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Messages - slow wing

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Arctic sea ice / Re: MOSAiC news
« on: February 22, 2020, 06:20:13 PM »
A steady tailwind bearing for 56 hours produced the incredible straight drift of the proxy buoys for the Polarstern seen in Uniq's #635 animation above. Chasing down the stats, the ice pack moved at 2.1% the speed of the 1000 hPa wind (confirming what 'they' have been saying for years).

This wouldn't be possible without unresisting exits for the ice such as Fram, Nares and SV-FJL gap because the ice pack cannot compress further against land. (Over-rafting pressure ridges provide too much pushback when the ice is thick.)

Data from awiMet should someone wish to refine the estimate by providing the std error:
wind m/s,bearing 12,110 12,110 12,110 11,110 11,110 12,110 12,120 13,110 12,110 12,110 11,110 12,100 12,100 12,110 13,110 14,110 14,110 13,110 13,100 13,100 14,100 14,100 14,100 15,110 16,110 16,110 16,110 16,110 16,100 14,110 15,100 14,100 12,100 12,110 12,110 12,110 12,110 12,110 13,110 11,110 11,110 9,110 10,110 10,100 10,110 11,100 10,90 9,90 9,90 8,90 9,90 8,90 

Both ImageJ and Gimp offer image enhancement by convolution kernels, both canned (Process -> shadows) and roll-your-own DIY. They have a very beneficial effect on the Kaleschke SIC lead product (and downstream overlays), enhancing lead visualization without blowing up the grayish white interstitial background like linear contrast change, local adaptive (clahe) or histogram equalization.

To the extend the leads are anisotropic -- and they will be from TPD or during passage of a cyclone -- the choice of convolution 'direction' matters. The mp4 below used 'northeast'. No rocket science is involved automating out from the canned convolution to converge onto a quasi-optimal element of GL(3,R) wrt to frame average and that extends to a rolling window of GFS winds.

While some people are twittering from the KD, others are not. Kaleschke did not have time to describe productions methods but it is clear from Uniq's remarkable match-up in#635 of microwave leads with WorldView infrared that SIC leads just takes a longer radar wavelength approach to heat escaping through the ice. The images can't help but agree.

In other words, low Ghz radar meets up with long wavelength infrared in the electromagnetic spectrum, the difference being WV infrared is at the mercy of cloud cover while low Ghz sees through them better (in winter). It benefits from processing to darken warmer regions (ie the leads). We don't know what processing steps were taken but clearly they can be improved for the purpose of overlays on GFS weather,  Ascat scatterometry etc etc which don't see the leads but have other, complementary strengths.

The tripods have proven a planning and operational fiasco. Just drill through the ice, freeze in some 5 m fiberglass poles with no guy wires, hang slack electric and data cables off them, your pressure ridge problems are over. And where did Mosaic get their no-go snowmobiles, out of a museum?

Arctic sea ice / Re: MOSAiC news
« on: February 22, 2020, 11:17:33 AM »
Verifying those large low concentration leads north of Greenland., feb21-22, Kaleschke sic leads inset. ctr

drift update. Below 45E they start drifting away from the pole. At the recent rate of ~3degrees/day that's maybe 5-6days away. KD might just make it.


Wipneus - thanks for all the efforts - how about a double thickness line for the current year - or a dashed version?

Equally maybe the ones say before 2010 could be finer / dotted lines so that even if they are  roughly same colour its easy to spot that they in a different category?

Arctic sea ice / Re: Latest PIOMAS update (February 2020)
« on: February 19, 2020, 10:14:10 AM »

Hi Wipneus, you asked the same question a year ago and I replied then with a suggested colour palette.

Did you try those colours and, if so, did they work OK?

[sorry for the late reply]

Hi slow wing.

Yes I have been using that approach: create an ordered set of colors nicely spaced out in RGB space. Unfortunately nice spaced in RGB is not perceived as such by our eyes. So I start tweaking colors, not to my complete satisfaction. 

PIOMAS has updated the gridded thickness data upto the 15th. Calculated volume at 2020-2-15 was 19.67 [1000km3], This is fifth lowest for the day, exactly the same as the volume on that day in 2016, the "final official" volume data may change that exact match.

Here is the animation for February so far.

Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: February 05, 2020, 09:50:32 PM »
Hi Jim,

Yes i also done a new script which allows to estimate volume direct to sea ice concentration, thickness and the area of the grids, results looks like this

the only thing i think about is to add is again the nrt data, but analysis is just 2 weeks behind so for that, i think it must not

Arctic sea ice / Re: Latest PIOMAS update (February 2020)
« on: February 04, 2020, 07:21:45 PM »
Thickness map on 2020-01-31, compared with recent years and the diff's. Click for full size.

Arctic sea ice / Re: Latest PIOMAS update (February 2020)
« on: February 04, 2020, 07:11:15 PM »
PIOMAS has updated. Volume on 31st January was 18.282[1000km3], this is fifth lowest behind 2011,2013,2017 and 2018.

Here is the animation.

Arctic sea ice / Re: The 2019/2020 freezing season
« on: February 04, 2020, 11:04:23 AM »
A quick look at the Atlantic side, jan10-feb3, uni-hamburg amsr2uhh

Arctic sea ice / Re: Arctic Image of the Day
« on: February 02, 2020, 11:28:22 PM »
Light level building up but extremely cold, door still shut ;)

Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: February 02, 2020, 11:04:52 PM »
Heat loss in the Laptev Sea, , jan14-feb1

Arctic sea ice / Re: Arctic Image of the Day
« on: February 02, 2020, 02:25:33 PM »
Canadian Polar Bear frolicking in a field of fireweed

Arctic sea ice / Re: The 2019/2020 freezing season
« on: January 19, 2020, 06:10:29 PM »
And ice-drift!

Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 12, 2020, 08:22:15 AM »
Update until 9.01

PIOMAS gridded thickness data was updated. last day 15th December. Calculated volume on that day was 12.345 [1000km3]. That is still third lowest for that day after 2016 and 2012.

Here is the animation for the first half of December.

Arctic sea ice / Re: Latest PIOMAS update (December 2019 )
« on: December 04, 2019, 01:09:52 PM »
Thickness map compared with previous years and their diff's. Click to size.

Arctic sea ice / Re: MOSAiC news
« on: November 11, 2019, 03:44:45 PM »
fish cam? bridge radar? gps? helmholtz? cruise report? ms piggy? ROV ice bottom?
I've not even seen a still. Can you not wait until 2023 when Pangea is unblocked and papers first start appearing? Mosaic has very restrictive top-down control of  ( :) ) information, trickle-down. Just because you paid 100% of expedition costs with your taxes doesn't give you any right to know what they are doing.

Another AWI snow buoy was pronounced dead this morning by IABP, the 8th such announcement that went unannounced. This one was defective from the day of installment, hardly ever reported air or snow temperatures but worked for 26 days as a GPS buoy.

They should really let the buoys start reporting to Iridium on shipboard to see if the sensors are working rather than wasting helicopter resources deploying. Or maybe test them back in Germany? The IABP record shows they did neither.

This didn't start with Mosaic -- the Arctic buoy program has always been a joke. A thousand second-hand iPhones dropped from a plane could do better tracking ice.

The Polarstern continues to drift back and forth, up and down. From the 3 Sentinels this morning, the ship can be seen moving north along the 116.4º meridian. Displacements are unremarkable: at 126.5 pxls between the 03:11 and 06:25 which pencils out to 2.8 km in 3 hrs 14 minutes or 20.8 km per day.

Since the last S1B, the ship has moved 0.2º east while holding the same latitude 85.9. Winds predicted by GFS seem to be picking up at the ship: they are at 14 m/s now and expected to reach 15.3 m/s or 55 km/hr.

This is close to the worst winds the ship has experienced so far, back on Oct 8th winds reached 60.7 km/hr according to sailwx. The attached graphic shows the wind speed distribution; the attached csv has columns the speeds in km/hr, m/s and knots. These October winds were being called gale force at the time, fair enough:

2019-Oct-08 0600   85.0   136.0   56.9
2019-Oct-08 0500   85.0   136.0   56.9
2019-Oct-08 0400   85.0   135.9   60.7
2019-Oct-08 0300   85.0   135.8   60.7
2019-Oct-08 0200   85.0   135.7   56.9
2019-Oct-08 0100   85.0   135.6   56.9
2019-Oct-07 2300   85.0   135.3   56.9
2019-Oct-08 0600   85.0   136.0   56.9
2019-Oct-08 0500   85.0   136.0   56.9
2019-Oct-08 0400   85.0   135.9   60.7
2019-Oct-08 0300   85.0   135.8   60.7
2019-Oct-08 0200   85.0   135.7   56.9
2019-Oct-08 0100   85.0   135.6   56.9
2019-Oct-07 2300   85.0   135.3   56.9
A gale force wind can be defined as a sustained strong wind, registering between 7-10 on the Beaufort Scale, which indicates wind speeds of 50 - 102 km/h

It's not entirely clear at what height above the ice these winds are measured and modeled. Usually wx tries to get clear of surface topography but that is exactly where wind stress is applied to the ice. The Polarstern has lost 0.4º of longitude in the last 14 hours; this is interesting/confusing because it suggests a wind coming from 180º (measured at the ship) blows the ice due east.T

The 14 m/s is just barely over 50 km/hr so a few more hrs will bring them into a sustained gale force stress regime. GFS today shows the winds peaking at 54 km/hr at 03:00 UTC from 205º on the 12th and not abating until 09:00 tomorrow. The S1B's will cover the ice response quite well.

  85.9  116.7 19-11-11 15:00   16  180
  85.9  116.7 19-11-11 14:00   14  180
  85.9  116.6 19-11-11 13:00   14  180
  85.9  116.6 19-11-11 12:00   13  180 [GFS predicted this perfectly: 13.9 m/s 175º, see above]
  85.9  116.6 19-11-11 11:00   13  180
  85.9  116.5 19-11-11 10:00   11  170
  85.9  116.5 19-11-11 09:00   11  170
  85.9  116.5 19-11-11 08:00   10  170 
  85.9  116.5 19-11-11 06:00   11  170   S1B 06:27
  85.9  116.4 19-11-11 05:00   10  160
  85.9  116.4 19-11-11 04:00    8  160   S1B 04:49
  85.9  116.4 19-11-11 03:00    9  160   S1B 03:11
  85.9  116.4 19-11-11 02:00    9  180
  85.9  116.3 19-11-11 00:00    7  190

The offset is mildly confusing: the 120º is at 75.00 on Sentinel images according to gimp and imageJ angle tools as appropriate to 'Greenland down'. So the offset is 45º, meaning the 116.4 should be drawn at 71.40º towards the pole which is ten thousand pixels off the image.

Arctic sea ice / Re: MOSAiC news
« on: November 04, 2019, 09:20:04 PM »
A closer look at whoi itp102
ITP102 was deployed on a 0.7 m thick ice floe in the Transpolar Drift on October 10, 2019 at 85° 7.9 N, 135° 34.1 E in collaboration with the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from the Russian Research Vessel Federov. On the same icefloe, a Naval Postgraduate School Arctic Ocean Flux Buoy (AOFB) and Seasonal ice mass balance buoy were also installed. The ITP includes a second generation prototype MAVS current sensor operating on a pattern profiling schedule including 2 one-way profiles between 7 and 760 m depth each day and SBE-37 microcat fixed at 6 m depth.
The profile contours show small changes down to 50m since the start and the microcat highlights temperature and salinity changes at 6m depth since day300. Here we are also using macid's 3d R analysis to focus on temperature down to 50m showing a small rise of up to 0.16C at ~30m.

A rise in temperature and drop in salinity  at shallow depth could imply some bottom melt but no doubt there are other reasons for these conditions in this area.

Arctic sea ice / Re: Latest PIOMAS update (November 2019)
« on: November 04, 2019, 05:42:45 PM »
PIOMAS Volume as at 31 October 2019   6.518  km3 '000

2 more graphs

The first is the plume of projections for November using daily change in the last 10 years. In contrast with the plumes for extent and area, the plume of projections is in a very narrow range.

Next is the graph of 365 day trailing averages, reflecting the low volume in 2016, the recovery in 2017-2018, and 2019 low volumes. At the current rate it will take until spring 2021 for a new record low.

Arctic sea ice / Re: 2019 sea ice area and extent data
« on: November 04, 2019, 05:37:20 PM »
JAXA ARCTIC SEA ICE EXTENT :- 7,804,258 km2(November 2, 2019)

Am I seeing a persistent gradual reduction in daily extent gain, and will that reduction continue?

For the last 40 years sea ice decline in winter has been a lot less than in the summer. So eventually 2019 sea ice extent would play catch-up to get closer to the trend values. I did not expect it to happen this quickly.

Will these 10 days of very high extent gains continue? 
Or will extent gains return to the average or even below?

2016 as I recall had a huge spike in cyclonic activity along the east coast of both Asia and North America which I think was key in slowing the refreeze.  I think for that reason 2016 will persist as an anomaly for some time, much as 2012 has.

Absent that vigorous activity, I do think the rapid extent gains will continue over the colder near-continental seas in particular - ESS, Laptev, Kara, CAA, Hudson, and Okhotsk.  However once that real estate is used up, I think we quite possibly will see a stall as the heat content in the Pacific side in particular is so huge that even without imported heat from further south it will resist freezing and provide its own local feedbacks to slow heat loss as well.

Arctic sea ice / Re: Latest PIOMAS update (June 2019)
« on: November 04, 2019, 05:26:45 PM »
PIOMAS Volume as at 31 October 2019   6.518  km3 '000
The standard graphs and tables as I use for the JAXA extent data are attached.

Volume gain in October mostly well below average, a bit above average gain in the last week.

2019 volume is still 3rd lowest in the satellite record, by 101 km3 above 2012, and only 33 km3 above 2016, and less than 2018 by 709 km3.
The last table is a look at projections to the next maximum. Far too early to take it seriously.

Arctic sea ice / Re: Latest PIOMAS update (November 2019)
« on: November 04, 2019, 09:42:14 AM »
Thickness map, comparisons with previous years and their diff's. Click for full size.

Arctic sea ice / Re: Latest PIOMAS update (November 2019)
« on: November 04, 2019, 09:30:19 AM »
Update volume and volume-anomaly graphs. 2012, 2016 and 2019 are very close.

Arctic sea ice / Re: Latest PIOMAS update (November 2019)
« on: November 04, 2019, 09:20:44 AM »
PIOMAS gridded thickness data has updated. Volume calculated from thickness was 6.52[1000km3] on 31st October, third lowest for the day. 2012 and 2016 had a lower volume.

Here is the animation.

Arctic sea ice / Re: MOSAiC news
« on: November 04, 2019, 03:42:15 AM »
Incredible floating effect! The Polarstern buoy array is such a neat idea for extending outwards from the intensively studied Mosaic floe, too bad they hardly ever work for more than a couple weeks. Maybe just stick an iphone inside instead of all that no-good custom electronics?

Below is ice thickness according to the laser altimeter and soil moisture radar ice thinness ... the palette is monotonically proportional to ice thickness (though not linearly) so it displays more or less correctly in bump map view. Because the .nc file is provided, the data can be redisplayed in polar stereographic with one of the carefully designed linear palettes available in Panoply.

However, it appears that the Cryo2Smos project has died or gone into hibernation. Its daily archive has not been updated since the week ending Oct 30th. Only nine days of product were ever produced. Meanwhile, U Bremen continues to update smos-smap and smos alone even though these were supposedly taken away by U Hamburg/AWI.

Index of /sea_ice/product/cryosat2_smos/v202/nh/LATEST/

The surface plot (needs click) bears an uncanny resemblance to grayscale values on plain vanilla Ascat, especially that extended pocket of thick white (low salinity) mature MYI ice around the pole that has been there consistently on Ascat for many many months.

It's not quite clear why the ice above the CAA is thiner (as historically that has been the very thickest) but that is seen in multiple ice thickness products. The Polarstern (white star) is currently situated in fairly thin ice, surprisingly with thicker ice shown farther south on flanking meridians.

The ship has been moving rapidly east due to a persistent clockwise rotation of the ice pack (as seen on OsiSaf: red star within green cruise bounding wedgie). If this keeps up (it won't), the Polarstern would be home for christmas. The cruise history to date:

Lat  Lon  Day   Hour  Wind(m/s) Wind (dir)
85.9 119.7 04 11 19   12:00    9 80
85.9 119.8 04 11 19   11:00    8 80
85.9 119.9 04 11 19   10:00    8 90
85.9 119.9 04 11 19   09:00    9 90
85.9 120.0 04 11 19   08:00    9 90
85.9 120.1 04 11 19   07:00    8 90
85.9 120.1 04 11 19   06:00    8 90
85.9 120.2 04 11 19   05:00    8 90
85.9 120.2 04 11 19   04:00    9 90
85.9 120.3 04 11 19   03:00    9 90
85.9 120.4 04 11 19   02:00    9 80
85.9 120.5 04 11 19   00:00    9 90
85.9 120.6 03 11 19   23:00    9 90
85.9 120.6 03 11 19   22:00    8 90
85.9 120.7 03 11 19   21:00    9 90
85.9 120.8 03 11 19   20:00   9 100
85.9 122.2 02 11 19   20:00   5 120
85.8 122.7 01 11 19   20:00   4 160
85.8 123.2 31 10 19   20:00   5 120
85.7 124.0 30 10 19   20:00   7 100
85.7 124.9 29 10 19   20:00   7  90
85.6 125.9 28 10 19   20:00   8 100
85.5 126.7 27 10 19   20:00   7 110
85.5 127.2 26 10 19   20:00   6 120
85.5 127.7 25 10 19   20:00   4  90
85.4 128.5 24 10 19   20:00   8  90
85.4 129.6 23 10 19   20:00   4 100
85.3 130.7 22 10 19   20:00   10 100
85.2 132.2 21 10 19   20:00   12 110
85.0 132.8 20 10 19   20:00   9 190
84.9 133.2 18 10 19   20:00   11 170
84.8 133.0 17 10 19   20:00   2 220
84.8 133.3 16 10 19   20:00   5  40
84.8 134.1 15 10 19   20:00   6  50
84.8 134.4 14 10 19   20:00   4 330
84.8 134.8 13 10 19   20:00   8 340
84.9 135.4 12 10 19   20:00   4  50
84.8 135.8 11 10 19   20:00   4 290
84.9 135.3 10 10 19   20:00   6 290
84.9 135.9 09 10 19   20:00   4  80
84.9 136.2 08 10 19   20:00   6 350
85.0 135.1 07 10 19   20:00   13 270
85.1 134.0 06 10 19   20:00   5 280
85.1 133.8 05 10 19   20:00   4 270
85.1 134.1 04 10 19   20:00   7 70

Arctic sea ice / Re: MOSAiC news
« on: October 17, 2019, 04:50:58 PM »
A quick overview of mosaic Pbuoy drift before moving on to others.

Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 16, 2019, 12:35:19 PM »
The Centre for Polar Observation and Monitoring have just published the first CryoSat-2 Arctic sea ice thickness map of the 2019/20 freezing season:

Note in particular the dark blue area north of the Canadian Arctic Archipelago.

Arctic sea ice / Re: MOSAiC news
« on: October 13, 2019, 05:54:10 PM »
Mosaic is posting the daily location radar in quasi-lagrangian coordinates, with the point position of the Polarstern and the North Pole determining the moving axis. In normal ship-based lagrangian coordinates, the bow-stern center line and main mast would determine the coordinate system (alternately some asymmetry axis on the floe to which the Polarstern is afixed). The difference is in how rotation is represented.

We are more used to eulerian coordinates in satellite archives where the graticule stays fixed. We went through this all before in the time of Ptolemy and Galilleo.

Whoever painted on the red lines and circle, over-writing the value of the most important pixels, seems not have centered them accurately on the ship which shows clearly as a bright white dot (all that metal reflecting Sentinel's beam back). Perhaps those circles reference a valid timestamp but one different from the S1 which would appear in its file name had it been correctly cited.

At any rate, I adjusted the six dates for which for which they archived S1 at higher resolution, so from Oct 7th to Oct 12th so far. As noted above, some of these are either mis-cropped or slightly rescaled from the others. The Polarstern tied on Oct 4th but those dates are missing (4-6 Oct).

We need to go back to the original files and do this over, right. I am not sure though that all of them are S1 as it does not seem that polarview carries them all at the needed resolution. If so that would mean a tedious navigation deep through the ESA server.

At any rate, despite the visual competition from the crazy graticule and red paint, it was possible to re-register six days of imagery. The four gifs below present the data at four levels of zoom. A lot could be said about leads opening and closing, scene deformation, rotation of the PS floe and so on. These run at 150 ms per frame; download and view frame by frame. I also prepared a single concatenate mp4 that has a better controller but am out of attachments here.

Arctic sea ice / Re: MOSAiC news
« on: October 05, 2019, 02:10:48 PM »
Take an inside tour of the Polarstern?

"During the historic meeting of USCGC Healy and Germany's RV Polarstern at the North Pole on 07 Sept 2015 we had the opportunity to exchange visits.  Both ships were conducting Arctic GEOTRACES cruises."

Goddard Institute assembled the last cloud-free visible satellite mosaic of the Arctic Ocean over Sept 17-23. The PS is shown by a red dot at its selected floe on 01 Oct 19.

“We’ll have to wait and see if it’s also stable enough to withstand the autumnal storms that are now brewing,” PI Markus Rex said, adding that the team is “prepared for all scenarios.”

Right. The ice in the northern Laptev has not really set up yet. They have made the best possible decision under the circumstances. A lot of laboriously deployed instrumentation and infrastructure would have to be pulled back on board in the event of swells, flooding of the floe, ridging or shearing.

I worked out the scale on the Polarview imagery Uniq posted in #74 using the distance between 85º-86º as 111.67 km in WGS84 ellipsoid which all GPS devices reference. From the approximate dimension of the selected floe 3.5 x 2.5 km, it is possible to identify the object as a dark oval on S1 radar.

When the next image surfaces on Polarview, we can use the pair to compute real non-gridded velocities because the PV file name provides the UTC time the image was taken to the second.

Arctic sea ice / Re: Latest PIOMAS update (October 2019)
« on: October 05, 2019, 09:13:14 AM »
More graphs to prepare (the ones with annual minimum), but that will be much later. Paint job to do.

Arctic sea ice / Re: Latest PIOMAS update (October 2019)
« on: October 05, 2019, 08:57:45 AM »
PIOMAS gridded thickness data has updated. Volume calculated from thickness was 4.57[1000km3] on 30th September, second lowest for the day.
The 2019 minimum was around the 10th, 4.06[1000km3]. As these number are not exactly the same as the official PIOMAS volume numbers, wait for the release of those.

Here is the animation.

Arctic sea ice / Re: MOSAiC news
« on: October 03, 2019, 12:06:18 AM »
Mosaic is a fantastic endeavor that will provide a massive amount of observational data via an incredible array of modern instrumentation (relative to the last go-round, SHEBA, of 1999). Results will dominate the scientific literature on the Arctic Ocean for years to come because the interior basin has heretofore largely gone un-instrumented.

Mosaic will greatly improve the interpretability of satellite imagery and provide a reality check on model predictions never regularly confronted with observation. Just having real weather assimilated into daily ECMWF initializations is a huge step forward over meagre shoreline inputs, for example measured 2m winds responsible for icepack motion and export.

Ice-atmosphere couplings (eg radiative balance, boundary layer turbulent flux, cloud properties) depend on location and weather, not on the floe selected. While the Polarstern provides the center of observation, the secondary deployments go out a radius of 40 km. With drift, this generate a swath of measurements nearly a degree of latitude wide (111 km) wide, rather than point data (mooring) or line data (buoy).

The second study component is the ice itself. It has not yet proved possible to determine ice mass balance issues (thickness, bottom growth, melt ponds) year-round with any accuracy from remote sensing, much less modeling, so the comprehensive thicknesses will be a real breath of fresh air.

The third focus is water column under the ice. The anticipated drift across the Eurasian Basin does not seem ideal for the study of encroaching Atlantification (like N-ICE2015 or the PS's recent visit to the upper Fram), though the northern Laptev is an area of very active concern for mixing of thermal and saline stratifications.

It's never been clear what provides the vast volumes of return water to the East Greenland Current because the Waddell Sea and points north have been under thick ice for ages. Mosaic has an acoustic tomography experiment going relative to new moorings that can address this.

Mosaic planners knew from the outset that finding a suitable floe would be mission-critical. They allocated a full week for that search; as I write, the ship has been at N 85°12' E 134°18' for eight hours. They are looking for 1.2 m or thicker ice, a port-side mooring for logistics, and a large enough floe so that electricity and LAN data lines can reach remote instrumentation.

The safety issues involve pressure ridges heaving experimental set-ups, leads opening suddenly, nearby floes over-rafting, patches of very thin ice, strong swells from remote storms, aggressive penguins walruses and bears, plus working long hours in cold, dark and possibly very windy conditions. (The PS serves alcohol at two on-board bars.)

I am skeptical -- based on the multi-satellite September time series below -- that they will find the perfect floe at 85ºN because the Laptev is in such poor condition but if they go much farther towards the Pole, there may not be notable net drift towards the Fram.

The gif below shows Osisaf, Ascat and Smos embedded within a novel differential AMSR2. The complex palette is provided in the lower left corner. The Polarstern search wedge, called a spherical rectangle or section double frustrum, is shown as an overlay (map adornment) for each satellite. The base resolution is 6.25 km/pxl for AMSR2 unchanged from archive.

With so much data coming in so many forms, synchronized integration becomes increasingly important in science-retaining visualizations. While this one was easy enough to make, it doesn't roll forward because of the differencing wrt a fixed final day, 30 Sep 19.

Arctic sea ice / Re: MOSAiC news
« on: October 01, 2019, 12:16:49 PM »
Polarview 16bit jp2 of yesterday's red triangle area with heavy contrast (saved as jpeg)

Arctic sea ice / Re: MOSAiC news
« on: October 01, 2019, 11:46:50 AM »
Spot the boat.
Polarstern position 2019-Sep-30 04:00   N 85°06' E 137°48'
Polarview, 20190930T044920, slight contrast adjustment. Click for full resolution.

Arctic sea ice / Re: MOSAiC news
« on: September 27, 2019, 06:13:08 PM »
AMSR2 concentration is a great product but doesn't scale well to Sentinel1 resolution. Meereisportal are now providing a version of the multisensor map without the overlay

sep25-26, small.
It's a real bonus from this expedition already that we can now see clear daily Sentinel1 coverage of this area.

Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: September 21, 2019, 07:53:31 PM »
It's hard to match the ITP buoys temperature & salinity profiles with their location using the standard plots provided, so I practiced my R and took a stab at it.

Because of the constraint of one type of value displayed per location point, I started with the average temperature of the 0-60 dbar ocean layer. I'd like to animate it based on date with a fading trail, but if anyone has suggestions for a better calculated value to display, let me know please.

L3 data was available for years 2005-2014

Arctic sea ice / Re: "Stupid" Questions :o
« on: September 15, 2019, 09:01:07 AM »
1) The date of minima is not showing a drift either earlier or later.
2) I don't know. But I think the event you refer to was in Dec 2015.

Arctic sea ice / Re: The 2019 melting season
« on: September 14, 2019, 01:09:52 PM »
A "low bandwidth" animation of Arctic sea ice age since the 2015 minimum:

Arctic sea ice / MOSAiC news
« on: September 11, 2019, 11:43:21 AM »
The MOSAiC expedition begins on the Sep20.

MOSAiC - Multidisciplinary drifting Observatory for the Study of Arctic Climate

It could be the largest-scale Arctic research expedition of all time: in September 2019 the German research icebreaker Polarstern will depart from Tromsø, Norway and, once it has reached its destination, will spend the next year drifting through the Arctic Ocean, trapped in the ice. A total of 600 people from 19 countries, who will be supplied by other icebreakers and aircraft, will participate in the expedition – and several times that number of researchers will subsequently use the data gathered to take climate and ecosystem research to the next level. The mission will be spearheaded by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI).

The expedition programme is here
More information here:

Image of the general set-up
Area of MOSAiC start location overlaid onto unihamburg amsr2-uhh, aug1-sep11
edit: tidied up a bit and updated Polarstern position image

Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 04, 2019, 09:07:31 AM »
A late century drop in extent shows there are still possibilities for second lowest place ( in my limited data set).

Here is an animation of the Arctic Basin compared with 2012. Click to start.

Arctic sea ice / Re: Latest PIOMAS update (September 2019)
« on: September 04, 2019, 08:28:36 AM »
PIOMAS gridded thickness data has updated (official volume data not yet). Volume on 31st August was 4.17 [1000km3], second lowest behind 2012 (3.93[1000km3]).

Here is the animation for August.

Arctic sea ice / Re: The 2019 melting season
« on: September 03, 2019, 11:53:31 AM »
The NOAA-ESRL temperatures for August are out and show just  how warm the Arctic was over summer.
The first  number is the ranking and the number in brackets the variation from the record. This shows air temperatures at  record levels in August and over summer (Jun-Aug). SST were near record in the same period.  Globally 2019 is running second or 3rd warmest. This does nothing to  explain the flatlining of extent  loss but  suggests that the melt  could continue over the next few weeks.

                         August        Summer         YTD
Air 80N+           1 (+0.134)   1 (+0.482)     6 (-1.619)
SST 80N+         2 (-0.027)    1 (+0.007)     11 (-2.114)

Air 67N+           1 (+0.630)   1 (+0.229)    2 (-0.795)
SST 67N+         3 (-0.056)    1 (+0.277)    3 (-0.918)

Air Global          2 (-0.039)    2 (-0.032)     2 (-0.164)
SST Global        4 (-0.153)    2 (-0.113)     3 (-0.174)

Arctic sea ice / Re: The 2019 melting season
« on: August 31, 2019, 03:02:32 AM »
The dispersal to the Pacific and Eursian sides which has driven the extent stall looks likely to turn around given the forecasts, The CAB adjacent to the western Beaufort and eastern Chukchi sea will have 20 knot winds pushing the ice north which should lead to extent drops. Any export will be via Fram strait and the Barents between Svalbard and FJI. The storms that may follow also seem likely to drive ice north from the Laptev region.

A long lag in extent drops is usually followed by a catch up period, altough since its so late it may be reflected in an extended stall in the freezing season. But temps have failed to fall much below 1C above 80N so far, and have bounced back upto about -0.5C again today - there has been nothiung to halt bottom melt, so we might see some nasty surprises in some gauzy low concentration areas if winds get as strong as (or stronger than) forecast

Arctic sea ice / Re: The 2019 melting season
« on: August 30, 2019, 05:44:02 PM »
There doesn't appear to be an update of the nsidc ice age map but I assume that the 'rump' of the ess arm is the remains of last year's Beaufort 'arc', see,2591.msg221812.html#msg221812.
As bottom melt takes over from top melt, here is a look at yesterdays amsr2-uhh overlaid onto gmrt bathymetry, mercator 34m salinity (to show pacific and atlantic current) and 0m sea temperature.

Interesting to look at the jet from the river Ob through Kara to the CAB (if the model is correct)
click to run                                 edit: forgot scales

Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 30, 2019, 12:58:03 AM »
PIOMAS volume provides monthly data, soon... DMI does have a daily tracker. I searched the forum for any comments on its validity and didn't see anything concerning, feel free to correct me.

I am waiting for this, will help tell us how much of the stall is due to dispersion vs a real stall in melting.
Biases in PIOMAS are discussed here:

PIOMAS won't help a lot at this stage because it overstates the volume of thin ice. With more thin ice widely distributed the PIOMAS volume estimate may hold up despite a reality of less ice. The last few days appear to have spread the ice and lowered the concentration which will lead to an increase in the error in the PIOMAS estimate.

As the attached graph shows the over estimate of volume, on ice below 1m thick according to  submarine measurements, could be double what the submarines are seeing.

Arctic sea ice / Re: The 2019 melting season
« on: August 29, 2019, 12:41:32 PM »
As there is some discussion about ice drift direction, here is osisaf ice drift overlaid onto unihamburg amsr2-uhh, aug18-28.
Arguably amsr2 should be overlaid onto the previous 2 day osisaf but 1 pixel of amsr2, ~15km^2 of slush probably has a fair bit of inertia so in this case day n-2 to dayn osisaf is overlaid onto dayn amsr2-uhh(25-27aug onto 27aug)
Note that although both products use algorithms to interpret the data, both are based on real data and not models.

Low Resolution Sea Ice Drift product (OSI-405)

Which satellite sensors are processed?
The sensors and channels used are SSMIS (91 GHz H&V pol.) on board DMSP platform F17, ASCAT (C-band backscatter) on board EUMETSAT platform Metop-A, and AMSR-2 on board JAXA platform GCOM-W.

What is the spatial resolution of this product?
The low resolution sea ice drift product is a gridded dataset. The grid has 62.5 km spacing on a Polar Stereographic projection mapping. Definitions for the projection parameters can be found in the NetCDF files as well as in the Product User's Manual.

What is the time-span of this product?
Two days (48 hours). This is the time delay between the start and the stop time of the motion described by one vector. For comparison, the merged products from IFREMER/CERSAT is a 3 days lag dataset while the AMSR-E product by the same data centre is 2 days (using 89 GHz channels).

Several datasets are distributed every day, which one should I use?
The OSI SAF low resolution sea ice drift product is indeed composed of several single-sensor products and one multi-sensor analysis, every day. They are all at the same spatial resolution , on the same grid and with a 48 hours time-span.

The multi-sensor (aka merged, multi-oi) is intended for users requiring a spatial covering dataset. In this product, missing vectors are indeed interpolated from the neighbours and each vector is computed from the individual single-sensor products. In this merging process, however, some level of aliasing and averaging is to be expected that slightly degrade the quality of the dataset.
click to run

Arctic sea ice / Re: The 2019 melting season
« on: August 28, 2019, 09:44:17 AM »
You are correct binntho... the Coriolis force combined with frictional effects between the wind and sea surface causes the ocean currents to deviate to the right of the wind in the NH.  Look up Ekman transport/spirals for more info.  So, somewhat counterintuitively, low pressures cause dispersion from the center; and high pressures compaction towards the center.

The recent/current LP that moved from the CAA into the northern Beaufort/CAB has definitely caused some ice to disperse.  This effect has stalled the extent numbers somewhat... an artifact of the dispersion, and not an actual improvement in the state of the ice.

Arctic sea ice / Re: The 2019 melting season
« on: August 28, 2019, 04:56:16 AM »
Nice. Didn't realise you could drag the base layers and have semi transparent modis over bathy.
No gifs with transparency though
Yesterday I compared 2012 ice cover with this year on the same date. This tool makes it easy to compare both years, and I don't see any way how we could catch up to 2012 without an apocalyptic storm.

2012 vs 2019

Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: August 28, 2019, 12:41:52 AM »
New whoi buoy itp116 north of Greenland.
No microcats, only the profiler.

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