Support the Arctic Sea Ice Forum and Blog

Author Topic: The 2018 melting season  (Read 616718 times)

oren

  • Moderator
  • First-year ice
  • Posts: 5509
    • View Profile
  • Liked: 1694
  • Likes Given: 1593
Re: The 2018 melting season
« Reply #2800 on: August 13, 2018, 02:43:07 PM »
DR may I politely ask to limit this thread to discuss the actual melting season, instead of speculation of what could the melting season be like if some fantasy scenario played out? You already have the "ice-free CAB" thread for that.

RoxTheGeologist

  • Frazil ice
  • Posts: 492
    • View Profile
  • Liked: 144
  • Likes Given: 106
Re: The 2018 melting season
« Reply #2801 on: August 13, 2018, 04:25:54 PM »
The images below look into a suggestion of FishOut that the north Greenland anomaly has to do with warm Atlantic Water somehow making its way west rather than (or in addition) to its usual circling to the east around Yermak and Svalbard.

This could result from a weakening of the East Greenland Current, or an eddy from countercurrent flow or layers at different depths passing under/over each other, perhaps as a 'new normal' for late summer or just a pulse due to one-off wind or salinity patterns.


Thanks A-Team, great graphics, as always.

It makes sense that the interaction of the Warm Atlantic, the Cold Fresher Surface and deeper Arctic waters exciting the Fram are turbulent and complicated. I picture a cold fresh water layer and a deep Arctic Bottom waters layer moving south and mixing with the warm salty Atlantic mid-layer. It's compelling that the salinity and warmth in the last slide are in the same places. It supports FOW's hypothesis that the winds blowing the ice away from the land will cause upwelling of Atlantic Waters on the shallow shelf.

My guess would be that it's not a permanent feature, but I fear that it will become more frequent as the pycnocline 'weakens' and the density difference resisting vertical mixing declines.

A-Team

  • Young ice
  • Posts: 2547
    • View Profile
  • Liked: 360
  • Likes Given: 29
Re: The 2018 melting season
« Reply #2802 on: August 13, 2018, 06:48:44 PM »
Quote
picture a cold fresh water layer and a deep Arctic Bottom waters layer moving south and mixing with the warm salty Atlantic mid-layer. compelling the salinity and warmth
There are at least six head-scratchers going on right now, with a full month still to go in the formal melt season: the Laptev, the SV-FJL-SZ corridor, the persistent pockets off Alaska and and Wrangel, the developing bight in the CAB at the BeauChuk junction, retreating ice at the Fram and open water above 85ºN above the Nares.

We might have to spend the first month of the freeze season trying to understand what happened the last month of the melt season!

Looking at the north Greenland situation with a 1.5 km UH AMSR2 (which has enough resolution to show individual floes circling about), that event is continuing despite a declining show of blue yesterday (first graphic concatenates Aug 01-12 thumbnails), as a closer look shows at the swirling floes in the stomach-churning first gif below shows compaction and over-weathering of sea ice concentration.

Something seems seriously amiss these days with the normally reliable East Greenland Current. There too the floes are milling about in crazy ways instead of preceding in an orderly manner down the Fram. Floe motion here is indicating surface water eddies as GFS-nullschool is showing blah winds that haven't resulted in outlandish floe motion in the past.

This is a very complex region oceanographically, especially on the Yermak-Svalbard side where rough topography has allowed internal diurnal tide-induced waves despite being north of the critical latitude at which the Coriallis force forbids it. None of the many published studies are applicable though to the sea ice retreat conditions we have today.

Ironically the Polarstern is out there right now. It's not likely they could repurpose the mission on the fly for this event; their focus -- so last year -- is more on warm waters accelerating loss of East Greenland ice shelves. It would be great if they could drop a profiler right at the flux gate as that could reveal how current direction and speed vary with depth (along with temperature, salinity and density).

Beyond that, ditto the Korean icebreaker Aaron out there now in the Chukchi with J Stroeve et al on board, they wouldn't be sharing anything of substance with us over twitter as data must be held back until 2020-21 journal papers can appear. Still we do have members here who are in regular contact with the Polarstern so it might be worth a question or two for their take on the current Fram situation.
« Last Edit: August 13, 2018, 07:11:31 PM by A-Team »

johnm33

  • Nilas ice
  • Posts: 1414
    • View Profile
  • Liked: 171
  • Likes Given: 64
Re: The 2018 melting season
« Reply #2803 on: August 13, 2018, 06:53:23 PM »
With the winds as they are I would expect the ice to lift off the garlic press, but there's a high pressure in Beaufort and a low in north Baffin and the easiest fraction of water to move is the surface water by the channels. It looks, on uniquorns gif and on hycom as if ice is pouring through even if none arrives in Baffin

nullschool

bbr2314

  • Nilas ice
  • Posts: 1817
    • View Profile
  • Liked: 166
  • Likes Given: 53
Re: The 2018 melting season
« Reply #2804 on: August 13, 2018, 07:11:53 PM »
With the winds as they are I would expect the ice to lift off the garlic press, but there's a high pressure in Beaufort and a low in north Baffin and the easiest fraction of water to move is the surface water by the channels. It looks, on uniquorns gif and on hycom as if ice is pouring through even if none arrives in Baffin

nullschool
If the ice is pouring through then so is the freshwater lens.

It appears the Gulf Stream has now given up almost entirely over its old path, with so much warm water blocked by the cold melt / albedo driven anomalies E of Canada that it is partially back-flowing with warm eddies heading toward the East Coast, diverting a portion of what would normally flow NE. I am not sure if this is exactly what is happening, but it appears to be the case.

The partial or full collapse of the traditional Gulf Stream may explain (partially) why portions of North America had their coldest April / May in the historical record (since 1895). With CO2 at something like +50% vs. what it was in 1895, I can't think of anything else that would explain why certain places in the mid-latitudes are now snow-covered into April and May.

The question is whether this spring was a one-off, or if it will be repeated imminently but we get a break of a yr or two, or if we return to the exact same state in the fall, if we have passed some sort of tipping point. Long range modeling is now showing a ridiculously resilient ridge over the Rockies extending into the ice-free parts of the Arctic, in fact, they are showing trans-continental ridging sustaining itself from Asia and Siberia over the open areas of the High Arctic, and down into the Rockies.

This could lead to a situation where mid-latitude oceanic heat is continually evacuated into the Arctic through severe troughing in the Aleutians and Eastern North America, prolonging the melt season for some parts of the Arctic (the ATL front and ESS?) and bringing a very early winter to the CAA and parts of the CAB. The models are now beginning to become much more consistent in dropping sustained snows over the CAA and parts of the CAB, as well as the bits of the Beaufort still covered in ice -- I suspect the ice remaining shorefast against AK will also survive the summer.

Dharma Rupa

  • Frazil ice
  • Posts: 493
    • View Profile
  • Liked: 55
  • Likes Given: 26
Re: The 2018 melting season
« Reply #2805 on: August 13, 2018, 07:18:40 PM »
Something seems seriously amiss these days with the normally reliable East Greenland Current. There too the floes are milling about in crazy ways instead of preceding in an orderly manner down the Fram. Floe motion here is indicating surface water eddies as GFS-nullschool is showing blah winds that haven't resulted in outlandish floe motion in the past.

I see that nothing seems orderly lately, but would you please clarify what you mean by "milling about"?   Does this seem to be a wind thing, or does the current seem to be stalling?

A-Team

  • Young ice
  • Posts: 2547
    • View Profile
  • Liked: 360
  • Likes Given: 29
Re: The 2018 melting season
« Reply #2806 on: August 13, 2018, 07:23:44 PM »
Quote
clarify milling about?
Watch the trajectories of a few small white particles, they are incoherent. Or, because these gifs will download as separate frames, pick a particle and color it green over 5-6 days. Pick another and color it purple. And so on. Now run the animation again to see the trajectories more easily. This is not wind-driven as it would take multiple simultaneous adjacent mini-cyclones. But what has set the water into such turbulent motion -- and to what depths -- is not yet clear.

Quote
expect the ice to lift off the garlic press
Right, there's been lift-off within the Arctic basin the last couple of days with more to come, note the triple west of Ellesmere. The westerly lift-off along M'Clure took place a bit earlier. Overall, the ice in the lesser channels can be seen breaking off, with the whole situation there rapidly deteriorating. It wouldn't come as a surprise to see the garlic press export starting up in a few days across the whole Canadian side.

It's not so easy to go from a five day local wind forecast to ice developments in out the CAA channels. First, the whole central basin ice pack moves as a rigid yet deformable body even with the compressibility of today, yet winds on a basin scale are blowing every which way with variable momentum couplings to the ice. Here we are concerned not with ivory tower 850 HPa nor with 2 m wind readings from sparse to non-existent weather stations but rather undetermined winds at the skin.

Second, if we can believe Fridtjof Nansen, the ice doesn't drift with the wind nor at a 45 angle to it but rather at lesser angles determined by the latitudinally varying coriolis force and various boundary conditions, of which the worst in this instance are the narrow twisting passages, interior islets and shoals, and sometimes vicious tides inside the CAA.

In some ways, wind forecasts have more to say about what isn't going to happen than about what will. Here, we may have a situation of earlier warmed water from below having worked its way through a backlog of seasonally thick and now fragile ice, with neither winds nor air temperatures playing as much of a role as the tides and currents.
« Last Edit: August 13, 2018, 10:40:36 PM by A-Team »

Bruce Steele

  • Nilas ice
  • Posts: 1744
    • View Profile
  • Liked: 410
  • Likes Given: 15
Re: The 2018 melting season
« Reply #2807 on: August 13, 2018, 07:43:41 PM »
Although ITP 108 isn't working as a profiler it is still sending out it's location. It looks like it is going to exit the Beaufort Sea via the Amundsen Gulf. Too bad the profiler is broken , it would be interesting to see how much  fresh water is exiting with it. This is a strange track for a profiler buoy.

gerontocrat

  • First-year ice
  • Posts: 8405
    • View Profile
  • Liked: 3129
  • Likes Given: 25
Re: The 2018 melting season
« Reply #2808 on: August 13, 2018, 09:51:35 PM »
A little uptick today in Temperatures North of 80 that might last a bit longer
"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)

Shared Humanity

  • Guest
Re: The 2018 melting season
« Reply #2809 on: August 13, 2018, 10:44:01 PM »
Fall ends December 21.

As far as I know, sea ice does not follow the Gregorian Calendar. By December 21, we are deep into the freeze season.


Greenbelt

  • Frazil ice
  • Posts: 145
    • View Profile
  • Liked: 24
  • Likes Given: 20
Re: The 2018 melting season
« Reply #2810 on: August 13, 2018, 10:44:43 PM »
On the Pacific side, it will be fun to watch the Healy, now at 71.6n and headed north. Water temp 6.8C
http://icefloe.net/uscgc-healy-track-map
http://icefloe.net/Aloftcon_Photos/

oren

  • Moderator
  • First-year ice
  • Posts: 5509
    • View Profile
  • Liked: 1694
  • Likes Given: 1593
Re: The 2018 melting season
« Reply #2811 on: August 13, 2018, 10:49:32 PM »
Thank you A-Team for your recent two posts. The animations are highly educational. Indeed it's a mystery what is setting the Lincoln Sea floes in such erratic motion. And I notice that the CAA seems to have finally started moving south the last few days, after a long time just sitting there.

Viggy

  • New ice
  • Posts: 66
    • View Profile
  • Liked: 33
  • Likes Given: 21
Re: The 2018 melting season
« Reply #2812 on: August 13, 2018, 11:47:03 PM »
So, to add to the discussion on the North Greenland open water event going on, I got a little bored today and started to track individual floe movements from when a large chunk broke off on July 31 to the latest image today (August 13). The event actually seems to have been re-invigorated today, despite looking like it was done 2 days ago.

Looking at the 3 images below (7-31, 8-4 & 8-13) and tracking what was the south-eastern tip of the floe (now the north-western tip), it can be seen that the tip of that floe has traveled ~80 miles and rotated ~150o clockwise in 2 weeks.

I went very low tech (using paint and the scale at the bottom of the map) and I will let people with a lot more of a technical flair for the subject chime in on what all this actually means.

P.s. - The yellow line on the bottom image is 20 miles long. The red horizontal line has 3 x 20 mile segments and the vertical has 2 x 20 miles segments (red) and what I eyeballed was about 13 miles in the yellow 20 mile segment. Hypotenuse = 80 miles. Again, uber low tech
« Last Edit: August 13, 2018, 11:52:42 PM by Viggy »

CalamityCountdown

  • New ice
  • Posts: 46
    • View Profile
    • Calamity Countdown
  • Liked: 2
  • Likes Given: 21
Re: The 2018 melting season
« Reply #2813 on: August 14, 2018, 02:16:49 AM »
As pointed out by Gerontocrat over on the Area and Extent thread, there seems to be a huge dichotomy between the last few days of declining melt reported on the aggregated extent and area  summaries versus the observations on this thread that conditions may be primed for a significant August melting event. As Gerontocrat stated, "On the melting season thread there is evidence of strong ice loss along the Atlantic front and predictions of weather favourable for further ice loss. Will above average area losses return strongly in the last 30 days or so of the season?"

be cause

  • Nilas ice
  • Posts: 1232
    • View Profile
  • Liked: 489
  • Likes Given: 357
Re: The 2018 melting season
« Reply #2814 on: August 14, 2018, 03:13:14 AM »
Viggy's last image shows more land-fast ice breaking away . This now leaves the most Northerly point of land-fast ice exactly where it was on the 28th Feb this year .
 The flow I have been watching since lift off from tip on Aug.1st has travelled 110km in 12 days

My Worldview observations has me wonder at the low rate of melt being reported ... I feel this melting season is far from done .But then I thought it would start early when it immediately stalled :)
b.c.
 ps .. I notice the Worldview mappers have an opportunity to redraw Ellesmere island's North coast more accurately as land fast ice ( and apparently large chunks of Ellesmere ) head North .. :)
« Last Edit: August 14, 2018, 11:49:55 AM by be cause »
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

slow wing

  • Grease ice
  • Posts: 797
    • View Profile
  • Liked: 146
  • Likes Given: 434
Re: The 2018 melting season
« Reply #2815 on: August 14, 2018, 05:07:46 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-08-13...

Aluminium

  • Grease ice
  • Posts: 638
    • View Profile
  • Liked: 536
  • Likes Given: 355
Re: The 2018 melting season
« Reply #2816 on: August 14, 2018, 08:24:52 AM »
August 9-13.

johnm33

  • Nilas ice
  • Posts: 1414
    • View Profile
  • Liked: 171
  • Likes Given: 64
Re: The 2018 melting season
« Reply #2817 on: August 14, 2018, 09:11:03 AM »
Do we have a big block by FJL?

meddoc

  • Frazil ice
  • Posts: 261
    • View Profile
  • Liked: 11
  • Likes Given: 0
Re: The 2018 melting season
« Reply #2818 on: August 14, 2018, 09:23:36 AM »
Anyone fancy a swim?
This is gonna vaporize Ice instantly, leaving the Fram.

AvantGuardian

  • NewMembers
  • New ice
  • Posts: 12
  • Night walking
    • View Profile
  • Liked: 19
  • Likes Given: 92
Re: The 2018 melting season
« Reply #2819 on: August 14, 2018, 10:47:19 AM »
More good sentinel images available of the Lincoln. There's actually lots of recent clear ones off the CAA quite far out into the basin, and over the ESAS where the central packs been getting expelled. This stuff in the Lincoln actually looks in the best condition of anywhere. The biggest floe in the sea zoomed in on. And an area of 100% concentration, area, and extent, because the gaps are below 250m ::)
Navy brat, student at Hawaiki state, majoring in oceanography, climate and parapsychology.

uniquorn

  • Nilas ice
  • Posts: 2273
    • View Profile
  • Liked: 1186
  • Likes Given: 209
Re: The 2018 melting season
« Reply #2820 on: August 14, 2018, 12:22:44 PM »
Today's ecmwf wave, temps and wind from windy

A-Team

  • Young ice
  • Posts: 2547
    • View Profile
  • Liked: 360
  • Likes Given: 29
Re: The 2018 melting season
« Reply #2821 on: August 14, 2018, 02:55:15 PM »
The north Greenland anomaly seems to have spread farther west, almost past Ellesmere. Blocks can be seen tumbling in full rotation, supporting an incoming surge of water from the upper Fram Strait  (as seen also in Mercator salinities, uniquorn below) with return eddies and turbulent anomalies centrally.

The longstanding pocket of thickest Lincoln Sea ice, along the east shore, is gone. The Nares Current has returned to surface-manifested export but with its funnel now towards the east Lincoln Sea, unlike non-exporting East Greenland and West Spitsbergen currents in the upper Fram.

The second animation shows the last 3 weeks relative to the 15 Sept 17 (first frame, yellow outline for open water). Daily basin numbers like extent are being influenced primarily by large areas of slow melt, dispersion, compaction and advection in the ESS, Chukchi, Beaufort and much less so by the smaller but more unusual developments in the Laptev, SV-FJL-SZ corridor and Lincoln Sea which are already well inside their 'starting position' of last fall.

However bean counters on other forums could make the point that residual peripheral ice that does not melt out on the Pacific side will nucleate a more rapid freeze-up (which holds ocean heat in and supports a snow blanket), graduating to a SYI matrix within newly forming ice.

Osi-Saf has been showing dispersive motion of remnant ice, pushing it towards the Bering Strait and warmer waters. It is based on AI motion detection in two day pairs. Ice pack motion in north Greenland has been moderate in recent weeks, indicating unexceptional winds not explaining event development there.
« Last Edit: August 14, 2018, 04:28:30 PM by A-Team »

Jim Hunt

  • Young ice
  • Posts: 4523
  • Stay Home, Save Lives
    • View Profile
    • The Arctic sea ice Great White Con
  • Liked: 436
  • Likes Given: 30
Re: The 2018 melting season
« Reply #2822 on: August 14, 2018, 03:09:47 PM »
On the Pacific side, it will be fun to watch the Healy

See also this venerable USCGC Healy topic:

https://forum.arctic-sea-ice.net/index.php/topic,436
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

effbeh

  • New ice
  • Posts: 19
    • View Profile
  • Liked: 0
  • Likes Given: 0
Re: The 2018 melting season
« Reply #2823 on: August 14, 2018, 03:41:07 PM »
A bit concerned about that open water area north of Greenland.  I'm not that experienced, but when I started looking at those maps some years ago, that seemed to be the "safe haven" for multi year ice.  Now it's not only NOT multi year ice, but totally gone.  Is this a troublesome development?

wili

  • Young ice
  • Posts: 3037
    • View Profile
  • Liked: 486
  • Likes Given: 344
Re: The 2018 melting season
« Reply #2824 on: August 14, 2018, 03:42:44 PM »
eff, if you're interested in learning more about that, you could do worse than to peruse Neven's excellent (as always!  :)) recent blog post on the topic: http://neven1.typepad.com/blog/2018/08/circumnavigating-greenland.html
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

uniquorn

  • Nilas ice
  • Posts: 2273
    • View Profile
  • Liked: 1186
  • Likes Given: 209
Re: The 2018 melting season
« Reply #2825 on: August 14, 2018, 03:48:53 PM »
Mercator 0m salinity, jul12-aug12.
https://tinyurl.com/y6wuqguv (if you need the to read the scale)
edit:image name dates were incorrect
« Last Edit: August 14, 2018, 04:10:54 PM by uniquorn »

oren

  • Moderator
  • First-year ice
  • Posts: 5509
    • View Profile
  • Liked: 1694
  • Likes Given: 1593
Re: The 2018 melting season
« Reply #2826 on: August 14, 2018, 04:37:29 PM »
A look at the southwest corner of the Lincoln Sea (at the entrance to Nares) on Worldview confirms a very disturbing development as shown by A-Team's recent posts. The ice is actually melting in-situ in the Lincoln Sea, not simply blown northward by winds (as happened in February 2018 for example).
The animation begins around July 1st when the Nares entrance plug first cracked and broke. At first the ice was lifted off Ellesmere to the east, then part of it including some very large floes spilled into the Nares. All of this is rather common for this time of year. But afterwards, as evidenced by the fast ice breaking off the fjord to the right of the image, the ice started moving erratically with open water appearing and growing rapidly within the ice field, showing a very strong melting process. This location should not be having such a rapid melt-out of local ice. It shows both relatively thin ice and (probably) very warm/saline sea surface.
Note the last image is showing another breakup of the fast ice in the fjord.

A-Team

  • Young ice
  • Posts: 2547
    • View Profile
  • Liked: 360
  • Likes Given: 29
Re: The 2018 melting season
« Reply #2827 on: August 14, 2018, 05:32:16 PM »
I'll just toss this little essay out, it would benefit greatly from further development (or maybe abandonment):

Excessive heat accumulating in equator waters redistributes itself northward via the Gulf Stream (AMOC); however water volume entering the Arctic must be balanced by water volume leaving. That much was known in the nineteenth century.

Petermann's 1874 map envisioned the Gulf Stream reaching the central Arctic and creating a pocket of open water surrounded by land-based ice, with water volume balance restored by cold water exiting in the Labrador Current. The first half of this hypothesis wasn't abandoned until Nansen and Johansen set off for the pole from the frozen-in Fram in March 1895.

Modern oceanographic considerations (barotropic flow) instead force this branch of the Gulf Stream to follow shelf break bathymetry after rounding Svalbard. Although some Atlantic Water later returns centrally along the Lomonosov Ridge (still following bathymetry, now translocated continental shelf) the remnant core is by now too cool, deep and double-diffused to realize Petermann's hypothesis.

Open water is found north of Svalbard all year now as Gulf Stream (WSC) heat manages to come up somewhat from depth due in part to turbulent eddies over the Yermak Plateau. Return flow occurs primarily via an adjacent EGC countercurrent along east Greenland, with lesser and variable amounts returning through the Fram, CAA channels and the Bering Strait, but with volume numbers always quick to add up.

What then makes the Gulf Stream (WSC) turn right at Svalbard? It is being pushed from behind to move on but can't continue heading north (oceanographic theory) nor go left because it would be rebuffed by massive southward return flows of the EGC.

But if the EGC and the ice-melt freshwater it brings south have been tipped by ever-warming West Spitsbergen Current water into overall system instability, could flows, eddies or upwelling chimneys conceivably turn west advecting part of their flow, rounding north Greenland as we are perhaps seeing this week, with turbulent confusion in surface waters (and to some depth) at both the EGC crossing and the Lincoln Sea, with the Nares picking up the slack in return flow south? Indeed, several earlier current forks have occurred in the AMOC en route.

http://oceancurrents.rsmas.miami.edu/atlantic/spitsbergen.html

https://www.npr.org/2018/04/13/602240020/atlantic-ocean-current-slows-down-to-1-000-year-low-studies-show

This, if it continues for a few weeks along the CAA as it appears to be doing, would lead to the anti-matter version of Petermann's idea, central ice surrounded on all sides by open water. Conceivably this might have happened to a limited extent in previous seasons (volume flow does slow in August per wipneus) but has not been noticeable because masked by more robust ice in earlier years and less diversion of WGC waters.

The gif below compares 2018 to prior Augusts for the years 2012-17, showing that the event this season has no counterpart in the earlier years available.

Here are three gateway papers (71+ cites) to the many many studies of this region, including Goszczko's 2018 review of regional Ekman transport, eddies and water chimneys:

Quote
The West Spitsbergen Current volume and heat transport from synoptic observations in summer
W Walczowski et al 28 June 2004 free full text
https://brage.bibsys.no/xmlui/bitstream/handle/11250/2366362/021202.pdf?sequence=1

Mesoscale eddies in the Fram Strait marginal ice zone during the 1983 and 1984 Marginal Ice Zone Experiments
J. A. Johannessen et al 30 June 1987
https://doi.org/10.1029/JC092iC07p06754 Cited by: 120

During the summer Marginal Ice Zone Experiment in Fram Strait in 1983 and 1984, fourteen mesoscale eddies, in both deep and shallow water, were studied between 78° and 81°N. Sampling combined satellite and aircraft remote sensing observations, conductivity‐temperature‐depth observations, drift of surface and subsurface floats and current meter measurements. Typical scales of these eddies were 20–40 km. Rotation was mainly cyclonic with a maximum speed, in several cases subsurface of up to 40 cm s−1. Observations further suggest that the eddy lifetime was at least 20 to 30 days. Five generation sources are suggested for these eddies. Several of the eddies were topographically trapped, while others, primarily formed by combined baroclinic and barotropic instability, moved as much as 10–15 km d−1 with the mean current. The vorticity balance in the nontrapped eddies is dominated by the stretching of isopycnals accompanied by a change in the radial shear. In the most completely observed eddy south of 79°N the available potential energy exceeded the kinetic energy by a factor of 2. Quantitative estimates suggest that the abundance of these eddies enhances the ice edge melt up to 1–2 km d−1.

A Comparative Study of Moored/Point and Acoustic Tomography/Integral Observations of Sound Speed in Fram Strait Using Objective Mapping Techniques
BD Dushaw and H Sagen 17 December 2015
https://doi.org/10.1175/JTECH-D-15-0251.1

Fram Strait, the passage between Spitsbergen and Greenland, is a significant “choke point” for the general circulation of the world’s oceans (Fieg et al. 2010; Schauer et al. 2008). This strait is the only deep connection between the Arctic and the world’s oceans. Through this strait, warm, salty North Atlantic water flows northward in the West Spitzbergen Current, while cold, fresher water, together with considerable quantities of ice (Smedsrud et al. 2011), flows southward in the East Greenland Current. The transports of heat and salt between the Atlantic basin and the Arctic Basin by the deep and shallow current systems in Fram Strait are important aspects of ocean circulation, with profound impacts on the ocean’s climate.

The details of these current systems are, however, difficult to observe. Not only are the natural scales of variability small at these high latitudes but the powerful current systems have turbulent and recirculating features. These features influence and obscure transports of mass or heat. Eddy variability may be an important contributor to these transports.

The Fram Strait moored array (Fig. 1) has been deployed across the strait since 1997 to measure the properties of these current systems (Fieg et al. 2010; Schauer et al. 2008). Temperature, salinity, and current data from this array have been noted for their great variability (von Appen et al. 2015). Even with 16 moorings deployed along a 325-km line across the strait, however, the separation of the moorings (20–28 km) is a few times larger than the natural scales of variability, 4–10 km (Fieg et al. 2010; Nurser and Bacon 2014).

The moored array has therefore undersampled the ocean variability; the Fram Strait moored array forms an incoherent observing array. This situation has made it challenging to employ the moored array data directly to estimate heat flow (Schauer et al. 2008; Schauer and Beszczynska-Möller 2009), or as constraints on numerical ocean models through data assimilation. The high noise of the observations overwhelms the signals of interest to the ocean modelers and introduces the effects of aliasing. Other observing approaches, such as glider or conductivity–temperature–depth (CTD) sections, have obvious, different sets of complications or deficiencies. It is clear that no one type of measurement offers a comprehensive solution to the observation problem in Fram Strait.
« Last Edit: August 15, 2018, 01:07:42 AM by A-Team »

VeliAlbertKallio

  • Frazil ice
  • Posts: 177
    • View Profile
    • Sea Research Society (SRS)
  • Liked: 58
  • Likes Given: 73
Re: The 2018 melting season
« Reply #2828 on: August 14, 2018, 05:44:37 PM »
Today's phenomenal scale of sea ice pulverisation is contrasted here with second / multi-year ice in this now historic satellite multiplex image from 2006 which reveals the second year sea ice blocks from 2005 as immense white patches within the dark and thin sea ice of 2005-6 winter season as seen during 2006 summer. Today, the previous years' broken sea ice is pulverised into a mosaic with myriad fragments now occurring in smaller scales than satellite image can capture. All those hundreds to thousand mile blocks of fragmented MYI a little over a decade ago are non existent today.

In my view it is important to refer back to some historic images to remind ourselves how far the sea ice has fragmented in the last 10 years and what this will mean for the next ten years. (No multi-year or second year sea ice at all.)  :'(

More good sentinel images available of the Lincoln. There's actually lots of recent clear ones off the CAA quite far out into the basin, and over the ESAS where the central packs been getting expelled. This stuff in the Lincoln actually looks in the best condition of anywhere. The biggest floe in the sea zoomed in on. And an area of 100% concentration, area, and extent, because the gaps are below 250m ::)

VeliAlbertKallio

  • Frazil ice
  • Posts: 177
    • View Profile
    • Sea Research Society (SRS)
  • Liked: 58
  • Likes Given: 73
Re: The 2018 melting season
« Reply #2829 on: August 14, 2018, 06:13:14 PM »
The extremely warm water near the Svalbard on the Fram Strait must come from south. When water at +20C mixes with sea ice and sea water (only -2.5C), water in sea becomes turbulent. I now believe some of the sinking north-heading Gulf Stream current is captured and thrown into surface trajectory. However, this current stir-melting and mixing off NE Greenland may not be entirely novel:

There have been vertical water chimneys and vertical eddies in the Fram Strait area as seen in these three images from 2006 with curvilinear ice formations formed up by the rising eddies. They are seen patterning thick sea ice in curious, curvilinear forms behind the Svalbard. (I showed these to Peter Wadhams and we thought at the time, them possibly being cold freshwater eddies fallen off from continental shelf to the deep water, then warmed and and rising to surface. In that case they would have drifted from the Kara Sea to the Fram Strait. But now the recent developments suggest that these vertical eddies then seen (2006) imprinted on sea ice behind the Fram Strait could be veered off tentacles of the deep current: - sort of grand parents to the eddies now seen north of Greenland. ;) 

A look at the southwest corner of the Lincoln Sea (at the entrance to Nares) on Worldview confirms a very disturbing development as shown by A-Team's recent posts. The ice is actually melting in-situ in the Lincoln Sea, not simply blown northward by winds (as happened in February 2018 for example).
The animation begins around July 1st when the Nares entrance plug first cracked and broke. At first the ice was lifted off Ellesmere to the east, then part of it including some very large floes spilled into the Nares. All of this is rather common for this time of year. But afterwards, as evidenced by the fast ice breaking off the fjord to the right of the image, the ice started moving erratically with open water appearing and growing rapidly within the ice field, showing a very strong melting process. This location should not be having such a rapid melt-out of local ice. It shows both relatively thin ice and (probably) very warm/saline sea surface.
Note the last image is showing another breakup of the fast ice in the fjord.
« Last Edit: August 14, 2018, 06:20:19 PM by VeliAlbertKallio »

Neven

  • Administrator
  • First-year ice
  • Posts: 7621
    • View Profile
    • Arctic Sea Ice Blog
  • Liked: 990
  • Likes Given: 501
Re: The 2018 melting season
« Reply #2830 on: August 14, 2018, 06:39:14 PM »
Note the last image is showing another breakup of the fast ice in the fjord.

Perhaps a stupid question, but does this fast ice break up regularly during melting seasons? I know it does east of Cape Morris Jessup, but to the west as well?
Il faut comparer, comparer, comparer, et cultiver notre jardin

johnm33

  • Nilas ice
  • Posts: 1414
    • View Profile
  • Liked: 171
  • Likes Given: 64
Re: The 2018 melting season
« Reply #2831 on: August 14, 2018, 07:08:39 PM »
"What then makes the Gulf Stream (WSC) turn right" imo- the WSC water has moved almost due north from Norway, 10deg at 24kph per it must retain some inertia thus its preferred route is due east.
 Then there's the coincidence of low mslp off the coast of Norway, and in north Baffin, the low off Norway would enhance the tidal peak of new moon bringing an excess of water north, once there it rotates as normal some of which enhances the WSC, then you have the low in Baffin pulling in a big tide of its own, some straight through Nares.  At peak tides both highs and lows are extreme

all it takes then is for the water pressure north of Fram to coincide with the draw of water through Nares, it helps if the winds have been easing the ice off the coast too. Normally at peak tides there's some northward flow up the south/west Canadian side of Nares too. Tide heights.

 edit images missing + strike thanks Tor
« Last Edit: August 14, 2018, 09:13:01 PM by johnm33 »

FishOutofWater

  • Grease ice
  • Posts: 767
    • View Profile
  • Liked: 333
  • Likes Given: 119
Re: The 2018 melting season
« Reply #2832 on: August 14, 2018, 08:12:51 PM »
That's an excellent little essay that summarizes and adds to what I have been observing and thinking. Note that the atmosphere responds to increasing amounts of heat in the Barents sea by forming deeper low pressure areas there in the late summer and fall. This pressure pattern enhances the clockwise flow of the Atlantic layer at 300m and mixed Atlantic/Arctic ocean water at 100m.

The eddies in the ice flow movies have been stunning. Eddies are responsible for vertical heat and salt mixing in many parts of the global oceans, now, apparently, including the Lincoln sea.

Today's 5 to 10 day ensemble forecast shows the pressure pattern I am discussing. Please don't take this as an actual forecast. What's important is that it shows the tendency to lower than normal pressure centered over the Barents sea, extending into the central Arctic. High pressure is enhanced this time of year over ice covered areas that tend to loose heat quickly when the sun angle is approaching the horizon.

A-Team

  • Young ice
  • Posts: 2547
    • View Profile
  • Liked: 360
  • Likes Given: 29
Re: The 2018 melting season
« Reply #2833 on: August 14, 2018, 08:49:24 PM »
Unusual cloud pattern there at the Fram choke-point ... do we know what it means?

Meanwhile, Worldview for the 14th has come in. It is a day ahead of most of the processed satellite products, gifs above. The event seems to have propagated about 45% of the way east along Ellesmere Island, with landfast ice popping off and some floe disintegration seen. This is 1160 km from the easternmost cape of Greenland.

Quote
does fast ice break up regularly during melting seasons? I know it does east of Cape Morris Jessup, but to the west as well?
Easy enough to post August AMSR2 animations for 2012-2017, in a bit. Lift-offs are common. The years 2012, 2016 and 2017 did not show anything resembling the features of this year.
« Last Edit: August 14, 2018, 09:24:49 PM by A-Team »

Dharma Rupa

  • Frazil ice
  • Posts: 493
    • View Profile
  • Liked: 55
  • Likes Given: 26
Re: The 2018 melting season
« Reply #2834 on: August 14, 2018, 08:58:00 PM »
https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017JC013271

Can't say that I have fully absorbed this, but so far my main takeaway is that the Yemak Pass Branch of the West Spitsbergen Current is stronger in Winter than Summer...

I might be wrong about this providing the water for the Lincoln Sea.

uniquorn

  • Nilas ice
  • Posts: 2273
    • View Profile
  • Liked: 1186
  • Likes Given: 209
Re: The 2018 melting season
« Reply #2835 on: August 14, 2018, 09:24:43 PM »
Worldview, north of  Ellesmere, aug10-14
Edit:Interesting that ice lifts off the coast but travels inland in the inlet (left). Similar to the Mclure Strait further west.
Added wider view of north CAA, amsr2-uhh-aug6-13
« Last Edit: August 14, 2018, 09:55:27 PM by uniquorn »

A-Team

  • Young ice
  • Posts: 2547
    • View Profile
  • Liked: 360
  • Likes Given: 29
Re: The 2018 melting season
« Reply #2836 on: August 14, 2018, 09:57:47 PM »
For what it is worth, Mercator Ocean is showing a SSTA temperature anomaly bridge developing on August 5th between the West Spitsbergen Current and the Northeast Polyna, predicted to largely dissipate by August 23rd.  (The latter open water has been around for decades, it is an eddy formed by the East Greenland Current as it rounds the peninsula off Nord, Greenland.)
« Last Edit: August 15, 2018, 12:50:58 AM by A-Team »

NeilT

  • Nilas ice
  • Posts: 1786
    • View Profile
  • Liked: 174
  • Likes Given: 11
Re: The 2018 melting season
« Reply #2837 on: August 14, 2018, 10:40:16 PM »
NSIDC Extent Chartic continues to walk away from 2012/16/17 and towards 2015.

The longer this happens, the more dramatic the melt will have to be, over the next month, in order to come in the top 3.

The Atlantic does, however, seem to be suffering quite significant heat and melt right now.  So, as they say, it won't be over till the fat lady sings.
Being right too soon is socially unacceptable.

Robert A. Heinlein

LDorey

  • New ice
  • Posts: 24
    • View Profile
  • Liked: 11
  • Likes Given: 27
Re: The 2018 melting season
« Reply #2838 on: August 14, 2018, 10:56:02 PM »
I was nosing around nullschool looking at currents, and I noticed the currents in Baffin Bay are weirdly in sync. Now it could very well be this isn't that unusual? but I jumped around temporally a bunch, in previous years and this year and I couldn't find anything remotely similar, I've don't recall ever seeing anything like it before, but I don't follow currents daily.

Here's what the currents usually look like as far as I can tell:

https://earth.nullschool.net/#2018/08/06/0000Z/ocean/surface/currents/overlay=currents/orthographic=-68.20,75.11,3000/loc=-66.352,73.172

Here's what they look like right now:
https://earth.nullschool.net/#current/ocean/surface/currents/overlay=currents/orthographic=-67.33,74.09,3000/loc=-60.217,73.141v

Which is against the decent surface winds...
https://earth.nullschool.net/#current/wind/surface/level/orthographic=-71.48,74.00,3000

Does anyone recall seeing something like this before? but right now to me it looks like Baffin bay is draining into the Lincoln Sea....

Liam







magnamentis

  • Guest
Re: The 2018 melting season
« Reply #2839 on: August 14, 2018, 11:21:11 PM »
A bit concerned about that open water area north of Greenland.  I'm not that experienced, but when I started looking at those maps some years ago, that seemed to be the "safe haven" for multi year ice.  Now it's not only NOT multi year ice, but totally gone.  Is this a troublesome development?

it's more blown away than just gone, means the ice has not melted out entirely but drifted away from the cost, mostly wind and current driven.

of course there is more to it, one thing is certainly that the thin and fragmented ice in general is becoming more mobile, hence even though it's not all gone for good, there is still good reason to be concerned after all it happened mid-winter and now again during the same year.

johnm33

  • Nilas ice
  • Posts: 1414
    • View Profile
  • Liked: 171
  • Likes Given: 64
Re: The 2018 melting season
« Reply #2840 on: August 14, 2018, 11:50:36 PM »
"Unusual cloud pattern" I'll take a punt, it looks like some fraction of deeper arctic basin water is making it's way south on the Greenland shelf. It's made it's way into some of the fjords, i suspect 79N, and mixed with the cool freshwater. Pushed south it's flowing out of the trough that usually allows these waters in at greater depth. Energetically it's arctic bound and thus the second link[an adjustment of L.Doreys] shows it flowing north and turbulently mixing with the warmer WSC.

.



Nullschool
  Just to add that previously when I've observed turbulent cloud formation, or cloud streets very often it's been when expecting turbulent waters, [which is what drives my interest] and have become convinced that spin/ rotational energy survives phase transition and is rapidly  expressed and dissipated in the vapour.
 If anyone can find a sentinel image for the appropriate time/place it'd be appreciated.
« Last Edit: August 15, 2018, 10:01:06 AM by johnm33 »

bbr2314

  • Nilas ice
  • Posts: 1817
    • View Profile
  • Liked: 166
  • Likes Given: 53
Re: The 2018 melting season
« Reply #2841 on: August 15, 2018, 05:30:33 AM »
Latest Bremen. Note Foxe Basin is still holding out, and on visible satellite, you can see the ice is very thick and may even last through summer if the extended weather forecasts pan out.

Meanwhile the PAC front is caving deeper and deeper into the CAB. The Laptev front is also dwindling day by day. I still think this year is a contender for #2 spot, and we will have a GAC that will put us there (taking care of most of the ESS in the process), with all the heat in the Laptev the question is not if but when.


slow wing

  • Grease ice
  • Posts: 797
    • View Profile
  • Liked: 146
  • Likes Given: 434
Re: The 2018 melting season
« Reply #2842 on: August 15, 2018, 08:18:53 AM »
U. Bremen's false colour ice concentration maps show a week's action in the Arctic basin, ending on the map just released, 2018-08-14...

oren

  • Moderator
  • First-year ice
  • Posts: 5509
    • View Profile
  • Liked: 1694
  • Likes Given: 1593
Re: The 2018 melting season
« Reply #2843 on: August 15, 2018, 08:35:24 AM »
Continuing on the Lincoln Sea theme, and following Neven's question about the fast ice breaking in other years, I prepared this animation showing a selected clear mid-Aug day for each of the years 2001-2018. The only year that looks similar to this year's state of the ice is 2015, though I don't know if the wind played a larger factor that year. The fast ice OTOH does break on many of the years.
It is very educational to witness the huge size of the floes in many of the years.

Neven

  • Administrator
  • First-year ice
  • Posts: 7621
    • View Profile
    • Arctic Sea Ice Blog
  • Liked: 990
  • Likes Given: 501
Re: The 2018 melting season
« Reply #2844 on: August 15, 2018, 09:14:34 AM »
Thanks, oren!
Il faut comparer, comparer, comparer, et cultiver notre jardin

uniquorn

  • Nilas ice
  • Posts: 2273
    • View Profile
  • Liked: 1186
  • Likes Given: 209
Re: The 2018 melting season
« Reply #2845 on: August 15, 2018, 12:02:25 PM »
Today's ecmwf wave, temp and wind from Windy.
That plucky Alaskan coastal ice in the Beaufort may be shaken up a bit over the next 48hours.
I've included the forecast for sunday, which has been fairly constant, of 3m waves (maybe more) in the Barents/CAB and Fram Strait

bairgon

  • Frazil ice
  • Posts: 133
    • View Profile
  • Liked: 16
  • Likes Given: 0
Re: The 2018 melting season
« Reply #2846 on: August 15, 2018, 12:12:40 PM »
I've tried a different exercise with the Lincoln sea ice.

I chose a floe visible in a Sentinel image, and followed it backwards (and forwards - this took a little time to prepare) in time. The animation below shows images rotated and matched.

The floe is currently about 20km north of the fast ice breaking out of the bay to the south of the Lincoln Sea.

The images were captured at the 300m scale and the floe is about 2km x 2km.

It seems that it suffered a lot of fracturing early on, but more recently has held its shape very consistently.
« Last Edit: August 15, 2018, 12:45:21 PM by bairgon »

AvantGuardian

  • NewMembers
  • New ice
  • Posts: 12
  • Night walking
    • View Profile
  • Liked: 19
  • Likes Given: 92
Re: The 2018 melting season
« Reply #2847 on: August 15, 2018, 12:19:33 PM »
Some sentinel playground shots of the ice in the north Beaufort off the mid CAA.
And a couple of the shrapnel pouring out of the CAA into Foxe basin. Sentinel may have a tricky and frustrating interface to master. But its worth taking the time. The 250m pixel size on worldview can make stuff like this look like solid ice that's not moving. Clearly not  true.
Navy brat, student at Hawaiki state, majoring in oceanography, climate and parapsychology.

oren

  • Moderator
  • First-year ice
  • Posts: 5509
    • View Profile
  • Liked: 1694
  • Likes Given: 1593
Re: The 2018 melting season
« Reply #2848 on: August 15, 2018, 12:27:01 PM »
Amazing animation Bairgon. What is the size of the floe? I am guessing it's fairly large.

Neven

  • Administrator
  • First-year ice
  • Posts: 7621
    • View Profile
    • Arctic Sea Ice Blog
  • Liked: 990
  • Likes Given: 501
Re: The 2018 melting season
« Reply #2849 on: August 15, 2018, 12:40:57 PM »
Very nice, Bairgon. It reminded me of the work commenter Epiphyte did back in 2014: Poof, it's gone.
Il faut comparer, comparer, comparer, et cultiver notre jardin