Basic questions and discussions about melting and freezing physics

[binntho]

Walrus, don't even start this line of argument unless you can show specific global data that shows summers are getting cooler. I will snip otherwise.

Sorry, I thought the cloud effect in the summer was common knowledge.

https://acp.copernicus.org/articles/23/2579/2023/

If you were to stumble across my previous post #494 you would perhaps like to rephrase that? There is no "common knowledge" about a "cloud effect" in the summer.

[binntho]

Given the low insulation effect, the difference in thickness will probably not create a parabolic change in rate of refreeze after the very first cms.

It seems this is where we disagree. I believe the rate of thickening does depend on thickness itself -  the thicker the ice, the slower the rate of further thickening, given the same weather.

Also look for the terms Lebedev formula and Stefan formula, I know this was discussed in some threads in the past.

Note: this is indeed the very basis of the "Slow Transition" postulation. If ice grows at the same rate regardless of thickness, there is no compensating factor for the loss of thicker ice, and the Arctic extent/area/volume will crash (should have crashed) by 2016 or whatever.

What I am arguing is not whether ice growth depends to some extent on thickness. I think everybody will agree on this. The thicker the ice, the slower it grows.

But the "slow transition" hypothesis states that the relationship between ice growth and thickness is non-linear, and is much faster below a certain threshold than above. The "slow" in "slow transition" means that once the average thickness reaches a certain threshold, ice re-freezes much faster and melts much faster, essentially reaching an equilibrium which results in a slowdown in the transition from a mid-20th century MYI thick icepack to eventual BOE.

Implied in this is that the non-linear rate of growth is intrinsic to the ice: Thinner ice below a certain threshold will grow much faster than above the same threshold. Which is exactly what you would expect if the insulation effect of ice was the main cause of the different growth/thickness ratios. This is how all decent insulators work.

But then it turns out that ice is a very shitty insulator. What may be happening is that it is the snow cover that gives the impression of the rate of growth slowing down significantly at a certain thickness. Without the snow cover, the rate of growth would probably decline linearly, but with snow cover, it declines non-linearly.

Which makes the non-linearity of the growthrate/thickness ratio not intrinsic to the ice, but extrinsic or contingent to the amount of snow cover. Nothing to do with thickness.

The opposite applies to melt: Bottom melt can easily overtake top melt, but apparently only if there is open water in the vicinity. So the rate of melt becomes contingent on the amount of open water. The more dispersion, the more bottom melt, and the faster the ice melts. Nothing to do with thickness.

[The Walrus]

Walrus, don't even start this line of argument unless you can show specific global data that shows summers are getting cooler. I will snip otherwise.

Sorry, I thought the cloud effect in the summer was common knowledge.

https://acp.copernicus.org/articles/23/2579/2023/

If you were to stumble across my previous post #494 you would perhaps like to rephrase that? There is no "common knowledge" about a "cloud effect" in the summer.

Much has occurred in the 25 years since the article in your post.

[Jim Hunt]

Sorry, I thought the cloud effect in the summer was common knowledge.

From the conclusions of your reference:

"The higher reflectance of clouds results in a more negative radiative forcing at the surface, thereby locally dampening Arctic amplification, especially where sea ice retreats and most notably in summer."

"Locally dampening Arctic amplification" is not the same as "reversing Arctic amplification"

Also "Arctic" != "global"

[gerontocrat]

There was an article recently (which I failed to download) suggesting Russia's plans for the Northern Sea Route may be delayed due to increased cloud cover over open water (including fog).

This would not only cause visibility problems but also slow down (but not stop) the decline in sea ice along the Russian shore.

ps: The Chukchi Sea used to be known as The Smoky Sea due to the prevalence of fog as sea ice melt progressed that was a real threat in the days of sail to the seal and walrus hunters and smugglers.

[The Walrus]

Sorry, I thought the cloud effect in the summer was common knowledge.

From the conclusions of your reference:

"The higher reflectance of clouds results in a more negative radiative forcing at the surface, thereby locally dampening Arctic amplification, especially where sea ice retreats and most notably in summer."

"Locally dampening Arctic amplification" is not the same as "reversing Arctic amplification"

Also "Arctic" != "global"

I never caliming that it "reversed arctic amplification" which encompasses all season.  Just than the clouds, themselves, exhibit a cooling effect.

As the reference states "This leads to a cooling trend by clouds being superimposed on top of the pan-Arctic amplified warming ... the rate of surface cooling by clouds has increased, both in spring (−32 % in total radiative forcing for the whole Arctic) and in summer (−14 %)."

[The Walrus]

Further reading:

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GL102850

"Clouds influence SSTmax during the melt season by cooling the surface and delaying the start of upper ocean warming."

"These findings suggest that when the Arctic becomes seasonally ice free, clouds will have a stronger net cooling effect on the ocean during summer."

[oren]

Not sure if this is pertinent to Walrus's comment, but for global warming overall, more extensive and/or thicker low cloud cover causes more warming by reflecting back long wavelength radiation at night.  This effect is stronger than the blocking of incoming short-wave radiation during the day.

The warming is occurring predominantly when the sun is not shining; nighttime and winter in the Arctic. The cooler occurs when the sun is shining.  Hence, warmer winters and cooler summers would be expected, with warming in winter being stronger than cooling in summer.

Walrus, just to be clear, my warning was a reaction to the bolded comment above.
I know you sometimes like to spread this particular line of reasoning - which is unfounded as far as I can tell.
You have since dialed back your statements to something which appears to be founded on science, just don't repeat the original claim unless you can show very good support.

[The Walrus]

Not sure if this is pertinent to Walrus's comment, but for global warming overall, more extensive and/or thicker low cloud cover causes more warming by reflecting back long wavelength radiation at night.  This effect is stronger than the blocking of incoming short-wave radiation during the day.

The warming is occurring predominantly when the sun is not shining; nighttime and winter in the Arctic. The cooler occurs when the sun is shining.  Hence, warmer winters and cooler summers would be expected, with warming in winter being stronger than cooling in summer.

Walrus, just to be clear, my warning was a reaction to the bolded comment above.
I know you sometimes like to spread this particular line of reasoning - which is unfounded as far as I can tell.
You have since dialed back your statements to something which appears to be founded on science, just don't repeat the original claim unless you can show very good support.

My original post was in response to the effects of increased Arctic cloud cover in summer.  See Glen's post #483 about clouds blocking LWR at night and SHR during the day.  My response was meant to address the cloud effect specifically, and was not a sweeping generalization of Arctic temperatures.

[oren]

Fine.

[Phil.]

Given the low insulation effect, the difference in thickness will probably not create a parabolic change in rate of refreeze after the very first cms.

It seems this is where we disagree. I believe the rate of thickening does depend on thickness itself -  the thicker the ice, the slower the rate of further thickening, given the same weather.

Also look for the terms Lebedev formula and Stefan formula, I know this was discussed in some threads in the past.

Note: this is indeed the very basis of the "Slow Transition" postulation. If ice grows at the same rate regardless of thickness, there is no compensating factor for the loss of thicker ice, and the Arctic extent/area/volume will crash (should have crashed) by 2016 or whatever.

What I am arguing is not whether ice growth depends to some extent on thickness. I think everybody will agree on this. The thicker the ice, the slower it grows.

But the "slow transition" hypothesis states that the relationship between ice growth and thickness is non-linear, and is much faster below a certain threshold than above. The "slow" in "slow transition" means that once the average thickness reaches a certain threshold, ice re-freezes much faster and melts much faster, essentially reaching an equilibrium which results in a slowdown in the transition from a mid-20th century MYI thick icepack to eventual BOE.

Implied in this is that the non-linear rate of growth is intrinsic to the ice: Thinner ice below a certain threshold will grow much faster than above the same threshold. Which is exactly what you would expect if the insulation effect of ice was the main cause of the different growth/thickness ratios. This is how all decent insulators work.

But then it turns out that ice is a very shitty insulator. What may be happening is that it is the snow cover that gives the impression of the rate of growth slowing down significantly at a certain thickness. Without the snow cover, the rate of growth would probably decline linearly, but with snow cover, it declines non-linearly.

Which makes the non-linearity of the growthrate/thickness ratio not intrinsic to the ice, but extrinsic or contingent to the amount of snow cover. Nothing to do with thickness.

The opposite applies to melt: Bottom melt can easily overtake top melt, but apparently only if there is open water in the vicinity. So the rate of melt becomes contingent on the amount of open water. The more dispersion, the more bottom melt, and the faster the ice melts. Nothing to do with thickness.

As I pointed out above above the conductivity of the seaice leads to slowing of growth with thickness.
From NSIDC:
"Once ice begins to grow, it acts as an insulator between the ocean and atmosphere. Heat from the ocean must be conducted, or pass through, the sea ice before being emitted to the atmosphere. Ice growth slows as the ice thickens because it takes longer for the water below the ice to lose its heat through ice to reach the freezing point.

The relationship between thermodynamics and sea ice thickness can be thought of most simply in terms of freezing degree days (FDD), which is essentially a measure of how cold it has been for how long. The cumulative FDD is simply the daily degrees below freezing summed over the total number of days the temperature was below freezing.

The freezing temperature of ocean (saline) water is typically -1.8°C (28.7°F). If the average daily temperature was -5.8°C (21.6°F), this would be -4°C (24.8°F) for one day, as the following equation shows:
4 degrees below freezing, Day 1 = 4 cumulative FDD
Scientists have developed different formulas to estimate ice thickness from thermodynamic growth, using the FDD. One such formula (from Lebedev 1938) is:

Thickness (cm) = 1.33 * FDD (°C)^0.58

The ice thickness increases at a rate roughly proportional to the square root of the cumulative FDD. Formulas such as this are empirical, meaning they are calculated only with observed data, so they really are simplifications of the ice growth processes. The formulas assume that the ice growth occurs in calm water and is reasonably consistent, and they do not take into account sea ice motion, snow cover, and other surface conditions."
So using your terminology the non-linearity is intrinsic to the ice

[jdallen]

................
Ah - you're making the same mistaken assumption I made years ago.

Even with very high temperatures, truth be told, the direct uptake of heat from atmosphere is comparatively trivial.  The lions share of melt comes primarily from heat transferred directly from water - either melt ponds or ocean itself - which in turn is captured from insolation.
.................

That may be so, but if you look at summer temperatures in the Arctic (defined here as 70-90 N, chart: climatereanalyzer, data: ECMWF reanalysis), you can see that summer temperatures are highly correlated with the September minimum.

<snip>

There is no denying that the trend in summer Arctic temperatures is up but also, it seems that year-to-year variation ("weather") decides each seasons's fate.

I'm going to double down.

The lion's share of the heat reducing the ice isn't being transferred from the atmosphere.  That's a matter of *physics*.  When you look at the energy required to cause a phase change for water, going from freezing (ice) to freezing (water) requires over 300 times the energy it takes to raise the temperature of either ice or water 1 degree C.  Air just simply doesn't have the mass - and by extension, the heat density - required. 

The energy required comes from sunlight, either applied directly via insolation, or indirectly via sea water, which captures the heat and stores it. 

So, your correlation is exactly that, a correlation, not a cause.  Believe me when I say I've crunched a lot of numbers around this trying to find exactly this sort of cause.  Higher seasonal temperatures are a signal, and indirect consequence of other forces in play, not the driving one.

[kiwichick16]

@  jdallen ...... +1   ...... i think most climate scientists look at Global warming as essentially Ocean warming

https://en.wikipedia.org/wiki/Ocean_heat_content#/media/File:Earth's_Heat_Accumulation.png

[binntho]

I'm going to double down.

The lion's share of the heat reducing the ice isn't being transferred from the atmosphere.  That's a matter of *physics*.  When you look at the energy required to cause a phase change for water, going from freezing (ice) to freezing (water) requires over 300 times the energy it takes to raise the temperature of either ice or water 1 degree C.  Air just simply doesn't have the mass - and by extension, the heat density - required. 

And I am not disputing this in itself. In Iceland we have two types of weather that melts the ice - direct sunlight during summer (of course) and high humidity / rainy / windy weather at practically any time of year. The latter is more noticeable since it can quite easily hit at times when farmland is covered in ice and snow (strong sunlight tends to come when the lowlands are free of snow) and the farmers describe it as weather that "strips the ice" off the surface.

The Arctic probably doesn´t get many "stripping" events of that kind, but they are nonetheless real and if you see high winds and rain over the ice, melt may well be significant underneath. And I believe that this is something that we have noticed - Arctic sea ice emerges from under cyclonic rainy weather considerably battered, also due to transfer of kinetic energy to the floes.

Actually it might be interesting to take the accumulated albedo graphs that we see regularly, convert that into energy absorbed and calulate how much ice this could melt. A bit above my abilities I am afraid.

[kassy]

The albedo change graphs don´t include clouds so the are some abstract max number.

When we consider isolation are we just look at incoming solar?

Another change might be the amount blocked by green house gasses. Quite a bit off additional methane now vs 2012. So in summers when it is not cloudy a lot of incoming solar reflects off the ice but some portion will be trapped by additional greenhouse gasses so it comes back down?

With cloudy conditions the big thing is water on the ice and that will increase over time as things warm.

[GrauerMausling]

What about the moisture in the air, could this have effect?
As warm air can carry more moisture it could also carry quite a bit of energy in the form of water vapour. I remember discussions here in the forum about humid air causing a lot of melt as 1 g water vapour can melt 8 (?) g of ice.
 

[jdallen]

The albedo change graphs don´t include clouds so the are some abstract max number.

When we consider isolation are we just look at incoming solar?

Another change might be the amount blocked by green house gasses. Quite a bit off additional methane now vs 2012. So in summers when it is not cloudy a lot of incoming solar reflects off the ice but some portion will be trapped by additional greenhouse gasses so it comes back down?

With cloudy conditions the big thing is water on the ice and that will increase over time as things warm.

When we talk about insolation, it is *just* incoming direct solar.  Any other source of radiation is going to be miniscule by comparison.

Greenhouse gasses slow but do not stop out-going heat.  The result is to cause the entire system to heat up until the energy of out-going black body radiation balances what energy is captured, across the entire system. 

You could think of our dilemma as a kind of "Pit and Pendulum" scenario in reverse.  Instead of the pendulum (insolation) descending, the wooden frame our victim (sea ice) is tied to is floating on water (total system enthalpy) that is steadily increasing from multiple sources, steadily lifting it towards the pendulum.  They will inevitably meet; there are no metaphorical rats to gnaw through the bonds tying our victim to the frame.

The movement of the pendulum (annual insolation) will not change, and will without question be what delivers the final blow.

[The Walrus]

The albedo change graphs don´t include clouds so the are some abstract max number.

When we consider isolation are we just look at incoming solar?

Another change might be the amount blocked by green house gasses. Quite a bit off additional methane now vs 2012. So in summers when it is not cloudy a lot of incoming solar reflects off the ice but some portion will be trapped by additional greenhouse gasses so it comes back down?

With cloudy conditions the big thing is water on the ice and that will increase over time as things warm.

Yes, more of the incoming solar radiation gets blocked by greenhouse gases.  Technically, absorbed and re-emitted, but the effect is the same.  This is part of the reason that summer temperatures have not changed much over the past decades, while winter temperatures have risen significantly.

<This claim is not true, readers should disregard it. O>

[oren]

Walrus, don't get started on this again, not in this thread and not without substantial evidence showing actual global summer temperatures over the last few decades.
Otherwise I will intervene.

[The Walrus]

Walrus, don't get started on this again, not in this thread and not without substantial evidence showing actual global summer temperatures over the last few decades.
Otherwise I will intervene.

How about six decades worth of summer temps?

https://ocean.dmi.dk/arctic/meant80n_anomaly.uk.php

<This is unrelated to the previous false claim of summer temps not changing much due to GHGs. O>

[El Cid]

C'mon Walrus! Those summer temps (80-90N) are anchored to zero because of the essentially constant presence of ice. How about JJA (summer) Northern Hemisphere temperatures (chart1)? Or even Arctic (60-90N ) temperatures during summer (chart 2)?

[oren]

I am tired of denialism, even when it's served in the guise of minimizing and chipping away, rather than outright denial. Be warned and do not carry this further.

[binntho]

The insolation graphs can give a feeling for a theoretical upper limit to melt caused by insolation. That is all. Knowing the theoretical upper limit compared with actual melt seen could give us an indication of the importance of insolation to total melt.

Each year sees 18.000 km3 of ice actually melting. If we look only at the phase transmission and ignore the temparature increase required to reach melting point, we need 6E21 Joules of energy (all figures are based on the Piomas site).

The annual trend of 280 km3 requires 8.6E19 Joules, or 0.4 W/m2 when spread over the entire Arctic, according to Piomas. This tells us that the energy needed to melt the 18.000 km3 would equate to 25 W/m2 when spread over the entire Arctic.

The accumulated albedo melting potential graphs should give us an idea of the maximum total W/m2 received from the sun during melting season. Might be interesting ...

[The Walrus]

C'mon Walrus! Those summer temps (80-90N) are anchored to zero because of the essentially constant presence of ice. How about JJA (summer) Northern Hemisphere temperatures (chart1)? Or even Arctic (60-90N ) temperatures during summer (chart 2)?

Using the 60-90 N temperatures includes significant land areas of Alaska, Canada, and Siberia, roughly 75% land between 60 and 70 N latitude alone.  This skews the data away from Arctic ocean temperatures towards the landmasses. 

Yes, the ice has a significant impact on the surface temperatures - no argument there.  However, the atumnal temperature history, which has similar sea surface ice as the summer, shows a significant temperature increase.

[oren]

Winter ice at minus 30C can warm significantly when energy is added to the system.
Summer ice at 0C cannot warm, instead it melts, still remaining at 0C.

[The Walrus]

Wintet ice at minus 30C can warm significantly when energy is added to the system.
Summer ice at 0C cannot warm, instead it melts, still remaining at 0C.

Well, duh!
<Please avoid pointless posts. O>

[Niall Dollard]

Fascinating article here on the summer melt of Arctic sea ice ridge keels by the Mosaic Team.

https://tc.copernicus.org/articles/17/4873/2023/

They performed a very detailed analysis on the melting of large ridge keels. They even named some of them. "Jaridge" was the name of the one they studied the most. It had an average draft of 3.8 metres.

Some of the conclusions :

"a first-year ridge melted faster than adjacent level ice types. The total ridge melt was on average 0.95 m, compared with 0.55 m for level second-year ice and 0.46 m for level first-year ice. These observations can largely be explained by the difference in initial average ice draft of 1.4 m for first-year ice, 2.6 m for second-year ice, and 3.9 m for the ridge. Ridge bottom melt was three to four times higher than the bottom melt of first-year level ice, while surface melt was almost identical. "

I must admit to being very surprised by the opening statement "Sea-ice ridges constitute a large fraction of the total Arctic sea-ice area (up to 40 %–50 %)"

[kassy]

Well it is ice flows that bump into each other which (still) happens quite a lot.

According to the definition by the World Meteorological Organization, an ice ridge is a line or wall of broken ice that is forced up by pressure (WMO, 2014). Ridges consist of a sail above and a keel below the water level. The keel initially consists of randomly packed ice blocks separated by water-filled voids, described by the ridge macroporosity (fraction of water-filled voids in the keel). The initial macroporosity of first-year ice ridges is in the range of 20 %–45 % (Bowen and Topham, 1996), with an average porosity of 30 % (Timco and Burden, 1997). The upper part of ridge keels usually refreezes, forming a consolidated layer defined by zero macroporosity. Some ridges become fully consolidated (with near-zero keel macroporosity) during the melt season (Marchenko, 2022).

Fascinating indeed.

[binntho]

Well it is ice flows that bump into each other which (still) happens quite a lot.

According to the definition by the World Meteorological Organization, an ice ridge is a line or wall of broken ice that is forced up by pressure (WMO, 2014). ...

It's the pressure that is wanting in today's Arctic. Floes bumping into each other isn't enough to create ice ridges.

[Niall Dollard]

Well it is ice flows that bump into each other which (still) happens quite a lot.

So is it fair to say that what we frequently call "rubble" during the Arctic summer is probably a lot of ridged ice, slabs of different age on top of each other and between the ridged slabs you have a lot of first year ice that melts out (outside of 85N) giving it the characteristic rubble appearance.

That is not to be confused with the huge pressure ridges that were once common.

[kassy]

Well the thinner ice melts first so that might be true.

Less and less of this thicker ice will be created because there is less time where freezing in it´s various forms can pileup the ice.

[Steven]

I am interested in the Watts per m² so I cheated and asked chatgpt. I started with this question:

How can I calculate the energy from the ocean in watts if sea ice is melting at 1cm per day and the air temperature is -20C?

but had to refine it a bit. After a short while:

The answer for ice melt at 0C was 84.62W

For sea ice of 50cm thick and air temperature of -20°C and assuming no snow, I calculate that the ocean contributes 117 Watts per square meters to melt the ice by 1 cm per day, based on Stefan's equation.  (Thanks to FredAroulette in the other thread for links.)

Without ocean heat, the sea ice would thicken by 2.3 cm per day under these conditions and the upward heat flux through the ice would be 81.5 Watts per square meters.  So the ocean heat has to counteract the ice thickening and additionally provide heat to melt the ice at 1 cm per day, which would give a total of 117 Watts per square meter.

Here is my own attempt to summarize the main points of Stefan's formula, focusing on the heat flux in Watts per square meter.  Hopefully I didn't make any errors...



Edit: fixed typo in equation (4)

[kassy]

What if the sea ice is 4 M thick?

[uniquorn]

I am interested in the Watts per m² so I cheated and asked chatgpt. I started with this question:

How can I calculate the energy from the ocean in watts if sea ice is melting at 1cm per day and the air temperature is -20C?

but had to refine it a bit. After a short while:

The answer for ice melt at 0C was 84.62W

For sea ice of 50cm thick and air temperature of -20°C and assuming no snow, I calculate that the ocean contributes 117 Watts per square meters to melt the ice by 1 cm per day, based on Stefan's equation.  (Thanks to FredAroulette in the other thread for links.)

Without ocean heat, the sea ice would thicken by 2.3 cm per day under these conditions and the upward heat flux through the ice would be 81.5 Watts per square meters.  So the ocean heat has to counteract the ice thickening and additionally provide heat to melt the ice at 1 cm per day, which would give a total of 117 Watts per square meter.
<>

Thanks for this Steven.

If your calculations are correct, 2.3cm bottom freeze per day would be fast. As a comparison 151920 further north thickened from 32cm to 66cm at an average 0.7cm/day.

The WSC west of Svalbard is still coming in at +4.18C at 2.7m depth.
https://fleetmonitoring.euro-argo.eu/float/6903587

[Steven]

If your calculations are correct, 2.3cm bottom freeze per day would be fast. As a comparison 151920 further north thickened from 32cm to 66cm at an average 0.7cm/day.

The 2.3 cm per day assumes that there is no ocean heat and no snow on the sea ice.  Both of these would counteract the ice thickening.

Snow seems to insulate about 10 times better than ice, although this degrades over time as the insulating air bubbles in the snow layer escape as it compacts.  But even a compacted snow layer would still insulate about 3 times better than ice.   

So a snow layer of 10 cm which is not too compacted would be the equivalent of the insulation of an extra meter of ice on top of the sea ice.

I double-checked the formulas in my previous post from a couple of websites.  This was Chris Reynolds' take on it:

http://dosbat.blogspot.com/2015/01/the-simplest-model-of-sea-ice-growth.html

The comments in that link are also interesting and give some alternative formulas for sea ice thickening based on actual observations.  As expected, those show a bit less thickening than Stefan's equation, but it's still a useful ballpark estimate.

[Steven]

What if the sea ice is 4 M thick?

4 meters is 8 times thicker than 50 cm, so the rate of thickening would be 8 times less (and the heat transfer through the ice would also be 8 times less), since the formulas above have the ice thickness in the denominator.

So the 4 meters thick ice would thicken by 0.29 cm per day, and the heat flux through the ice would be about 10 W/m².  But in practice the slow thickening may not occur if it is outweighted by ocean heat.

[icy voyeur2]

I've been fascinated by Fram export for the last 3 years, especially some of the sustained winds we saw last winter. When you get sustained strong southernly winds off the East coast of mid-upper Greenland, 25 - 45 km/hr, I'm assuming sail effects help flush the ice to the South. Does it induce surface currents further North by a kind of backfilling, water/ice flowing in to replace water ice blown South? How significant is that flow? Or does it just induce upwelling?

[Linus]

I have often wondered the same when it comes to highly mobile ice. What does the movement induce for currents or upwelling?

[Niall Dollard]

I've been fascinated by Fram export for the last 3 years, especially some of the sustained winds we saw last winter. When you get sustained strong southernly winds off the East coast of mid-upper Greenland, 25 - 45 km/hr, I'm assuming sail effects help flush the ice to the South. Does it induce surface currents further North by a kind of backfilling, water/ice flowing in to replace water ice blown South? How significant is that flow? Or does it just induce upwelling?

If I am reading your post correctly, did you mean sustained strong northerly winds ? Most times I see the pack as pretty uniform as it heads down eastern Greenland before finally dispersing/melting breaking up. By the end of summer the end line can retreat way up to NE Greenland especially when export is weak.
But one peculiar feature is the formation of the Northeast Water Polynya. at circa 78N to 80N Its formation was a common feature at the start of this century but ironically when the big exporr/melt in 2007 occured it was almost non existent.

https://www.issibern.ch/teams/Polynya/

[Glen Koehler]

The Respective Roles of Ocean Heat Transport and Surface Heat Fluxes in Driving Arctic Ocean Warming and Sea Ice Decline
Dylan Oldenburg, Young-Oh Kwon, Claude Frankignoul, Gokhan Danabasoglu, Stephen Yeager,
and Who M. Kim
26 Jan 2024
DOI: https://doi.org/10.1175/JCLI-D-23-0399.1

Abstract
Arctic Ocean warming and sea ice loss are closely linked to increased ocean heat transport (OHT) into the Arctic and changes in surface heat fluxes. To quantitatively assess their respective roles, we use the 100-member Community Earth System Model, version 2 (CESM2), Large Ensemble over the 1920–2100 period. We first examine the Arctic Ocean warming in a heat budget framework by calculating the contributions from heat exchanges with atmosphere and sea ice and OHT across the Arctic Ocean gateways. Then we quantify how much anomalous heat from the ocean directly translates to sea ice loss and how much is lost to the atmosphere. We find that Arctic Ocean warming is driven primarily by increased OHT through the Barents Sea Opening, with additional contributions from the Fram Strait and Bering Strait OHTs. These OHT changes are driven mainly by warmer inflowing water rather than changes in volume transports across the gateways. The Arctic Ocean warming driven by OHT is partially damped by increased heat loss through the sea surface. Although absorbed shortwave radiation increases due to reduced surface albedo, this increase is compensated by increasing upwelling longwave radiation and latent heat loss. We also explicitly calculate the contributions of ocean–ice and atmosphere–ice heat fluxes to sea ice heat budget changes. Throughout the entire twentieth century as well as the early twenty-first century, the atmosphere is the main contributor to ice heat gain in summer, though the ocean’s role is not negligible. Over time, the ocean progressively becomes the main heat source for the ice as the ocean warms.

Significance Statement
Arctic Ocean warming and sea ice loss are closely linked to increased ocean heat transport (OHT) into the Arctic and changes in surface heat fluxes. Here we use 100 simulations from the same climate model to analyze future warming and sea ice loss. We find that Arctic Ocean warming is primarily driven by increased OHT through the Barents Sea Opening, though the Fram and Bering Straits are also important. This increased OHT is primarily due to warmer inflowing water rather than changing ocean currents. This ocean heat gain is partially compensated by heat loss through the sea surface. During the twentieth century and early twenty-first century, sea ice loss is mainly linked to heat transferred from the atmosphere; however, over time, the ocean progressively becomes the most important contributor.

[binntho]

Thanks Glen. The "Most signifcant statement":

During the twentieth century and early twenty-first century, sea ice loss is mainly linked to heat transferred from the atmosphere; however, over time, the ocean progressively becomes the most important contributor.

In other words, atmospheric heat transfer has so fra been the greatest contributor, but the ocean is slowly catching up?

[Glen Koehler]

Dai,P.,Chu,M.,Guo,D.,Lu,Y.,Liu,X.,Wu,T.,eT al.  2024. Seasonal prediction of regional Arctic sea ice using the high‐resolution Climate Prediction System CMA‐CPSv3. J. Geophys. Res.: Atmospheres, 129, e2023JD039148. https://doi.org/10.1029/2023JD039148Received23APR2023Accepted30JAN2024

Key Points
The China Meteorological Administration Climate Prediction System (CMA-CPSv3) is used for seasonal predictions of Arctic sea ice

CMA-CPSv3 has skill to predict regional Arctic sea ice up to 7 months and shows the highest skill in the Bering Sea

Good performance of ocean subsurface temperature provides crucial sources of regional sea ice prediction skills

Plain Language Summary
     The reduction of Arctic sea ice has a significant impact on the climate and ecosystems, and accurately predicting Arctic sea ice is of broad interest. In this work, we investigate the seasonal prediction skill of sea ice in a high-resolution climate model. Using the anomaly correlation coefficient as the skill metric, we find that the prediction skill of sea ice is good up to 7 months and varies by region and target month. Notably, the Bering Sea shows the highest prediction accuracy among the 14 Arctic subregions. Then, we explore the sources of sea ice prediction skill and find that the skill is closely related to the good performance of upper ocean temperature in the model. Furthermore, we show that the regional Arctic sea ice variability is significantly modulated by surface heat fluxes. These results suggest that improving the representation of air-sea heat exchanges in climate models can enhance the prediction skill of sea ice. Our study contributes to an improved understanding and predicting of the Arctic sea ice variability.

[Glen Koehler]

Dai, P., Chu, M., Guo, D., Lu, Y., Liu, X., Wu, T., et al. (2024). Seasonal prediction of regional Arctic sea ice using the high‐resolution Climate Prediction System CMA‐CPSv3. Journal of Geophysical
Research: Atmospheres, 129, e2023JD039148. https://doi.org/10.1029/
2023JD039148

Key Points
The China Meteorological Administration Climate Prediction System (CMA-CPSv3) is used for seasonal predictions of Arctic sea ice

CMA-CPSv3 has skill to predict regional Arctic sea ice up to 7 months and shows the highest skill in the Bering Sea

Good performance of ocean subsurface temperature provides crucial sources of regional sea ice prediction skills

Plain Language Summary
     The reduction of Arctic sea ice has a significant impact on the climate and ecosystems, and accurately predicting Arctic sea ice is of broad interest. In this work, we investigate the seasonal prediction skill of sea ice in a high-resolution climate model. Using the anomaly correlation coefficient as the skill metric, we find that the prediction skill of sea ice is good up to 7 months and varies by region and target month. Notably, the Bering Sea shows the highest prediction accuracy among the 14 Arctic subregions. Then, we explore the sources of sea ice prediction skill and find that the skill is closely related to the good performance of upper ocean temperature in the model. Furthermore, we show that the regional Arctic sea ice variability is significantly modulated by surface heat fluxes. These results suggest that improving the representation of air-sea heat exchanges in climate models can enhance the prediction skill of sea ice. Our study contributes to an improved understanding and predicting of the Arctic sea ice variability.

[Rodius]

I just learned that water requires a particle within it to freeze at about 0 C (exactness is not the point here as salt water freezes at different temps to fresh water etc etc etc.)

Pure water with no particles freezes at a much lower temp.
https://www.rsc.org/news-events/journals-highlights/2018/04-april/water-freezing/#:~:text=Thomas%20Whale%2C%20from%20the%20University,low%20as%20%2D38%C2%B0C.

ANYWAY....I am now wondering about the article aspect of this... namely, if there are more particles floating about, does the speed up the ability of water to freeze?
ie - more particles provides more opportunity for water to freeze?

And does the mix of particles matter in the freezing/melting conditions?

I doubt this affects the sea water freezing in the Arctic... but, just in case, does it?

I am assuming this is a completing stupid question with what will be an obvious answer but I felt like asking anyway because I don't mind looking stupid.

[Richard Rathbone]

See

https://en.wikipedia.org/wiki/Supercooling

Sea water has a whole lot of particles in it, but it can be relevant for meltwater.

[SteveMDFP]

I just learned that water requires a particle within it to freeze at about 0 C (exactness is not the point here as salt water freezes at different temps to fresh water etc etc etc.)

Pure water with no particles freezes at a much lower temp.
https://www.rsc.org/news-events/journals-highlights/2018/04-april/water-freezing/#:~:text=Thomas%20Whale%2C%20from%20the%20University,low%20as%20%2D38%C2%B0C.

ANYWAY....I am now wondering about the article aspect of this... namely, if there are more particles floating about, does the speed up the ability of water to freeze?
ie - more particles provides more opportunity for water to freeze?

And does the mix of particles matter in the freezing/melting conditions?

I doubt this affects the sea water freezing in the Arctic... but, just in case, does it?

I am assuming this is a completing stupid question with what will be an obvious answer but I felt like asking anyway because I don't mind looking stupid.

Yes, supercooled liquids will freeze and release heat energy.  It only takes one nucleation site (or a few) for the entire mass of liquid to crystalize.  We see this in the commonplace reusable hand warmers:
How do re-usable hand warmers work?
https://www.sciencefocus.com/science/how-do-re-usable-hand-warmers-work

A supercooled solution of sodium acetate is apparently all that is needed.  It can stay in a supercooled state (room temperature or below) almost indefinitely.  Provide a tiny spot of nucleation, and the whole mass converts immediately to crystal form, releasing heat.

For seawater, or probably even meltwater, nucleation sites are certainly numerous.  Establishing a supercooled state at all seems improbable to me.  But it's a fascinating phenomenon. 

[morganism]

Slowdown in Arctic sea ice movement, impacting marine transport and climate

A groundbreaking study by York University researchers reveals a significant shift in Arctic sea ice dynamics, forecasting a slowdown in sea ice movement in the coming decades. This change could have profound effects on marine transportation safety and the broader implications for ecosystems, Indigenous communities, and global climate patterns.

Traditionally, Arctic sea ice has been observed to move more rapidly, posing increased risks for marine transportation. However, the latest climate models suggest a reversal of this trend during summer months, sparking debate over the models' accuracy.

The study, conducted by Neil Tandon, Associate Professor at the Lassonde School of Engineering, and Postdoctoral Visitor Jamie Ward, and published in The Cryosphere, explores the mechanisms behind the anticipated slowdown. "The shift in sea ice dynamics is a critical area of study, as it affects marine navigation, ecosystem health, and Indigenous livelihoods," Tandon explains. "Our research indicates a future decrease in sea ice speed, although the exact timing remains uncertain."

The acceleration of sea ice has been likened to a spring's expansion and contraction, with thinner ice moving more freely. However, as ice becomes extremely thin, it transitions to a free drift state, where external forces like wind and ocean currents predominate, leading to the projected slowdown.

predictions vary, with some indicating the slowdown could begin within a decade, while others suggest a longer timeline. Despite this variability, the study highlights the potential benefits of a slowdown in ice movement for marine transportation. Yet, Tandon cautions, "The overarching issue of diminishing sea ice cover remains a pressing global concern, affecting not just navigation but also the Arctic's ecological and cultural landscapes."

https://www.energy-daily.com/reports/York_University_Study_Predicts_Slowdown_in_Arctic_Sea_Ice_Movement_Impacting_Marine_Transport_and_Climate_999.html


Why is summertime Arctic sea ice drift speed projected to decrease?

https://tc.copernicus.org/articles/18/995/2024/


Abstract

Alongside declining Arctic sea ice cover during the satellite era, there have also been positive trends in sea ice Arctic average drift speed (AADS) during both winter and summer. This increasing sea ice motion is an important consideration for marine transportation as well as a potential feedback on the rate of sea ice area decline. Earlier studies have shown that nearly all modern global climate models (GCMs) produce positive March (winter) AADS trends for both the historical period and future warming scenarios. However, most GCMs do not produce positive September (summer) AADS trends during the historical period, and nearly all GCMs project decreases in September AADS with future warming. This study seeks to understand the mechanisms driving these projected summertime AADS decreases using output from 17 models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6) along with 10 runs of the Community Earth System Model version 2 Large Ensemble (CESM2-LE). The CESM2-LE analysis reveals that the projected summertime AADS decreases are due to changes in sea surface height (SSH) and wind stress which act to reduce sea ice motion in the Beaufort Gyre and Transpolar Drift. During March, changes in internal stress and wind stress counteract tilt force changes and produce positive drift speed trends. The simulated wintertime mechanisms are supported by earlier observational studies, which gives confidence that the mechanisms driving summertime projections are likely also at work in the real world. However, the precise strength of these mechanisms is likely not realistic during summer, and additional research is needed to assess whether the simulated summertime internal stress changes are too weak compared to changes in other forces. The projected summertime wind stress changes are associated with reduced sea level pressure north of Greenland, which is expected with the northward shift of the jet streams. The projected summertime SSH changes are primarily due to freshening of the Arctic Ocean (i.e., halosteric expansion), with thermal expansion acting as a secondary contribution. The associated ocean circulation changes lead to additional piling up of water in the Russian shelf regions, which further reinforces the SSH increase. Analysis of CMIP6 output provides preliminary evidence that some combination of wind stress and SSH changes is also responsible for projected AADS decreases in other models, but more work is needed to assess mechanisms in more detail. Altogether, our results motivate additional studies to understand the roles of SSH and wind stress in driving changes in Arctic sea ice motion.