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Freegrass

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Re: The 2020/2021 freezing season
« Reply #200 on: October 07, 2020, 08:16:33 AM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Wind + Temp @ 850hPa
Wind @ 250hPa
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BornFromTheVoid

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Re: The 2020/2021 freezing season
« Reply #201 on: October 07, 2020, 03:02:15 PM »
The current forecast is for quite a strong dipole to continue, with winds compressing the sea ice along the Chukchi and Russian facing edges, and spreading it out towards the Atlantic (animation below).
This shows up very nicely in the CMEMS sea ice forecasts to the 13th (2nd attachment) which predicts, amazingly, further significant losses along the Chukchi, ESS and (to a lesser extent) the Laptev ice edge. Gains in the other regions barely enough to produce growth overall.

I'd expect area and extent to be below 2012 next week, with truly exceptional regional record low ice values and further record smashing air temperatures as a result.
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wdmn

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Re: The 2020/2021 freezing season
« Reply #202 on: October 07, 2020, 03:10:50 PM »

I'd expect area and extent to be below 2012 next week, with truly exceptional regional record low ice values and further record smashing air temperatures as a result.

NSIDC area crossed paths with 2012 and is now record low for the date according to Nico Sun's page.

Shared Humanity

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Re: The 2020/2021 freezing season
« Reply #203 on: October 07, 2020, 03:27:22 PM »
There is still a massive amount of oceanic heat
Agreed.
amsr2, awi dev v103 overlaid onto mercator 0m ocean temperature, sep4-oct5

What a fantastic gif. It shows how warm waters cause melt and prevent refreeze. Look at how the warm waters along the Alaskan coast continue to cause melt of the ice closest to Alaska. There is another example in Fram Strait. The Laptev is really going to struggle to freeze.

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Re: The 2020/2021 freezing season
« Reply #204 on: October 07, 2020, 06:20:03 PM »
Some great new forecast data made free by the ECMWF.
Includes sea ice, snow, waves, cloud and all the usual meteorological stuff.
A few sample below.
https://apps.ecmwf.int/webapps/opencharts/

I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

pearscot

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Re: The 2020/2021 freezing season
« Reply #205 on: October 07, 2020, 06:33:20 PM »
Wow, this is kinda insane to see play out. I mean I can't say I'm in shock given how the melting season progressed, but there's just still sooo much open water. This year's freezing season will be one to watch.

I just can't help but wonder how all of this open water is mixing and affecting halocline, especially as the temperatures drop more. Anyways, thanks for the gifs/images thus far, they are appreciated.
pls!

Aluminium

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Re: The 2020/2021 freezing season
« Reply #206 on: October 08, 2020, 07:27:19 AM »
October 3-7.

2019.

Freegrass

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Re: The 2020/2021 freezing season
« Reply #207 on: October 08, 2020, 09:29:18 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!
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jens

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Re: The 2020/2021 freezing season
« Reply #208 on: October 08, 2020, 10:16:30 AM »
2019 had a slow refreeze until late October. 2020 is following the same path at least till mid-October. I'd wager a guess that "slow refreeze" is the new normal.

sailor

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Re: The 2020/2021 freezing season
« Reply #209 on: October 08, 2020, 12:12:34 PM »
2019 had a slow refreeze until late October. 2020 is following the same path at least till mid-October. I'd wager a guess that "slow refreeze" is the new normal.

This is "good", in the sense that, although the Arctic seas contain more energy that the yesteryears, it is a recognized negative feedback that same Arctic seas are so wide open that refreeze is hard to come, and a lot of this energy excess is lost in the process. Otherwise Arctic sea ice would be collapsing much faster.
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binntho

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Re: The 2020/2021 freezing season
« Reply #210 on: October 08, 2020, 12:20:59 PM »
It's an interesting point: Is ever-slower refreeze a big negative feedback on planetary warming in general and Arctic warming in particular? Is it enough to cause a noticeable slowdown in warming? How does it compare quantitatively with the positive feedback of less albedo during months of insolation?

Or in other word: Will the positive feedback of less ice during insolation be neutered and even overcome by the negative feedback of large areas of open ocean once the sun goes down? Perhaps the latter is not so big as it could be since it also causes increased cloudiness and H2O in the atmosphere, thus replacing one blanket with another?
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Freegrass

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Re: The 2020/2021 freezing season
« Reply #211 on: October 08, 2020, 12:51:12 PM »
It's an interesting point: Is ever-slower refreeze a big negative feedback on planetary warming in general and Arctic warming in particular? Is it enough to cause a noticeable slowdown in warming? How does it compare quantitatively with the positive feedback of less albedo during months of insolation?

Or in other word: Will the positive feedback of less ice during insolation be neutered and even overcome by the negative feedback of large areas of open ocean once the sun goes down? Perhaps the latter is not so big as it could be since it also causes increased cloudiness and H2O in the atmosphere, thus replacing one blanket with another?
If the arctic ocean contain enough heat to melt the ice twice over, wouldn't all that stirring up of the open ocean cause all that heat to come up to the surface through mixing, and wouldn't that be of concern for the halocline?
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cognitivebias2

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Re: The 2020/2021 freezing season
« Reply #212 on: October 08, 2020, 01:18:19 PM »
It's an interesting point: Is ever-slower refreeze a big negative feedback on planetary warming in general and Arctic warming in particular? Is it enough to cause a noticeable slowdown in warming? How does it compare quantitatively with the positive feedback of less albedo during months of insolation?

Or in other word: Will the positive feedback of less ice during insolation be neutered and even overcome by the negative feedback of large areas of open ocean once the sun goes down? Perhaps the latter is not so big as it could be since it also causes increased cloudiness and H2O in the atmosphere, thus replacing one blanket with another?

Interesting paper, with open access, discusses both energy balance and the halocline:
Cooling down the world oceans and the earth by enhancing the North Atlantic Ocean current
https://link.springer.com/article/10.1007/s42452-019-1755-y

"Recent climate models have shown that the increase in solar radiation absorption with the melted Arctic water is slightly higher than the increased longwave irradiation into space, as shown in Fig. 2b [16]. In other words, heat balance in the Arctic region is reached with or without the ice cover, warming up the atmosphere, cooling down the ocean and maintaining the overall heat balance of the Arctic region at equilibrium.

A study by [17] has calculated the net heat flux of the Arctic region (Fig. 2c). In locations covered by ice, the net heat flux loss is around 8 W/m2 smaller when compared to areas not covered by ice."


The article cited above as [17] from 2007 has a few famous names attached:

The large‐scale energy budget of the Arctic
Mark C. Serreze  Andrew P. Barrett  Andrew G. Slater  Michael Steele  Jinlun Zhang  Kevin E. Trenberth

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2006JD008230


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Re: The 2020/2021 freezing season
« Reply #213 on: October 08, 2020, 02:18:10 PM »
Pretty clear from Freegrass's animation that the Arctic is struggling to establish cold temperatures over the Siberian side of the ocean. Combine this with continuous lows in the Laptev pulling air off of Siberia and stiring the open ocean...well, I think the very slow refreeze will continue here.

aslan

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Re: The 2020/2021 freezing season
« Reply #214 on: October 08, 2020, 02:25:37 PM »
This article pretty much ignore clouds or overall atmospheric circulation, or anything else, and is just saying that if you remove sea ice, a lot, lot, lot of energy will be radiated to space in winter. Yes of course, nothing new. But it is likely that things will not proceed as linearly. Studies and measures are showing that it seems likely that open water during fall and winter is going to destabilize the PBL. Implying more clouds and moisture, which is going to limit the amount of heat lost to space. And atmospheric circulation, and oceanic circulation, and etc... are also going to respond to an ice free Arctic and establish a new equilibrium which is definitively not going to be the same that "all else equal excepted for sea ice".

binntho

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Re: The 2020/2021 freezing season
« Reply #215 on: October 08, 2020, 02:35:19 PM »
The first paper linked by cognitivebias2 above states:

Quote
This paper argues that if the North Atlantic Ocean current could maintain the Arctic Ocean ice-free during the winter, the longwave radiation heat loss into space would be larger than the increase in heat absorption due to the albedo effect.

Which implies that the negative feedback from outgoing winter radiation is ultimately bigger than the positive feedback of increased albedo in summer. But as aslan points out, increased cloud cover could very easily change this calculation.

And I seem to remember that during the last interglacial, when we know that the Arctic was at leas seasonally ice-free, Arctic Amplification was significant which implies that the positive feedback of increased albedo trumped the negative of increased outgoing radiation.
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aslan

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Re: The 2020/2021 freezing season
« Reply #216 on: October 08, 2020, 02:41:55 PM »
Yes, Arctic was ice free many times in the geological time. It is true that loosing ice cover in winter would in theory implies a massive heat loss by longwave radiation to space, but things are not as simple as "If I pull out your blanket, you are going to freeze to death.". And there is over factors at play. This discussion will lead us off topic if we continue, but an ice free Arctic means also a complete reorganization of the atmospheric and oceanic circulation.

gandul

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Re: The 2020/2021 freezing season
« Reply #217 on: October 08, 2020, 03:21:36 PM »
It's an interesting point: Is ever-slower refreeze a big negative feedback on planetary warming in general and Arctic warming in particular? Is it enough to cause a noticeable slowdown in warming? How does it compare quantitatively with the positive feedback of less albedo during months of insolation?

Or in other word: Will the positive feedback of less ice during insolation be neutered and even overcome by the negative feedback of large areas of open ocean once the sun goes down? Perhaps the latter is not so big as it could be since it also causes increased cloudiness and H2O in the atmosphere, thus replacing one blanket with another?
If the arctic ocean contain enough heat to melt the ice twice over, wouldn't all that stirring up of the open ocean cause all that heat to come up to the surface through mixing, and wouldn't that be of concern for the halocline?

Your scenario has however two problems:
1. The Arctic has had enough heat to be melted out several times since basically forever. (At least since the last glaciation). It is not a new thing.
2. If storms in Fall pull out ocean heat in enormous quantities as you suggest, this heat will be lost in a very large sink: winter night. The result would be that the Arctic as a system loses heat.

Do the math. The heat to keep the ocean open in winter is huge. Several times the heat input during the melting season. I have done the math before.

The Walrus

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Re: The 2020/2021 freezing season
« Reply #218 on: October 08, 2020, 03:25:26 PM »
This article pretty much ignore clouds or overall atmospheric circulation, or anything else, and is just saying that if you remove sea ice, a lot, lot, lot of energy will be radiated to space in winter. Yes of course, nothing new. But it is likely that things will not proceed as linearly. Studies and measures are showing that it seems likely that open water during fall and winter is going to destabilize the PBL. Implying more clouds and moisture, which is going to limit the amount of heat lost to space. And atmospheric circulation, and oceanic circulation, and etc... are also going to respond to an ice free Arctic and establish a new equilibrium which is definitively not going to be the same that "all else equal excepted for sea ice".

True, however the same could be said for cloud cover in summer.  Blocking the major source of incoming heat would have an effect on summer ice melt also.

SimonF92

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Re: The 2020/2021 freezing season
« Reply #219 on: October 08, 2020, 04:04:52 PM »
Would really like to see that math, from a curiosity point of view
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Re: The 2020/2021 freezing season
« Reply #220 on: October 08, 2020, 04:16:22 PM »

BornFromTheVoid

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Re: The 2020/2021 freezing season
« Reply #221 on: October 08, 2020, 08:16:36 PM »
CMEMS sea ice forecast shows almost no growth over the next week. Should it come off, record lows, and by huge margins, should be expected soon.

Below is a comparison between 2012 and 2020, with AMSR2 data to the 7th for 2020, and CMEMS for 8th to 14th.
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wdmn

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Re: The 2020/2021 freezing season
« Reply #222 on: October 08, 2020, 11:44:36 PM »
CMEMS sea ice forecast shows almost no growth over the next week. Should it come off, record lows, and by huge margins, should be expected soon.

Below is a comparison between 2012 and 2020, with AMSR2 data to the 7th for 2020, and CMEMS for 8th to 14th.

Wish I had the skill (or at least the application) to overlay this on bathymetry. A lot that new ice in 2012 was in the shallower Siberian seas growing from the ice edge. Ice edge this year looks to be mostly over deeper waters still.

gandul

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Re: The 2020/2021 freezing season
« Reply #223 on: October 09, 2020, 12:14:25 AM »
Would really like to see that math, from a curiosity point of view
It involves Boltzmann equation for typical winter temperatures, and assumption of mostly clear skies.

As Bintho points out, this is a bad approximation (clouds) but gives you an order of magnitude, trust me, the resulting kw/m2 are overwhelming. Any believable heat pulled out now by storms over open ocean will be radiated out to space during the 6-month winter night.

So the longer the ocean remains open and agitated, the more energy is released now and evacuated from planet Earth.
« Last Edit: October 09, 2020, 12:19:32 AM by gandul »

gandul

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Re: The 2020/2021 freezing season
« Reply #224 on: October 09, 2020, 12:29:24 AM »
The forecasts keep predicting a disruptive polar ridge (an Autumn GAAC) rather than a solid PV. Guess the more energy out to space, the colder 2021 melting season will be?

Sounds like rejoicing news (I know how much you guys care and root for the polar bears).

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Re: The 2020/2021 freezing season
« Reply #225 on: October 09, 2020, 12:54:24 AM »
gandul I'm confused as to how energy leaving now (from upper layers of the water) would affect the next melting season, when the water is not even cold enough to freeze yet. Isn't what is being observed the result of an energy surplus "venting" towards baseline, not a baseline amount of energy venting towards "even colder"? (If we are actually assuming this effect is as significant as some are stating)
Additionally, isn't most of the energy in the basin stored in the depths, which is not leaving in large enough quantities to decline on a year to year basis? I feel like the effects of this hypothesized development are being a little overstated since this transition from polar day to polar night happens every year and yet the net energy in the basin continues to grow. Even last year's decent recovery did not stop the weather from shaking things up this summer, so I feel like it is very bold to make such a direct connection when there are many factors at play in a quite chaotic system
If I am misunderstanding though, I'd appreciate if someone could clarify what I am missing

A-Team

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Re: The 2020/2021 freezing season
« Reply #226 on: October 09, 2020, 01:16:19 AM »
Quote
Would really like to see that math
It won't be forthcoming because in addition to imperative cloud considerations, it would also have to explain why the Barents no longer freezes over in winter despite reaching 80ºN where it's also rather cold. Ice may blow in from the Kara or across the FJL-SV line but apparently no longer forms significant sea ice on its own.

Like the Yermak, Barents too receives a branch of Atlantic Water inflows and has largely lost its stratification (previously maintained by fresh water from ice melt); in terms of wind mixing, over a third of the Arctic Ocean (mostly on the Siberian side) has shallower water than the ~300m deep Barents.

The Bering Sea too no longer freezes over in winter despite large water exchanges with the Chukchi -- which still has open water on Jan 1st in recent years. The Chukchi is well over a thousand km south of the Barents and only partly above the Arctic Circle.

There are no instances over the last 7 years of Jan 1st open water in the ESS or Laptev. This year bears watching however for open water persisting after mid-November because of the cumulative impact of double diffusion of Atlantic Waters over the years and the massive solar heat input this July to early low albedo open waters of the Laptev.

The AW brings in enough heat each year to melt all the ice, the question has always been how much of that heat it leaves behind -- more and more per Mercator Ocean and Laptev moorings (Polyakov 2019).

It should not be assumed that all the open water in the Arctic Basin will magically refreeze in winter. As time goes on, more and more open water will persist later and later into the depths of winter. A lot of blackbody radiation (Planck effect) comes right back down so it doesn't have the cooling effect that one might imagine.

It's all about clouds and moisture intrusions from mid-latitude:

Following moist intrusions into the Arctic using SHEBA observations in a Lagrangian perspective
S. Mubashshir Ali  Felix Pithan  19 June 2020
https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/qj.3859

"Warm and moist air masses are transported into the Arctic from lower latitudes throughout the year. Especially in winter, such moist intrusions (MIs) can trigger cloud formation and surface warming. While a typical cloudy state of the Arctic winter boundary layer has been linked to the advection of moist air masses, direct observations of the transformation from moist midlatitude to dry Arctic air are lacking.

"The Surface Heat Budget of the Arctic (SHEBA) and the Norwegian Young Sea Ice (N‐ICE2015) expeditions have shown that the wintertime Arctic boundary layer is characterized by a bi‐modal distribution between a radiatively clear and an opaquely cloudy state. This bi‐modality is also observed in the time series from the ARM site at Utqiaġvik for the boreal winter (F Pithan 2014, fig 10). The two states have different net surface long‐wave radiation (NetLW) as the clear state is characterised by strong long‐wave cooling (NetLW ∼ − 40 W·m−2) under clear skies or ice clouds and the cloudy state with little to no surface cooling (NetLW ∼ 0 W·m−2) under low‐level mixed‐phase clouds."

Cloud Radiative Forcing of the Arctic Surface: The Influence of Cloud Properties, Surface Albedo, and Solar Zenith Angle
Matthew D. Shupe; Janet M. Intrieri
J. Climate (2004) 17 (3): 616–628.  classic paper on subject from co-leader of Mosaic
https://journals.ametsoc.org/jcli/article/17/3/616/30440/Cloud-Radiative-Forcing-of-the-Arctic-Surface-The

"An annual cycle of cloud and radiation measurements made as part of the Surface Heat Budget of the Arctic (SHEBA) program are utilized to determine which properties of Arctic clouds control the surface radiation balance. Surface cloud radiative forcing (CF), defined as the difference between the all-sky and clear-sky net surface radiative fluxes, was calculated from ground-based measurements of broadband fluxes and results from a clear-sky model. Longwave cloud forcing (CFLW) is shown to be a function of cloud temperature, height, and emissivity (i.e., microphysics). Shortwave cloud forcing (CFSW) is a function of cloud transmittance, surface albedo, and the solar zenith angle. The annual cycle of Arctic CF reveals cloud-induced surface warming through most of the year and a short period of surface cooling in the middle of summer, when cloud shading effects overwhelm cloud greenhouse effects."

Arctic amplification is caused by sea-ice loss under increasing CO2
Aiguo Dai, Dehai Luo, Mirong Song & Jiping Liu   10 January 2019
https://www.nature.com/articles/s41467-018-07954-9

"Increased outgoing longwave radiation and heat fluxes from the newly opened waters cause Arctic Amplification, whereas all other processes can only indirectly contribute to it by melting sea-ice. Seasonal sea-ice melting from May to September opens a large portion of the Arctic Ocean, allowing it to absorb sunlight during the warm season. Most of this energy is released to the atmosphere through longwave (LW) radiation, and latent and sensible heat fluxes during the cold season from October to April when the Arctic Ocean becomes a heat source to the atmosphere10 (Supplementary Figure 1)"
« Last Edit: October 09, 2020, 01:42:43 AM by A-Team »

Wildcatter

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Re: The 2020/2021 freezing season
« Reply #227 on: October 09, 2020, 05:17:48 AM »
Am I thinking of this correctly?

"Heat loss" is a big factor, along with clouds and water vapor, in the more extreme autumn/fall and winter arctic amplification? Along with clouds, water vapor, etc. Ie, greater "heat loss" will generally lead to warmer air temperatures?  Because heat isn't just teleported right into space

If so, state transitions are probably underrated. For example, GFS forecasting about a +4C temp anomaly in the Arctic through the third week of October, and that's relative to 1979-2000. Not sure what last year was, but probably fairly high given how it played out. Stands to reason, those kinds of anomalous temps inevitably lead to environment changes if they become the new "normal", and as environment transitions to a new, warmer state, logical to assume that state is less conducive to "heat loss", except there will be even greater heat up-take + various factors and likely even higher "heat loss". Which just exacerbates the situation into greater temp anomalies, greater changes. And so it goes.

Pretty nasty feedback loop, if that's more or less, a reasonable assertion. Not a great signal 2020 wasn't a "rebound" year, and seeing slow re-growth similar to year prior. Will need to see how it plays out, and probably next year for better confirmation, but could be evidence we're starting to enter a new-er transitional state.

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Re: The 2020/2021 freezing season
« Reply #228 on: October 09, 2020, 05:28:49 AM »
IMO A-Team's in depth write-up and Wildcatter's hypothesis seem to reconcile better with what we are currently observing as well as the trend in seas such as the Barents than the other theories that have been presented in this thread recently regarding radiating heat loss, but I guess ultimately time will tell. I would assume that if we reach mid-late November and the basin (especially the Siberian side) is still extremely anomalously low, that we will not be seeing any sort of above average ice cover in the ESS, Kara or Laptev seas by the end of spring 2021.

Personally, I think the massive energy influx into the Siberian Arctic this summer may have begun the push over the edge for those seas, which may be trending faster towards a Barents-like state than before, opening up potential for more rapid Atlantification, but I do not want to wholeheartedly commit to this hypothesis with only a data point or two. The next few summers should provide a clearer trend picture, at which point a more definitive call can be made regarding the rate of change of that region.

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Re: The 2020/2021 freezing season
« Reply #229 on: October 09, 2020, 05:40:16 AM »
I think it is also worth noting that the last 2 weeks of October and the first few days of November were the stretch that significantly differentiated 2019's refreeze from 2016's refreeze, so we are likely rapidly approaching a critical period of development and therefore important observation, since the next month or so may heavy-handedly shape the progression of the ice growth this winter.

binntho

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Re: The 2020/2021 freezing season
« Reply #230 on: October 09, 2020, 06:01:45 AM »
Truly fantastic input by A-Team which has in effect turned my understanding of Arctic amplification upside down - expanding open water is the driving mechanism, but higher albedo is not the primary cause of Arctic Amplification as I have always assumed, and neither can winter heat escape be deemed a negative feedback.

Rather it is the winter heat escape from open water, combined with increased water vapor and cloudiness, that is the primary cause of Arctic amplification. The negative feedback has been turned into a positive one, and a nasty one at that, according to Wildcatter.

Following from this, one is tempted to draw the conclusion that a late refreeze will increase the likelihood of a warmer winter and thinner ice. Nasty indeed.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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Re: The 2020/2021 freezing season
« Reply #231 on: October 09, 2020, 06:46:05 AM »
On another note, the transformation of the Beaufort tail over the last 2-3 weeks has been pretty dramatic when directly compared. I was pretty surprised myself when I looked at the two images side-by-side. September 17 vs October 8 AMSR2 product.
« Last Edit: October 09, 2020, 07:22:54 AM by I’M IN LOVE WITH A RAGER »

oren

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Re: The 2020/2021 freezing season
« Reply #232 on: October 09, 2020, 06:51:41 AM »
The issue is quite simple. Heat escape is driven by more heat in the system. The more heat, the longer it remains, the longer open water refuses to freeze. Sure, the heat is eventually lost to space during the long winter. Sure, the more heat is there the more heat is lost. But this process by itself cannot protect the Arctic and its sea ice. It cannot be called a proper negative feedback. The Arctic is trying to heal its summer wounds, is all.
Eventually a time will come when the freezing season ends while some open water has still not frozen. Currently this doesn't happen within the Arctic Basin, with maybe some localized exceptions. However, a late freeze is disastrous in itself, as the resulting ice is thinner and more prone to melt next season.

oren

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Re: The 2020/2021 freezing season
« Reply #233 on: October 09, 2020, 06:59:47 AM »
On another note, the transformation of the Beaufort tail over the last 2-3 weeks has been pretty dramatic when directly compared. I was pretty surprised myself when I looked at the two images side-by-side. September 17 vs October 8 ASMR2 product.
Thanks for the comparison. Indeed, all that thick MYI diligently exported from the CAB has mostly melted out or thinned considerably, with bottom melt enhanced by the vigorous movements to and fro. The deep freezing temps have never reached this far south in the Beaufort yet, though they've been around more central parts of the basin for nearly a month. Finally the forecast now calls for cooling of the "tail" region in the next few days, but too little too late IMHO.

jdallen

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Re: The 2020/2021 freezing season
« Reply #234 on: October 09, 2020, 08:04:22 AM »
It's an interesting point: Is ever-slower refreeze a big negative feedback on planetary warming in general and Arctic warming in particular? <snip>

I'd say no.  The slow refreeze is happening exactly because there is so much heat in the system, outgoing radiation can't cool things off fast to drop it to where the sea surface freezes.

Secondary effects from this are going to be general disruption of northern hemisphere atmospheric circulation, with massive break outs of cold air from the polar regions, and massive inflows of heat and moisture out of the similarly but not as severely overheated tropics.  The Enthalpy bucket is overflowed faster and more voluminously than the drain can carry away the extra.
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binntho

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Re: The 2020/2021 freezing season
« Reply #235 on: October 09, 2020, 08:21:46 AM »
It cannot be called a proper negative feedback. The Arctic is trying to heal its summer wounds, is all.

Increased outgoing long-wave radiation (LWR) from open waters can and has been called a negative feedback working against Arctic amplification as opposed to the positive feedback of increased albedo during peak insolation.

But it turns out that increased LWR is neither a "proper" nor a "non-proper" negative feedback at all. It seems that heat loss from ice-free waters outside of peak insolation is itself the positive feedback that I and many others assumed was simply linked to higher albedo during peak insolation. Turns out that the two are inexorably linked, with increased albedo being a primary cause and increased LWR the proximate cause in Arctic amplification (with loss of sea ice being the root cause).

So the mental equation goes from:

Code: [Select]
(increased insolation as positive feedback ) - (increased LWR as negative feedback) = ?
where ? is either positive or negative but always smaller than the positive feedback of increased insolation, to the following:

Code: [Select]
Increased insolation => increased LWR => increased temperature
No negative feedback, only a positive feedback loop. Which to my mind makes a big difference.
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oren

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Re: The 2020/2021 freezing season
« Reply #236 on: October 09, 2020, 10:34:18 AM »
Binntho, I admit I cannot figure out if the above is sarcastic or not, but if it is then please avoid that. If not then ignore this comment.

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Re: The 2020/2021 freezing season
« Reply #237 on: October 09, 2020, 11:01:22 AM »
Thank you for the stimulating discussion points everyone. A-team, its good to see you post in these threads, I follow you closely on the MOSAIC thread.

Reminds me of an article I wrote last year for my uni's student mag. I struggled to pitch it to a correct level and tie it up in so few words, but they really liked it and put it in their print edition too.

https://the-gist.org/2019/10/the-problem-with-arctic-amplification/

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binntho

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Re: The 2020/2021 freezing season
« Reply #238 on: October 09, 2020, 11:17:26 AM »
Binntho, I admit I cannot figure out if the above is sarcastic or not, but if it is then please avoid that. If not then ignore this comment.

Well it's not sarcastic on purpose! Although I agree with most of what you said, I still felt it necessary to clarify the point that LWR is apparently not a negative feedback. I was unable to read that from your comment, your dismissal of LWR as being not a "proper" negative feedback indicated that you still understood it as a negative feedback in some sense.

I started this discussion several posts back after a couple of posts from other users who (as so many of us both this autumn and practically every year before that) were saying or wondering about the negative feedback of so much open water going into the polar night.

A-Team's post opened my eyes to the fact that it is actually the other way around: Open water during the polar night *is* the positive feedback, the ultimate cause of Arctic amplification. To me this seems a very important distinction, and from my reading of the posts of other members, not something that everybody has understood. Including, it seemed to me, yourself.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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oren

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Re: The 2020/2021 freezing season
« Reply #239 on: October 09, 2020, 11:57:57 AM »
Thanks for the clarification!

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Re: The 2020/2021 freezing season
« Reply #240 on: October 09, 2020, 01:50:13 PM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!
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Re: The 2020/2021 freezing season
« Reply #241 on: October 09, 2020, 02:27:04 PM »
Forgot to mention, but 2018 is also an example of the recent trend of a slow refreeze in October, despite not having a particularly low September minimum. Currently 2012 is (still) in the lead, but 2020, 2019 and 2018 are all right after it in next positions.

And also interesting to see, how big the gaps could be stretched out. 2010's average is losing by a whole 1M km2 to 2020 now. 8th position (2017) is 1.3M down on 2020. At some point of course gaps will start coming down again, so let's see how long does it take before it happens.
« Last Edit: October 09, 2020, 02:32:09 PM by jens »

gerontocrat

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Re: The 2020/2021 freezing season
« Reply #242 on: October 09, 2020, 02:35:05 PM »
Laptev Sea Ice Area & Extent

Lots of posts about whether ocean heat will keep the Arctic ice-free all winter. Perhaps the Laptev will give us some clues...

Siberian heatwave + early and rapid record melting gives extreme Alebedo Warming Potential (AWP).

Then add the GACC at exactlly the right time to convert Albedo Warming Potential into far above average real ocean heating.

Result - something approaching the maximum possible ocean heat in the Laptev Sea given the current Arctic climate.

So for how long will the Laptev resist re-freeze?
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SimonF92

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Re: The 2020/2021 freezing season
« Reply #243 on: October 09, 2020, 04:05:35 PM »
Evidence of sea ice formation at Protoka Ularova in Yakutiya (ESS) today
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Re: The 2020/2021 freezing season
« Reply #244 on: October 09, 2020, 05:07:33 PM »

Like the Yermak, Barents too receives a branch of Atlantic Water inflows and has largely lost its stratification (previously maintained by fresh water from ice melt); in terms of wind mixing, over a third of the Arctic Ocean (mostly on the Siberian side) has shallower water than the ~300m deep Barents.

The Bering Sea too no longer freezes over in winter despite large water exchanges with the Chukchi -- which still has open water on Jan 1st in recent years. The Chukchi is well over a thousand km south of the Barents and only partly above the Arctic Circle.

There are no instances over the last 7 years of Jan 1st open water in the ESS or Laptev. This year bears watching however for open water persisting after mid-November because of the cumulative impact of double diffusion of Atlantic Waters over the years and the massive solar heat input this July to early low albedo open waters of the Laptev.

The AW brings in enough heat each year to melt all the ice, the question has always been how much of that heat it leaves behind -- more and more per Mercator Ocean and Laptev moorings (Polyakov 2019).

It should not be assumed that all the open water in the Arctic Basin will magically refreeze in winter. As time goes on, more and more open water will persist later and later into the depths of winter. A lot of blackbody radiation (Planck effect) comes right back down so it doesn't have the cooling effect that one might imagine.


Well, thank you A-Team as always! It seems that my understanding of the late-refreeze negative feedback is outdated, or, to say the least, this negative feedback comes accompanied by other positive feedbacks due to winter weather disruption (like 2016/2017 that resulted in the thinnest ice that has been seen out of a Winter). Will be interesting to see what is going on this freezing season.

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Re: The 2020/2021 freezing season
« Reply #245 on: October 09, 2020, 05:21:29 PM »
...
https://the-gist.org/2019/10/the-problem-with-arctic-amplification/
Very nicely written, Simon.  You got the 'water vapor from the South' part, but missed (with most of the rest of us) the 'local water vapor where there isn't as much (or any) sea ice' part.
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Re: The 2020/2021 freezing season
« Reply #246 on: October 09, 2020, 06:05:01 PM »
Binntho, I admit I cannot figure out if the above is sarcastic or not, but if it is then please avoid that. If not then ignore this comment.
A-Team's post opened my eyes to the fact that it is actually the other way around: Open water during the polar night *is* the positive feedback, the ultimate cause of Arctic amplification. To me this seems a very important distinction, and from my reading of the posts of other members, not something that everybody has understood. Including, it seemed to me, yourself.

I'm not sure about this, and I'd like to hear A-Team's take. It seems to me that many of A-Team's partial BOE posts argue strongly for the accumulated, summer, albedo-driven energy gain caused by ever earlier open water as a massive positive feedback and cause/example of arctic amplification.

I read the above post as simply arguing that expecting all this accumulated energy to be quickly and harmlessly "vented to space" during the arctic night is misguided.

FWIW, the "open water heading into the arctic night = GOOD" argument has always struck me as a violation of Occam's Razor: Less ice, more open water, later and later into the fall just does not seem "good" to me. 

binntho

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Re: The 2020/2021 freezing season
« Reply #247 on: October 09, 2020, 06:34:06 PM »
... It seems to me that many of A-Team's partial BOE posts argue strongly for the accumulated, summer, albedo-driven energy gain caused by ever earlier open water as a massive positive feedback and cause/example of arctic amplification. ...

I'd be the first to admit to having misunderstood the whole thing! But here is a simple version of my naive understanding of the insolation / LWR / negative vs. positive feedback thing.

To begin with, we are talking about Arctic amplification, or the fact that the Arctic warms up faster than the rest of the globe. This is valid during our current antrophogenic warming, and was also something that happened during the last interglacial.

The standard explanation, as also repeatedly expounded by A-Team, is that less sea ice means lower albedo during peak insolation which again means that a lot more heat is absorbed by the ice-free parts of the Arctic ocean. And of course, that is exactly the correct explanation for the Arctic amplification.

But the addendum missing from the explanation is that getting extra energy into open waters during the short period of peak insolation every summer is not enough to explain the Arctic amplification which is a year-round phenomenon, raised air temperatures rather than increased ocean heat content. Lower albedo is only playing the leading role, the second and equally necessary part is played by open ocean going into the polar night, the side-kick that I and probably a lot of other people have not realised was there.

The open waters radiate the extra heat out as long-wave radiation, while at the same time contributing strongly to an isolating blanket of clouds and water vapor. The heat does of course eventually escape into space, but not before causing that good old Arctic amplification and enabling it to linger well into winter.

Which is totally opposite the claim that sees having more open water going into the polar night as some sort of negative feedback working against the Arctic amplification caused by lower albedo during peak insolation. Which was what started the whole discussion.
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Re: The 2020/2021 freezing season
« Reply #248 on: October 09, 2020, 07:58:53 PM »
FWIW, the "open water heading into the arctic night = GOOD" argument has always struck me as a violation of Occam's Razor: Less ice, more open water, later and later into the fall just does not seem "good" to me.
It’s not that it is good. It is that there are physical reasons (Stefan-Boltzmann Law) to expect that the more energy you make available now, the more energy will radiate out to space during the NH night.

The net effect is energy loss and therefore another factor to moderate, rather than precipitate, the decline of sea ice in the years to come.

A-Team is conflating this negative feedback effect that he, as scientist, knows well, with other atmospheric effects which are less clear and of more conjectural nature, to produce an overtly alarming picture.

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Re: The 2020/2021 freezing season
« Reply #249 on: October 09, 2020, 08:16:46 PM »
It’s not that it is good. It is that there are physical reasons (Stefan-Boltzmann Law) to expect that the more energy you make available now, the more energy will radiate out to space during the NH night.

It's you who are confusing the whole thing. Plank feedback (function of T^4) is well known but others feedback also: lapse rate, water vapor, clouds, etc. Overall, climate sensitivity is 3 degres to doubling co2. Nothing new. With your reasoning, more co2 would mean a cooling earth. Open arctic in winter is stable state. Point in case: barents and bering sea, kara sea in 2012 and 2016, likely laptev sea winter 2021. You are pushing this topic off road with unbased statement. Open arctic in winter is definitively not a giant radiator cooling down the earth. It is a stable system from an energy POV.