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Messages - JayW

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1
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: November 21, 2020, 02:51:42 AM »
Yermak plateau area.  36 hour loop
Band I4 inverted colors


2
Arctic sea ice / Re: The Rammb Slider Thread
« on: October 21, 2020, 07:41:47 AM »
Longwave IR shows neat clouds streaming off the open leads north of the CAA.
Large gif click to run

3
Arctic sea ice / Re: The 2020 melting season
« on: August 17, 2020, 07:28:02 AM »
Something is definitely going on here
Some of this is surface wetness from rain.

4
Arctic sea ice / Re: The caa-greenland mega crack
« on: August 16, 2020, 07:41:41 PM »
A brief peek through the clouds of the eddies north of Ellesmere Island.
Click to run

5
Arctic sea ice / Re: The 2020 melting season
« on: August 15, 2020, 11:52:42 AM »

[
NOAA-20 formerly JPSS-1 has an improved microwave channel and a design life of 7 years it was launched November 2017 22 bands from 23 GHz to 183 GHz. Nadir resolution 15.8-74.8 km 32 kbps in addition to the Advanced Technology Microwave Sounder (ATMS)

6.925/7.3, 10.65, 18.7, 23.8, 36.5 and 89 Ghz resolution from 3 to 62km
Know of anywhere this data is available?  I've been looking, can't find it.   I've sent a couple emails to the RAMMB folks inquiring about it,  and asking if there was a way to add it to the slider.  No response yet.   Perhaps if others also ask, we could talk them into adding it.  :)

6
Arctic sea ice / Re: Tides
« on: August 12, 2020, 12:06:56 PM »
Regarding the Yermak plateau
Quote
Turbulent mixing near the Yermak Plateau during the Coordinated Eastern Arctic Experiment
Abstract
Recent current measurements obtained from drifting platforms over the Yermak Plateau in the eastern Arctic Ocean confirm that the plateau is a region of greatly enhanced diurnal tidal currents. Modulation of the diurnal currents is clearly related to the plateau topography, as has been previously proposed. We show, however, that temporal variability due to spring‐neap modulation must also be considered in interpreting records from drifting platforms. We review simple models of tidal current amplification in this region and find that the previous assumption of near‐resonant, barotropic shelf waves propagating around the plateau's entire perimeter is inconsistent with the true topography. Instead, we propose that the diurnal variability is due to topographic shelf waves at the K 1 and O 1 tidal frequencies that are generated at points on the plateau's perimeter where the waves' group velocities are near zero. Observed cross‐slope variations in ellipticity, orientation, and magnitude of tidal oscillations are consistent with the presence of topographic waves generated in this manner. The topographic enhancement of the diurnal tide near the Yermak Plateau has important consequences for the sea ice cover, hydrography, and general circulation of this region. For example, the stress divergence applied by the tidal currents at the ice base greatly exceeds the typical divergence of the surface wind stress, and tides may therefore be important to local ice deformation. The strong cross‐slope tidal currents also appear to be responsible for the production of high‐frequency internal wave packets, which are associated with energetic diapycnal mixing in the pycnocline. We also consider the possibility that tidal rectification is responsible for a mean current transporting Atlantic Water clockwise around the plateau.
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/92JC01097

Quote
Effects of tides on the quasi-steady upwelling-downwelling regimes and water mass exchange between the Arctic and Atlantic Oceans.
Abstract
Astronomical tides are strong in the regions of the Arctic shelf and GIN Seas, with amplitudes reaching up to 4.4m in the Hudson Strait, 2-3m in the White Sea and greater than 1m in the Canadian Archipelago. If nonlinear friction is present, at the sea bed or within a stratification water column, periodical motions transfer energy to shear stresses with a substantial non-periodic component. Over bottom topography, anomalous bottom shear stress generates vorticity and vertical motions, resulting in either an ageostrophic circulation or geostrophic upwelling/downwelling of isopycnals. Using a pan-Arctic and a North Atlantic ocean-ice model, both of which explicitly resolve tides, we examine the effects of tides on the vertical motions generated by Ekman pumping near the sea bed and at the ice-ocean interface, and the stretching and tilting of vorticity. We found that tides significantly increase the intensity of vertical upwellings and downwelling regimes near the shelf break. We extend the semi-geostrophic two dimensional Eliassen -Sawyer equation and three-dimensional omega-equation to take into account the effects of tides. We also discuss the application of the equations for the analysis of watermass transformations and dense water overflow in the main gateways between the Atlantic and Arctic Oceans : Fram Strait, Yermak Plateau, Barents Sea shelf break, Denmark Strait and Faroe Channel.

https://ui.adsabs.harvard.edu/abs/2016EGUGA..18.6301L/abstract

7
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: August 09, 2020, 10:54:43 PM »
Thanks JayW. Been wanting that for ages :)
Even more active than I imagined. 280km from nearest land. I think that's 82.5N which puts the eddy near the white blob.  https://col.st/5Us0O (available for a while)
I agree, seems more expansive than what we saw last year.  Wonder if it's due to ice thickness, perhaps due to the higher tide cycle,  interesting for sure.   I see it starting at roughly 7°E.  I see a separate feature at 81.3°N at the ice edge that I don't see is directly related.

Sverdrup channel using I4 with snow RGB for ice.  Relatively warm water being input from the fjords.
Contrast and brightness boosted. Click to run.

8
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: August 08, 2020, 04:07:08 PM »
Yermak plateau area.  Contrast increased. Needs a click.

9
Arctic sea ice / Re: The 2020 melting season
« on: August 02, 2020, 09:11:01 PM »
It's nice to see several people are taking note of what's going above Greenland/the Lincoln Sea. This entire region just continues to surprise and I wish I understood more of the dynamics which facilitated such a vast separation plus an ever-widening crack.
This is today.  There is a lot going on.  Interesting swirls in the open areas extending north from Greenland.  Then there's the interesting feature in the lower right, and the subsequent waves propagating northward.  After seeing this gif from blumenkraft.
https://forum.arctic-sea-ice.net/index.php/topic,2649.msg277039.html#msg277039
I get the feeling the "plunger" action of the tide moving north through the Nares sends a wave that gets trapped along the coast due to coriolis. It's then forced upwards due to bathymetry, creating the swirl, with some of the wave reflect back, but much of it continuing poleward.
There is a lot of "sloshing" in the Lincoln Sea area.
Contrast boosted.  Click to run.

10
Arctic sea ice / Re: The 2020 melting season
« on: August 01, 2020, 10:52:01 PM »
PGAS has fractured and is on the move.
Lots of contrast.  Click to run
 

12
Arctic sea ice / Re: The 2020 melting season
« on: August 01, 2020, 01:49:54 PM »
There's been persistent downsloping winds north of Greenland.  Looks to me like a fair amount of rifting going on here, in addition to the warm breeze flowing northward.
Contrast boosted.  Click to run.

13
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 31, 2020, 02:00:52 AM »
Center of the Beaufort storm really cleared out today.
Click it.

14
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 12:17:28 PM »
A look at ice motion under the center of the storm.
Latitude line is 77.5°N
Needs click.

15
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 11:58:04 AM »
As it appears (to my non-expert eyes) that clouds cause artifacts in the concentration products, the big question in my mind is whether they cause high-concentration streaks, or whether they cause low concentration streaks... Can some kind soul superimpose (and synchronize) the cyclone and the concentration images and prove it one way or the other?
p.s. Of course it's also possible the storm causes actual concentration changes that appear to be in its shape. Would love an expert opinion.
I'm not an expert, but I have seen enough artifacts caused by clouds and rain to agree, they do confuse the sensors.  I'd also add that like worldview, these concentration/area products are stitching together multiple satellite passes over the course of 24 hours.  When sea ice is moving around, I wonder how much this motion also plays into the final product. In my humble opinion, these figures should include error bounds to describe the inherent uncertainty in the data being displayed.   

16
Arctic sea ice / Re: The 2020 melting season
« on: July 29, 2020, 12:48:31 PM »
Loop of the heavily occluded storm. Any fresh snow that fell a could days ago has melted.  I don't see evidence of any new snow that has fallen, that doesn't mean some of these thinks bands can't be generating snow, it's just not showing up on the surface.
Needs click.

17
Arctic sea ice / Re: The 2020 melting season
« on: July 29, 2020, 01:17:18 AM »
Quick look between rain bands in the Beaufort.
Click to run.

18
Arctic sea ice / Re: The 2020 melting season
« on: July 28, 2020, 12:09:25 PM »
More stretch marks showing up above 88°N.
Click to run. Contrast increased for detail.

19
Arctic sea ice / Re: The 2020 melting season
« on: July 28, 2020, 01:52:04 AM »
Another view of that gap that has appeared near the pole. 
RAMMB contrast boosted.
Needs click

20
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 28, 2020, 01:02:35 AM »
Love watching these eddies.
Needs click.


21
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 27, 2020, 05:57:33 AM »
A little snow still seen north of the storm, but a lot of dark red elsewhere. 
Click

22
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 10:43:21 PM »
Peeks through the clouds show the effects of the stiff breeze over the Peary channel.
Click to run.

23
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 26, 2020, 11:57:14 AM »
Svalbard on the bottom. I flipped to put north upwards. Band I4 to show the SSTs. Overlayed with snowmelt RGB (blue) to show the ice edge.
Contrast boosted.
Needs click

24
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 09:07:23 AM »
RAMMB band M8 shows a bit of snow has fallen. Area circled in blue on last frame.
Click to run.

25
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 25, 2020, 12:06:45 PM »
Nice, though I'm not sure what band I4 is showing. Mercator temperature resolution is too low to show much change on the Ellesmere coast yet. Salinity is often a better indicator of up/downwelling. Here is the modelled 0m salinity jul1-24 and 0m temperature, jul18-24

It could just be insolation, probably both.
It's sensitive to temperatures.  I was thinking insolation was playing a role as well.  The eddies are interesting.

26
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 25, 2020, 05:51:38 AM »
Band I4, opening north of Ellesmere Island. Heavy contrast.
87 ish hour loop.
Click to run.

27
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 25, 2020, 12:03:08 AM »
NW Greenland. Revisiting a feature from lat year. I included more of the opening in case there is interest in the motion there.  82 hours, kinda big sorry, did my best.
Click to bring to life.

28
Arctic sea ice / Re: The 2020 melting season
« on: July 24, 2020, 01:21:46 AM »
Corner of Banks island in the lower left corner.  Parry channel breaking up, starting to sway with the tides.
Contrast enhanced.  Click to run. 34 hour loop.

 

29
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 23, 2020, 01:22:37 AM »
I was making a gif of the Yermak plateau area, but noticed some other interesting motions, hence the wider shot. Hopefully we get another clear day and updating RAMMB...
Click it.

30
Arctic sea ice / Re: The 2020 melting season
« on: July 22, 2020, 02:26:45 PM »
A lot of MYI ice in the Beaufort that has not suffered big heat nor big storms. These things can quench the melting season if August weather come dull.
They are currently breaking up under a weak cyclone. Same is happening near Banks island.
https://forum.arctic-sea-ice.net/index.php/topic,2649.msg275928.html#msg275928

31
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 22, 2020, 01:38:07 AM »
Beaufort doing what the Beaufort does, pulverizes.

32
The rest / Re: Astronomical news
« on: July 21, 2020, 11:54:04 PM »
The comet was visible last night here in Calif.  It was about halfway between the horizon and the Big Dipper at 9:45pm.  Kinda fuzzy with the naked eye but nice using binoculars. You only see so many comets in one lifetime. I can remember where I watched four memorable ones.
Quite visible in the Maine darkness. Snagged a few shots last night.

33
Arctic sea ice / Re: The 2020 melting season
« on: July 20, 2020, 09:34:58 AM »
82 hour loop ESS, contrast boosted. Needs a click. 

34
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 20, 2020, 09:33:30 AM »
Northern ESS/Chukchi. 84 hours. Needs click

35
Spotted these cloud formations on Worldview today. First between Svalbard and Franz Josef Land, second between FJL and Novaya Zemlya. I was struck by their small scale "cyclonic" appearance, don't think I've noticed anything like them before. My first thought was thuderstorm, especially the first image. The central structure in each is about 15 - 25 miles across. Just wondering if I'm correct, I'd be grateful for any insight.
These mesoscale lows adre actually pretty common, especially if you look at enough RAMMB imagery. Unfortunately, I don't think they are thunderstorms (not to say nT- storms can't happen in the artic), but isee them as nteresting circulations in the mid or lower atmosphere.
This is from last year.
https://forum.arctic-sea-ice.net/index.php/topic,2649.msg205085.html#msg205085
 
Here's one today on the north coast  of Greenland.

Needs click.

36
Arctic sea ice / Re: The 2020 melting season
« on: July 19, 2020, 11:03:02 AM »
Close up of roughly 135°-150°E, . 74 hour loop, edit: oops, 59 hour loop. Contrast boosted.
Click to run.

37
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 19, 2020, 10:11:47 AM »
Jay, do you know, which band would be capable of showing the sediments?
Geocolor would likely be best, but a far as individual bands, I've seen high resolution band I1 "red" pick it up (M5 "red" also), and band M4 "green".  Sediment is normally brown, a color combination of red and green, so I'd use one of those.  The green band could also pick up algae as well I'd think.  When toggling though the bands, I'd say green does best.

38
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 19, 2020, 12:51:19 AM »
So what are we actually seeing in these shots? The water temperature or sediments?

Because if it's the sediments, we can assume river discharge.
It is shortwave IR, it's temperature, I've used it with GOES imagery as well.

39
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 19, 2020, 12:49:05 AM »
Got every image available in the archive, slim pickings at times. It's unfortunate there is no imagery except day night updating today, clear skies help. Anyhow, I sped it up to help see through the clouds.  Perhaps I'm biased, but I see a plume extending out, but certainly curious as others interpretation. Incidentally, you can see the enhanced cloud/fog formation off the warmest SSTs.
Click, kinda big

40
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 18, 2020, 09:28:40 PM »
Toggling between the last available frame from I4 and I2 bands. Trying to show, what I suspect is, Lena discharge extending into the Laptev.
Needs click

41
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 18, 2020, 08:14:17 AM »
50 hour loop day night band (only one updating currently...) Laptev nibbling.


42
Arctic sea ice / Re: The 2020 melting season
« on: July 17, 2020, 12:10:45 PM »
24 hour loop, this covers 0:11z-23:52 July 16.  Right under the center of the high pressure, an inversion likely formed allowing the ice surface to cool slightly.  The winds are not strong enough in the center to mix the warmer air down from aloft, so warm temps aloft mix down most efficiently along the periphery.  This shows up in AMSR2 data as (2nd attachment) well.  Once again, clouds can be seen creating an apparent increase in concentration elsewhere.

Click, sorry for the larger gif, I tried to reduce its size.

43
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 17, 2020, 11:39:09 AM »
North of Ellesmere.
Interesting little counter current there.

44
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 17, 2020, 11:22:04 AM »
I was hoping for another cloud free day in the Lincoln to have two days, but isn't happening.  Just happy to have the full suite of RAMMB imagery updating.
 Here's Lincoln see with heavy contrast.  I see two possible areas of upwelling.  Normally, I'm used to cooler water being upwelled, as that's what happens outside of the arctic.  One is in the upper left, the other is near the mouth of the first fjord up from the Nares entrance.  I also see a slight daily rhythm in the opening, I'm attributing to the sun. 
Needs a click

45
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 17, 2020, 04:54:56 AM »
Interesting eddies along 75°N in the northern ESS.  What are the chances the shelf break is there?
Click it.

46
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 17, 2020, 12:51:46 AM »
Comparison of bands I2 and I4. Attempting to highlight the highest ssts in relation to the ice.

First attachment, Nares entrance in lower right.

Second is part of the chukchi, note the ssts are cooler than the ice in the upper left.  The warm plume is attacking the ice edge in the center.

Both need a click.  Contrast boosted.

47
Arctic sea ice / Re: The 2020 melting season
« on: July 15, 2020, 05:56:36 AM »
JayW - great loop. If you watch the protruding arm it is really interesting to watch as the ice spreads and then contracts twice and is just starting a third expansion at the end of the loop - each time it contracts you can see it has also suffered significant melting. Not sure what is the cause - it is so regular it must be some tidal movement (or a pulsing upwelling?)

The face of the rest of the ice does not seem to be affected by whatever is cause that arm to 'pulse'.
Not every orbital swath can capture the area, so there's a roughly 12 hour gap between days that the JPSS satellites can't see, that's the "surge" you see.  Otherwise, it's about 50 minutes between frames, sometimes 100 depending on image availability.

48
Nice eddy there helping to draw that ice out.

49
Arctic sea ice / Re: The 2020 melting season
« on: July 15, 2020, 05:22:17 AM »
52 hour loop, Laptev bite. Click to run.

50
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 15, 2020, 04:58:15 AM »
Belcher channel/penny Strait area.  I boosted contrast to help see the rifting in the lower left.
Click

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