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Re: The 2020/2021 freezing season
« Reply #1000 on: January 08, 2021, 03:40:35 PM »
As far as I know Hycom is not comparable across the years from 2016 to 2020 as the model was changed in the interim.
That's a bummer...
What was the year it changed? Which years are we able to compare?
Hycom is meant to be accurate as possible on the day it is produced. For comparison purposes the focus is on doing things exactly the same measuring and processing data. When a new satellite goes up the focus is on the new satellite providing the same results for the same conditions. Even if that causes a bias in the current data as happens when better sensors are used. Hycom doesn't attempt this and in some cases a human analyst makes decisions that override the model. Generally speaking Hycom claims that comparisons over a month or two are reasonable but not year to year comparisons. They have a full time dedicated staff that makes tweaks frequently. They post generally what these changes are. These changes make the model more accurate on each day. The Hycom model is a global hybrid 3d model that uses higher resolution on more chaotic areas like near the ocean surface or near land. Where action tends to be uniform they use larger grid sizes. It also gives and receives input from an global atmospheric model. Hycom runs on a dedicated super computer designed for the task. If their is a problem with the run. They don't have time to rerun that day they have to limit it to an abbreviated run.

My point is that in my opinion it is more accurate for comparison purposes than any other source within stated accuracy. In order to validate that claim would take substantially more processing than running the model itself. Since the model requires a dedicated supercomputer that runs the model only somewhat faster than real time it seam unlikely that such would be done. Inconsistency is viewed as more suspect by scientists than systemic errors so I would lose the argument without proof. The magnitude of those errors is the most important factor. But the magnitude of inconsistency is much harder to prove. While I have spent considerable time looking at publicly available information on the subject I do not have enough information or experience with the model to truly know one way or the other.

Summery: Comparisons of Hycoms results are considered suspect beyond two months.

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Re: The 2020/2021 freezing season
« Reply #1001 on: January 08, 2021, 04:03:45 PM »
A rebound is a change in direction. To most that implies a sustained change. While their is not a precise definition in this case that would be a major increase in ice.  A minor uptick does not qualify. Their is a well established trend of decreasing ice with some yearly variation. Minor variations are not a rebound to most people even if your views are different.

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Re: The 2020/2021 freezing season
« Reply #1002 on: January 08, 2021, 04:38:39 PM »
Kara loses another 42k today ! It's claim to be a Central Arctic sea is becoming ever more questionable ..
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 =  ' if only we could have seen it coming ' ...

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Re: The 2020/2021 freezing season
« Reply #1003 on: January 08, 2021, 05:05:59 PM »
I note Sea Ice Extent increases during the past week have been lethargic (Gerontocrat's graph).  Is there a described weather event causing this? Anything to do with the stratospheric sudden warming (SSW) event Gerontocrat described a couple days ago?  (If so, how?)
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Re: The 2020/2021 freezing season
« Reply #1004 on: January 08, 2021, 05:40:20 PM »
The sun will be coming up over the Kara fairly soon (~Jan. 21st).  Feebly at first, but by early February quite significantly (>6 hours of sunlight for 71N by February 10th).

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Re: The 2020/2021 freezing season
« Reply #1005 on: January 08, 2021, 07:06:39 PM »
I note Sea Ice Extent increases during the past week have been lethargic (Gerontocrat's graph).  Is there a described weather event causing this? Anything to do with the stratospheric sudden warming (SSW) event Gerontocrat described a couple days ago?  (If so, how?)
For some time there has been high presuure in the mid-Atlantic west of Eire.
Warmer moister weather has been pushing up into the Svalbard Barents / Kara areas causing sea ice extent and area losses instead of reaching the UK and NW Europe.

Looks like maybe next week normal service will be resumed?
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Re: The 2020/2021 freezing season
« Reply #1006 on: January 08, 2021, 08:46:31 PM »
A look at the rapid retreat/melt in the Kara sea in the last few days:

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Re: The 2020/2021 freezing season
« Reply #1007 on: January 08, 2021, 09:19:25 PM »
A rebound is a change in direction. To most that implies a sustained change. While their is not a precise definition in this case that would be a major increase in ice.  A minor uptick does not qualify. Their is a well established trend of decreasing ice with some yearly variation. Minor variations are not a rebound to most people even if your views are different.

In this case it is a matter of language. People, probably Neven or some early blogger, coined the term "rebound years" for relatively cold seasons 2013-2014 after the 2012 record, and 2008-2009 after 2007 (then, a record too).

The "melting" expectations generated by the record thin Arctic in early 2017 didn't verify, leading to a strong feeling of "rebound year". 2018 was not that warm either.

But I digress, probably off-topic, I agree with Oren that there is no so early indication on how the weather is going to come in summer.

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Re: The 2020/2021 freezing season
« Reply #1008 on: January 08, 2021, 09:53:02 PM »
A look at the rapid retreat/melt in the Kara sea in the last few days:

Thanks for this animation.  Looking at Aluminium's latest Bremen AMSR2 animation the ice cubes are sloshing around merrily in the glass throughout this whole Atlantic margin area -- from Svalbard to FJL to north of NZ.   It is not just the Kara Sea that is showing rapid losses in extent...

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Re: The 2020/2021 freezing season
« Reply #1009 on: January 09, 2021, 05:18:11 PM »
Kara ice loss impressive

Running out of time to freeze.

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Re: The 2020/2021 freezing season
« Reply #1010 on: January 09, 2021, 10:15:58 PM »
That's pretty wild to see such losses in JANUARY in the Kara. I'm very interested in following the entire 2021 season and I feel as though 2020's melt will be almost impossible to erase. Even the sea surface temp anomalies far north, and adjacent to the ice is "warm."

I will say, I'm quite surprised by the extremely persistent la niña pattern that's existed since at least last summer.

pls!

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Re: The 2020/2021 freezing season
« Reply #1011 on: January 10, 2021, 04:01:53 AM »
<Making a correction to a slightly misleading statement made on this thread, will post duplicate to 2020/2021 freezing season thread where it belongs better. Can be deleted from here after couple days as I assume people reading the thread will have noticed the correction put forward here.>

Incorrect. The peak winter cold is January 25, if not later. We are still definitely 3 weeks to 1 month away from annual peak winter cold based on annual averages. It is likely to be somewhat frozen soon. However, I drew attention to the Russian nuclear submariners and navy GCMs which I cited last summer who expect major mid-winter recirculation this year from around December 2021  that moves the typical storm tracks north of the British Isles to the latitude of Gibraltar with Pleistocene rains pouring in Sahara. This development is an ongoing: already this mid-winter now we can see it starting to take shape:
https://www.bbc.co.uk/news/world-europe-55586751 By end of 2021 it is multimillennial anomaly. If not right and next Christmas not delivering rainy Sahara, blame the Russians and their navy. ;) 

Kara ice loss impressive

Running out of time to freeze.
« Last Edit: January 10, 2021, 04:24:33 AM by VeliAlbertKallio »
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oren

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Re: The 2020/2021 freezing season
« Reply #1012 on: January 10, 2021, 10:25:37 AM »
Posts moved here where they belong, thank you VAK.

uniquorn

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Re: The 2020/2021 freezing season
« Reply #1013 on: January 10, 2021, 01:50:45 PM »
<Even the sea surface temp anomalies far north, and adjacent to the ice is "warm." >
Bering Sea ice perhaps reacting to that 'warmth' and persistent northerlies by building up an ice front rather than an ice edge. Could be cloud interference causing lower concentration further north though.
amsr2-uhh, bering, dec20-jan9 (click for movement)
https://go.nasa.gov/3orir0B  jan9

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Re: The 2020/2021 freezing season
« Reply #1014 on: January 10, 2021, 04:27:22 PM »
. However, I drew attention to the Russian nuclear submariners and navy GCMs which I cited last summer who expect major mid-winter recirculation this year from around December 2021  that moves the typical storm tracks north of the British Isles to the latitude of Gibraltar with Pleistocene rains pouring in Sahara.

VAK,

Yes you did write about these GCMs that predicted changed storm tracks but I never found any quotes  (by you or anyone else) to any studies that showed this. Can you point me to the right direction?

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Re: The 2020/2021 freezing season
« Reply #1015 on: January 11, 2021, 11:02:57 PM »
Another strong anticyclone i shaping up later this week.

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Re: The 2020/2021 freezing season
« Reply #1016 on: January 12, 2021, 07:02:20 AM »
What's going on in the upper atmosphere? The polar vortex is getting pushed aside...
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Re: The 2020/2021 freezing season
« Reply #1017 on: January 12, 2021, 09:46:42 AM »
What's going on in the upper atmosphere? The polar vortex is getting pushed aside...

Petition to rename it to "trans-Barents stream"?
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Re: The 2020/2021 freezing season
« Reply #1018 on: January 12, 2021, 09:46:50 AM »
<Please post only relevant stuff. O>
« Last Edit: January 12, 2021, 11:16:25 AM by oren »

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Re: The 2020/2021 freezing season
« Reply #1019 on: January 12, 2021, 12:26:13 PM »
amsr2-uhh comparison of 2021 with 2016 again, jan5-11, mercator surface temps inset for 2021. The warm West Spitzbergen current clearly winning at the moment.
Polarview S1B of the area north east of Svalbard this morning (UTC)
gnrt bathy of the same area. The round indent in the ice edge in 2021 sits over the turbulent waters above the entry (or exit) to the Yermak plateau dip

edit:Those indents look like they are more to do with the shelf break than the Yermak when overlaid.
« Last Edit: January 12, 2021, 07:59:35 PM by uniquorn »

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Re: The 2020/2021 freezing season
« Reply #1020 on: January 12, 2021, 01:47:39 PM »
What's going on in the upper atmosphere? The polar vortex is getting pushed aside...

A Sudden Stratospheric Warming event happened at the beginning of the year. Events like this may destroy the vortex for a while and/or displace it, thereby changing the direction of stratospheric winds and eventually messing with troposheric processes (eg beast from the east et al.). I posted about it in this thread at the end of last year and there are more posts about it in the atmospheric connections thread

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Re: The 2020/2021 freezing season
« Reply #1021 on: January 12, 2021, 02:08:26 PM »
Animation of the Barents and Kara Seas since December 20th.

Large file, click to play.
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 #1022 on: January 13, 2021, 03:18:08 AM »
The AO was at historic lows below-3 on the 4th . Well I did find Jan. 1966 at -3.2 , Feb. 2010 -4.2 and Feb. 2020 also below -3 but those are the only numbers below -3 since 1950.

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table

Also lots of warming at 30hPa

https://www.cpc.ncep.noaa.gov/products/intraseasonal/temp30anim.shtml
« Last Edit: January 13, 2021, 03:30:10 AM by Bruce Steele »

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Re: The 2020/2021 freezing season
« Reply #1023 on: January 13, 2021, 08:56:49 AM »
January 2-12.

2020.

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Re: The 2020/2021 freezing season
« Reply #1024 on: January 16, 2021, 06:20:09 PM »
Looking at old ice drift and thickness using a rough overlay of cs2smos onto ascat interferometry,  oct22-jan11
thickness scale is a guide due to overlay

Daylight over the Bering Sea  https://go.nasa.gov/38PbLnu
« Last Edit: January 17, 2021, 11:26:22 AM by uniquorn »

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Re: The 2020/2021 freezing season
« Reply #1025 on: January 17, 2021, 02:06:21 PM »
Slow animation for the week. Mostly subtle changes overall.
Click to play
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 #1026 on: January 17, 2021, 02:14:17 PM »
Following up on the West Spitsbergen current, unfortunately the 2 argo floats in the current north east of Svalbard are now inactive. Here are the latest temperature and salinity charts for the 3 nearest floats to the west of Svalbard (from south to north)
SST is 4.8C close to the southern tip of Svalbard dropping to 3.4C further north.

Kolås, E. and Fer, I.: Hydrography, transport and mixing of the West Spitsbergen Current: the Svalbard Branch in summer 2015, Ocean Sci., 14, 1603–1618, https://doi.org/10.5194/os-14-1603-2018, 2018.
https://os.copernicus.org/articles/14/1603/2018/
Quote
Abstract

Measurements of ocean currents, stratification and microstructure were made in August 2015, northwest of Svalbard, downstream of the Atlantic inflow in Fram Strait in the Arctic Ocean. Observations in three sections are used to characterize the evolution of the West Spitsbergen Current (WSC) along a 170 km downstream distance. Two alternative calculations imply 1.5 to 2 Sv (1 Sv = 106 m3 s−1) is routed to recirculation and Yermak branch in Fram Strait, whereas 0.6 to 1.3 Sv is carried by the Svalbard branch. The WSC cools at a rate of 0.20 ∘C per 100 km, with associated bulk heat loss per along-path meter of (1.1−1.4)×107
 W m−1, corresponding to a surface heat loss of 380–550 W m−2. The measured turbulent heat flux is too small to account for this cooling rate. Estimates using a plausible range of parameters suggest that the contribution of diffusion by eddies could be limited to one half of the observed heat loss. In addition to shear-driven mixing beneath the WSC core, we observe energetic convective mixing of an unstable bottom boundary layer on the slope, driven by Ekman advection of buoyant water across the slope. The estimated lateral buoyancy flux is O(10−8) W kg−1, sufficient to maintain a large fraction of the observed dissipation rates, and corresponds to a heat flux of approximately 40 W m−2. We conclude that – at least in summer – convectively driven bottom mixing followed by the detachment of the mixed fluid and its transfer into the ocean interior can lead to substantial cooling and freshening of the WSC.

AMSR2-UHH north of FJL struggling with weather related ice surface changes more than usual this year.
« Last Edit: January 17, 2021, 02:22:13 PM by uniquorn »

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Re: The 2020/2021 freezing season
« Reply #1027 on: January 18, 2021, 10:28:42 AM »
A closer look at surface features detected by amsr2-uhh, atlantic side, dec1-jan17. Ascat inset for drift comparison. Some correlation recently with the FYI/SYI white band discussed up thread.
« Last Edit: January 18, 2021, 11:36:51 AM by uniquorn »

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Re: The 2020/2021 freezing season
« Reply #1028 on: January 18, 2021, 04:34:16 PM »
How bad is the front in the CAB vs other years? It looks atrocious, it also looks like there was just a major surface melt event on the FYI that has migrated into the CAB as the MYI has exported through FRAM...

I am very nervous about the CAB situation as we head into spring. The sun will be coming up again soon, while we still have some time for freezing, it looks as though we may enter the melt season with the front further north than ever before in this region.

We have year over year HYCOM available in the same bandwidth. It appears we have avoided the same situation in 2019-20 (ice drifting off the Russian coast) but the outcome this year may be even worse to the overall sea ice as we have seen ice drifting into the Siberian coastline AND the Beaufort to the detriment of the CAB and ATL front in a very significant way.





My preliminary outlook for the melt season would be a very stout Beaufort that sees little melt. There is a major amount of MYI now in this area and it is quite thick. The Siberian Seas are also possibly going to melt more slowly than 2020. BUT, the situation in Kara is not really better, in fact it may be worse, and in the Barentz and CAB, it appears much worse. In fact, if there were a "look" that portended the Arctic pack splitting in two, this might be it.

I would assert with some confidence, the wind direction this year and the increase in wind speed over other years out of the ATL front (due to the warmer ATL? and warmer continents?) is now shunting ice growth increasingly to the periphery of the Arctic Ocean, instead of allowing ice to grow in its heart (the CAB). This has some benefit in that the CAB can build ice longer into spring than other regions due to its higher latitude / its insulation from heat intrusions thanks to peripheral seas being frozen -- but this year? The Barentz is still wide open and the Kara is almost the same or very thin besides the coastline, and the front is basically still in the CAB...

Perhaps we see a 2017, perhaps we see a new permutation on a catastrophic melt season a la 2012. With snowcover growth so far lackluster across the continents this winter season (to my surprise) and snow water equivalents also not so much above average, I think the sum of these factors favors a melt season more like 2012 than 2017 in terms of worsening sea ice vs. recovery. We are also still dealing with the rapid drop in aerosols that began in 2020 and has largely continued (though it may abate again in 2021-22).
« Last Edit: January 18, 2021, 04:43:14 PM by bbr2315 »

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Re: The 2020/2021 freezing season
« Reply #1029 on: January 18, 2021, 05:02:41 PM »
from NSIDC Data

There is usually a record breaker somewhere. The St Lawrence is at record low sea ice for the time of year both in Area (4 days) and in Extent (2 days).

Given that this sea is very much the smallest sea with the max sea ice extent in March well below 200 k in recent years, it will probably not be that significant is the wider scheme of things.
The St. Lawrence is significant because it feeds into the Gulf Stream (or rather, interacts with it). The HYCOM maps clearly show how much more saline and WARM the Northwest North Atlantic is this year vs. 2020. There is also a major snowfall deficit in southeast Quebec this year.

This may portend a much more vigorous push of warmth from the NW NATL into the CAB come spring and summertime, as the snowfall / snowmelt / cold airmasses that normally temper the sea surface temps in these regions are apparently largely absent this year, or at least, so far this winter.

uniquorn

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Re: The 2020/2021 freezing season
« Reply #1030 on: January 18, 2021, 09:40:41 PM »
How bad is the front in the CAB vs other years? It looks atrocious, it also looks like there was just a major surface melt event on the FYI that has migrated into the CAB as the MYI has exported through FRAM...

Not sure about major surface melt but there is some surface change. There are a couple of mosaic buoys recording ice surface temperature north of Svalbard. P156 and P157

amsr2-uhh, Atlantic side, jan17, 2013-2021

added SMOS/SMAP, Atlantic side, dec1-jan17. Almost certainly not surface melt.
« Last Edit: January 19, 2021, 12:06:40 PM by uniquorn »