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gandul

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Re: The 2020/2021 freezing season
« Reply #500 on: October 23, 2020, 06:57:23 PM »
Have you seen the snow extent growth over Siberia and Western Canada? Anything to comment or you only rejoice on the bad feedbacks?
...
apart from this, the weather is about to become propitious for a quick rebound of sea ice next week.

This seems like an emotional type response, especially as a reply to such an informative post which did not actually feature any rejoicing...

The previous posts were an actual attempt at figuring out some of the extent of the damage done.

A quick rebound next week would already be late but both recent comments in this thread and in the SIA&E thread hint that the it might not be quick.

You are thinking too much about the area/extent (so 2D) while ignoring the 3D problems like the stall in TPD.

Quote
In other words, 2021 and 2022 could be rebound years as probable as big melt years. I don’t see the doom scenario here (more in line with the scientific consensus of 2040+)

In case you missed it we are discussing what we see. Oh and i think that scientific consensus might have shifted a bit...
Yes Kassy it’s an emotional response because I get the feeling people choose to not talk about that, there may be other mechanisms that kick in and explain why the Arctic didn’t completely tank 8 years ago.

Rebound years (08/09, 13/14, 17/18) are surrounded by certain mystery or silence.

Ok I’ll try to open that discussion in another thread.
In any case the posts here lately are excellent, I don’t deny people are well informed, much better than me in any case.

SimonF92

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Re: The 2020/2021 freezing season
« Reply #501 on: October 23, 2020, 07:33:08 PM »
My apologies if this is an ignorant or rookie question, but has anyone looked at the integral of sea ice extent, area and volume across a given year, or year-to-date, in order to quantitatively compare them with regard to sea ice coverage?

I think that would highlight 2020's prominance more clearly over past years, even 2012, with regard to the amount of time its been in the lead and by how much. This comparison would give equal measure to all time points (as I think they 'deserve') rather than having bias as to the minimum and maximum. Such an analysis may help to see an overall trend over the years, relative to looking at particular time-points.

I think volume may be the most sensitive metric to use, as sea ice area and extent seem to have much less variation during the winter, and those large numbers may blunt changes occurring from year-to-year.

I think this is a really good idea, would you be willing to have a go at it? Otherwise I can try to pick it up
If I understand correctly, this would partly be covered by Gero's 365-day extent average, posted regularly in its own thread. As for volume I seem to recall he also made such a chart, and there's also my own modest chart detailing the number of daily records held by each year. For all measures, 2020 is still behind a combination of 2016-17, however this could change quite quickly as the "Siberian Seas problem" continues to develop and considering the low minima achieved this year.

It did it myself just for a bit of practice parsing .dat files
Bunch of small python Arctic Apps:
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SimonF92

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Re: The 2020/2021 freezing season
« Reply #502 on: October 23, 2020, 07:34:11 PM »
Actually this is clearer

(And i added up to day313 so that we could see 2020)
« Last Edit: October 23, 2020, 07:47:26 PM by SimonF92 »
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I’M IN LOVE WITH A RAGER

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Re: The 2020/2021 freezing season
« Reply #503 on: October 23, 2020, 07:47:28 PM »
Pardon my potential lack of comprehension, but what does the 0 baseline on the Y-axis of the graph mean, Simon? How significant is the sub-0 data point in 2016? Regardless, this seems to be a very interesting representation of the data and I am excited to see how this line of thought continues to develop.

SimonF92

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Re: The 2020/2021 freezing season
« Reply #504 on: October 23, 2020, 07:57:45 PM »
Pardon my potential lack of comprehension, but what does the 0 baseline on the Y-axis of the graph mean, Simon? How significant is the sub-0 data point in 2016? Regardless, this seems to be a very interesting representation of the data and I am excited to see how this line of thought continues to develop.

I actually dont know Rager, i think it might be something to do with a weighted value to the polyfit? I checked it using Simpsons integration and there were even more -'s. Any statisticians around here at the moment care to wade in?
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FishOutofWater

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Re: The 2020/2021 freezing season
« Reply #505 on: October 23, 2020, 08:24:51 PM »
Those Arctic sea ice recovery years had major sudden stratospheric warming events in midwinter.

A dry clear dome of high pressure over the pole in February or early March is ideal for radiating heat to space and thickening the ice around the pole.

https://www.researchgate.net/publication/329104906_The_Stratospheric_Sudden_Warming_Event_in_February_2018_and_its_Prediction_by_a_Climate_System_Model

and

https://www.mdpi.com/2073-4433/10/9/519/pdf

Freegrass

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Re: The 2020/2021 freezing season
« Reply #506 on: October 23, 2020, 10:35:32 PM »
The Laptev is still warm at 30m depth. Is that heavier salty water? Too bad we can't see the temperature at 10 or 20 meters depth on the Siberian shelf....

Edit:
Just saw that you can create links to a zoomed in area directly on the website.
http://bulletin.mercator-ocean.fr/en/permalink/PSY4/20201023/map/3/1/2#5/68.302/-54.075
« Last Edit: October 23, 2020, 10:44:12 PM by Freegrass »
Now let's pray...

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morganism

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Re: The 2020/2021 freezing season
« Reply #507 on: October 23, 2020, 11:26:12 PM »
That sure looks like the Greenland Crack is opening again....?

https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=3299.0;attach=289522;image

A-Team

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Re: The 2020/2021 freezing season
« Reply #508 on: October 24, 2020, 12:14:31 AM »
Quote
Too bad we can't see the temperature at 10 meters depth on the Siberian shelf
Measurement of SST is quite complex, involving numerous satellites:

"For the Global Ocean- Sea Surface Temperature L3 Observations . This product provides daily foundation sea surface temperature from multiple satellite sources. The data are intercalibrated. This product consists in a fusion of sea surface temperature observations from multiple satellite sensors, daily, over a 0.1° resolution global grid. It includes observations by polar orbiting (NOAA-18 & NOAAA-19/AVHRR, METOP-A/AVHRR, ENVISAT/AATSR, AQUA/AMSRE, TRMM/TMI) and geostationary (MSG/SEVIRI, GOES-11) satellites . The observations of each sensor are inter-calibrated prior to merging using a bias correction based on a multi-sensor median reference correcting the large-scale cross-sensor biases"

There's a reason for not showing the 10m (see image below):

"SST is a challenging parameter to define precisely as the upper ocean (~10 m) has a complex and variable vertical temperature structure that is related to ocean turbulence and air-sea fluxes of heat, moisture and momentum.

The interface temperature (SSTint): At the exact air-sea interface a hypothetical temperature called the interface temperature (SSTint) is defined although this is of no practical use because it cannot be measured using current technology.

The skin sea surface temperature (SSTskin): The skin temperature is defined as the temperature measured by an infrared radiometer typically operating at wavelengths 3.7-12 µm (chosen for consistency with the majority of infrared satellite measurements) that represents the temperature within the conductive diffusion-dominated sub-layer at a depth of ~10-20 µm. SSTskin measurements are subject to a large potential diurnal cycle including cool skin layer effects (especially at night under clear skies and low wind speed conditions) and warm layer effects in the daytime.

The sub-skin sea surface temperature (SSTsub-skin): The subskin temperature represents the temperature at the base of the conductive laminar sub-layer of the ocean surface. For practical purposes, SSTsubskin can be well approximated to the measurement of surface temperature by a microwave radiometer operating in the 6-11 GHz frequency range, but the relationship is neither direct nor invariant to changing physical conditions or to the specific geometry of the microwave measurements.

[[See https://tinyurl.com/yyab3s5e for subskin temperatures loaded at CMEMS-Lobelia]]

The surface temperature at depth (SSTz or SSTdepth): All measurements of water temperature beneath the SSTsubskin are referred to as depth temperatures (SSTdepth) measured using a wide variety of platforms and sensors such as drifting buoys, vertical profiling floats, or deep thermistor chains at depths ranging from 0.01 – 1000m. These temperature observations are distinct from those obtained using remote sensing techniques (SSTskin and SSTsubskin) and must be qualified by a measurement depth in meters (e.g., or SST(z) e.g. SST5m).

The foundation temperature (SSTfnd): The foundation SST  is the temperature free of diurnal temperature variability, defined as the temperature at the first time of the day when the heat gain from the solar radiation absorption exceeds the heat loss at the sea surface. For conditions, when the SST increases or decreases monotonically over several days, the Tfnd occurs on a given day when the time rate of change of temperature is at a minimum (increasing SST), or a maximum (decreasing SST). If such a point in the daily time series cannot be identified, the SSTfnd should be set to a clearly stated time. SSTfnd is named to indicate that it is the foundation temperature upon which the growth and decay of the diurnal heating develops each day. Only in situ contact thermometry is able to measure SSTfnd and analysis procedures must be used to estimate the SSTfnd from radiometric retrievals of SSTskin and SSTsubskin taken at other times of the day."

https://www.ghrsst.org/ghrsst-data-services/products/

Quote
you can create links to a zoomed in area
The problem with that, as noted many times earlier, is that Mercator Ocean does not use quite the same scale for 0 and 30m, meaning that the colors cannot be compared directly. Instead, the fixed palette png's have to be used but these lose the zoom.

The animation below provides a flash comparator of the 0 and 30m temperatures with the same color definitions of temperature. The 30m is considerably warmer in the Bering Strait and Chukchi region. That holds for the Laptev as well possibly reflecting AW intrusion. The continental shelf to 30m has been grayed out on the 0m to minimize confusion.
« Last Edit: October 24, 2020, 01:06:50 AM by A-Team »

FishOutofWater

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Re: The 2020/2021 freezing season
« Reply #509 on: October 24, 2020, 12:53:23 AM »
There's an apparent current of warm salty Atlantic water along the shelf edge, Freegrass. You can see the shelf margin and warm salty water at the 100m depth.

http://bulletin.mercator-ocean.fr/en/PSY4#5/68.302/-54.097
http://bulletin.mercator-ocean.fr/en/PSY4#5/68.302/-54.097
The next 2 figures show the current at 100m, according to the Mercator model& the sea surface height which is a critical input to the model.
http://bulletin.mercator-ocean.fr/en/PSY4#5/68.302/-54.097
http://bulletin.mercator-ocean.fr/en/PSY4#5/68.302/-54.097

Aluminium

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Re: The 2020/2021 freezing season
« Reply #510 on: October 24, 2020, 05:38:58 AM »
October 19-23.

2019.

Sublime_Rime

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Re: The 2020/2021 freezing season
« Reply #511 on: October 24, 2020, 06:04:30 AM »

It did it myself just for a bit of practice parsing .dat files

Thanks Simon! Nice work with those last two. I tried doing the same by just taking the average of the monthly data for each year as a bar graph, but it didn't come out as nicely so far. Suggests as Oren said that 2020 hasn't overcome the long stretches of low volumes in 2016-2017, but may still in the weeks to come.
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BornFromTheVoid

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Re: The 2020/2021 freezing season
« Reply #512 on: October 24, 2020, 12:06:52 PM »
Here's the slow animation for the past week. Still areas of loss occurring, which surprised me a little.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Freegrass

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Re: The 2020/2021 freezing season
« Reply #513 on: October 24, 2020, 12:53:46 PM »
Here's the slow animation for the past week. Still areas of loss occurring, which surprised me a little.
It doesn't really surprise me. When you look at the HYCOM ice animation I posted a few days go, you can see that the ice there is expanding instead of freezing from the edge. So my guess is that there's a lot of dispersion going on, with leads at the center freezing up, while the ice edge moves over warmer water. And that can still melt the ice edge of course...

https://forum.arctic-sea-ice.net/index.php/topic,3299.msg290729.html#msg290729

Thank you for the explanation A-Team and FOoW! Love the animation with the temperature difference at different depths. Hope to see more of those throughout the year. That may tell us how fast the water is warming up or cooling down in the shallows.

Will that warmer water at 30m prevent ice from forming? Or will it be added to the energy balance in the deep ocean as it's been dragged down with the brine that's released out of the big icemaker?
« Last Edit: October 24, 2020, 01:46:59 PM by Freegrass »
Now let's pray...

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gandul

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Re: The 2020/2021 freezing season
« Reply #514 on: October 24, 2020, 01:53:07 PM »
Here's the slow animation for the past week. Still areas of loss occurring, which surprised me a little.
Could it be a late Bering pulse affecting the ice edge?
Chukchi sea looks really warm and I wonder if there has been significant Bering inflow in Sep/Oct while we were not particularly looking in that direction.

gandul

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Re: The 2020/2021 freezing season
« Reply #515 on: October 24, 2020, 02:02:03 PM »
Mercator's take on SST's.
amsr2, awi dev v103 overlaid onto mercator 0m ocean temperature, sep4-oct22  (7MB)
Ok, from your animation is it correct to say all the regions susceptible to warming from Atlantic Waters are already covered by ice or about to be covered? (exception Barents and Kara but we know those two seas are already lost to climate change)
It seems to me the anomalously warm Laptev and ESS areas are basically over the shallow shelf, which will have a record heat release (consistent with the record heat income from GAAC and the season in general). So no Atlantic warmth here to speak about.

The Laptev sea extent beyond the shelf (and so the heat anomaly, by the way). Intrusion of Atlantic waters are discernible on the salinity maps of the mercator. (P.S. : And acknoledging that the heat and salinity extent beyond the Laptev into the central bassin, even under the sea ice).
Yes, SST is more useful if we also show SSS
amsr2, awi dev v103 overlaid at 75% transparent onto mercator 0m ocean salinity, sep4-oct22  (7MB)
mercator label is just visible.
edit: It has often been proposed that the Atlantic waters would meet the Pacific incoming at some point. The delay in refreeze and perhaps some mixing from recent strong winds would seem to make that prospect more likely (according to the model). The Siberian shelf and the Chukchi plateau help to prevent it. (Shown on the 92m salinity map upthread)

This animation by Uniquorn shows, I believe,Bering inflow late in the season and beyond, and the pool of warm water being dragged, at least superficially, well into the Pacific side of the Arctic (by winds?)

Freegrass

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Re: The 2020/2021 freezing season
« Reply #516 on: October 24, 2020, 02:15:12 PM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Wind + Temp @ 850hPa
Large GiFS!

Another heat bomb is about to enter the Arctic again...
Now let's pray...

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uniquorn

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Re: The 2020/2021 freezing season
« Reply #517 on: October 24, 2020, 03:10:02 PM »
A closer look at refreeze not keeping up with dispersion in the Beaufort yesterday, amsr2 awi v103 oct12-23. Winds were not strong, just a little warmer.

Also moving the conversation about whoi itp121 from the melting season to this thread. Latest temperature/salinity profiles and drift path.
Temperature at 50m still high at over 2C.

itp121 shares a floe with ice mass balance buoy www.cryosphereinnovation.com/441910 currently maintaining thickness at ~2m.
« Last Edit: October 24, 2020, 03:27:34 PM by uniquorn »

Général de GuerreLasse

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Re: The 2020/2021 freezing season
« Reply #518 on: October 24, 2020, 03:11:29 PM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Wind + Temp @ 850hPa
Large GiFS!

Another heat bomb is about to enter the Arctic again...

Hi Freegrass, I hope your heat bomb won't do too much damage. I was thinking that Mercator's forecast for 11/02 was already not very good...
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FishOutofWater

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Re: The 2020/2021 freezing season
« Reply #519 on: October 24, 2020, 03:24:14 PM »
The warm salty Atlantic water inflow to the Laptev sea will increase the "Atlantification" of the Siberian seas as winter progresses. Of course, it's going to get cold in the coming winter months and ice will form but the ice will be thinner than it used to be and more heat will escape to the atmosphere. This heat transfer will increase the formation of relatively dense water which will sink along the continental shelf margin.

Over the past 2 years we have watched an influx of Atlantic water into the Siberian seas, the formation of a subsurface summer water layer by flow off the Chukchi shelf, and the movement of a very large volume of relatively fresh sea water towards the Canadian side of the Arctic ocean. We have measures of the amount of ice flowing out of the Fram strait, but we have not been accounting for the large volume of melted ice that is flowing out below the surface down to the 300m level.

Also note that Mercator animations show that fresh Siberian shelf water separates the Atlantic waters from the Pacific waters as they all flow off the Chukchi and Siberian shelves. Those waters sink to different depths depending on their density. Mixing occurs in eddies.

Freegrass, that's an excellent cartoon of flow off the shelf edge, but there's one thing that needs updating. All the ice will be first year ice this year. There is no multi-year ice anywhere close to Siberia.
« Last Edit: October 24, 2020, 03:31:41 PM by FishOutofWater »

FishOutofWater

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Re: The 2020/2021 freezing season
« Reply #520 on: October 24, 2020, 03:39:42 PM »
Thanks, Uniquorn for that visualization of the Beaufort sea. The rapid ice area increase was caused by advection from the CAA side of the Arctic ocean. Although we have seen evidence of freezing and ice formation, that animation shows evidence of ongoing bottom melt. That's quite unsettling given that it's late October. The thickest multi year ice in the CAA is moving towards the Beaufort sea, setting it up for melting out next summer.

Niall Dollard

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Re: The 2020/2021 freezing season
« Reply #521 on: October 24, 2020, 04:16:27 PM »
Sample forecast chart (for yesterday) from NOAA's Physical Science Lab backing up what has been said already. Bottom melt (greens/blues) is still ongoing on the edges of the pack. In particular near Severnaya Zemlya and also in the far SE of Beaufort. Of the order of about 1cm per day.

Meanwhile bottom growth (beige/reds) is indicated away from the edges (about 1cm per day).

A-Team

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Re: The 2020/2021 freezing season
« Reply #522 on: October 24, 2020, 06:22:37 PM »
As being noted above, it's difficult to distinguish lateral ice extension from just the wind pushing things around. The first graphic below just overlays OsiSaf's observed floe motions over BVoid's gain'/oss for the week. The outflows/inflows line up quite closely with green/red for gain/loss suggesting growth towards the Siberian side has stalled.

The 2nd image just shows the vertical salinity gradient. As FooW notes, that cartoon above of the Barents front is not applicable to the Laptev; atlantification has joined up with pacification of the Chukchi which FooW/Uniq anticipated last year.

Aslan #482 posted very helpful direct links to sea surface temperatures data. Usually these go to a massive opaque portal featuring guys in suits cheering a satellite rocket launch; you then spend an hour drilling around for actual data only to find no thumbnails and the netCDFs formatted all wrong. Here everything was done perfectly (3rd image): from seamless ftp to Geo2D, land/ice masks, error analysis etc.

ftp://ftp.star.nesdis.noaa.gov/pub/socd2/coastwatch/sst_blended/sst5km/night/ghrsst_ospo/2020/

The inset, lower right, shows a bit of the raw numerical temperature array in kelvin for the point in the Laptev at 77.77ºN whose time-dependent temperature series was calculated in #491 above from Nullschool (which uses this same data source for its popups).

CMEMS-Lobelia and Mercator Ocean also use this same data -- it's all provided by an SST expert group from 11 institutions called GHRSST. No way we can approach this quality looking at WorldView infrared bands on our own!

https://www.ghrsst.org/latest-sst-map/

The arithmetic operations shown as available within Panoply allow differencing of SST between any two dates across the entire Arctic Ocean. From there, it is straightforward to make a red gain in temperature png and a blue loss that are easily combined in Gimp (4th illustration). It's also easy to copy out a column of the raw data display and plot a constant-longitude transect from the Siberian shore to the ice edge.

Regardless how this or that online service might display SST, we can always go back to this raw data to see what the real spatial resolution was and the uncertainty associated with the SST determination. Here the polar latitude and longitude both bump by 0.05º per bin making pixels 5.7km on a side with temperature provided to 0.1K precision.
« Last Edit: October 24, 2020, 09:04:42 PM by A-Team »

Freegrass

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Re: The 2020/2021 freezing season
« Reply #523 on: October 24, 2020, 06:49:02 PM »
Who is going to ask Google Earth to add all this data to their globe? How awesome would it be if we could use Google Earth Ocean to go below the surface to see the salinity and temperature of the water in 3D...
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RoxTheGeologist

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Re: The 2020/2021 freezing season
« Reply #524 on: October 24, 2020, 09:30:29 PM »
...
Freegrass, that's an excellent cartoon of flow off the shelf edge, but there's one thing that needs updating. All the ice will be first year ice this year. There is no multi-year ice anywhere close to Siberia.


.... and the halocline is much closer to the surface.

Freegrass

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Re: The 2020/2021 freezing season
« Reply #525 on: October 24, 2020, 10:24:14 PM »
...
Freegrass, that's an excellent cartoon of flow off the shelf edge, but there's one thing that needs updating. All the ice will be first year ice this year. There is no multi-year ice anywhere close to Siberia.


.... and the halocline is much closer to the surface.
I understand things are a lot more complicated than what the cartoon depicted. But when I look at that cartoon, I start thinking about the feeding mechanism for the halocline. When less ice is formed, there will also be less salt released. I'm curious how this will affect the halocline. I'm pretty sure its bad, and another invisible positive feedback loop?

One more thing I'd like to know is if that 200m should be 80m now?
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morganism

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Re: The 2020/2021 freezing season
« Reply #526 on: October 24, 2020, 10:55:16 PM »
Will this toxic spill In Siberia act like antifreeze?

"The Russian branch of Greenpeace pointed to a nearby toxic waste dump as a possible source of the leak. Kamchatka officials revealed Tuesday that the perimeter at Kozelsky site, which stores over 100 tons of toxic substances, including pesticides, had been breached. (high phenol levels measured too).

There was also a large oil spill near Novilisk few months ago.

Cnn n Siberian Times carrying stories

A-Team

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Re: The 2020/2021 freezing season
« Reply #527 on: October 25, 2020, 12:52:51 AM »
Here is the Oct 23rd situation. Panoply makes a quite decent no-click map out of GHRSST data with a little help from AMSR2_AWI, OsiSaf and Gimp. Click to see at full resolution of the data source. Note this is SSTfnd, not skin or subskin temperatures. The contour lines correspond to tick mark bins in the palette.

What this is saying is the open water is far too warm from the surface down to 10m depth to even be talking about ice forming without really cold air. Right now, the 2m air temperature at 85º on the 140th meridian connecting the NSI to the North Pole is -2ºC. Please remind me to make a new map when it is has been -35ºC for a couple weeks!

Late fall temperatures seen by the Polarstern:
https://www.awi.de/fileadmin/user_upload/MET/PolarsternCoursePlot/psobsedat.html


20201023000000-OSPO-L4_GHRSST-SSTfnd-Geo_Polar_Blended_Night-GLOB-v02.0-fv01.0.nc
« Last Edit: October 25, 2020, 02:55:50 AM by A-Team »

Glen Koehler

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Re: The 2020/2021 freezing season
« Reply #528 on: October 25, 2020, 02:46:11 AM »
      The Panoply map is very interesting.  What are typical cooling rates for November, December, and January?  In other words, what does a current temperature of 273-275K in most of the ESS and Laptev, and much of the Kara, suggest for when those waters are likely to freeze?
      Here is CR temperature anomaly map for same day.  It is an apples vs oranges comparison because Panoply and CR  are not representing temperature at the same depth in addition to using different data sources.     
« Last Edit: October 25, 2020, 02:45:31 AM by Glen Koehler »

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Re: The 2020/2021 freezing season
« Reply #529 on: October 25, 2020, 08:25:25 AM »
      The Panoply map is very interesting.  What are typical cooling rates for November, December, and January?  In other words, what does a current temperature of 273-275K in most of the ESS and Laptev, and much of the Kara, suggest for when those waters are likely to freeze?
 
It's not what they suggest now.

It's what they augur for spring that is significant.

There is no ice.  There will likely be no ice over large stretches of that open water for weeks.

Right now, it looks like we'll be flying under 2016's numbers by close to half a million km2 for most of the refreeze season.  Come March, that will potentially be half a million km2 of exposed ocean sucking up heat and not reflecting it back out of the atmosphere as the sun returns.

Even when enough heat has been dumped for that water to freeze, with the coverage we'll get, those higher temperatures will mean thinner ice, by 10's of centimeters, which will be more vulnerable and melt out faster when the sun starts to return.

I'm expecting an early max, and a return of May melt ponds next spring, is the take-away I have of these numbers.

This space for Rent.

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Re: The 2020/2021 freezing season
« Reply #530 on: October 25, 2020, 09:31:43 AM »
The later it refreezes the steeper the ramp rate will be. Still at those lattitudes in late October there is probably so little sun the ramp rate of sea ice is pretty close to maximum.

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Re: The 2020/2021 freezing season
« Reply #531 on: October 25, 2020, 09:37:13 AM »
Quote
Right now, it looks like we'll be flying under 2016's numbers by close to half a million km2 for most of the refreeze season.  Come March, that will potentially be half a million km2 of exposed ocean sucking up heat and not reflecting it back out of the atmosphere as the sun returns.
The Siberian seas are currently very much delayed. However extent max is set elsewhere, in Baffin, Barents, Bering and Okhotsk alongside the Greenland Sea. While I don't doubt everything is connected in the Arctic, I do doubt how much of an effect the Siberian seas now have on these peripheral seas in March. The current Siberian delay is deeply concerning as is and will cause lots of damage locally and across the CAB (due to trans polar drift) but I wouldn't go as far as extending the damage to open water in March soaking up sun.

uniquorn

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Re: The 2020/2021 freezing season
« Reply #532 on: October 25, 2020, 11:16:46 AM »
Here is the Oct 23rd situation. Panoply makes a quite decent no-click map out of GHRSST data with a little help from AMSR2_AWI, OsiSaf and Gimp.
20201023000000-OSPO-L4_GHRSST-SSTfnd-Geo_Polar_Blended_Night-GLOB-v02.0-fv01.0.nc
An excellent combination.

IABP raw data is available in the format shown below. The map shows the locations and the data can be looked up using the table

iabp204672 204762 is shown below. The default scales are large but you can create your own chart from the data.
« Last Edit: October 25, 2020, 06:43:13 PM by uniquorn »

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Re: The 2020/2021 freezing season
« Reply #533 on: October 25, 2020, 11:48:12 AM »
Temperature on Kotelny Island finally falls below -10°C. Winter is coming.

uniquorn

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Re: The 2020/2021 freezing season
« Reply #534 on: October 25, 2020, 12:46:16 PM »
IABP buoy drift and surface temperature update. A steady drift along the line from Chukchi to Fram since oct6 until recently. My buoy list needs updating since it doesn't appear to include 204672 above. (12MB is a bit large) edit: updating this updated below

Unrelated but also interesting is the amount of heat escaping from the Nth Greenland Coast. https://go.nasa.gov/2HxW0GH

amsr2 awi v103, oct14-24
click for animations.

polarview S1B
« Last Edit: October 25, 2020, 06:37:09 PM by uniquorn »

Freegrass

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Re: The 2020/2021 freezing season
« Reply #535 on: October 25, 2020, 01:52:41 PM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!
Now let's pray...

If the science don't fit our beliefs, we pray to God and cuddle up in our own delusional fantasy where everything makes sense again...

A-Team

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Re: The 2020/2021 freezing season
« Reply #536 on: October 25, 2020, 01:56:51 PM »
Quote
Winter is finally here, Kotolny Island is really cold!
No it isn't. The quite moderate 10 day forecast is attached below. The icons indicate extent of cloud cover which affect radiative balance. The weather station reports 2m temperatures but those are relative to its elevation of 8m above sea level.

http://www.aps-polar.org/mv_html/j00001/2015-02/20150206_APS.htm congelation land-fast ice

While ECMWF and GFS assimilate this station in their regional forecasts (and CR in turn), it's not at all clear which hPa over the Laptev (925? boundary layer?) is most relevant to the cold experienced by open water (near-surface air is somewhat clamped to surface water temperature).

GFS is currently reporting air temperatures of -4.5, -4.7, -15.9 at the surface, 1000 hPa, 850 hPa respectively at UTC noon today. These bear no immediate relationship to highs or lows at Kotolny (-12. -7).
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Can buoys in Laptev validate or improve on SST measurement
That 204672 buoy is in a good location but it does not currently appear in IADP's table!
https://iabp.apl.uw.edu/TABLES/ArcticTable.php

However 204761 and 204762 do: these are global drifters of type SVP-B, placed by AARI-USIABP (Russian Arctic and Antarctic Research Institute joint US Interagency Arctic Buoy Program). The former is at 75.23 114.88 on 10/25/2020 measuring water temperature at the bottom of the buoy at 0.96ºC. The latter is at 76.78 118.34 showing 1.68ºC.

It seems like 204763 and 204764 are also worthy of consideration. These are at 76.70 111.48 showing -1.68ºC and 79.90 121.38 seeing -0.80ºC. Uniq has picked these up in #538 below.

"These SVP (surface velocity drifters) were standardized in 1991 with small spherical hull, floats and large Holey-Sock drogues 15m below the surface. In 1993, drifters with barometer ports, called SVPB drifters measure sea surface currents, sea surface temperature baryometric pressure and lat/lon."

The hourly data is in .dat format which opens as tab-ready row & column in any text editor. It uses day number instead of dates: 299 is today Oct 25th. The most recent 557 readings from 204761 average 1.36ºC with a range of 0.58 to 4.08 ºC and stdev of 0.97, that is, the buoy has not seen any temperatures below zero and has mostly been around 1.4±1.0 ºC during its drift.
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Do direct buoy measurements provide an independent check on the daily SST product from GHRSST?
More likely, the buoy data is assimilated into the product but that's unconfirmed.
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Can radiative heat loss be determined from Worldview?
No. Clear weather allows that dramatic definition of heat loss leads via band 15 of Suomi VIIRS along the upper CAA. Note this is calculated from top-of-atmosphere in kelvin and is not suitable for determining overall blackbody heat loss:

"It does not provide an accurate temperature of either clouds nor the land surface, but it does show relative temperature differences which can be used to distinguish features both in clouds and in sea ice and open water over the polar regions during winter (in cloudless areas).... The sensor resolution is 375m, the imagery resolution is 250m, and the temporal resolution is daily."
Quote
How unusual is the current pattern of open water?
The image below calculates the frequency of open water at each position on Nov 1st for the seven years 2013-19 (this date in 2012 is not available from AMSR2_UHH). This gives the lightest gray for open water in all seven years, a slightly darker gray for open water in six of seven years and so on. The progression is fairly orderly Chukchi; the Laptev has mostly been frozen over. The pink shows areas that have never before been open on Nov 1st.

The base image is Smos-Smap ice thinness for Oct 23rd. It has an interesting green fringe of presumably nascent ice in the 2-3 cm thinness range. The interior ice thicker than 0.5m has been replaced with OsiSaf ice motion for the same date; the exterior open water has been removed to reveal the historical open water probabilities.
« Last Edit: October 26, 2020, 02:28:18 AM by A-Team »

uniquorn

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Re: The 2020/2021 freezing season
« Reply #537 on: October 25, 2020, 02:50:27 PM »
IABP buoy drift and surface temperature update.(11MB)

closer look at iabp204761 and 204762 in the Laptev (3.5MB)
click

SimonF92

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Re: The 2020/2021 freezing season
« Reply #538 on: October 25, 2020, 03:03:07 PM »
Building on uniquorns nice code. (current date only)
« Last Edit: October 25, 2020, 07:39:13 PM by SimonF92 »
Bunch of small python Arctic Apps:
https://github.com/SimonF92/Arctic

uniquorn

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Re: The 2020/2021 freezing season
« Reply #539 on: October 25, 2020, 03:28:53 PM »
Thanks SimonF92. Animation scope widened to include the 2 newer buoys 204763 and 204764
Looking forward to your animations

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Re: The 2020/2021 freezing season
« Reply #540 on: October 25, 2020, 06:20:54 PM »
Here's the sea ice forecast to the end of the month from the CMEMS NeXtSIM model. It appears to suggest a continuation of the very slow growth, mainly around the Laptev and Kara seas, with even a little loss around Chukchi.

Thomas Lavergne looked at another model which shows more significant growth overall, especially towards the ESS.
https://twitter.com/lavergnetho/status/1320340626127323136
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: The 2020/2021 freezing season
« Reply #541 on: October 25, 2020, 07:13:28 PM »
Just a friendly reminder that there is no proof whatsoever that what we are observing over the Laptev sea is effect of Atlantic waters.
There has been an incredible year-long blob of heat excess over the land adjacent to the Laptev sea.
There was a twenty-day long powerful GAAC in July which warmest region was exactly over the Laptev and north west of it
Weather has been very agitated in September with frequent southerlies from land over Laptev sea.
Weather has been very agitated in October with a mega-ridge that caused very strong winds and, if thermodynamics still go in the right direction, accumulated ocean heat release. The current ocean temperature excess over Laptev sea can be perfectly explained by all of the above that we have just witnessed over the months. At least that explanation seems more simple than a thermohaline staircase  collapsing etc.

The Atlantic Water effect is, as much, a hypothesis to be corroborated by future models.
« Last Edit: October 25, 2020, 07:20:30 PM by gandul »

uniquorn

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Re: The 2020/2021 freezing season
« Reply #542 on: October 25, 2020, 07:22:05 PM »
amsr2-awi-v103, atlantic side oct24-25. Sea ice crossing the shelf close to SZ.

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Re: The 2020/2021 freezing season
« Reply #543 on: October 25, 2020, 08:21:14 PM »
The first AWI merged CryoSat-2/SMOS thickness map of the freezing season is now available:

https://GreatWhiteCon.info/2020/10/facts-about-the-arctic-in-october-2020/

Quote
Whichever way you look at it there certainly isn't much ice on the Siberian side of the Arctic at the moment! However CryoSat-2 and PIOMAS don't seem to be able to agree on where the thickest ice in the Arctic is at the moment. It certainly isn't anywhere near the North Pole though.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

A-Team

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Re: The 2020/2021 freezing season
« Reply #544 on: October 25, 2020, 08:53:38 PM »
Here is Lavergne's forecast to Nov 1st using the CMEMS GLO model. It is five days old. No links to to the forecast sites are being provided. It appears to be using the same ECMWF forcings.

https://marine.copernicus.eu/about-us/about-producers/glo-mfc/ from Mercator Ocean GLO

https://www.mercator-ocean.fr/en/portfolio/wizard/  neXtSIM

WIzArd aims at improving our understanding and modelling of the interactions between sea ice, ocean and wave at arctic ocean surface, with a particular focus on the Marginal ice Zone (MIZ). We will couple the Lagrangian sea ice model, neXtSIM, with an ocean model (NEMO) and wave model (WAVEWATCH III), using the configuration CREG12 previously developed for CMEMS. The novelty of neXtSIM lies within its ability to better reproduce the sea ice mechanical properties, as well as the interplay between sea ice and waves propagating into the sea ice pack.

A link to the neXtSIM forecast seems to be implicit in CMEMS sea ice fraction forecast to Oct 31st but until Lobelia gets image and time series downloads going next month, it seems necessary now to tediously step through the dates. It seems that none of the 12 CMEMS sea surface temperature products provide complementary companion forecasts, ie they don't go out beyond the 24th. The second image is a mixed-date composite.

https://t.co/JSBMKl00Nm?

Wave–ice interactions in the neXtSIM sea-ice model
TD Williams,P Rampal S Bouillon 7 Sep 2017
https://tc.copernicus.org/articles/11/2117/2017/tc-11-2117-2017.pdf

In this paper we describe a waves-in-ice model (WIM), which calculates ice breakage and the wave radiation stress (WRS). This WIM is then coupled to the new sea-ice model neXtSIM, which is based on the elasto-brittle (EB) rheology.

We highlight some numerical issues involved in the coupling and investigate the impact of the WRS  and of modifying the EB rheology to lower the stiffness of the ice in the area where the ice has broken up (the marginal ice zone or MIZ).

In experiments in the absence of wind, we find that wind waves can produce noticeable movement of the ice edge in loose ice (concentration around 70 %) – up to 36 km, depending on the material parameters of the ice that are used and the dynamical model used for the broken ice. The ice edge position is unaffected by the WRS if the initial concentration is higher (& 0.9).

Swell waves (monochromatic waves with low frequency) do not affect the ice edge location (even for loose ice), as they are attenuated much less than the higher-frequency components of a wind wave spectrum, and so consequently produce a much lower WRS by about an order of magnitude. In the presence of wind, we find that the wind stress dominates the WRS which while large near the ice edge decays exponentially away from it. This is in contrast to the wind stress, which is applied over a much larger ice area."
« Last Edit: October 25, 2020, 10:01:45 PM by A-Team »

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Re: The 2020/2021 freezing season
« Reply #545 on: October 25, 2020, 09:03:21 PM »
The first AWI merged CryoSat-2/SMOS thickness map of the freezing season is now available:

https://GreatWhiteCon.info/2020/10/facts-about-the-arctic-in-october-2020/

Great, I am looking forward to calculate the total volume with your (?) script tomorrow.  :)

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Re: The 2020/2021 freezing season
« Reply #546 on: October 25, 2020, 09:12:31 PM »
The first AWI merged CryoSat-2/SMOS thickness map of the freezing season is now available:

https://GreatWhiteCon.info/2020/10/facts-about-the-arctic-in-october-2020/

Quote
Whichever way you look at it there certainly isn't much ice on the Siberian side of the Arctic at the moment! However CryoSat-2 and PIOMAS don't seem to be able to agree on where the thickest ice in the Arctic is at the moment. It certainly isn't anywhere near the North Pole though.
Right, PIOMAS and Cryosat-2 do not agree. Observations, that is Cryosat-2, find pretty thick ice in the near 1.5 million km2 region of Western CAB where the NASA/NSIDC Lagrangian model finds 3 and 4+ year old ice. According to A-Team, that region between the Pole and Beaufort does not drift really fast, usually takes its time to go either way, so that most of thar ice ain’t going nowhere in 2021 and probably 2022 (unless it melts out which is very very much improbable given that it doesn’t since 2016).

If it was at the Pole, you are right it isn’t, it could go down the Fram drain by next April.

A-Team

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Re: The 2020/2021 freezing season
« Reply #547 on: October 25, 2020, 10:10:22 PM »
Quote
The first AWI merged CryoSat-2/SMOS thickness map of the freezing season
The thickest ice on that image is 2.56m, the top range is boxed in black below and shown better in #550. The white outline is the ice between 0.5 and 1.0 which is just beyond Smos/Smap thickness reliability limits. The palette is really bad at the low end so it has been replaced below with brighter colors. The archival Smos-Smap thinness map of the 23rd is shown below that at the same scale.

It takes many orbits of the CryoSat2 satellite to observe the freeboard because its swath is so narrow. By that time of course the ice has had more time to thicken on the earlier swaths so the product is not even quasi-isochronous in the manner of daily SMOS thinness. However it is observational unlike Piomas and the Smos component has addressed its weakest components. There would not be issues with the snowpack yet or lingering meltponds.

Freeboard is still several assumptions away from ice thickness, namely buoyancy (density), presumption of buoyant equilibrium, state of brine exclusion, condition/definition of ice bottom and so on.

It's not easy to compare Piomas (which has a its own complicated history of production and goofy pixel griding) with this product. Both need to be put in netCDF for array subtraction but so far it seems only cryo2smos has been. There the lat line graticules could be shut off that currently disrupt comparison. On twitter, one ice expert opined that the agreement was excellent, only differing by 0.5m. That's actually terrible on a percentage error basis, like applauding a dog walking awkwardly on its hind legs.

The sea ice age product 'gives the idea' but is very rough (how can they track floes accurately over the summer?!?) and thus unsuitable for comparison to either of these. We have no idea at this point how much CAB ice will be sent how far up the Beaufort Arm nor whether the TransPolar Drift will set in nor at what width.

We're definitely getting deeper into uncharted waters on the Siberian side. It's better just to wait and see how it plays out, not waste effort on a few days of forward prediction. No one saw this coming even by mid-September, no one knows where it will end, no one can say what specific downstream consequences will follow.

Multiple scientific teams are drafting up papers as we speak, articles will be finalized the day the Laptev freezes over and submitted shortly thereafter, just like what happened with GAAC 2012 (Simmons 2012) or the 2018 Fram cyclone (Boisvert 2018).

GlennK suggested several interesting things in #527 that could be done now, the easiest of which is setting up a daily refresh for SSTfnd velocity-of-cooling, apportioning the heated water between long-term atlantification and a big solar insolation summer coupled with Siberian heat wave.

Inverting that to get at the reanalyzed atmosphere's contribution to the so far inadequate energy flux is really the key to nailing down the many adjustable parameters in these coupled models. We could probably use CR and TPW to pick the low hanging fruit but the models themselves can't be run from online portals.
« Last Edit: October 26, 2020, 02:46:01 AM by A-Team »

oren

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Re: The 2020/2021 freezing season
« Reply #548 on: October 25, 2020, 10:39:30 PM »
Thank you A-Team. I find the original C2S palette quite unreadable.

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Re: The 2020/2021 freezing season
« Reply #549 on: October 25, 2020, 11:10:57 PM »
I am looking forward to calculate the total volume with your (?) script tomorrow.  :)

Well yes, albeit with much assistance from Wipneus and Stefan Hendricks.

I look forward to seeing your results!
Reality is merely an illusion, albeit a very persistent one - Albert Einstein