last 28 39 hours, holding at 86.0  59.5. This cannot be because of thick ice as they have come 214 km at an average speed of 7.6 km/hr at mild temperatures, mist/drizzle and moderating winds after the brush with the first Barents cyclone. Daylight is fading fast right at their location, 3rd image below.

Note this is just great circle haversine(first,last) distance and not on the ellipsoid; parallels are not great circles for either datum; adding up track segments would give a greater distance in fewer hours of actual movement and so considerably higher speed, implying little resistance from the ice despite its 100% concentration.

Presumably the ship is now moored or at least idling at a floe of interest after doing some unscheduled study of weather, water and ice at constant longitude. FOMO mentions sending up weather balloons at six hour intervals up to 35km on each of the 370 days of the trip but nothing specific to the 86º. FOMO today is a week back, showing the massive open lead out of all context.

GFS is showing precip bands associated with the cyclones; going by the temperatures, these are an undifferentiated mix of rain, freezing rain and snow; which matters quite a bit for the ice.

They could angle down later through the gap between FJL and Sv to reach Bremerhaven which seems likelier than going down the Fram to the bad weather of the North Atlantic but that means continuing west to the 45th meridian or so.
« Last Edit: September 24, 2020, 07:05:12 PM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #1210 on: September 24, 2020, 12:24:28 PM »
  Lat  Long  YY-MM-DD  UTC     Wind       T(C)  N  h  VV  wwWW  ICE  Pnn(hPa)
  86.0   59.5 20-09-24 09:00    8  130     -0.3  8  2  96  7872 57/9/  985.1
  86.0   59.5 20-09-24 08:00    8  120     -0.6  /  /  //  //// /////  985.5
  86.0   59.5 20-09-24 07:00    9  120     -0.4  /  /  //  //// /////  986.1
  86.0   59.5 20-09-24 06:00    9  120     -0.4  8  1  94  1052 57/9/  986.9
  86.0   59.5 20-09-24 05:00    9  110     -0.4  /  /  //  //// /////  987.8
  86.0   59.5 20-09-24 04:00   10  110     -0.4  /  /  //  //// /////  988.5
  86.0   61.4 20-09-24 02:00   10  110     -0.3  /  /  //  //// /////  990.1


edit: jp2 (some gamma alteration)
overview with rough PS location highlighted
« Last Edit: September 24, 2020, 12:42:19 PM by uniquorn »

uniquorn

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Re: MOSAiC news
« Reply #1211 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

interstitial

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Re: MOSAiC news
« Reply #1212 on: September 24, 2020, 02:01:25 PM »
@interstitial - Many of the new buoys have thickness and some additional information like 'placed on ridge' listed under buoy info here
That is great. Even if it ends up proving me wrong I like more information.

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Re: MOSAiC news
« Reply #1213 on: September 25, 2020, 12:17:12 PM »
The Polarstern is proceeding again along its 86º transect in newly graduated SYI after pausing for 16 hours. The ship is due north of western FJL so could cut over later today to the gap with Svalbard. Possibly they wish to intersect their previous drift location with the original floe before heading home.

Bow radar shows a surprising amount of open water consistent with the ice showing limited sub-100% concentration on AMSR2_AWI. The patches are small relative to the 3x3 km pixels but still seem to contribute. Smos-SMAP over OsiSaf shows ice less than 0.5m thick not recently moving much at the PS location.

Update: they've stopped again at 86.0 35.5 on 20-09-26, must be taking some samples along  this preferred parallel, interesting concept.

Update: they've stopped again to award themselves another award:

  Lat  Long  YY-MM-DD  UTC     Wind       T(C)
  86.0   48.4 20-09-25 13:00    4  140     -1.8

   Lat  Long  YY-MM-DD  UTC     Wind       T(C)  N  h  VV  wwWW  ICE  Pnn(hPa)
  86.0   48.7 20-09-25 08:00    7  140     -1.6  /  /  //  //// /////  988.1
  86.0   49.2 20-09-25 07:00    8  140     -1.7  /  /  //  //// /////  987.9
  86.0   49.7 20-09-25 06:00    9  150     -1.4  /  /  //  //// /////  987.9
  86.0   50.2 20-09-25 05:00    8  150     -1.3  /  /  //  //// /////  987.9
  86.0   50.5 20-09-25 04:00    9  160     -1.4  /  /  //  //// /////  987.8
  86.0   51.3 20-09-25 03:00   10  160     -1.5  8  3  98  0272 56/92  987.8
  86.0   52.6 20-09-25 02:00   10  170     -1.2  /  /  //  //// /////  987.9
  86.0   53.5 20-09-25 01:00   11  170     -1.2  /  /  //  //// /////  988.0
  85.9   54.7 20-09-25 00:00   10  160     -1.2  /  /  //  //// /////  987.8
  85.9   55.8 20-09-24 23:00   10  170     -1.1  /  /  //  //// /////  987.6
  86.0   57.1 20-09-24 22:00   10  170     -1.1  /  /  //  //// /////  987.6
  86.0   57.7 20-09-24 21:00   12  180     -1.1  /  /  //  //// /////  987.2
  86.0   59.0 20-09-24 20:00   12  190     -1.1  /  /  //  //// /////  986.8
  86.1   59.7 20-09-24 19:00   12  190     -1.0  /  /  //  //// /////  986.4
« Last Edit: September 26, 2020, 02:04:37 PM by A-Team »

A-Team

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Re: MOSAiC news
« Reply #1214 on: September 26, 2020, 10:01:08 PM »
Because the ice is so thin and mechanically weak, the Polarstern is able to make very good time. The ship needs to stick to its Bremerhaven arrival schedule of Oct 4th but is thus able to make additional stops at ice stations, which they are able to schedule along the 86th parallel.

None of the data will be shared, even routine observations like ice thickness along the long transects, because informing the current melt/freeze season in nrt has never been a priority. Indeed, disclosure is verboten. Some data types, like L25 in sea ice diatoms, aren't suitable for sharing as they need to be measured back at land labs.

In theory, the PS could continue along 86.0 until the Greenwich meridian which would involve another 2-3 days of travel including brief ice station stops from their current longitude of 31.5º. Winds are picking up though and possibly blowing them somewhat south. It's not clear the ship will exit through the Fram or have time for observations if they do.

Update 1: the ship has turned south under steam, attaining ~33 km in 4 hours along the 32nd meridian. They could reach Bremerhaven in 4-5 days if they don't stop at the ice edge for another station.

Update 2: the Polarstern has advanced 111 km south in the last 10 hours to 84.3  32.1 so will be crossing the ice edge into open water in a couple of hours. Bow radar is already showing large patches of open water as of midnight on the 26th. The weather is unfavorable for a final ice station given the 14m/s wind, cold, precip and low light conditions so this is effectively the end of the Mosaic expedition (except for working up the data into publications).

Update 3: they have stopped right at the ice edge for 5-6 hours, 20-09-28 at 01:00, 4th image.


The ice photo is apparently from Thursday, Sept 24th. The melt ponds are frozen over enough to stand on but do not have a coat of snow. Bootprints can be seen in 5cm snow that seems mushy. Bow radar caught ice motion at one of the ice stations.

It's worth pondering whether a future expedition could make complete loops at fixed latitude in August, say at 85-87º. This might require a dedicated contract icebreaker for the CAB portions with the Polarstern following close behind to spare fuel. What though would be the scientific rationale for doing constant latitudinal circuits?

The top-of-cloud insolation would be held constant though it would vary down on the ice, along with air temperature. The coriolis effect would also be constant in magnitude but then it varies very little at high latitudes (it goes as the sine of latidude; the sine function barely budges at large angles). Wind patterns and origins would vary greatly. On the whole, it does not seem holding one variable constant really helps isolate the others for study.
« Last Edit: September 28, 2020, 04:34:47 AM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #1215 on: September 28, 2020, 10:02:40 PM »
  Lat  Long  YY-MM-DD  UTC     Wind       T(C)  N  h  VV  wwWW  ICE  Pnn(hPa)
  82.9   22.6 20-09-28 18:00    6  300     -8.1  8  5  93  4842 52/91 1012.1

48 -- fog, depositing rime, sky visible

Wispy bow radar

PS in pancake ice

A-Team

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Re: MOSAiC news
« Reply #1216 on: September 29, 2020, 01:00:54 AM »
This is quite creative use of the last week before heading for port, in some ways more interesting than just studying a single possibly unrepresentative floe. The Polarstern can do CTD casts, ice thickness, and water temperature while on the move.

With periodic stops on the the 86º transect, the various teams can go out and take cores, water samples and weather parameters in the boundary layer and above. The new twist is going back and forth across the marginal ice zone (ice edge) to study conditions allowing new ice formation (which as usual takes place laterally along the periphery of the existing ice side.

The "position buoys" that coordinate with the Polar5/6 overflight campaign haven't been mentioned before. Normally, the teams out on the ice try to coordinate with the time of the overflight but that could not happen this year as access to the base airport in Svalbard only became available at the last moment (because of virus).

Update 1: 81.6  11.6 20-09-29 14:00  14m/s -2.9ºC. The ship has left the ice edge for good and is heading down the Fram to study the position buoy floes before heading to the destination fjord in Svalbard. FOMO is showing engine room pictures again. The wind up the Strait is strong but there is no ice above it to be imported.

Update 1: 81.7 1.6 20-09-30  09:00 12m/s -5.7ºC. The PS is in the middle of the Fram west of Svalbard doing another 24 hour constant-latitude transect to synergize with Polar 5/6 flights earlier this month. Winds are still blowing north at near gale force..

By AWIPEV, they mean the joint German-French portion of the large research station at Ny-Ålesund, Alfred Wegener and Institute Paul Emile Victor (a Greenland explorer). Some eleven countries do field and lab work there on the ocean, ice tundra, glaciers, troposphere, stratosphere, magnetosphere where there is a benefit (or necessity) to be so far north at 79º.  It's not clear what's involved with Mosaic to 'exchange material" with AWIPEV.

The links below describe some of the research going on. One study is looking how to protect GPS accuracy at high latitude from ionosphere disturbance.

https://www.awi.de/en/expedition/stations/awipev-arctic-research-base.html
https://www.awipev.eu/
https://en.wikipedia.org/wiki/AWIPEV_Arctic_Research_Station
https://www.ursi.org/proceedings/procGA20/papers/YSASummaryJin.pdf
https://www.andoyaspace.no/the-grand-challenge-initiative/
https://www.grandchallenge.no/project-cusp/
« Last Edit: September 30, 2020, 01:52:19 PM by A-Team »

A-Team

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Re: MOSAiC news
« Reply #1217 on: October 01, 2020, 12:25:22 PM »
Some interesting detail has emerged about the Polar5/6 flights out of Svalbard that could have been a major component of Mosaic had they been fully executable as initially planned.

The idea with these Arctic-adapted planes which can fly as low as 100m is to close the resolution gap between detailed but very costly ground exploration and large-scale remote sensing from satellites (whose view is often obscured by cloud tops).

The MACS camera mounted underneath Polar 6 is an amazing device that captures high resolution ice detail simultaneously in the visible, near infrared and thermal infrared. Some 300,000 images at a frame rate of four per second have been taken in the first flights, meaning serious AI is necessary for processing and interpretation.

The camera was developed and operated by DLR (Deutsches Zentrum für Luft- und Raumfahrt) which is similar to NASA and a separate organization from AWI/Helmholtz but participating in Mosaic.

DLR provides a single example on their web page for 84ºN 6ºE in September; there is no link to an archive. This would be truly massive given the number of scenes at the ground resolutions mentioned. No serious description of scene or camera specs is given. A DLR image on twitter has dimension 4096 x 2722 pixels.

https://www.dlr.de/content/en/articles/news/2020/03/20200915_studying-ice-at-the-centimetre-scale.html

The visible is said to measure roughness of the ice and snow; elsewhere this unit has been run as stereo triples which could map pressure ridges but here seems to rely on low angle sun shadows. The near-infrared images provide automatic discrimination of water from floe at 2 cm resolution; the thermal infrared images show temperature differences between ice and freezing fissures at 40 cm.

The conventional thermal palette does not seem optimal for interpretation as a glasbey palette more clearly shows geometric rim features of some of the melt ponds.

Meanwhile, Polar 5 is outfitted quite differently to do cloud and atmospheric research such as determine droplet size distribution, analyze ice crystal shapes, ice and liquid water content of mixed phase clouds and factors relevant to cloud formation. Again the route follows the Polarstern ice station route to synergize with field data. No sample data is available.
« Last Edit: October 01, 2020, 12:43:15 PM by A-Team »

A-Team

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Re: MOSAiC news
« Reply #1218 on: October 02, 2020, 11:17:42 PM »
The Polarstern seems to be moored in a Svalbard fjord for the exchange of material (ice cores?) with the AWIPEV lab in Ny-Ålesund. No purpose would be served by following the expedition back to Bremerhaven.

Nothing new emerged looking today for published expedition research at The Cryosphere preprints and Google Scholar (for 'Mosaic Arctic'). Articles will be dribbling in for 3-4 years, thus not terribly helpful for nrt understanding of 2019-20.

It is possible that some areas of the big central database will open earlier than 2023 or at least be discussed on Meereis forums or insider twitter accounts.

Three new blogs have appeared on the ticker site:
https://www.meereisportal.de/en/mosaic/sea-ice-ticker/

'Non-Sentinel-1AB high-resolution satellite SAR images had to be ordered two days in advance with precise lat lon information for floe 2.0. To provide that information, drift forecasts relied on the Sea Ice Drift Forecast Experiment SIDFEx  [[despite its total failure in predicting the very rapid TPD drift last spring that ruined the Mosaic program design] That did ok on a 7-day spaghetti forecast for 19 – 26 September zonally but missed the meridional as wind forecasts are only good 3-4 days out.]. For the 120-day forecast, we largely expect to see a southwest drift that generally follows the Transpolar Drift Stream [[duh]]".

https://swift.dkrz.de/v1/dkrz_0262ea1f00e34439850f3f1d71817205/SIDFEx_Graphical/SIDFEx_Polarstern_Graphical_floe2_latest.pdf

"On 21 August the MOSAiC Team set up a new Ice Camp for the fifth leg of the expedition at ca. 87° 43’ N and 104° 30’ E. On 20 September we then left (were forced to leave) the second floe. Here, too, a network of autonomous buoys, smaller than the first, was deployed on the main floe and in its vicinity, and was once again left behind. 

On the central floe, the Sea Ice Team deployed three sets of buoys, outfitted with complex systems for observing various parameters: in Met City there are snow and ice buoys, as well as a buoy for monitoring flows and turbulences, from the ocean to the atmosphere. A second station, set up on level ice, focuses on energy flows and optical properties, as well as the mass balance for snow and sea ice.

We also installed buoys in the pressure ridge near the ship’s bow, which are above all used to compare the distribution of snow there to the distribution on level ice. There are also three cameras among the buoys, which offer us a daily record of the conditions on site. [[no links provided to cam archive]]

Beyond the main floe, 28 buoys were installed on smaller individual floes: 20 in its immediate vicinity (up to 10 km away) and the remainder as far as 40 km away. One of the buoys was deployed at the North Pole itself, and another near the sea-ice edge."

Extent on 31 August was 4.19 million km² and had declined by ca. 1.85 million km² – an area roughly the size of about 5 times the size of Germany. In the second half of August and until mid of September, a strong ice retreat was observed in the Canadian Basin, which led so far to the lowest ice extent of 3.784 million km² on 09 September this summer.

Meteorological conditions in July and August included a distinct temperature anomaly over the Central Arctic producing fluctuations in air temperatures at 925 hPa (~760 m; note they make no use of DMI 80 or its 2m temperatures) of more than 6°C above the long-term average for the years 1981 to 2010 notably in July, when the high-pressure cell was directly over Siberia. A detailed assessment of this year's sea ice minimum is given here:

https://www.meereisportal.de/en/archive/2020-kurzmeldungen-gesamttexte/arctic-sea-ice-extent-on-an-extremely-low-course/

=-=-=-=-=-=

What becomes of all these thousands of weather balloons? They burst in the upper atmosphere after two hours of reporting and fall to earth with their instrument package, usually far from the launch site and unrecoverable.

Some latex ones are said biodegradable but that seems highly implausible at Arctic temperatures; many would just sink to the ocean bottom along with their ewaste. A staggering number are released each year by various countries, 22,630 in 2018 just from Canada. Birthday balloons are coated mylar (not biodegradable) and found everywhere in parks, deserts and wilderness of the US.

https://www.cbc.ca/news/politics/balloon-weather-environment-canada-radiosondes-ewaste-toxic-batteries-1.4897720
« Last Edit: October 02, 2020, 11:47:17 PM by A-Team »

oren

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Re: MOSAiC news
« Reply #1219 on: October 03, 2020, 10:32:26 AM »
Big thanks for all the Mosaic updates.

A-Team

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Re: MOSAiC news
« Reply #1220 on: October 03, 2020, 02:42:58 PM »
And thx to Uniquorn for getting this forum off the ground and contributing so much to buoy and other visualizations!

The wartime secrecy surrounding mundane data such as ship location, ice thickness, experimental layout, timestamps on photos, weather balloons etc etc was astonishing -- who was the enemy?

Not our melt and freeze forums. The enemy was the rest of the scientific community who might, most implausibly, steal data and publish first or worse, publish better. Wars always bring civilian casualties -- here the collateral damage was to public understanding of climate change.

They missed a great opportunity at the north pole, dropping memorializing trash and passing out souvenir water instead of doing scientific work, then rushing on for a short stay at a meaningless secondary floe. This year's ice mobility and melt ponds were especially auspicious for reaching the public, that didn't happen.

The public paid for the entirety of this expedition (includes $25 million from US public). If these scientists wish to do private science, let them pay for it out of their own pocket. In terms of ducking responsibility for public understanding of climate change (stale papers published in 2023 have zero impact), silence from scientists simply does not work.

Mosaic floated the preposterous notion that policy makers will read these 2023 papers and make the needed inferences about climate change abatement. Mosaic is an extreme version of controversy avoidance and seeking the least drama -- the scientists involved are fully aware it's already too late for the Arctic.

AWI is not an educational institution; even though everyone on staff lists themselves as professor, there are no students. Outreach was self-promotional and mis-directed, not overseen by anyone with a scientific background and often wrong.

Anything that went amiss -- and inevitably a lot did given the unexpected drift and floe shifts -- was strictly sanitized to present an unrelenting smiley face to the world. Information did emerge but was scattered all over Twitter and institutional blogs with no central directory.

I've attached their final weather summary. Like all graphics to date, it's done ineptly (eg scaling, wind rose, summary stats). The data going into is attached as a text file if someone wants to work on it. The source web page could disappear with the end of the expedition; the data will be retained but as a deep dive into archival petabytes.

https://www.awi.de/fileadmin/user_upload/MET/PolarsternCoursePlot/psobsedat.html
« Last Edit: October 04, 2020, 03:20:55 PM by A-Team »

Niall Dollard

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Re: MOSAiC news
« Reply #1221 on: October 04, 2020, 12:56:03 PM »
And thx to Uniquorn for getting this forum off the ground and contributing so much to buoy and other visualizations!

+1

A somewhat grainy screenshot from the Zeppelin Station webcam at NY-ÅLESUND, showing the Polarstern.


uniquorn

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Re: MOSAiC news
« Reply #1222 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.

FishOutofWater

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Re: MOSAiC news
« Reply #1223 on: October 13, 2020, 10:02:42 AM »
Thanks, Uniquorn and A-Team for all the images that you were able to pull out of this award winning expedition.

Update: they've stopped again to award themselves another award:

To those of us who have worked to communicate the science and stories of the climate crisis to the public, this mission was bitterly disappointing, but that was never the goal or even a concern. They did what they intended to do and are proud of it.

castaway

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Re: MOSAiC news
« Reply #1224 on: October 13, 2020, 06:26:22 PM »
Congratulations for all that helped in this thread with data and opinions.
Specially uniquorn and A-team (because these are the ones I remember the most).
I read most of the posts over the last year, and it was great to know the insides and outs of this expedition thanks to you guys.
Everyone is going to try and make sense of the generated data, most amiss conclusions will be contaminated with fear.

A-Team

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Re: MOSAiC news
« Reply #1225 on: October 14, 2020, 12:34:58 AM »
Quote
Expedition leader Markus Rex returned with a warning. "The sea-ice is dying," he told a media conference in Bremerhaven on Oct 12th "The region is at risk. We were able to witness how the ice disappears and in areas where there should have been ice that was many meters thick, and even at the North Pole - that ice was gone" ...BBC
It's looking now like early Mosaic abstracts will emerge at the EGU meeting this spring (and AGU too in Dec 2021). In past years, neither professional society has shared poster session material much less recorded talks for non-attendees.

That could change as meeting mingling is out of the question with covid19 resurgent everywhere in the EU.  Indeed they are saying 22nd EGU General Assembly will be held online 4-8 May, 2020. It's not clear if only paid registrants can hear the talks nor if they will be archived say on youtube with separate poster session or ppt graphics.

Looking at google scholar under 'Mosaic Arctic', quite a few EGU abstracts emerge. Some of these are 'works in progress' that don't have any results, only indicate later inclusion. Others address complex issues that cannot be effectively communicated in brief text.

It might make better sense to check in regularly at The Cryosphere for preprints and reviewer comments. However, not all Mosaic articles will be published there. Twitter sites often have links to new releases but that is difficult to follow systematically.

https://tc.copernicus.org/preprints/  nothing new through Oct 12
https://os.copernicus.org/  oceans
https://twitter.com/sthendric
https://twitter.com/seaice_de
https://twitter.com/lavergnetho
https://twitter.com/CKatlein
https://twitter.com/IlkerFer

Large Eddy Simulations of the Arctic atmospheric boundary layer around the MOSAiC drift track
Littmann, Daniela; Dorn, Wolfgang; Bresson, Hélène; Maturilli, Marion; Rex, Markus

The present study focuses on the influence of the surface conditions on the atmospheric boundary layer by applying the large eddy simulation model configuration of the icosahedral non-hydrostatic model.. ICON-LES is used here with a grid spacing between 50 m and 800 m and set up to a domain with radii of 10 km to 100 km around the MOSAiC drift track. The model is driven by output data from weather forecast simulations for selected stormy and calm days. Results of simulations with various spatial horizontal resolutions and with different surface conditions such as ice fraction, ice thickness, snow cover will be compared and evaluated against observational data.

Precipitation isotope (δ1⁸O, δ2H, d-excess) seasonality across the Pan-Arctic during MOSAiC
Mellat, Moein; Bailey, Hannah; Mustonen, Kaisa-Riikka et al

Stable isotopes of oxygen and hydrogen in precipitation (δ18OP, δ2HP, d-excess) are valuable hydrological tracers linked to ocean-atmospheric processes such as moisture source, storm trajectory, and seasonal temperature cycles. However, characteristics of δ18OP, δ2HP and d-excess and the processes governing them are yet to be quantified across the Arctic due to a lack of long-term empirical data. The Pan-Arctic Precipitation Isotopes Network (PAPIN) is a new coordinated network of 24 stations aimed at the direct sampling, analysis, and synthesis of precipitation isotope geochemistry in the north. Our ongoing event-based sampling provides a rich spatial dataset during the MOSAiC expedition and new insight into coupled climate processes operating in the Arctic today. Using back-trajectory analysis, we attribute these nuances to divergent moisture sources and transport pathways into, within, and out of the Arctic, and demonstrate how atmospheric circulation processes drive changes in isotope geochemistry and climate that are linked to sea ice concentration.

For example, Alaska moisture derived from the North Pacific Ocean, Sea of Okhotsk, and the Bering Sea remains relatively enriched in 18OP/2H due to higher sea surface temperatures, whereas moisture originating from ice-covered seas to the north is characterized by relatively depleted values.

Variability of Lagrangian pathways and coherent structures in the Arctic and its effect on the predictability of MOSAiC drift and material transport
Wilson, Chris; Rynders, Stefanie; Vredenborg, Myriel; Kelly, Stephen; Aksenov, Yevgeny

Since operational ocean forecasts have a limited time horizon (~weeks), we focused on hindcast to examine typical sea ice/ocean circulation scenarios for 2005-15. We applied off-line ARIANE particle tracking in an eddying 1/12 deg. global NEMO sea ice-ocean model to estimate the most likely drift pathways. Over 10,000 trajectories were initialised in October each year, started at the best estimated MOSAiC location, advected for one year and analysed for key coherent drift structures. The advection and deformation of the initial particle cluster provided information about MOSAiC drift predictability, but also elucidated transport processes of the biogeochemical tracers, such as nutrients and carbon, and spread of pollution and microplastics.

We analysed observations from a newly curated dataset of the Arctic to examine various water mass properties, their origin, fate and connectivity.The MOSAiC surface drift trajectories depend on release time and location, but to leading-order, they are governed by the interannual variability of the wind and of the underlying ocean circulation. Mesoscale flow deformation is linked to a spreading of the cluster of particles and is associated with reduced potential predictability of separation of particles within the cluster (~ 450 km after 12 months).

Gyre-scale flow affects the ensemble drift path over long times and influences whether particular coherent structures are encountered by the particles, their location and strength (in terms of velocity magnitude and gradient). Saddle-type structures play a major role in bifurcation of particle trajectories. In the examples studied, saddles north of Nares Strait, near Northern Greenland and Northern Iceland, topologically associated with streamline connectivity between gyres, coastal boundary currents and inflow/outflow at the Arctic gateways, were significant.

Fine scale motion tracking of sea ice over central Arcticusing TerraSAR-X data
Anja Frost, Suman Singha, Stefan Wiehle, Sven Jacobsen
https://elib.dlr.de/135033/2/FROST_interactive_Poster_CRSS2020.pdf

MOSAiC's Pan Arctic Water Isotope Network: Sea ice-water vapor isotope interactions and transport processes within, into and out of the Arctic
Kopec, Ben et al

Our MOSAiC project is focused on how the Arctic Basin's water cycle behaves throughout the year, especially now that sea ice loss allows for a new source of moisture to the atmosphere during times when this basin was formerly frozen over. These massive changes in open water and corresponding fluxes in conjunction with significant shifts in atmospheric circulation, are altering how moisture is transported into, within, and out of the Arctic Basin. In order to help quantify these Arctic hydrologic cycle variations, we have established the AWIN (Arctic Water Isotope Network) that uses continuous water vapor isotope measurements (δD, δ18O, and deuterium excess) at eight land-based stations from Barrow in Alaska to Ny Alesund in Svalbard, as well as on board the Polarstern.

For this analysis, we focus on the first months of the expedition (October-December 2019) to closely examine cases of critical events including a major low-pressure system in mid-November that impacted much of the Arctic Ocean basin and three key repeating transport regimes - 1) transport into the Arctic from the North Atlantic via the Greenland Sea, 2) transport into the Arctic via Baffin Bay, and 3) transport out of the Arctic via the Greenland Sea, as well as transport within the Arctic during each of these regimes. For example, in the scenario of transport into the Arctic via Baffin Bay, at our site in Thule, Greenland, we see significant reductions in deuterium excess each time the southerly flow initiates, suggesting significant moisture evaporating from nearby in Baffin Bay. We then can track that moisture to another site to observe how much of that locally-sourced vapor is transported to a given downwind location, allowing us to quantify vapor fluxes and isotopic fractionation processes across the Arctic.
« Last Edit: October 14, 2020, 01:37:44 AM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #1226 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.
« Last Edit: October 14, 2020, 01:45:17 PM by uniquorn »

A-Team

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Re: MOSAiC news
« Reply #1227 on: November 02, 2020, 08:08:19 AM »
The Polarstern needed to head into port after a full year, in part because even icebreakers can become hopelessly frozen-in over winter. However here we are in November and the Siberian side is still open water. Indeed the Arctic Ocean basin is still 29% open water (fig.1) whose temperatures are still thermodynamically distant from seawater's -1.8º freezing point throughout the mixed layer (taken here as SSTfnd).

Thus we can continue a virtual voyage of the Polarstern far into the fall using microwave satellite data in the darkness and a half dozen buoys adrift in the open water.

The Smos-Smap ice thinness product provides an accurate way of tracking progress of the freezing season that is a better choice than area, extent or concentration which are strongly affected by cancellation bias and lack of regional nuance just being single numbers.

The first 46 days are shown below for Sept 15th to Oct 30th. The light green outer band detects the very earliest ice formation, late pancake. Note the odd island of thicker ice (tan color: >0.5m) that forms in the northern Beaufort by Oct 30th.

The current lopsidedness of the Arctic Ocean is quite noticeable: the Canadian side has frozen over with the Beaufort notably early; the Siberian side is open water except for a land-fast fringe, the Lena delta and a pending surge towards the ESS. Unsurprisingly, the Chukchi, which receives inputs from the warm Pacific, remains open; the Laptev though is in a historically unprecedented open state between 86º and the NSI for the date.

A daily temperature map of seawater to 10m depth called SSTfnd is posted online in netCDF format based on satellite data, buoy data assimilation and models by the GRHSST expert consortium. Notably, winds and tidal currents, as well as sinking surface water (cooled by air and blackbody emission to slightly greater density), mix the upper water column though only the very top will eventually freeze.

To address the question of why waters of the Laptev aren't freezing, it is first necessary to go back into August to establish what contributed to their initial warming. For this, daily SST maps were constructed in Panoply, contoured for 1º temperature bins, and then animated (fig.3) and characterized statistically (fig.4).

A wave of cooling can be seen extending erratically out from the icepack periphery. 'Peak heat' was attained on Aug 25 but subject to considerable bias from the Chukchi because warm Bering Strait inflows may overwhelm diminishing summer insolation. The Chukchi can stay partly open into late December, this year possibly into mid-January.

Since the extreme anomaly involves mainly the Laptev and ESS, the next posts will restrict the region of interest to a wedge bounded by the 85th parallel and 90-180º longitude (which agrees with historical graphics for the 'Siberian side' complied by @zlabe).
« Last Edit: November 02, 2020, 04:14:36 PM by A-Team »

A-Team

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Re: MOSAiC news
« Reply #1228 on: November 02, 2020, 09:53:35 AM »
The Laptev wedge is explained below. It spans 90º so can be rotated 45º ccw relative to conventional 'greenland down' orientation to a rectangle more suitable for analysis. Its purpose is to exclude distortion from the Chukchi and its inflows; the Svalbard-FJL-SZ open water band is a separate Atlantic Waters and Barents story (though Atlantification is now affecting the Laptev, Polyakov 2019).

August 2020 seawater temperatures are shown to 10m depth for alternate days; a colorpicker thermometer is attached. As an example, yellow highlights gray 60 which is 1ºC, in effect providing that contour line. The grayscale bar has been doubled without dithering from its initial 256 pixel width (the Panoply color bar is off).

The ImageJ 'measure' tool collects various statistics associated with the kelvin temperature histogram on each of the layers in turn.

The Laptev wad quite warm out to high latitudes (and still is). Quite a bit of the variability is probably attributable to tidal currents which are known to be considerable in the vicinity of the NSI. This means the water temperatures are not changing that much (which takes a vast amount of energy, too much for a day) but rather it is moving around on a daily scale bringing different temperatures to a given scene pixel.
« Last Edit: November 02, 2020, 10:06:12 AM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #1229 on: November 02, 2020, 11:57:01 AM »
Further north at 88-89N meereisportal added data for 2 more Tbuoys since I last looked. T84 and T85 are close to T78 and T81, possibly on the same floe. Will take a closer look at the floe cluster if I get time.

Air temperatures near to surface dropped briefly below -30C but have generally been considerably warmer. The ice/ocean interface temperature showing steady thickening, though T81 still looks unusual to me.
air temps left, snow/ice, ocean temps right

The drift animation is rotated 45deg, Greenland down.

No idea what IBOBAZFP is.
« Last Edit: November 02, 2020, 12:18:26 PM by uniquorn »

A-Team

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Re: MOSAiC news
« Reply #1230 on: November 03, 2020, 08:58:18 PM »
Quote
IBOBAZFP?
The IBO stands for Ice Based Observatory (a cluster of instruments put out together on the ice). The rest is just the station identification number in the master Mosaic database (?). The idea is to simultaneously deploy atmospheric, ice and seawater sensors to get an integrated picture over a season. There's a helpful level of detail on the deployment pages (fig.1).
Quote
ITP 25 was deployed as part of the first 'Super Station' (or Ice-Based Observatory) established during the ARK-XXIII/3 expedition on the Polarstern, and consisted of the ITP, a PAWS meteorological station and ITAC acoustic current profiler buoy. Arriving near the desired deployment location on September 21, fog limited helicopter operations to a short distance away from the ship, during a few time periods of clear weather. Potential floes were surveyed using a 2" portable ice auger, but the weak and thin ice made finding a suitable floe difficult. Eventually, the ship docked alongside a relatively level 1.5-1.7 m thick ice floe and sites were selected within 300 m of the edge. The actual deployment operation began early the next morning when the weather was fortunately clear enough to transport gear by helicopter. After some difficulties with the 10" ice augers, the ITP was successfully installed about 100-150 m from the ice-floe edge where the Polarstern was docked, the PAWS was located about 30 m away and the ITAC about 100m away in 2m thick ice. There were refrozen melt-ponds in several places around the deployment sites.

https://www.frontiersin.org/articles/10.3389/fmars.2019.00429/full
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6750219/
https://www.arcus.org/files/page/documents/19695/iaoos_document.pdf
https://www.whoi.edu/page.do?pid=141716

The future of the buoys currently in open water isn't clear as the Laptev may freeze up around them fairly soon though not the Chukchi. Do these buoys continue to report atmospheric pressure and sub-ice temperatures? Or do they go to sleep, if not crushed, until floating again in the 2021 melt season? That can be determined by updating the IABP tracking page from time to time (fig.2).

Looking now at how best to measure the Laptev anomaly, the attached figure shows a low resolution history of Nov 3rd back to 2002 from the Bremen site (https://seaice.uni-bremen.de/databrowser) and a higher resolution Nov 3rd slide show from UHH for 2013-2020 (needs click).

From these, it is clear that extensive open water on this date has been the norm for the Chukchi for 19 years at least, no doubt attributable to Pacific Ocean influences and a latitude reaching 2600 km south of the north pole. [Edit: Uniq found data taking this conclusion back to 1979 in #1231 below.]

It's also clear that 2018 was the only previous year that had any appreciable area of open water off the New Siberian Islands. The extreme melt year 2012 had a rapid freeze-up in this region; the rest had little or none left by this date [back to 1979 #1231].

Note the method here, counting pixels selected by a color-picker finds every last ocean-colored pixel, even if there is just one. (The area taken up by a pixel increases slightly with its latitude in polar stereographic.) The 2020/2018 ratio is product-independent. For the main Laptev (purple blob: 35,618 pxl), this ratio is 8.1 to 1 so Nov 3rd this year is 810% greater than any opening since 1979 (and probably many centuries).

The other thing to note is the nine Arctic "seas" were defined by a small self-selected committee of geographers in the mid-1950's. There is no physical basis for any of them except possibly Kara and Barents. Something might have been done around shelf bathymetry for the ESS/Laptev or Gyre salinity but was not. The same holds for the regional boundaries defined at NSIDC -- arbitrary divisions that have no basis in oceanography, icepack or meteorology.

The Nov 3rd frame for 2020, fig.4 below, suggests a possible resolution. First, the open Chukchi is often contiguous with parts of the Beaufort and East Siberian Sea. This means the appealing 90-180 meridian definition of 'Siberian side' open water picks up the Laptev open water correctly but also some of the "Greater Chukchi" aka ESS after passing across Wrangel Island.

That inflates the measured Laptev anomaly in many years, which dilutes the special aspect of autumn 2020. Variations in Chukchi freeze-up is a study on its own. The choice of 90º meridian below Severnaya Zemlya has an issue too, picking up too much of the Kara and SV-FJL-SZ Barents but this could be narrowed to the 105th meridian. The area between the Lena Delta and NSI and its shallow land-fast ice is also unrepresentative. In any case, the definition of "Laptev" and 'Siberian side' should be clearly declared via an embedded thumbnail (attn: @zlabe).
« Last Edit: November 03, 2020, 10:58:53 PM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #1231 on: November 03, 2020, 10:32:23 PM »
Quite interesting to look back through NOAA SIC images for Nov2,  1979-2020.
1998 stands out from the last century in the Beaufort. A few earlier years have no data.

A-Team

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Re: MOSAiC news
« Reply #1232 on: November 03, 2020, 10:33:06 PM »
We've been very fortunate in studying the fall freeze-up to have five good sources of information: resumption of cryo2smos ice thickness (alternatively Smos-Smap), OSPO-GHRSST foundational sea surface temperature SSTfnd 10m, the new AMSR2_AWI and a great many hourly reporting buoys fixed on the ice or drifting with drogues in open water that can provide boots on the ground validation to satellite and model based products..

The open water sources are only transiently available: as soon as the ice freezes over, the SST for the water underneath becomes, or is taken as, fixed at -1.8ºC. Only the Bering Strait and Yermak areas by Svalbard will have any open water by December. This past spring, they did not start to open up until mid-May.

No sooner will the Laptev freeze over than the ice thinness tools will come into play. One of the most common predictions is the Laptev ice will never make up for lost time. Smos-Smap, though limited to less than <0.5m thick, will take over monitoring, probably into 2021 (even though ice thickens very rapidly at first).

For any in-depth analysis of freeze-up, it's necessary to drill into the data itself, which means spreadsheets for the buoys and maps derived from Panoply netCDF for the rest. The first figure below looks at SST on Nov 1st. It is showing some remarkable seawater temperatures. To the extent the immediate surface is mixed by various processes, it will take tremendous cold to bring such a large water volume to the point of freezing.

Panoply maps are close to exact: selecting a point or range with a color picker on the scale highlights all the water at that temperature; conversely clicking on a particular lat lon gives the temperature readout on the scale.

The second figure uses the array subtraction feature to compare SST between two dates, then displays temperature gain/loss with blue/red colors relative to the zero of scale mid-point chosen in the Panoply set-up. Surprisingly, Sept 28-Sept 02 shows expected regions of cooling (insolation and Siberian heat wave are gone) but also regions of warming. (The same can also happen subtracting two arrays of ice thickness data.) This could be real or just a problem with the data reliability, precision or error -- more extensive sampling is needed.

The time series of ice advance from the Sept 15th minimum to Nov 03 has many interesting features, for example the velocity of loss of open water which can be measured quite readily with an ImageJ tool. Whether future freeze will stall depends on weather systems, surface water temperatures and rapidity/depth of water column mixing.

Technical note: the first figure is made using Panoply's 256 grayscale palette. This is then re-displayed in ImageJ as 8-bit so the lookup table called '16 colors' can be applied. This has the effect of creating well-separated color blocks, in effect colored-in contours. Panoply has several thermal palettes; some of these are discretized but only to a limit of 10. Both programs allow users to build customs LUYs and import them -- this is surprisingly easy to do. The idea is roughly like 'histogram equalization' to have more colors but only where more discrimination is needed.
« Last Edit: November 04, 2020, 02:24:47 AM by A-Team »

A-Team

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Re: MOSAiC news
« Reply #1233 on: November 04, 2020, 10:00:04 PM »
How much will the long-delayed freeze-up affect ice growth during the winter (and ice quality going into melt season)? We have no idea how cold the air will be between now and then. However we do have reanalysis products up through early November plus daily ice thinness from Smos-Smap and even rate of growth from Cryo2Smos.

It's also feasible to make a map showing how many days each point in the Arctic Ocean has had an ice cover and what the 'deficiency' has been this season given the Laptev, ESS and Chukchi open water anomaly. This can be done from the Sept 15th minimum by coloring open water of each day with grayscale 250 and then averaging. Areas still open will be all 250 and so average 250 whitish; areas that become ice-covered will darken proportionately (fig.1_

The 2nd image shows the Nov 2nd Smos-Smap ice thinness map. This product has a peculiar palette that is very dark and barely visible at the low end, suggesting newly forming ice of 1-2 cm thinness that the two remarkable sensors can detect. This fringe has been enhanced in the figure. Depending on temperatures, winds and upwelling, it may or may noy grow into thicker stable ice.

The two slides of the 3rd figure shows the odds that a given spot in the Arctic Ocean has had ice thicker than a half meter over the last 49 days. The cross-hatched area, which includes the unobservable pole hole, has been thicker the entire time. The edge of this >0.5m ice has advanced since the minimum but not by much and is barely above 85º in one area.

The Nov 3rd seawater temperatures from OSPO-GHRSST are shown in the final figure. In order to maximize contrast in the Laptev region, the overly warm Chukchi and Svalbard areas go off scale. Note too the influx of AW warmth from the St Anna Trough of the Kara.

Bremen does furnish a netCDF whereby the palette could be corrected but its format is defective -- Panoply requires geo-referenced data of file type Geo2D.

https://seaice.uni-bremen.de/data/smos_smap/netCDF/north/2020/

Glen Koehler

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Re: MOSAiC news
« Reply #1234 on: November 05, 2020, 02:16:17 AM »
<snip>How much will the long-delayed freeze-up affect ice growth during the winter (and ice quality going into melt season)? We have no idea how cold the air will be between now and then. However we do have reanalysis products up through early November plus daily ice thinness from Smos-Smap and even rate of growth from Cryo2Smos.

It's also feasible to make a map showing how many days each point in the Arctic Ocean has had an ice cover and what the 'deficiency' has been this season given the Laptev, ESS and Chukchi open water anomaly.   <snip>----etc.
    Great info A-Team.   It would be great to have an average age metric to add to an Arctic Sea Ice Multi Metric Index.  It seems like that info is embedded in the data used to create the ice age map.  Specifically, do those data allow conversion into a daily "average ice days" value across a grid cell map of the Arctic Ocean, or the central Arctic seas? Or at least the CAB?

    Do you think that average ice days would carry within it some proxy/correlated information about salinity or other characteristics that affect melt resistance?  Thickness already does that to some degree, but I think it does so incompletely.   That is because I suspect that not all ice of the same Thickness has equal physical characteristics or melt resistance.  My guess is that 2-meter ice that has been around for a while and thus had more time to expel salt content or get compressed by pack motion is different than younger 2-meter thick ice. 

     Just a bunch a notions and questions from an amateur ASI watcher who does not know the details but looking for patterns.  Thanks for your contributions to our understanding this very complex system.   
« Last Edit: November 05, 2020, 04:53:05 PM by Glen Koehler »

A-Team

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Re: MOSAiC news
« Reply #1235 on: November 05, 2020, 08:35:12 PM »
Quote
GK: measuring ice quality is important ... but how?
Right, it seems the current set of descriptive parameters is becoming increasingly inadequate as older sea ice age and the thicker thickness classes pinch out. The question is, do we need new/better satellite and buoy/glider/seaplane observables or can anything come of re-mixing the same old, same old material?

Another Mosaic or SHEBA is off the table because of long lead times, expensive logistics and localized coverage. A whole lot of fancy buoys could be set out for a fraction of the cost without the planning delays.

Here's an interesting proposal but it's just that -- new satellites too very long lead times (and what will be left of the ice then); most recent advances have come from re-purposing existing satellite data (eg Ascat, Smos):

CryoRad: Low Frequency Wide Band Radiometry A New EO Tool For Investigating Polar Regions
https://tinyurl.com/yykt6sem youtube slide show

Remote Sensing of Sea Ice Thickness and Salinity With 0.5–2 GHz Microwave Radiometry
KC Jezek et al 2019
https://sci-hub.se/10.1109/TGRS.2019.2922163 airborne study of Lincoln Sea

Mosaic itself returned with a lot of new data that is just now being processed. A 4th preprint has just surfaced at The Cryosphere. It's good to wait on these for a least one reviewer to post comments -- here the authors ran into one with rather strong opinions. These cannot be read on the web as the notes are done as clickable yellow highlighted pdf (requiring download). Some suggestions have merit but others the authors may simply dismiss.

Interannual variability in Transpolar Drift ice thickness and potential impact of Atlantification
HJ Belter et al 2020
https://tc.copernicus.org/preprints/tc-2020-305/

Arctic warming interrupts the Transpolar Drift and affects long-range transport of sea ice and ice-rafted matter
T Krumpen et al April 2019 (similar set of authors, similar topic)
https://www.nature.com/articles/s41598-019-41456-y

I don't see a future for antiquated single-number concepts such as total ice volume or ice surface extent/area because of what might be called cancellation bias, especially applicable during fall when Arctic Amplification is at its highest. (There's a consensus AA is happening but no consensus yet as to why or to what effects.)

For example, ice may bottom-melting at some locations but freezing on in others. The net single-number graph is flattened so mis-characterizes what is going on. In late October this year, extent increased along part of the ice pack edge but decreased in another. This is easily captured by graphics tools; the single-number chart is the wrong tool. In software terms, photoshop has taken over from excel.

Cancellation bias can disrupt year-on-year comparisons such as 2018 vs 2020 ocean-wide extents. People are forgetting 2018 itself was unique in the satellite record of the Laptev and indeed over prior centuries. The proper comparison is the area time series, not single close-up dates (which show steep compression).

From an information-theoretic standpoint, single-numbers lose too much. It is rather like the inadequacy of mean, median and mode in describing the SST histogram above(which is not remotely gaussian). As functions, they are ambiguously invertible: a great many initial 2D states give the same single number outcome. Neither the scalar variable fields nor their time series can be recovered.

Once upon a time, line graphs and regression of single number lines were cutting edge. Today, climate models and satellites products provide daily geo-referenced whole-Arctic condition maps. Analyses have to be based on those as validated by whatever sparse boots are on the ground.

Cancellation bias took on a special form during the current unprecedented event, losing the systemic regional asymmetry: normal growth on the Canadian half driven by an un-warmed Beaufort, offset by a massive stall on the Siberian side.

We need to understand not only the descriptive what but the analytic why: the Siberian regionality isn’t happenstance but a critical stall component driven in part (but what part?) by a persistent extreme warmth anomaly over the Siberian land mass and adjacent half-ocean. One-off weather or new abnormal piling on to marine atlantification reaching the Laptev (Polyakov 2019).

The 2nd image below explores display issues that arise with netCDF SST data. The first is intrinsic data resolution vs what Panoply displays, here at the 'maximal' size which it may reach via its built-in bilinear interpolation. Would it be better to take at the closest size to intrinsic, say 'jumbo', and then resize via bicubic in gimp?

The attached image was made at 'maximal' with Panoply's linear grayscale palette, with upper and lower temperature bounds set at 272-273.5 so as to yield a full spectrum distribution of histogram values across the 0 to 255 scale. A meridional wedge has to be defined to reduce extraneous gamut from the off-the-scale Chukchi SST, done here by cropping to the 110º and 180º meridians.

To make a maximally distinct contour map, the number of values has to be lowered, to say 128 before redisplay with glasby palette in ImageJ, lest the product be 'too busy'. This can be done in gimp by converting the image from grayscale to indexed color setting the number of grays to 128. This will open in ImageJ in 24-bit color so has to be reset to 8-bit before applying the lookup table. The outcome shows excellent detail in the SST data, better than themal contouring would.

The last image shows some gain in size but no quality advantage in changing the lat lon center. This will preclude overlays unless they too come in netCDF Geo2D format.
« Last Edit: November 06, 2020, 04:51:20 PM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #1236 on: November 05, 2020, 11:13:03 PM »
Modelled sea surface salinity at 0m from Mercator with awi amsr2 overlay at 80% transparent. Apologies for the 1 day date mismatch
click for movement, salinity scale is a rough match due to overlay

A-Team

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Re: MOSAiC news
« Reply #1237 on: November 06, 2020, 06:35:35 PM »
We've seen above that 2018 was the worst year for fall Laptev freeze delay in the satellite record and indeed for many earlier centuries. However 2020 has been far far worse quantitatively. It's imperative to avoid the 'cancel culture' approach of single-numbers with a wrong noisy background and limit Laptev investigations to the Laptev. As shown, the 110-180º meridional wedge is ideal for this purpose and convenient to implement.

Open water areas for these two years are compared below in various ways for the 52 days from the Sept 15 minimum to Nov 5th using AMSR2_UHH. The first sets compares averages and the main time series compares them directly in one of the booleans (2020 not 2018 green, 2018 not 2020 gold), other to follow. Don't be taken in by forum trolls -- fall 2020 is a major departure from 2018 that will have serious and lasting consequences.
« Last Edit: November 06, 2020, 07:30:22 PM by A-Team »

gandul

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Re: MOSAiC news
« Reply #1238 on: November 06, 2020, 07:00:34 PM »
ZLabe’s Ranking of Arctic atmospheric temperatures. Notice the difference between 2018 and 2020?
https://twitter.com/zlabe/status/1324737964182700033?s=21
What are we looking at here? How warmer a sea is in a much warmer weather year?
Would be interesting if we could observe a warmer Laptev in 2018. THAT would be interesting news.


gerontocrat

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Re: MOSAiC news
« Reply #1239 on: November 06, 2020, 08:36:28 PM »
SST anomalies from DMI - http://ocean.dmi.dk/satellite/index.uk.php

One hotspot left in the Laptev.
Kara & Barents pretty warm.

As is Chukchi & Bering.

2020 and 2019 maps attached. I do not have 2018
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uniquorn

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Re: MOSAiC news
« Reply #1240 on: November 07, 2020, 05:36:31 PM »
iabp buoy sea temperature update, laptev, nov1-6
amsr2-awi, nov1-6
« Last Edit: November 07, 2020, 06:08:33 PM by uniquorn »

oren

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Re: MOSAiC news
« Reply #1241 on: November 07, 2020, 06:11:44 PM »
Atmospheric warmth drives sea ice but it's also the reverse. Open water in autumn emits heat that keeps the atmosphere warm. And a sea that stood ice free for four months, a whole month more than any previous year,  had more time to mix and lose its freshwater top, which surely has an effect on delaying refreeze as well. So harping endlessly and confidently about atmospheric warmth as the only explanation is neither right nor helpful. Gandul you have stated your position, don't make it a pet theory.  If you have new material or insights about it feel free to return to it.

uniquorn

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Re: MOSAiC news
« Reply #1242 on: November 08, 2020, 10:33:25 AM »
Temperature difference over the Laptev shown by Suomi NPP viirs brightness temperature https://go.nasa.gov/3lc8oL5
rough overlay of amsr2 awi v103, nov7 
click for defaults and full res

A-Team

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Re: MOSAiC news
« Reply #1243 on: November 09, 2020, 01:56:02 PM »
Our favorite satellite archives are experiencing data glitches. This may be at the server level rather than at the satellite source. This could be related to weekend lack of staffing, covid19, elections, departure of staff, policy change and so on.
[[Update: most of the missing files have been posted as of 22:37 UTC Monday 09 Nov 2020.]]

The most serious of these has been SMOS ice thinness since it is used in mulltiple products, notably Cryo2SMOS and SMOS-SMAP. However it has recovered and is gapless over the freeze season. The glitches in other products are unlikely to ever be repaired so for our time series so we will be 'walking in' from the boundaries with duplicated data since it is not possible to interpolate without netCDF grayscales.

SMOS-SMAP is an improved version of SMOS and is served with a respectable enlargement. However given the complex palette it is difficult to make an autumn comparison of the two. After the last of the open water in the Laptev disappears over the next few days (?), the next thing to do is follow the creep of >0.5m thickness which helps measure the delay in the 2020 freeze season.

The very thin regions of ice are too dark in the original palette but can be replaced fairly well via a color-picker. These special peripheral regions will remain of interest into January for the Bering Strait and Sv-FJL-SZ area.

The SSTfnd 10m water column temperature may still be several degrees from the -1.8ºC below the newly forming ice. This product successfully predicted the last regions of the Laptev to stay open via its earlier hotspots.

Oren and FooW have brought up the issue of buoyant fresh river water draining into the Arctic Ocean to form a stratified surface layer with a more easily attained freezing point, eg 0ºC. (Because newly forming ice extrudes brine, when that ice melts, it too provides an extensive freshwater layer.)

That's complicated for the Lena whose delta lies south of the NSI island barrier but fortunately a Sept 2020 paper and three recent others address this very subject. The Lena is the largest Arctic riverine source and still has a substantial in-flow up to November. The authors provide a very detailed history of average freeze-up and melt-out dates that can be the basis for a 2020 anomaly map here.

"On the Variability of Stratification in the Freshwater-Influenced Laptev Sea Region
M Janout et al   15 Sep 2020  free full text
https://www.frontiersin.org/articles/10.3389/fmars.2020.543489/full

We investigate seasonal and spatial variability of stratification on the Siberian shelves with a case study from the Laptev Sea based on shipboard hydrographic measurements, year-round oceanographic mooring records from 2013 to 2014 and chemical tracer-based water mass analyses. In summer 2013, weak onshore-directed winds caused spreading of riverine waters throughout much of the eastern and central shelf.

In contrast, strong southerly winds in summer 2014 diverted much of the freshwater to the northeast, which resulted in 50% less river water and significantly weaker stratification on the central shelf compared with the previous year. Our year-long records additionally emphasize the regional differences in water column structure and stratification, where the northwest location was well-mixed for 6 months and the central and northeast locations remained stratified into spring due to the lower initial surface salinities of the river-influenced water.

A 26 year record of ocean reanalysis highlights the region’s inter-annual variability of stratification and its dependence on winds and sea ice. Prior the mid-2000s, river runoff to the perennially ice-covered central Laptev Sea shelf experienced little surface forcing and river water was maintained on the shelf. The transition toward less summer sea ice after the mid-2000s increased the ROFI’s (region of freshwater influence) exposure to summer winds.

This greatly enhanced the variability in mixed layer depth, resulting in several years with well-mixed water columns as opposed to the often year-round shallow mixed layers before. The extent of the Lena River plume is critical for the region since it modulates nutrient fluxes and primary production, and further controls intermediate heat storage induced by lateral density gradients, which has implications for autumnal freeze-up and the eastern Arctic sea ice volume.

Summer winds increasingly control the extent of the region of freshwater influence under decreasing sea ice. Further reductions in sea ice will increase surface warming, heat storage, and the interannual variability in mixed layer depth."

/=/=/=/=/=/

Surface waters properties in the Laptev and the East-Siberian Seas
in summer 2018 from in situ and satellite data
A Tarasenko et al     31 July 2019
https://os.copernicus.org/preprints/os-2019-60/os-2019-60.pdf   free full text

Variability of surface water masses of the Laptev and the East-Siberian seas in August-September 2018 is studied using in situ and satellite data. In situ data was collected during ARKTIKA-2018 expedition and then completed with satellite estimates of sea surface temperature (SST) and salinity (SSS), sea surface height, satellite-derived wind speeds and sea ice concentrations. Derivation of SSS is still challenging in high latitude regions, and the quality of Soil Moisture and Ocean 5 Salinity (SMOS) SSS retrieval was improved by applying a threshold on SSS weekly error. The validity of SST and SSS products is demonstrated using ARKTIKA-2018 continuous thermosalinograph measurements and CTD cast.

/=/=/=/=/=/

Surface waters properties in the Laptev and the East-Siberian Seas
in summer 2018 from in situ and satellite data
A Tarasenko et al     31 July 2019
https://os.copernicus.org/preprints/os-2019-60/os-2019-60.pdf   free full text

Variability of surface water masses of the Laptev and the East-Siberian seas in August-September 2018 is studied using in situ and satellite data. In situ data was collected during ARKTIKA-2018 expedition and then completed with satellite estimates of sea surface temperature (SST) and salinity (SSS), sea surface height, satellite-derived wind speeds and sea ice concentrations. Derivation of SSS is still challenging in high latitude regions, and the quality of Soil Moisture and Ocean 5 Salinity (SMOS) SSS retrieval was improved by applying a threshold on SSS weekly error. The validity of SST and SSS products is demonstrated using ARKTIKA-2018 continuous thermosalinograph measurements and CTD cast

/=/=/=/=/=/

Wind-Driven Coastal Upwelling near Large River Deltas in the Laptev and East-Siberian Seas
A Osadchiev et al 5 March 2020
https://doi.org/10.3390/rs12050844 free full text

“The Lena, Kolyma, and Indigirka rivers are among the largest rivers that inflow to the Arctic Ocean. Their discharges form a freshened surface water mass over a wide area in the Laptev and East-Siberian seas and govern many local physical, geochemical, and biological processes. In this study we report coastal upwelling events that are regularly manifested on satellite imagery by increased sea surface turbidity and decreased sea surface temperature at certain areas adjacent to the Lena Delta in the Laptev Sea and the Kolyma and Indigirka deltas in the East-Siberian Sea. These events are formed under strong easterly and southeasterly wind forcing and are estimated to occur during up to 10%–30% of ice-free periods at the study region. Coastal upwelling events induce intense mixing of the Lena, Kolyma, and Indigirka plumes with subjacent saline sea.”

Freshwater transport between the Kara, Laptev, and East-Siberian seas
AA Osadchiev … IP Semiletov et al.
Scientific Reports (2020)  03 August 2020
https://phys.org/news/2020-09-scientists-freshwater-arctic-ocean.html popular account
https://www.nature.com/articles/s41598-020-70096-w free full text

"Russian researchers have investigated the spreading of large river plumes—that is, freshened water masses formed as a result of river runoff mixing with ambient saltwater—in the Russian Arctic seas. The Ob, Yenisei, and Lena rivers provide a huge volume of freshwater discharge to the Kara and Laptev seas. The total annual runoff from these three rivers is estimated at 2,300 cubic kilometers.

The majority of this volume is discharged into the sea during the ice-free season, forming the Ob-Yenisei plume and the Lena plume. River plumes are freshened water masses that form near river mouths and spread at sea as a relatively thin surface layer. River plume dynamics are mostly determined by wind forcing and river discharge rate.

in the absence of strong wind, the Coriolis force and the density gradient between the plume and the ambient seawater cause alongshore spreading of river plumes. That process induces a large-scale eastward freshwater transport that is observed in the Arctic Ocean along large segments of the Eurasian and North American shores. This feature strongly affects ice conditions in the region.

The study described in this article revealed how the Ob-Yenisei plume spreads from the Kara Sea to the Laptev Sea through the Vilkitsky Strait, which is located between the Severnaya Zemlya archipelago and the Taymyr Peninsula. The paper also addresses the Lena plume and its spreading from the Laptev Sea into the East Siberian Sea through the Laptev and Sannikov straits.

The authors demonstrated that continental runoff from the Ob and Yenisei mostly accumulates in the Kara Sea during the ice-free season. Topographic barriers—namely, the western coast of the Taymyr Peninsula and the Severnaya Zemlya archipelago—generally hinder eastward spreading of the Ob-Yenisei plume to the Laptev Sea. This process occurs only as a result of very specific wind forcing conditions.

On the contrary, the Lena plume is almost constantly spreading to the western part of the East Siberean Sea as a large-scale water mass, forming a narrow freshened coastal current in the eastern part of this sea. Known as the Siberian Coastal Current, it is intensified by freshwater runoff from the large Indigirka and Kolyma rivers and flows farther eastward to the Chukchi Sea.

Freshwater from the rivers flowing into the Arctic Ocean very slowly mixes with seawater, therefore the large river plumes are very stable. Freshwater can spread eastward across hundreds of kilometers, forced by local winds."
« Last Edit: November 10, 2020, 12:21:19 AM by A-Team »

gerontocrat

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Re: MOSAiC news
« Reply #1244 on: November 09, 2020, 05:29:44 PM »
Laptev Ice-free days.

Quite some time ago I spent some time looking at how many days various seas had less than n% sea ice area, where n was a variable.

Here is the Laptev Sea graph with 3 values of n%, namely,
- n= 50%, i.e. the number of days Laptev sea ice area at least 50% ice-free ,
- n= 15% i.e. the number of days the Laptev sea was 85% or more ice-free***.
- n= 5% i.e. the number of days the Laptev sea was 95% or more ice-free which is totally ice-free near as dammit..

Looking at 2020 my carefully thought out remarks are "crikey, good heavens, luv-a-duck"

_______________________________________________
*** Imagine the Laptev Sea as one great big pixel. NSIDC extent data says if a pixel is less than 15% ice, it counts as zero which is ice-free, more than 15% counts as 100% which is ice-full. So when my great big pixel is less than 15% ice, the Laptev is ice-free.
« Last Edit: November 09, 2020, 05:36:07 PM by gerontocrat »
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Glen Koehler

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Re: MOSAiC news
« Reply #1245 on: November 09, 2020, 07:00:33 PM »
    Nice graph gerontocrat!  Any chance of getting a similar graph (and even better data table to go with it) for either the Central Arctic Seas or the CAB?

A-Team

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Re: MOSAiC news
« Reply #1246 on: November 10, 2020, 10:24:58 AM »
The first product combination below shows 10m SST for residual Laptev open water paired with SMOS ice thinness where there is ice, the second with AMSR2_AWI concentration. These are best done as slide shows because of palette clashes and the small 'holes' of Laptev waters. The Chukchi and Barents are so warm that they fall out of gamut if the Laptev temperatures are shown optimally. The two time series show ice closing in on the open water up to Nov 9th, with lumped concentrations and daily differences.
« Last Edit: November 10, 2020, 10:30:27 AM by A-Team »

A-Team

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Re: MOSAiC news
« Reply #1247 on: November 10, 2020, 03:58:44 PM »
Here is about the highest resolution contoured seawater temperature map that Panoply can produce from the OSPO-GHRSST data, the SSTfnd 10m water column for 08 Nov 2020. Peak temperatures have been following along quite well in location with open water as mapped by AMSR2_AWI.

This is a click-map in that selecting a temperature range in the scale bar (0ºC is shown in purple) selects the appropriate region in the image and vice versa. Any graphics app will have the tool for this if the full 1510 pixel wide image is first saved out.

The open water in the Laptev still has a peak SSTfnd temperature about 2ºC above the freezing point of 32 psu salinity seawater. As shown in ref.4 above, the Lena freshwater plume does NOT extend out north of the NSI to lower salinity and raise freezing temperature; instead it flows eastward through the Sannikov and Vilkoski Straits to the western ESS.

The Chukchi and adjacent Bering Sea are very much warmer, reaching 6ºC over the freezing point of seawater. Furthermore, GFS air temperatures are quite mild: +2ºC currently inside the straits.

Note the key products we use to track progression of the freezing season vary in their time of latest availability. For example, GFS recalculates air temperatures with at most a three hour delay whereas AMSR2_AWI will post Nov 10th sometime today but Cryo2Smos and Smos-Smap won't get farther than Nov 8th and OsiSaf will be displaying Nov 7-9 ice movement.

Mosaic did not deploy any buoys here but several joint Russian-US buoys have been drifting across the area measuring just subsurface water temperatures (though not necessarily where we want).

Tides and tidal currents have been studied in this area for well over a century. Below are a couple of pages from Sverdrup's 1926 article. He not only captained the Fram after Nansen left but also spent years as chief scientist aboard the Maud, a totally crazy expedition seeking new lands and to reach the pole

https://www.jstor.org/stable/24522570?seq=1#metadata_info_tab_contents
https://frammuseum.no/polar-history/expeditions/the-maud-expedition-1918-1925/

Technical note: the 'maximal' plot choice is re-centered to 75ºN 135ºE with a latitudinal radius or 12.5 with palette set to 'panoply_16.act' and the scale set to 271-277 kelvin with 8 one-degree divisions with %0f decimals in font 5.
« Last Edit: November 10, 2020, 04:26:15 PM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #1248 on: November 10, 2020, 09:02:38 PM »
iabp drift and sea temperature update, laptev. data attached as txt

A-Team

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Re: MOSAiC news
« Reply #1249 on: November 10, 2020, 09:45:22 PM »
The first image shows the spatial distribution of SSTfnd in the Laptev wedge; the second shows the pixel grayscale value frequency distribution for each of the 256 heat bins.

AMSR2_AWI for Nov 10th PM appears to be preliminary or partially defective. Many of the swaths are identical to those of Nov 9th PM. However freeze-up continues to stall. In fact, the 10th has 10,189 pixels of open water in the Laptev wedge whereas the 8th has 9,862. This appears attributable to wind drift and ice deformation about the open water hole than either melt or freeze.

Those helpful buoys are shown relative to open water on the Nov 10th AMSR2_AWI. On the final frame at 18:05 on the 10th UTC, #764 is showing -1.12 ºC. #762 -1.52ºC, and #763 -0.8ºC. These are measured at the bottom of the floating round buoys so represent the immediate sub-surface temperature. All are warmer than the freezing point of seawater at the applicable salinity.
« Last Edit: November 11, 2020, 01:58:33 AM by A-Team »