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Messages - RoxTheGeologist

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1
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: September 16, 2020, 04:43:40 PM »
Oddness in the Central Arctic Sea continues...

Just two out of 14 seas are keeping this melting season open, the Central Arctic Sea and the East Siberian Sea (ESS).
....

and, usually, area declines precede extent declines.

2
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: September 11, 2020, 03:44:17 PM »

As we see in the Arctic, stratification prevents heat loss. Ice is an added insulator. More stratification from freshwater, colder surface waters, more ice, less heat loss and therefore warmer deep waters to melt glaciers.

3
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 11, 2020, 03:22:16 PM »

My point (somewhat) is that whenever we fit a line we are assuming a model.

In response to A-Team: From what I read I thought freshwater input into the Arctic is largely from rivers e.g.

https://people.earth.yale.edu/sites/default/files/files/Carmack_etal_Freshwater2016.pdf








4
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 10, 2020, 10:48:40 PM »

I think we are in the tail of 1/x rather than y=x. The last sea ice close to the pole doesn't receive that many days of insolation and has a lot of FDD days to thicken the ice. Even in a super hot year, like this year, with melt ponds forming early, we aren't going to break the 2012 anomalous minimum.

The Arctic freshwater lens will persist, as much of it is created by input from the rivers. Only in years like 2012 will the ocean be adequately mixed to melt more ice (and lose additional heat).

To melt that last ice there have to be fewer FDD days and more insulation during the cold months.
Or, like in 2012, mixing melts the ice. At least the latter would help in the long run with additional heat vented.

5
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: September 10, 2020, 04:38:45 PM »

On the CO2 conversion - sadly, the amount of fuel used in a quarry generates enough CO2 to react with all the rock flour. It can be a local solution (haha). It just has to be cost-effective and fit within CARBs regulations to generate the required credits.

6
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: September 10, 2020, 04:35:52 PM »

At best trees store carbon, at worst they convert carbon dioxide to methane. With increased cycling of carbon and higher decay rates with increasing humidity and temperature, I would expect the latter to become more important; particularly as warm water contains less dissolved gasses.

7
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: September 09, 2020, 08:24:39 PM »
Yes, Bruce, I'm a geochemist and I've been aware for many years of the role of rock weathering and chemical buffering on global paleoclimates. Natural rock weathering is a slow process. A recent study showed that it may be practical to speed it up by using rock flour from crushed basalt as a soil amendment. This possibility has been known for a long time but the economics were not well known.

The thought is that it simply takes too much energy to crush rock in the first place. I believe total global weathering is around 0.1 GT per year, a drop in the ocean compared to the other parts of the carbon cycle.

I have a proposal on the table to work with a local construction company; they own quarries and rock flour is an issue for them. I'm looking at ways they can utilize it to soak up CO2 and produce bicarbonate and aqueous silicates.

One further complication is it's granitic, without the high number of cations one finds in more mafic rocks. The resulting absorption of CO2 is at a ratio of around 1:3. Even at $200 a ton for CO2 in California it is expensive to move the rock anywhere. A 20 ton truck costs around $500 per 100 miles.




8
One line in the quoted material caught my attention:
Quote
When the ice sheet shrinks, it will withdraw further and further from the coast and ice discharge into the ocean will become less important.
This phenomenon would apply to East Antarctica, but not to Greenland or West Antarctica.  The later two regions are largely iced over archipelagos, so the ice sheet won't 'withdraw from the coast', in fact, the coast will become more and more icy (less rocky) as the ice sheet retreats (until only a handful of mountain glaciers remain and there is no ice sheet).

There's a huge difference between West Antarctica, which has a great deal of exposure to the ocean and retrograde slopes beneath the ice sheet, to Greenland, which has fewer outlet glaciers to the central portion of its ice sheet.





Greenland appears to be less at risk than east Antarctica, based on the topographic maps with the ice sheets removed.

Are there maps adjusted for PGR?

9
Arctic sea ice / Re: MOSAiC news
« on: September 03, 2020, 03:12:38 PM »

Simon

May I ask what the scale on the left is?

I'm really struggling to see where the base of the ice is!

Would the winter ice be more clearly defined as the freeze causes mixing, the water convecting below the ice layer? As the ice melts the heat is transferred by conduction, leading to a much smoother gradient.



10
Greenland and Arctic Circle / Re: What's new in Greenland?
« on: August 26, 2020, 05:46:08 AM »

Thanks Oren!

11
Greenland and Arctic Circle / Re: What's new in Greenland?
« on: August 26, 2020, 01:28:35 AM »
Is this calving unusual? It seems to have been around for a while!


12
Arctic sea ice / Re: MOSAiC news
« on: August 22, 2020, 07:03:11 PM »

The end result is that ice at the bottom of a melt pond has a mid range albedo, reflecting more than open water, but still transferring a lot more solar energy to the water underneath than snow covered ice.


No, as I pointed out in a response to A-team submerged ice has an albedo of about one quarter of open water.

I thought open water has an albedo around 0.1, so 90% absorption and submerged ice is around 50, so 50% absorption. Open water absorbs about twice as much energy as submerged ice.



13
Arctic sea ice / Re: The 2020 melting season
« on: August 21, 2020, 07:23:20 PM »
Thanks to Neven for kindly updating the year-to-year Bremen map comparison page.
<snip>
I think we are closer to 2012 that people realize.
Without getting too far off topic. Think about it. Even with a virtual tie with 2012 this leaves 2020 a lot worse off, considering how much other permafrost, tundra, glacier ice, Ice sheet, Ice shelf, ect. type ice that has been lost since 2012. All of which served as back up to the world's a/c system.

2012 had the GAC that had the end result of venting a lot of ocean heat, melting ice, and, my guess, is that it lead to the following 'recovery' years of 2013 and 2014. This year is a warm year on-trend. Rather like this year might be the warmest year on record, warmer than the last el-Nino year, 2016, even as we have a mild la-Nina.

14
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: August 05, 2020, 04:49:26 PM »

I'm in too!

15

How high is the snout of the glacier now - do we have any idea?


16
Arctic sea ice / Re: The 2020 melting season
« on: July 28, 2020, 10:37:18 PM »
DMI Norh of 80 Temperatures.

The 2020 high blip first is getting to be a spike. 2016 had a blip around the same date but less above the green line.

Just maybe an indication of central arctic sea ice resistance to melt crumbling? Certainly one to watch?
I'm starting to feel prophetic now... My ego is swelling to exuberant proportions... :o

That can only happen when there is open water inside 80N.

17
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 06:58:12 PM »
Going back to some of the comments up thread, one of the disturbing things I see in the weather over the next 5 days is the precipitation - up to 5cm in some parts of the Beaufort and Chukchi - falling as rain.

That's a huge heat input and will devastate the thinner ice.  Won't particularly help the thicker either.  It will help with the general weakening of the pack.

A lot of rain will also wash over the CAA.  Not as much, but enough.

Id second that - I think most years you see dustings of snow that slow the melt. This year there hasn't been any.

18
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 10:54:59 PM »
What is the likelihood that the entire ice sheet will unfasten from the CAA and Greenland?  In the years I've been watching I don't remember seeing anything quite like this.  I did not go through every frame of every year, but it looks like it could just lift away in the not distant future.  The ice is very broken up in much of the Canadian, CAA, edge of the CAB, and it has lifted away from North Greenland. No fast ice?  The picture is today north coast of Greenland and nearby CAA.

With high winds perpendicular to the coast we can add upwelling of deeper and warmer water to the brew,

19
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 06:17:40 PM »
I believe this more of a coincidence than meets the eye. In normal years the deep Beaufort is much emptier of ice, the shallower ESS often has lots of ice at this stage. And this year the deep Laptev/CAB sector is ice-free.
amsr2-uhh overlaid onto gmrt bathymetry, minimum jaxa dates, 2012-2018
must add 2019 sometime

Great post, as always.

20
Arctic sea ice / Re: The 2020 melting season
« on: July 15, 2020, 08:59:12 PM »
...
1.  I think the notion that energy in the open Waters that are very warm next to the ice DOESN'T contribute quite powerfully to melting adjacent ice is utter rubbish.
...

Particularly if there is a warm wind blowing out of Siberia picking up water vapour. Each gram of water vapor melts 4g of ice if it condenses.

21
Arctic sea ice / Re: The 2020 melting season
« on: July 14, 2020, 04:48:26 PM »
I have no hope for the ice in the Beaufort and the Laptev bite is already at 80N. The weather is so bad for ice that 2020 could beat 2012 without a GAC in August or September. You are right, Friv that the ECMWF forecast is brutal for the ice.

if you click this link https://clima.caltech.edu/files/2018/11/Timmermans.pdf
you will see 20 pages of images by Prof Timmermans which describe the current patterns and the build up of heat in the Chukchi and Beaufort seas. Sustained easterly winds cause upwelling that brings up some of the stored heat. The Beaufort is a death zone for late summer ice now.

And no 'recovery years' in 2021 and 2022. The GAC vented a lot of oceanic warmth.

22
Arctic sea ice / Re: The 2020 melting season
« on: July 11, 2020, 07:36:27 PM »
RE: #2478 bathymetry

Love this post blumenkraft!  Are you trying to point out the similarity in the boundary between the deep Arctic Basin and the boundary of the minimum each year, there is certainly a relationship.




There is definitely a relationship. Can be overcome, but not easy. WAA from Siberia or NAM will overcome some of it and endless compaction could do the trick on the Atlantic side.

The match-up between the ice age and the bathymetry was even more pronounced during 2016!

https://forum.arctic-sea-ice.net/index.php/topic,382.msg84085.html#msg84085


23
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: June 19, 2020, 06:31:32 PM »
Area Graphs for the High Arctic Seas from NSIDC Data

Chukchi - after a late start area at 2010's average.
Beaufort - also a late start & area well above 2010's averge.
CAA - also late start at close to 2010's average and about to hit the elbow (someone remind me why this happens?)

Two distinct areas of melt with very different timing?

24
Arctic sea ice / Re: The 2020 melting season
« on: June 12, 2020, 05:50:24 PM »
Everything looks terrible for the ice but it has before and little melt has resulted.

I think, Armageddon's Blade is ready and possibly waited for this message. :)

earth.nullschool.net, 16.06.2020 00:00 UTC, 850 hPa.

1. A WAA near the Lena Delta. Temperature is 7.4°C. Doesn't sound outstanding. But wind speed is 90 km/h.
2. What about water vapor? 29.72 kg/m2.
3. Though it's just one point. How big is this WAA? It's everywhere.
4. Weak clouds don't provide good protection from the Sun.

Water vapour has a high enthalpy of vaporisation. That heat can melt approximately 4x it's mass of ice as it condenses. High winds blowing over warm and wet Land is an effective way of transferring heat into the ice. In this case, each 10M3 of air can melt 1M3 of ice.



25
Arctic sea ice / Re: The 2020 melting season
« on: May 28, 2020, 05:14:40 PM »
Lowered albedo does increase short wave solar absorption, but also long-wave earth radiation. Since in the winter the latter predominates and in the summer the former, they must be roughly equal somewhere, probably mid-May. Likewise aerosols both cool and warm. As anyone who has had a garden knows, the first frost is on a cloudless night. People seem to be writing about only half of the effects of these phenomena.

I'm not sure I read this correctly; note that emissivity is controlled by temperature and not by colour. Just because something is dark doesn't mean it will emit more radiation. Colour is largely controlled by how the object reflects visible light (unless the object is hot enough to emit light in the visible spectrum). The two properties are unrelated.


26
Arctic sea ice / Re: The 2020 melting season
« on: May 16, 2020, 01:40:03 AM »

...
Is this normal? ...

Perhaps the reduced aerosols are contributing to the reduced cloud cover more than would be expected.  I don't know much about the specifics there but maybe the relationship between aerosol density and cloud formation isn't linear or continuous.
I would think that besides the ~1/3 reduction in global aerosols (I could be grossly off o this # but I think it is reasonable), the 90% drop in air traffic is the biggest contributor to the lack of clouds. Or, the drop in air traffic at this point may be taking primacy even over the drop in aerosols. There was a study after 9/11 that showed a major rise in temperatures when air traffic halted. This is now being replicated much more severely across the entire planet.

Contrails are thought to have a net warming effect, particularly as they form more readily at night rather than day. Clouds keep the planet warm.

https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-19-0467.1

" In contrast, the level of understanding for contrail cirrus impact has been thoroughly upgraded during the last 10 years, and it is currently considered as the largest component contributing to aircraft-induced radiative forcing (Burkhardt and Kärcher 2011; Schumann and Graf 2013; Bock and Burkhardt 2016b; Grewe et al. 2017)."

27
Science / Re: Contrails & artificial clouds
« on: April 28, 2020, 08:58:10 PM »

Contrail cirrus is an interesting problem. Soot from contrails can produce more and wider cloud, and it's particularly prevalent in cooler air.

Current LCA models do not allow for contrail cirrus. If they did they are estimated to increase the GWP 2x to 4x the amount of other emissions.

Contrails act to warm the earth, not cool it.

28
Arctic sea ice / Re: The 2020 melting season
« on: April 20, 2020, 09:39:52 PM »

Also:

When insolation < emission, snow is bad as it insulates and prevents heat loss.
When insolation > emission, snow is good as it prevents the ice heating up.


29
Antarctica / Re: PIG has calved
« on: February 11, 2020, 08:02:49 PM »
The relative size of the ice to the water it needs to displace is significant.

Eureka.
The water you need to displace is one to one to the volume of ice under the water. Same mass according to Archimedes.
You would also see significant eddying around the perimeters if the forces of tension from the calving were responsible for the movement. I see mostly  uniform movement rather than the chaos you would expect from internal forces acting at different vectors.


If a 100km iceberg moves 10km, how much water is displaced relative to the size/mass of the ice?  Not 100%!

100% of the mass if the ice is floating, size wise its Volume*(density of freshwater)/(density of seawater).


30
Antarctica / Re: PIG has calved
« on: February 11, 2020, 07:26:06 PM »
Yes, that's what i think too.

And for how i see it, no one here thinks differently on that one.

It's going to be interesting to see if that whole 'wedge' of fractured ice clears out and we get calving along that face from both the PIG and the Ice sheet.


31
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: February 01, 2020, 01:03:36 AM »

That's what's meant by 'blast past'?

I'm sure he meant February...

32
Antarctica / Re: Thwaites Glacier Discussion
« on: January 30, 2020, 10:26:27 PM »

Thanks ASLR, that makes a lot more sense now. I didn't consider the pressure changes on melting temperature.

33
Antarctica / Re: Thwaites Glacier Discussion
« on: January 30, 2020, 07:47:55 PM »
Scientists Find Record Warm Water in Antarctica, Pointing To Cause Behind Thwaites Glacier Melt
https://phys.org/news/2020-01-scientists-antarctica-glacier.html

A team of scientists has observed, for the first time, the presence of warm water at a vital point underneath a glacier in Antarctica—an alarming discovery that points to the cause behind the gradual melting of this ice shelf while also raising concerns about sea-level rise around the globe

... The recorded warm waters—more than two degrees above freezing—flow beneath the Thwaites Glacier, which is part of the Western Antarctic Ice Sheet. The discovery was made at the glacier's grounding zone—the place at which the ice transitions between resting fully on bedrock and floating on the ocean as an ice shelf and which is key to the overall rate of retreat of a glacier.

... "The fact that such warm water was just now recorded by our team along a section of Thwaites grounding zone where we have known the glacier is melting suggests that it may be undergoing an unstoppable retreat that has huge implications for global sea level rise," notes Holland, a professor at NYU's Courant Institute of Mathematical Sciences.

... Aurora Basinski, an NYU graduate student who made the turbulence measurement, said, "From our observations into the ocean cavity at the grounding zone we observed not only the presence of warm water, but also its turbulence level and thus its efficiency to melt the ice shelf base." ... "This is an important result as this is the first time turbulent dissipation measurements have been made in the critical grounding zone of the West Antarctic Ice Sheet."

https://thwaitesglacier.org/projects/melt

2°C above freezing, so that would be....? Is that 0.2°C (assuming saltwater at -1.8°C) or 2°C? The latter is scary, the former, that's not much above the melt point of the freshwater glacier. Basically an order of magnitude less energy to melt the glacier. that 10x difference may become important....

34
Science / Re: Where are we now in CO2e , which pathway are we on?
« on: January 25, 2020, 11:53:48 PM »
While writing these lines a further question came into my mind:
Is a simple addition right at all? Maybe the IR spectra of the molecules (especially CO2 and N2O) overlap and reduce each other by some interference?

The overlapping (or not) of spectra is already built into the GWP.

One think I am not sure of is if aviation emissions are counted correctly, as they are largely in the stratosphere.

35
Antarctica / Re: PIG has calved
« on: January 25, 2020, 06:10:49 PM »
Confirmation from Sentinel-1 that the tip fell off.

That's just the tip of the iceberg from the upcoming calving.

(Sorry. I'm a Dad.)

36
Arctic sea ice / Re: The 2019/2020 freezing season
« on: January 25, 2020, 06:08:22 PM »
Aren't the poles the only places where the planet can lose its heat? I'm thinking that if there would be more ice, that the Arctic would be colder and able to release more heat into space, overall cooling the planet, and giving us more time before the feedback loops kick in and the climate runs out of our control.

The Arctic is heating up faster than any other place on earth, so cooling it down seems logical to me. And I don't think this would heat up the rest of the planet more.

My guess is that, based on my understanding of thermodynamics, more heat is lost in areas with combinations of highest temperature and lowest relative humidity (e.g. deserts, which typically have the highest spread between high and low temperatures on any given day). In such areas there is the greatest differential between the heat source (earth) and heat sink (outer space), coupled with the lowest combination of greenhouse gases (water being by far the most important).

If the poles were the only places to lose heat then nights wouldn't be cooler than days anywhere except the poles. All the surface of Earth is losing heat all the time, more rapidly where the Earth is warmer.

To illustrate FTBs point: From Wikipedia - on diurnal temperature ranges:

...diurnal temperature variations typically range from 10 or fewer degrees in humid, tropical areas, to 40-50 degrees in higher-elevation, arid to semi-arid areas, such as parts of the U.S. Western states' Intermountain Plateau areas...

Illustrating how daytime heating from insolation is lost to space, and how humidity (water vapor acting as a GHG) slows down that heat loss.


37
Arctic sea ice / Re: MOSAiC news
« on: January 21, 2020, 06:51:55 PM »
Close up on 2019O4 ctr
Added overview of temperature at 100m and whoi itp102 profile contours. cffr

Why is the salinity decreasing with time? The thickness of the low salinity layer is increasing - I'm going to assume that the ice is thickening and expelling brine so I'd expect the salinity of the water below the ice to increase. Am I missing something obvious? Does it take all year for freshwater input from the rivers to reach equilibrium under the ice?

38
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 15, 2020, 06:50:38 PM »
Thanks for the thread. Volume is more important than area or extant.

Well, except for aldebo and the whole Arctic amplification thing.

39
Antarctica / Re: PIG has calved
« on: January 14, 2020, 06:50:10 PM »

Seriously. I check this thread every day. it's a real (ice) cliff hanger.

40
Arctic sea ice / Re: The 2019/2020 freezing season
« on: January 09, 2020, 07:07:14 PM »
I'm still wondering what has changed to increase the ice in the Barent Sea over the last year.
Perhaps the ice is more mobile. osi-saf drift sep21-jan6

Thanks for the animation! Ether more cold input or less heat or a bit of both. It could be that there is much more ice being pushed out over the Barents, that the yearly changes are just noise. We remain avid observers.

If you had to pick one visible symptom of a slowing AMOC in a warming world? For me it would be less heat in the Barents, and more ice, it's far to the North and only the AMOC's heat keeps it ice free.

41
Arctic sea ice / Re: The 2019/2020 freezing season
« on: January 08, 2020, 06:07:38 PM »
Aren't the poles the only places where the planet can lose its heat? I'm thinking that if there would be more ice, that the Arctic would be colder and able to release more heat into space, overall cooling the planet, and giving us more time before the feedback loops kick in and the climate runs out of our control.

The Arctic is heating up faster than any other place on earth, so cooling it down seems logical to me. And I don't think this would heat up the rest of the planet more.

This is entirely wrong. Hot things emit more heat than cool things. The low latitudes gain heat through insolation. The whole planet is losing heat all the time, more rapidly at the low latitudes as they are warmer. The disparity in insolation heating causes the atmosphere and oceans to operate as heat pumps, transferring heat from the low latitudes to high latitudes and increasing the overall efficiency of heat loss. If you stop the transfer of heat to the poles you reduce the ability of the earth to lose heat.

42
Arctic sea ice / Re: The 2019/2020 freezing season
« on: January 08, 2020, 05:53:02 PM »
Great animation!

I'm still wondering what has changed to increase the ice in the Barent Sea over the last year. For the previous few of years it barely made it over the Nansen Basin continental shelf with incursions up the St Anna Trough. This year it's filling up the sea between FJL and Svalbard.

Is this a worrying indication of less heat transport from a slowing AMOC? Nothing else seems to have changed.

43
Arctic sea ice / Re: The 2019/2020 freezing season
« on: January 07, 2020, 06:24:12 PM »
If warmth can't enter the Arctic Ocean through the Strait then at other times cold can't exit the Arctic into the North Pacific. The Bering Sea would likely heat up even faster - perhaps large parts of Alaska and far East Russia too, accelerating permafrost melt and thus methane and CO2 emissions.

I actually think that by stopping hot water to enter from the Bering sea, that the cooling of the Arctic would help to protect the permafrost.

The flow of the water is always into the Arctic ocean, and so no cold water ever flows from the Arctic Ocean into the Bering Sea, unless there is a southern wind. (this needs a fact check) So by stopping hot water to enter the Arctic, you keep it cool, which will help to keep our planet cool.

AGW will indeed still continue. It needs to be stopped. But maybe we can stop a disaster by doing this. It's cheap, easy, and low impact on marine life IMHO. Although I'm sure a lot more educated people than me will have something to say about this...

Blocking the Bering is more akin to putting a blanket over your air conditioner heat exchanger, rather than closing your fridge door. The AC heat exchanger gets really cold: The rest of the room heats up until equilibrium is reached.

44
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: December 11, 2019, 07:25:16 PM »

Barents - will above average sea ice area continue?


Barents: I'm curious as to why we started seeing encroachment onto the Shelf. for a few years there was little ice on the shelf because of (presumably) Atlantic water effectively melting ice as it crossed the continental shelf before flowing down the slope. Why is less warm water (or more cold water) finding its way to the shelf boundary and increasing extent? Has the AMOC slowed?; Is the warm water deeper; is it finding its way around to the Nares? Should I post this on stupid questions?

45
Arctic sea ice / Re: The caa-greenland mega crack
« on: October 31, 2019, 05:32:13 PM »
Blumenkraft,

Every year in the freezing season, the volume of the Arctic sea surface expands by roughly 10 percent (due to the fact that density of sea ice is lover than that of sea water). If everything (including air pressure and sea level) remains constant, something will have to give in. . . .

I don't think that's how the physics works.  Certainly Nares and Fram surface currents are more robustly southward in winter than summer.  But not, I think, because sea water is freezing.  Sea ice displaces its *weight* and not its volume. 

Just as the water level in a glass of ice water doesn't change as the ice melts, neither does it change if ice forms in the glass.  Thus winter freezing of sea water into sea ice doesn't create any net change in forces of flow (all other changes being equal, which they never are in actuality).

I don't have an explanation for the observed seasonal flow patterns, but I'm pretty sure volume of ice formation isn't it.

If you put a piece of ice in a glass of saltwater, the freshwater from the ice flows to cover the saltwater. Freshwater/ice from the arctic is less dense and therefore there is an elevation difference. Hydrostatic stress is the same but the diviatoric stress makes the water flow (as its incompressible). its a long time since I did any continuum mechanics so my explanation may be wonky. Water flows downhill?

46
Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 27, 2019, 09:53:24 PM »
A Polar Vortex Split is coming in about a week.
This is again, very bad news, coming earlier Year by Year.
The Oceans are just spewing out Heat, relentlessly.

Why is the release of heat a bad thing since it can now radiate back into outer space? I am confused when the complaint is that heat is being trapped in the ocean and also when heat is not being trapped. I just want consistency.

Yup, it's better to release that heat. I guess the worse conditions for ice formation are a good thing when the energy balance is for heat loss. It's a worrying feeling though, hoping for less ice so the Earth can lose its excess heat. The problem is that the ocean just shouldn't be that warm.

47
Arctic sea ice / Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« on: October 25, 2019, 06:35:24 PM »

...
But the fundamental mechanism of sea ice formation (which you seem to have forgotten here) is that sea water is densest at freezing point, which means that before any ice has time to form, the surface water starts sinking and mixing downwards, and the underlying warmer waters start to move up.

This is presumably what is happening in all the open areas of the arctic right now. Very cold air is blowing in from the south (from Siberia) and from the ice itself, but the air heats up very rapidly over the open ocean where the sea surface temperatures are above freezing.
..


Isn't the mixed layer in summer salinity stratified? Salinity has a much greater impact on density than temperature. I thought that the freshwater lens from melting ice effectively prevented any convection, maybe if the water to 10m (?) has been warmed and homogenized it will turn over as the surface cools.

Sadly we don't have enough buoy data to really get a good picture of what is happening to seas like the Chukchi, distant from rivers, and with much longer exposure to wave and current action because of the early ice loss. It might be that as the sea becomes ice free for longer, the ocean becomes homogenized to deeper levels, evaporation concentrates salt in the surface, sea ice takes longer to form and is thinner and works as a positive feedback year on year.

And no, I didn't suddenly forget the properties of salt water :) If it were freshwater, the warming and melting in the spring would cause the water column to turn over (like a temperate lake).


 

48
Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 24, 2019, 10:29:35 PM »

I think I'm missing the point. I'll try stating this in a different way to try and understand.

If there is, say, typically, 0.5m of ice, then there is less transmission of heat out of the ocean to the atmosphere because of the ice's insulating properties. If there is no ice, the ocean heat can freely escape to the atmosphere. If there is more heat coming out of the ocean the air will be warmer than over sea ice. It doesn't take much of a drop in water temperature to warm the air to the same temp. Of course, there may well be more water vapor to trap heat from the ocean, but that would also correlate with lack of ice, as one would expect both the temp and the frost point to be higher than average.


49
Arctic sea ice / Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« on: October 24, 2019, 10:00:19 PM »
Have you all forgot the basics of sea ice formation? RoxTheGeologids, macid, slow wing?

Sea ice is densest at freezing point, and thus does not freeze in the same way that lake ice does. So slow wings "model" is patently wrong, and the increased density of surface waters as they cool and sink create enough convection to stir up the top tens of meters of ocean, getting all that heat to the surface.

Which is not to say that wave action will also create turbulence.

The current ice-free areas have a fair amount of wind according to NullSchool, but more importantly, the air temps are nowhere near low enough to start freezing.

I think that's what I said. I don't understand where I went wrong with my statement. Please edify!

50
Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 24, 2019, 08:56:40 PM »
I think the corresponding shape of ice-covered areas on the one hand and higher surface temperature anomalies on the other hand can be easily explained. If in the long term (e.g. median 1981-2010) a certain area of the Arctic Ocean has been usually covered with ice at a certain date and this year it is not, the difference in surface temperature (ice-covered = well below - 2°C; ice-free = above -1.8°C, maybe above 0°C) must be clearly visible in the SST anomaly map.

Exactly. That's a much better explanation than I gave. The air has a much lower specific heat capacity than water, so water is the temperature 'buffer'. Once ice forms the ocean can no longer transfer heat to the air as effectively, and the temperatures will tend to the long term average.
 

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