Arctic Ocean salinity, temperature and waves

[uniquorn]

uni-hamburg amsr2-uhh overlaid onto mercator salinity 34m at 60% transparent. amsr2 0% concentration, normally dark blue, has been set to fully transparent. sep21-Dec9, Large.
Posting temporarily - removed

[uniquorn]

same as above over gmrt bathymetry. Transparency percentages optimised for looking at the pacific side. Nansen basin gets a bit lost under all that salinity.
Experimental, posting temporarily - removed

[uniquorn]

whoi adjusted the map to cover the westward drift for itp116. Interesting that the warmer water at >200m doesn't appear to get past the Lomonosov Ridge.
Datawise, I'd prefer a drift around the N Greenland coast to the the almost inevitable destruction of the profiler down the Nares. We'll see...

[uniquorn]

whoi itp's in the beaufort.....

[uniquorn]

comparison of 2014-2019, sep19-jan1 using uni-hamburg amsr2-uhh. removed

[Niall Dollard]

Thanks Uniquorn.

1st Jan comparisons show the big variability on the Pacific front, but there probably has been less comment, in general on social media, on the variability of the Atlantic front.

Svalbard clearly stands out as an ice free island on 01/01/16 and 01/01/17. Then a slow build up after that to present day when it is similar to 01/01/15.

[uniquorn]

Chukchi plateau drift, unfortunately itp112 profiler isn't moving on the cable. https://www.whoi.edu/page.do?pid=165216

[uniquorn]

whoi itp buoys in the Beaufort, location and profile.

[uniquorn]

ascat overlaid with unihamburg amsr2-uhh at 80% transparent.
amsr2 100% concentration, normally white, has been set to fully transparent to allow ascat features to show through. Missing or poor quality ascat days have been duplicated with the nearest day causing stutter.
sep21-jan6 - posting temporarily - removed
ffmpeg -crf31 to reduce filesize

[uniquorn]

compressive strength zero to max
https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/beaufortstrength_nowcast_anim30d.gif

the rebound hadn't occurred to me before

[uniquorn]

https://go.nasa.gov/3am5TAP Atlantic side, jan7-17, rotated, north down.
Large, so posting temporarily. Replaced with a smaller gif
 

[johnm33]

Link Taken together the cloud streets and the break aligned with the islands suggest internal waves propagated in the basins are forcing orthogonal waves south and these are disturbing the ice as they wash up the contours.
Rebound, again suggests huge amount of activity at depth, at least some of which must be A.W forced into the basin by tides judging by Hycoms salinity gif.

[uniquorn]

An introduction to internal waves is quite easy reading for a few pages.

Internal waves were discovered more than a century ago. One of the first observations is due to Helland-Hansen & Nansen [41]. They found that temperature profiles may change substantially within the course of just hours (Figure1.3); they ascribed this to the presence of "puzzling waves", an example of which is shown in Figure 1.4. They stressed the importance of this newly discovered phenomenon:
"The knowledge of the exact nature and causes of these "waves" and their movements would, in our opinion, be of signal importance to Oceanography, and as far as we can see, it is one of its greatest problems that most urgently calls for a solution" [p. 88]
1The horizontal currents associated with these waves extend to the surface;

Ice melt over the Yermak Plateau, north of Svalbard, shown in more detail below, is more likely related to the warm west spitzbergen current. This continues to FJL but at depth, so would require a mechanism to mix with colder surface water. ctr

[johnm33]

"so would require a mechanism to mix with colder surface water" yes what I'm suggesting is that internal waves possibly generated by A.W. entering the basin as tidal surges, are travelling to Laptev and back towards Greenland are in turn generating orthogonal waves which are dashed against the bathymetry at depth, both north of Svalbard and at inconsistences in the gradients of the troughs and where the troughs terminate beneath Barentz. It's clearer in your 'season' thread animation though without the cloud streets suggesting extreme 'spin' I'd probably think simple wind action the likeliest explanation.

[uniquorn]

<what I'm suggesting>  agreed. Internal waves acting on the nansen slope could be a mixing method. Maybe a couple of mosaic buoys will drift that way and give us some data.
T68 is the nearest thermistor buoy.
I think SST's (or near surface) north of Svalbard are warmer and may not need much mixing from depth. Reposting this argo float ani from here last year where there are also charts. Obviously it was earlier in the season. Will have a look at mercator tomorrow.

[binntho]

internal waves possibly generated by A.W. entering the basin as tidal surges,

Illogical nonsense. The waves are generated by AW (atlantic waters?) how? Or in other words, what  mechanism do the atlantic waters use to generate these waves?

As for tidal surges, have you or anybody else for that matter ever seen a tidal surge in an open ocean? No, they do not exist. A tidal surge is a coastal phenomenon only.

[uniquorn]

Tidal movement in the Barents, jul2019. From the rammb thread
Checking nullschool shows fairly steady easterly winds at the time.

[blumenkraft]

Uniquorn, forget about it. I had this discussion with Binntho before. He is very convinced that waves can't cause lateral movement - at all.

[morganism]

 Ice disc forms in river, not Arctic , but still...

Didn't see this last year.

https://www.theguardian.com/us-news/2020/jan/19/maines-giant-spinning-ice-disc-looks-like-its-reforming

[uniquorn]

whoi itp116 profiler data stopped on jan12
https://www.whoi.edu/page.do?pid=164836

[blumenkraft]

Edit: States "Last buoy status on 2020/1/21 10402 UTC" now.

[uniquorn]

update of mercator 34m salinity, sep2017-jan2020
edit: forgot scale

[Freegrass]

update of mercator 34m salinity, sep2017-jan2020

That's an awesome animation Unicorn. Thanks for that! It clearly shows that the bering strait gets its water from the saltier Russian side. Is there an animation like this for surface salinity?

I posted this on the freezing thread, but it probably belongs here. I guess you guys already knew about this tool?

Bering Sea: Salinity Climatological Fields
https://www.nodc.noaa.gov/cgi-bin/OC5/PACIFIC2009/showclimatmap.pl?MapType=bs

[uniquorn]

PSY4 animations available here. Be aware that the scale is not static.
Individual static scale maps are here (just edit both dates in the address)

[johnm33]

Worth the read. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JC010310
"We conclude that tidal shear stresses at the bottom and the ice‐ocean interface facilitate the transport of warmer and saltier AW to the surface layers, while the effects of tides along the Siberian shelf result in mixing of fresh river runoff waters with saltier water below the eroding halocline. Mixed layers, being much thicker due to the effects of the critical latitude on the clockwise component of tidal currents, entrain saltier waters to the surface boundary layers. Along the Siberian coast with strong river runoff, thicker boundary layers result in mixing in halocline and penetration of freshened waters to depth. Finally we find that, in this particular model, tides are responsible for ∼15% of the ice volume reduction and the presence of more salt waters at the surface in average by ∼1–1.7 PSU (Figure 14). Tides significantly modify the freshwater pathways along the Siberian shelf, resulting in saltier water along the Greenland coast. Tides affect the fresh water and heat content in the AO, with a reduction in the former by 7% in the upper 100 m"

[uniquorn]

Also interesting from the mosaic thread: https://www.nature.com/articles/s41598-017-15486-3

To summarize, we have used co-located acoustic and CTD data to unequivocally demonstrate that there is a one-to-one correspondence of thermohaline stairsteps and acoustic layering. We were able to track a staircase continuously (with some interruptions due to ice breaking in between drift stations) for 36 h over a ship track of 91 km (Fig. 4a), and identify an isolated staircase, extending about 100 km laterally, in the Nansen Basin (Fig. 5). We also present observations of layers forming/disappearing and splitting/merging within a thermohaline staircase (Fig. 5d–f). Finally, we present, for the first time, continuous high frequency vertical displacements of individual steps within an Arctic thermohaline staircase caused by internal waves. It is hypothesized that a sudden transition within an internal wave, where much of the high frequency energy at the trailing side of the wave suddenly disappears, is related to shear instabilities.

The data presented here suggest that in order to fully understand vertical heat fluxes, not only the presence of staircases must be considered, but also the mixing caused by decaying internal waves, which is likely not accounted for in laboratory measurements, numerical simulations, or very localized (i.e., discrete profile) measurements. A synoptic view is needed where, ideally, acoustic observations similar to the ones presented here are augmented by concurrent CTD and microstructure observations. This acoustic observational technique should offer new insights into the mechanisms controlling layer formation and evolution, and eventually allow for greater understanding of interactions between double-diffusive convection and shear-induced turbulence, as well as their control on diapycnal fluxes.

[uniquorn]

https://go.nasa.gov/2TX24MY, jan7-26, rotated, north down, FJL(left) and Svalbard(right)

[uniquorn]

Looking closer at the breakaway ice edge north of FJL/Svalbard. FJL coast very top left.
rammb, very heavy contrast, jan22-26     https://col.st/ib7ix
GFS indicating wind fairly constant northeasterly at -28C or lower so it has to be warm water rising from depth doing that. Movement suggests tidal.

[uniquorn]

A better looking wider angle from rammb geocolour  https://col.st/SUTyp

[blumenkraft]

Amazing, you can see the Atlantic current splitting here (see GIF below). One moving north of Svalbard, the other takes a left turn, towards north Greenland.

[uniquorn]

Nice. I expect we will see more of that over the next couple of days. This paper noted on the mosaic thread suggests there may be a small current through the Yermak Pass..

https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2016JC012391

Regional circulation schematic of Atlantic Water inflow in Fram Strait and Nansen Basin, west and north of the Svalbard Archipelago following Sirevaag and Fer [2009] and Polyakov et al. [2012]. Dashed arrows represent uncertain Atlantic Water pathways around the Yermak Plateau and across the Plateau through the Yermak Pass

[blumenkraft]

I'll keep an eye on it!

[johnm33]

I'll take a punt at this

20m suggests inhibited turbulence above that so average ice depth 2-3m, let's guess 0-5m with ridges and leads. So plenty of freezing and salt being excluded by the ice formation, the denser water it takes down is at -1.8. below 20m turbulence increases and temp rises. Suggests flow beneath the ice and the alignment of features suggests waves?

[uniquorn]

Thanks johnm33. Better scale on salinity with this chart also legend is not obstructive. It's a shame 75m data is so patchy.
Posted O1 chart as it has better 75m data

[uniquorn]

Heat loss in the Laptev Sea, https://go.nasa.gov/2RSLf44 , jan14-feb1

[uniquorn]

From the rammb thread

Now that polar night is descending on the arctic, it's time to switch to band I04, shortwave IR discerns temperature.
link to location.

North of Svalbard/Yermak Plateau. The (hopefully) never ending battle between sea ice and the warm west spitzbergen current

[uniquorn]

chukchi export. Ice movement revealing underlying current or bathy perhaps. ctr

[Bruce Steele]

https://www.nature.com/articles/s41467-020-14449-z

Uniquorn, Here is a very good new article in Nature that is open access. Hat tip to Notadenier.

It explains a lot about how 2007 was transformative in how the Beaufort gyre has operated over the whole period since. It also shows changes with upwelling / downwelling strength during 2012 that might help explain what happened that year besides the GAC.

ps. Have you been looking at ITP 114 ? 

A very pregnant pig starts to look kinda like the t/s contours chart for 114.

[uniquorn]

Thanks Bruce Steele, who would have thought eddies were so important?
here are the temp/salinity charts, 7-200m
https://www.whoi.edu/page.do?pid=165196
microcat1 at 5m depth

[uniquorn]

caption for image below from Nature

a Before and b after 2007, including the wind work, W (comprised of atmosphere-ocean, Wao, and ice–ocean, Wio, components), available potential energy (APE), and eddy dissipation, Weddy. The atmosphere and ocean circulations are illustrated by ua and ug, respectively. The size of the arrows/vectors represents their relative strength. The loss of sea ice after 2007 led to increased wind energy input to the BG, increased APE, and increased energy dissipation and freshwater stabilization by eddies.

Implications for the changing Arctic
Increases in the eddy diffusivity and increased mixing by eddy activity in a more energetic Arctic Ocean is also expected to enhance vertical transport of warm Atlantic water, with consequences for sea ice growth and mixing of biogeochemical tracers.

[uniquorn]

Ran the numbers on itp113 also. https://www.whoi.edu/page.do?pid=165156

[uniquorn]

a rough and ready view of ascat, jan1-feb11 (no clean up, bad labelling)
The beaufort arch appears to have stalled. Hopefully normal service will be resumed in a couple of days.

[uniquorn]

or not

[uniquorn]

osisaf drift, beaufort, sep21-feb15

[uniquorn]

I find it particularly interesting that the leads and apparent wave structures move through the ice rather than with it, the PS' slow progress is the best indication of this I've seen. The emergent double features indicates an acceleration?

Long version probably off topic for the mosaic thread.
Kaleschke Sic Leads, oct1-feb20 for further perusal. Lead motion likely wind based, will try a nullschool overlay sometime.

[johnm33]

OT yes I was hesitant,  but without a more or less stationary PS it looks like the ice is moving, whereas it's stillness suggests waves moving beneath the ice.

[Tor Bejnar]

Watching where the "pole hole" drifts in Uniquorn's MP4, it seems it tended to be part of the "Beaufort Gyre" in 2019 and generally part of the "Transpolar Drift" (and heading toward Fram Strait) in 2020.  (Lucky for the PS!)

[Glen Koehler]

osisaf drift, beaufort, sep21-feb15

Thanks Uniquorn.  The changing directions and strengths of the Sept 21- Feb 15 drift observations looks more random than I expected.  I expected to see a consistent pattern of clockwise drift. 
   Is that a typical Sept - Feb drift pattern? 
   Does that view represent the famous Beaufort Gyre or is it just a subset of the larger system?
   Is there a seasonality for the Beaufort Gyre, i.e. is it more consistently clockwise during the melt season?

    PS In looking up "osisaf" (=Ocean and Sea Ice Satellite Application Facility), I found list of acronym definitions at http://www.osi-saf.org/?q=content/acronyms-and-links.  Most of the acronyms in that list are too narrow, technical. or not directly relevant ASI to add to the ASIF acronym list, but interesting to look through.

[uniquorn]

Great questions Glen Koehler. My apologies, osisaf low res drift is here and goes back to 2014 I think, but I only have data from 2019.
There are some mercator model animations upthread showing the beaufort ocean gyre. Since I've been paying attention (2016ish) no ice has completed the circuit but the arc usually continues moving around the coast. Sorry, typing text is not my strong point.

[Glen Koehler]

osisaf low res drift is here

    Thanks for that link.  The maps with arrows only go back to 2016 for most of the months and days I looked at.  But from January 2017 to present (but 2015 or 2016 for some month-dates), there is a map for every month and date. 

   Bouncing around from year to year for early, mid, and late days of the month for most of the months of the year gives me the impression that the drift pattern frequently changes greatly over 10-day spans.  But while the pattern is highly variable across the different months and dates, I think if you summarized it all (and somebody no doubt has) you would see a fairly strong average pattern of the clockwise motion within the Pacific side of the Arctic Ocean.  What changes most often is the size, and east-west placement of the rotation.  Thus, the drift direction and velocity for any single point would be more highly variable than the larger pattern overall.  But also true that in some images, there is a completely different pattern, or no pattern at all!

    My guess is that the variation in Uniquorn's OSISAF Sept 2019-Feb 2020 animation is more random and chaotic than the average of what I saw in my quick overview of 2017-2019. 

      So the "answers" to my questions become:
Is that a typical Sept - Feb drift pattern?
     With respect to the Sep 2019 - Feb 2020 anmiation -- No.  For the Pacific side of the Arctic (which is bigger than the Beaufort Sea of course), there is, overall, a fairly consistent pattern of clockwise rotation that heads westward along Alaska and Siberian coasts then turns back towards the CAA about halfway across the Arctic Ocean.

   Does that view represent the famous Beaufort Gyre or is it just a subset of the larger system?
   My overview of the 2017-2019 drift maps was for a much larger area (= the entire Arctic Ocean) vs. the more restricted area in Uniquorn's animation.  So the answer is again "No".  I think the area covered by the animation is smaller than the Beaufort Gyre area.  My impressions about the drift pattern stated above are for the Pacific side of the entire Arctic Ocean, not just the Beaufort Sea.

   Is there a seasonality for the Beaufort Gyre, i.e. is it more consistently clockwise during the melt season?
     Based on a superficial quick overview of the drift maps from 2017-2019, the clockwise Gyre pattern seems more consistent in Nov - April, and less consistent in May - Sept.  September seemed to be the month with the least consistent clockwise rotation - gyre pattern.  But caveat emptor - these are just impressions, absolutely zero analysis! 

     There are probably multiple published studies that make these rube-a-mentary impressions unnecessary and may show just how wrong such impressions can be.  I only looked at 3 days a month for 3 years, and skipped a few of those month-date combinations.  I don't have time to look for those articles, but if you know of one, please share.