Support the Arctic Sea Ice Forum and Blog

Author Topic: MOSAiC news  (Read 36467 times)

A-Team

  • Nilas ice
  • Posts: 2455
    • View Profile
  • Liked: 306
  • Likes Given: 22
Re: MOSAiC news
« Reply #400 on: December 10, 2019, 04:08:13 PM »
Thx, Jayw! It seems like the second latitudinal circle is not 86º as I thought but maybe 87.5º? (Best to have two  of each labelled for scale.) Indeed the PS has had a strong tailwind from the south.

Is there any meaning to the tumbling of the Polarstern image, or just variable cloud cover obscuring part of the heat source? (The Kapitan Dranitsyn steps are quite big as it is under steam.)

The bottom Lagranian/Eulerian double animation of the 4 S1AB today does not indicate major changes in the ship's orientation that could explain tumbling though the Mosaic floe seems to change quite a bit despite steady conditions.

It can very much be affected by 'action at a distance' elsewhere in the ice pack. That is, the area including the Mosaic floe is seen moving due north for several days but there is already thick ice between it and the CAA -- where does it go?

The 06:45 S1B came in ... it seems to show rapidly disappearing tracks relative to the three S1AB composite back in post #396. How much of the non-linearity is due to the KD following a favorable path through the ice and how much is due to ice shifting and shearing over five hours?

2019 12 10 0635
2019 12 10 0408
2019 12 10 0319
2019 12 10 0140
« Last Edit: December 10, 2019, 09:55:50 PM by A-Team »

blumenkraft

  • Nilas ice
  • Posts: 1593
  • Fans of Hans Club - circa 2018
    • View Profile
  • Liked: 712
  • Likes Given: 985
Re: MOSAiC news
« Reply #401 on: December 10, 2019, 04:13:12 PM »
And again, RAMMB-SLIDER is stuck at 07:02GMT ... ARGL!

KD here >>
Refugees welcome

blumenkraft

  • Nilas ice
  • Posts: 1593
  • Fans of Hans Club - circa 2018
    • View Profile
  • Liked: 712
  • Likes Given: 985
Re: MOSAiC news
« Reply #402 on: December 10, 2019, 05:21:26 PM »
Is there any meaning to the tumbling of the Polarstern image, or just variable cloud cover obscuring part of the heat source?

JPSS/SNPP is by default a little wobbly. There seems to be an alignment issue.

Atmospheric turbulences could be another reason.
« Last Edit: December 10, 2019, 05:42:41 PM by blumenkraft »
Refugees welcome

A-Team

  • Nilas ice
  • Posts: 2455
    • View Profile
  • Liked: 306
  • Likes Given: 22
Re: MOSAiC news
« Reply #403 on: December 11, 2019, 09:58:32 AM »
The Kapitan Dranitsyn is making surprisingly good time and on the S1B  04:00 this morning was only 112 km due south of the Polarstern. On the S1B 0538, the frozen-in Polarstern had passively drifted a slight distance north and west whereas the KD was actively underway as well benefitting from the same drift.

Since we have two lat,lon for the two ships from two satellite images 1.633 hours apart, it can be  calculated (haversine) that the KD has closed in on the PS 10.6 km in that time which suggests it is preceding rapidly in thin ice and would rendezvous in 15.6 hrs except that thicker ice will slow it down but still 24 hrs seems reasonable.

GFS nullschool has a different updated forecast, showing the Polarstern on the edge of an anti-cyclone centered in the Chukchi for the next few days. If so, winds will pick up somewhat and drift will less towards the pole and more (unwanted) drift east (yellow arrow). This represents less than ideal but still manageable conditions for docking and fuel, equipment and personnel transfer.

The KD will likely dock alongside but outside of the Polarstern which is moored with the starboard side along the Mosaic floe. The involves circling around from the east so as not to create a trail of fractured ice that would later affect leads and pressure ridges in the experimental area.
« Last Edit: December 11, 2019, 12:14:20 PM by A-Team »

uniquorn

  • Nilas ice
  • Posts: 1639
    • View Profile
  • Liked: 790
  • Likes Given: 164
Re: MOSAiC news
« Reply #404 on: December 11, 2019, 01:40:44 PM »
Quote
thicker ice will slow it down
Based on the ice mass balance buoys in the area it doesn't look like the ice will present much of a challenge. It's of some concern that the ~1m ice at 386850 doesn't appear to have thickened much at all.

drift update, a new northerly record? see below
edit: forum still displaying 700px gifs at 580px
« Last Edit: December 12, 2019, 03:05:15 PM by uniquorn »

blumenkraft

  • Nilas ice
  • Posts: 1593
  • Fans of Hans Club - circa 2018
    • View Profile
  • Liked: 712
  • Likes Given: 985
Re: MOSAiC news
« Reply #405 on: December 11, 2019, 05:45:21 PM »
Day&Night band overlayed with M15 band.

The KD captain seems to follow the leads.
Refugees welcome

blumenkraft

  • Nilas ice
  • Posts: 1593
  • Fans of Hans Club - circa 2018
    • View Profile
  • Liked: 712
  • Likes Given: 985
Re: MOSAiC news
« Reply #406 on: December 11, 2019, 06:52:44 PM »
Hmm, not much way was done towards PS between 09:17 and 14:21 UTC.  ???
Refugees welcome

A-Team

  • Nilas ice
  • Posts: 2455
    • View Profile
  • Liked: 306
  • Likes Given: 22
Re: MOSAiC news
« Reply #407 on: December 11, 2019, 07:03:45 PM »
Quote
drift update, a new northerly record?
Yes. Just paste the whole raw non-tabbed page into a database and sort descending, the northern most latitude will pop to the top since it is on the far left. However from five day GFS, drift will be mostly back east and south.

86.6  120.5 19-12-11 16:00    7  170    -26.1
https://www.awi.de/fileadmin/user_upload/MET/PolarsternCoursePlot/psobsedat.html

For the 128 S1AB times to date, the winds, heading and temperature statistics to date:

ave   7.8  137  -18.6  85.7474   122.9168
max   17   360  -3.9   86.4748   135.8584
min   2     10  -30.9  84.7617   113.0207


Hopefully we can get all caught up in our tracking endeavors at the time of transition from leg 1 to leg 2. The Kapitan Dranitsyn may be bringing a whole new batch of them.

We need a dedicated buoy adopter like in days of old. It was easier with 1-2 buoys, now it is a swarm. No more expesnive Mosaics after this; from here on out it will be more, sturdier, smarter buoys. By the tens of thousands if needed.

The overall situation with buoy monitoring is complicated. Meereis Portal does not keep up at all; IABP is more comprehensive but has strange reporting practices -- buoys appear and disappear over time whereas once a buoy is deployed and working it should only drop onto the non-reporting list of dead buoys, never be deleted.

Below the old Oct 31 buoy collection is reconciled with a new Dec 11 download. Of the 96 buoys currently listed, 15 are dead (have not reported in over a week). A disproportionate number of these were set out by AWI:

300234062881930   SVP-B   AWI   11 10 19   84.98   134.5
300234066081180   Snow    AWI   17 10 19   84.62   133.29
300234068519770   CTD     AWI   25 10 19   85.32   128.36
300234068713430   CTD     AWI   26 10 19   85.55   126.17
300234066346540   Snow    AWI   02 11 19   85.96   122.71
300234068160720   CTD     AWI   22 11 19   85.19   125.38
300234066080170   Snow    AWI   26 11 19   86.04   117.67
300234066344810   Snow    AWI   28 11 19   86.00   119.17
300234066415350   UT      OSU   26 09 19   81.57   107.51
300234066412350   UT      OSU   12 11 19   86.04   117.56
300234068210190   SVP     PRI   02 12 19   85.92   113.85
300234065982560   GPS     TUT   28 10 19   85.62   126.86
300234065988570   GPS     TUT   04 11 19   85.99   116.25
300234065980580   GPS     TUT   31 10 60   85.41   129.51
000000000900111   ITP     WHO   27 11 19   86.07   116.68


2
300234066412350   dead list, on new, missing old
300234066415350   dead list, on new, missing old


13
000000000900111   dead list, on old, on new
300234062881930   dead list, on old, on new
300234065980580   dead list, on old, on new
300234065982560   dead list, on old, on new
300234065988570   dead list, on old, on new
300234066080170   dead list, on old, on new
300234066081180   dead list, on old, on new
300234066344810   dead list, on old, on new
300234066346540   dead list, on old, on new
300234068160720   dead list, on old, on new
300234068210190   dead list, on old, on new
300234068519770   dead list, on old, on new
300234068713430   dead list, on old, on new


15
300025060314090   on new, missing old
300234060320930   on new, missing old
300234060320940   on new, missing old
300234065091110   on new, missing old
300234065094850   on new, missing old
300234067705700   on new, missing old
300234067705760   on new, missing old
300234067706680   on new, missing old
300234067707750   on new, missing old
300234068706290   on new, missing old
300234068706330   on new, missing old
300434063382860   on new, missing old
300434063384820   on new, missing old
300434063386850   on new, missing old
300434063387850   on new, missing old


7
300234066080220   on old, missing new
300234066081220   on old, missing new
300234066082230   on old, missing new
300234066084230   on old, missing new
300234066085220   on old, missing new
300234066087220   on old, missing new
300234066089220   on old, missing new

66
000000000090094   on both, still reporting
000000000900102   on both, still reporting
...


http://iabp.apl.washington.edu/TABLES/ArcticTable.php#BumBuoys
« Last Edit: December 11, 2019, 07:42:22 PM by A-Team »

A-Team

  • Nilas ice
  • Posts: 2455
    • View Profile
  • Liked: 306
  • Likes Given: 22
Re: MOSAiC news
« Reply #408 on: December 12, 2019, 10:51:46 AM »
The Kapitan Dranitsyn was not where I had expected it to be this morning but rather well east of the 120º meridian where the Polarstern sits becalmed at 86.6º. Still the KD track is almost to 86.0º so it has some 65 km to go. Location data from cruise mapper do not agree with the Sentinel track. The course of the KD stands out best on the 05:30 S1A:

http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201912/S1A_EW_GRDM_1SDH_20191212T053019_F6E3_N_1.8bit.jp2

The KD may have other assignments such as retrieving moorings or placing/servicing buoys and other instruments. Its mission was initially said to be 5-6 weeks, quite a bit more time than needed just for a refueling and crew swap.

Mild GFS weather the next five days will facilitate the KD's refueling task. No significant drift will be taking place through Dec 15th. The current ice thickness averaged over ~25x25 km is 1.41 m according to cryo2smos observational product. Specific micro sites will vary.

Quote
To avoid damaging the research camp during the resupply missions Kapitan Dranitsyn will drop anchor several hundred meters away and pump fuel to Polarstern using heavy-duty hoses. The remaining supplies and the researchers’ equipment will be hauled to camp on sledges pulled by snowcats. On her return journey, Kapitan Dranitsyn will take any waste that isn’t suitable for Polarstern’s special litter-incineration system... Fuel depots for long-range helicopters have been set up on Bolshevik Island but are not expected to be used... Mid-June 2020, the Swedish research icebreaker Oden handles exchanges .... The new Chinese icebreaker Xue Long 2 is assigned mid-August resupply.

https://www.mosaic-expedition.org/expedition/logistics/
« Last Edit: December 12, 2019, 04:23:11 PM by A-Team »

uniquorn

  • Nilas ice
  • Posts: 1639
    • View Profile
  • Liked: 790
  • Likes Given: 164
Re: MOSAiC news
« Reply #409 on: December 12, 2019, 03:05:54 PM »
drift update, ~12 days in 50 frames

A-Team

  • Nilas ice
  • Posts: 2455
    • View Profile
  • Liked: 306
  • Likes Given: 22
Re: MOSAiC news
« Reply #410 on: December 12, 2019, 07:16:55 PM »
Fabulous! The hairpin turn coincides with what we know from Sentinel imagery to be the most disruptive event of the trip. So far, it has gone unreported from the Mosaic camp; with all eyes now on the KD refueling, trip home, and a lull in the weather allowing repairs, it will probably never get reported other than in distant memoirs.

Continuity in data collection is quite important for some but not all instruments. The issue is not a few missing hours but rather permanent loss of experimental equipment and abandonment of deployment sites. Mosaic costs some $280,000 a day so loss of a million-dollar sensor is just a rounding error; the problem comes with the logistics of replacing it (or not).

The animation below cuts to 34 critical hours centered on the hairpin and adds available S1AB imagery, hourly weather data from sailwx-assisted awiMet (which is quite gappy as usual), plus revisited (but not reanalyzed) GFS wind motion links keyed to the hourly and PolarViewer links keyed to the S1AB.

The questions here: what caused the severe motion in and around the ice camp, to what extent were they local, regional or whole ice pack in scope, and could they have been anticipated from the GFS forecast?
« Last Edit: December 12, 2019, 07:29:26 PM by A-Team »

uniquorn

  • Nilas ice
  • Posts: 1639
    • View Profile
  • Liked: 790
  • Likes Given: 164
Re: MOSAiC news
« Reply #411 on: December 12, 2019, 09:12:15 PM »
<Catch up on buoys>
63 iabp buoys visible on this image, 86 are loaded so some are reporting late or not at all. An animation should show that up. Those in colour are reporting temperature at surface.
cffr
« Last Edit: December 12, 2019, 10:00:10 PM by uniquorn »

uniquorn

  • Nilas ice
  • Posts: 1639
    • View Profile
  • Liked: 790
  • Likes Given: 164
Re: MOSAiC news
« Reply #412 on: December 12, 2019, 09:58:16 PM »
Closer to PS
p201 is 8912800
p207 is 8918790
nearest buoy to PS on this selection is probably 8215980
cffr
« Last Edit: December 12, 2019, 10:14:26 PM by uniquorn »

blumenkraft

  • Nilas ice
  • Posts: 1593
  • Fans of Hans Club - circa 2018
    • View Profile
  • Liked: 712
  • Likes Given: 985
Re: MOSAiC news
« Reply #413 on: December 13, 2019, 09:07:23 AM »
The KD arrived as of 3:33 UTC !!

Will post aRAMMB-SLIDER GIF later today.
Refugees welcome

A-Team

  • Nilas ice
  • Posts: 2455
    • View Profile
  • Liked: 306
  • Likes Given: 22
Re: MOSAiC news
« Reply #414 on: December 13, 2019, 11:49:02 AM »
Round-about route the last day as the going got toughter but docking as expected to the east of the Polarstern on the 05:31 on Dec 13th. The Kapitan Dranitsyn is still moving into position between 03:43 and 05:21. The 07:00 S1B just misses in its coverage.

The tracks have to be captured within 24 hrs on a S1AB or they become all but impossible to follow.

The large extended black lead to the south (up) is an unexpected overnight development but so far seems to have no effect on fueling or Mosaic ice camp equipment. It is not notably active between 03:43 and 07:00. There is no sign of it yesterday on the 05:30 S1A.

Regionally, there is quite a bit of ice dynamics, mostly shearing. The PS and KD are perhaps 10 km north (down) of a massive block shear zone. The overnight pair of images below are being viewed in a coordinate system in which the Polarstern is fixed.

This would have been a full-on disaster had the shear line come through Ice Camp while the Polarstern was refueling or exchanging out equipment and scientists. It didn't and people on the ground may have been oblivious to it.

The explanation of the event is the passing of mild wind shear from southeast to northwest across the Polarstern's position. At no time were winds extreme; instead the delta of wind (6 km/hr to 31 km/hr) caused the ice to move differentially across the gradient.

The ice is still too mechanically weak this winter to distort south of the PS's position so brittle-fractured along a line parallel to wind stress where it is thicker. The event is largely over per GFS though ice movement is foreseen to somewhat reverse in coming days. Again, this was not a winter cyclone, just uneven regional wind stress.

On uniq's upcoming (we hope!) mega buoy animation, we can expect some sharp zigzags distinguishing buoy sets above and below the event. This will greatly improve time resolution of the main fracture over what 24-hr S1AB can do, in this instance 24 less 2:36 hrs compared to half-hourly or even ten minutes.

2019 12 13 0343
2019 12 12 0619


Start at the location below and step back in 3-hr steps (keyboard 'j').

https://earth.nullschool.net/#2019/12/13/0300Z/wind/isobaric/1000hPa/orthographic=-45.00,90.00,1100/loc=119.5,86.6
« Last Edit: December 13, 2019, 06:34:51 PM by A-Team »

Aleph_Null

  • Frazil ice
  • Posts: 138
    • View Profile
  • Liked: 50
  • Likes Given: 203
Re: MOSAiC news
« Reply #415 on: December 13, 2019, 06:59:45 PM »
I'll only do this once, because I have nothing to add but gratitude. A-Team's last 24-hr shear gif is jaw-dropping. It sure looks to be a dangerous place. The people on that boat are clearly risking their lives for invaluable understanding of the icecap. Above and beyond... what can you say?

The reporting in this thread has been riveting, and also invaluable for understanding the icecap.

uniquorn

  • Nilas ice
  • Posts: 1639
    • View Profile
  • Liked: 790
  • Likes Given: 164
Re: MOSAiC news
« Reply #416 on: December 13, 2019, 09:42:09 PM »
Festive season so a little bit late. Here testing animation of many iabp buoys, one showing a spurious latlon and a couple who think it's14dec already. It may take more analysis (than I am capable of right now) to detect that shear.
Interesting that one buoy to the south jumped backwards though

see update below.
« Last Edit: December 14, 2019, 03:53:17 PM by uniquorn »

A-Team

  • Nilas ice
  • Posts: 2455
    • View Profile
  • Liked: 306
  • Likes Given: 22
Re: MOSAiC news
« Reply #417 on: December 13, 2019, 10:04:11 PM »
Quote
24-hr shear gif is jaw-dropping
Early morning, just absent-mindedly updating the S1AB collection, not seeing any drama on the ingest of the three Dec 13's, not expecting much by way of drift at low wind, at best thinking about the KD cutting a swath pre-conditioning the ice camp to future lead and ridge problems, then wondering when that meaningless lead came about, checking with the 24 hr, making the overlay pair, running it real fast in ImageJ, then my jaw-dropping moment seeing the long shear boundary, to pondering what an event-driven diesel spill during refueling the PS would mean for Arctic research, to asking whether risk to researchers is maybe higher than anticipated (indeed higher than acceptable, this being the 4th major incident in 69 days), to looking at historical stats on expected major cyclones of winter still ahead.

We have the tools to do a lot more analysis on the Friday The 13th fracture (FT13). It does seem fairly easy to recognize conditions conducive to disruptive events a couple days out on GFS, though it seems we don't know enough about ice pack strength to differentiate between deformation and shear, much less predict location of shear lines relative to the Mosaic ice camp. The surprise is, we do know enough to make those predictions.

The attachments below are just two plain text documents giving active urls to all Sentinel Viewer back to mooring and their accompanying PS position- and S1AB-aware GFS nullschools. The buoy position repositories and ship weather are at their respective archives

Sure, we could post a swinging risk needle like the Forest Service does for fire hazard but would it really be actionable down at the ship, would someone not go out to tend a deployed instrument when the needle was on yellow or red?

The buoy swarm animation provides a very sensitive nrt tool that can detect and report occurrences of not-too-remote rifting, though their current distribution was not thought out and is sub-optimal. However an after-the-fact announcement is not a warning, unless the shearing is taking place in abrupt stages (like earthquake after-shocks).

Here Uniq will be looking for an upper zone of plastic buoy position deformation in conjunction with a lower zone of rigidity that preceded the rupture at the interface. Would that give hours of warning or minutes? Would that give warnings of all events or just some?

Here we need a whole lot less mickey mouse from the inhabitants of the Mosaic buoy deploying academic silos, like delays in posting, lack of Iridium redials, lack of time synchronization, irregular GPS reads, lack of gap repair, lack of QA, and worst of all, dumbing down the decimal points (AWI, I'm talking to you).

In other words, changing inter-buoy distances provide an interferometric mesh from which a tensiometer is built. GPS is not up to lasers but still very capable today since Every Decimal Point Matters even if the last is not quite as good as the first. Right now, buoy runs take too long for the desktop but there are ultra-fast migration options for anything in R.

Given eight years of planning, why are we scrambling today to put together risk mitigation software?

uniquorn

  • Nilas ice
  • Posts: 1639
    • View Profile
  • Liked: 790
  • Likes Given: 164
Re: MOSAiC news
« Reply #418 on: December 14, 2019, 03:51:31 PM »
Update of yesterday's test animation of many iabp buoys, one showing a spurious latlon and a couple who think it's15dec already. Will make a manual correction of their DOY at some point.

Tor Bejnar

  • Young ice
  • Posts: 3116
    • View Profile
  • Liked: 409
  • Likes Given: 200
Re: MOSAiC news
« Reply #419 on: December 14, 2019, 06:24:24 PM »
Quote
one showing a spurious latlon
Maybe it had to go to the loo, but came right back  ::) :D
Arctic ice is healthy for children and other living things.

A-Team

  • Nilas ice
  • Posts: 2455
    • View Profile
  • Liked: 306
  • Likes Given: 22
Re: MOSAiC news
« Reply #420 on: December 14, 2019, 08:46:17 PM »
Quote
one showing a spurious lat lon and a couple who think it's 15 dec already. Will make a manual correction at some point.
Somebody not doing a proper job of curation and posting in ingestible format at the upper end makes pipeline science all but impossible for everyone downstream. Buoys and AWI wx present new problems every day. (Despite that, the latter is ingested directly by ECMWF for Arctic forecasting.)

Even if you made manual corrections all the way back to Oct 4th (and posted them prominently), there is no mechanism to correct the source (ie fix shabby or non-existent QA tools there). Tomorrow, instead of rolling your animation forward on auto-pilot to the next day, the add-ons will have to be manually corrected. For 95 buoys? For 95 pipelines feeding large scale climate prediction?

Following up on the near-catastrophic shear on Dec 13, the buoy system should show a lurch to the right (west) on the more southerly buoys above the shear line relative to the buoys on the Polarstern side of the line (north is below).

However that is not immediately apparent, probably because we need to run the buoy data much closer to its intrinsic positional resolution. That is, it would suffice to limit the graticule to 86.50-86.65 and 117-121 or about a tenth of the area in uniq's animation above. This would allow more of the 4-5 decimal points in the buoys's GPS to come into play, not just one.

Alternatively, if the rupture was not abrupt but spread out over a few hours, we might have to dig into select buoy db numerical analysis rather than rely on graphics to date the event.

In terms of weather contribution to causality, 3-hour GFS shows a complete reversal of wind direction accompanied by an up down up cycle of wind strength with sharp wind curvature in between though not right at the Polarstern's location. Note this wx depiction would not be identical to the GFS forecast on Dec 12th because it re-initializes each day; the time series was made well after the fact.

Until the buoy reanalysis is finalized, it is not feasible to assign a time of shear rupture to a pair of bracketing GFS frames; even then we don't know the offset between cause and effect.
« Last Edit: December 14, 2019, 11:19:25 PM by A-Team »

uniquorn

  • Nilas ice
  • Posts: 1639
    • View Profile
  • Liked: 790
  • Likes Given: 164
Re: MOSAiC news
« Reply #421 on: December 14, 2019, 10:27:06 PM »
closer to the shear, dec11-13 in 200 frames for detail, removed the 4smb's with faulty DOY, kept the incontinent one, no grat labels. May have time tomorrow to compare a couple each from below and above.

uniquorn

  • Nilas ice
  • Posts: 1639
    • View Profile
  • Liked: 790
  • Likes Given: 164
Re: MOSAiC news
« Reply #422 on: December 15, 2019, 04:28:39 PM »
Quick messy comparison of 4 buoys close to the shear. The drift path difference would appear to be subtle at this resolution. The datetime and buoyid's are good. LatLon text is not updating yet.

#420 digitized shear...
p201 is 8912800
p207 is 8918790
PS should be located between these two buoys, one square to the left. Perhaps my manual labelling is suspect?

< the buoy system should show a lurch to the right>
 lurch may happen before the animation starts, though the timing is wrong. Will zoom in further I think.
« Last Edit: December 15, 2019, 04:48:39 PM by uniquorn »

uniquorn

  • Nilas ice
  • Posts: 1639
    • View Profile
  • Liked: 790
  • Likes Given: 164
Re: MOSAiC news
« Reply #423 on: December 15, 2019, 04:57:19 PM »
I'll only do this once, because I have nothing to add but gratitude.
An occasional 'pressure, wind & density' focussed on the mosaic area might be useful. Particularly for this recent event.

blumenkraft

  • Nilas ice
  • Posts: 1593
  • Fans of Hans Club - circa 2018
    • View Profile
  • Liked: 712
  • Likes Given: 985
Re: MOSAiC news
« Reply #424 on: December 15, 2019, 05:17:02 PM »
Agreed!
Refugees welcome

A-Team

  • Nilas ice
  • Posts: 2455
    • View Profile
  • Liked: 306
  • Likes Given: 22
Re: MOSAiC news
« Reply #425 on: December 15, 2019, 05:52:40 PM »
Right, this is all about getting to the right scale as constrained by forum image widths. Previously we've determined that a degree of latitude as marked on S1AB jpg with lines is 2712.26 pixels for what we know is 111.111 km on WGS84 (which we have to use here as all GPS data refers to the earth ellipsoid).

Thus image distances can be measured in pixels (often fractional if points are diagonal) and converted to meters by multiplying by 41.0 for both S1AB jpg and S1AB.8bit.jp2 (at 100% zoom in the polar viewer plugin).

Doing this, it emerges that the Polarstern was 3703 m north of the shear line. The 79 km long open lead created in this area ranged from 730 m in width to a more typical 487 m to 159 m at narrows. A lead of this width cannot be bridged by wooden palettes and a sled, nor is it feasible to kayak across regularly carrying staff, bear guards and fuel for instruments (as Mosaic was doing earlier).

The dramatic regional shear animation of post #412 that compared Dec 12 06:19 to Dec 13 03:43, repeated below, was done in Polarstern-stationary coordinates (lagrangian) which removes background ice pack movement (secular drift).

The rifting took place as the pack as a whole moved almost due westward by 4301 m but with a 410 m north component. Relative to the Polarstern, the shear area moved an additional 4146 m southeastward.



It's worth walking through GPS decimal points which have quite different associated measures for lon than lat.

At 86.6º, a tenth of a latitude degree increment represents 11.111 km, a hundredth 1111 m, a thousandth 111 m, a ten-thousandth 11.1 m and a hundred-thousandth 1.1 m.  The first is what we are looking at with sailwx and AWImet; the second what GFS-nullschool can discriminate at maximal scale, the third enough to show a buoy lurch and the last the nominal resolution claimed by typical Mosaic buoys (4th GPS decimal point).

Note the buoys are in motion during whatever time it takes for them to measure their position. Those speeds, given as the color scale on uniq's animations rarely exceed 1 km/hr which is 1000 m per 3600 seconds or 0.27 m/s. So if it took them 5 seconds, that would be 1.4 m which might amount to a correction to their last decimal.

2019 12 13 0343  86.6  119.5  86.5918  119.4764  rough and refined PS locations post shear
2019 12 12 0619  86.6  120.1  86.5982  120.1285  rough and refined PS locations pre shear

So what needs to be done -- and I am leaving this to Tor B -- is download the data files for 2-3 buoys above the shear and 2-3 below using the map below (or as provided by uniq), delete the irrelevant columns, combine into a single spreadsheet with times of reported synchronized by row. Then add a new column and fill with the subtraction of above/below longitude columns.

The graph should show a big lurch at the hour of rifting.

As a control, go back a week or so to establish the big lurch is way out of the ordinary, not 'normal variation'. Going forward, the winds have hardly been enough to stress the ice, meaning delaunay buoy triangulations across the shear line will have stable edges.

Nonetheless, this morning's pair of S1AB 3 hrs 16 min apart don't show a quiescent situation on the Mosaic ice pack (lower animation). Indeed a small rift seems to be closing at the later time. This does not necessarily affected deployed instruments as only a small flat area near the ship is currently used.

The Kapitan Dranitsyn can be seen crossing the shear line within hours of its formation. It's not clear what would happen to an icebreaker caught in a sudden shear event. The Polarstern, being frozen in for a year, is more at risk.

Shear events with km scale displacements are multi-daily events even at the scale of a single S1AB frame, but one crossing a 118 m object amidship would not be expected unless the ship, like Los Angeles, is sitting on an inactive fault line predisposed to re-awakening.

While the Polarstern has not disclosed the data that would allow analysis (it being below the resolution of S1AB), they have had slabs of ice sliding back and forth in front of the bow, micro-shear events. In addition, the undocumented Dec 6th event saw a larger faulting event come right through Mosaic ice camp.

In summary, the ice has been shifting around a lot already this winter at various scales with only 2 months down and 4-5 months to go. It's tempting to say 'more than usual' but hard to go beyond anecdotal impressions. This has been a very odd winter in terms of no coherent ice pack drift (as visualized above in Ascat whole-Arctic mp4).
« Last Edit: December 15, 2019, 06:39:23 PM by A-Team »

uniquorn

  • Nilas ice
  • Posts: 1639
    • View Profile
  • Liked: 790
  • Likes Given: 164
Re: MOSAiC news
« Reply #426 on: December 15, 2019, 09:01:05 PM »
Quite festive here today but also some interest in arctic buoys so here are 7 buoys close to the rift. We've voted that the one on it's own has a data glitch (8916790).

edit: I change my vote since it looks like 8916790 was right on the rift.
« Last Edit: Today at 12:47:27 AM by uniquorn »

gerontocrat

  • First-year ice
  • Posts: 6833
    • View Profile
  • Liked: 1732
  • Likes Given: 22
Re: MOSAiC news
« Reply #427 on: December 15, 2019, 09:11:20 PM »
In my naivety I thought the MOSAIC project might be lucky as far as the solidity of the ice pack was concerned.

For why? The Central Arctic Sea froze up so early this year from a minimum that was also higher than in recent years.

How wrong can I get?
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

A-Team

  • Nilas ice
  • Posts: 2455
    • View Profile
  • Liked: 306
  • Likes Given: 22
Re: MOSAiC news
« Reply #428 on: December 15, 2019, 09:11:52 PM »
Here are recent paper titles from the highly qualified Mosaic leg 2 leader, AWI's Christian Haas. His interests are much more remote sensing and ice-related than leg 1 atmospheric physicists. Let's hope that there will be a much more open science focus to Polarstern communications in coming months.

Winter rain, as Haas notes, would really be a game-changer for snow thermal properties and spring albedo. The recent polar lightning, detected by a Finnish company specializing in remote detection and employing my neighbor, also came as quite a surprise. The Polarstern is not set up to detect it unless it is right overhead. Rain? The PS may have doppler radar but not one dedicated to rare events.

Some strong winds are expected this week but nothing approaching gale force. The GFS outlook has changed so much from yesterday that it is hard to predict coming Polarstern drift, though it will be almost entirely to the west (smaller longitudes) with a small component north, so maybe 86.7, 114.0 by Dec 20th from where it is now, 86.6, 117.7.

-- Arctic warming interrupts the Transpolar Drift and affects long-range transport of sea ice and ice-rafted matter

-- Ice and snow thickness variability and change in the high Arctic Ocean observed by in situ measurements

-- Helicopter-borne measurements of sea ice thickness, using a small and lightweight, digital EM system

-- Arctic warming interrupts the Transpolar Drift and affects long-range transport of sea ice and ice-rafted matter

-- 13-years of sea ice draft observations in the Laptev Sea from moored ADCPS and ULSs

-- The timing and intensity of snowmelt processes on sea ice are key drivers

-- Seasonal changes in snow properties from passive and active microwave satellite observations: 

-- Vertical snow structures from in-situ and remote sensing measurements

-- The Arctic Permafrost Geospatial Center-a portal for high-quality open access scientific data related to permafrost

-- Snow depth on Arctic sea ice derived from airborne radar measurements

-- Large-scale ice thickness distribution of first-year sea ice in spring and summer north of Svalbard

-- Contrasting ice algae and snow dependent irradiance relationships between first year and multiyear sea ice

-- Snow-related variability of spectral light transmittance of Arctic First-Year-Ice in the Lincoln Sea

-- Seasonal changes in snow properties from passive and active microwave satellite observations

-- Snow depth on Arctic sea ice derived from airborne radar measurements

-- 13-years of sea ice draft observations in the Laptev Sea from moored ADCPS and ULSs

-- Contrasting ice algae and snow dependent irradiance relationships between landfast firstyear and multi year sea ice

-- The 2018 North Greenland polynya observed by a newly merged optical and passive microwave sea-ice concentration

-- Snow-related variability of spectral light transmittance of Arctic First-Year-Ice in the Lincoln Sea

-- Contrasting ice algae and snow dependent irradiance relationships between landf-ast first year and multi-year sea ice

-- Ice and snow thickness variability and change in the high Arctic Ocean observed by in situ measurements
« Last Edit: Today at 12:33:19 AM by A-Team »