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Messages - RoxTheGeologist

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51
Arctic sea ice / Re: The 2019/2020 freezing season
« on: September 27, 2019, 08:24:44 PM »

More snow = more sunlight reflected = cooling. 

Not cooling but less or later warming, that's not the same.

Cooling would happen if temps would generally be lower than before but as they are generally higher (AGW!) we have reduced/later/ warming over snow covered area than over not snow covered area.

The biggest problem with more snow is that it makes it harder for the permafrost to refreeze, and that would lead to warmer landmass during summer, and more methane in the air.

Early snow traps heat in the ground and in the ice. Instead of the surface being able to radiate heat directly to and through the atmosphere (say - 40°C) it has to conduct the heat through all those nice air pockets in the snow. On sea ice it would effectively lower the number of FDDs

Early snow = slows down heat loss (insulator)
Late snow = slows down heat gain (albedo, specific heat of melt to overcome before ice and ground heat up, insulator)

Of course and model would depend on the latitude and time of year


52
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 24, 2019, 06:32:50 PM »
When looking at the AREA graphs for the principal seas that surround the Central Arctic sea, the Laptev, ESS and Beaufort all came in well under the 2010's average.

Quite a substantial difference from the Central Arctic, the area of which is now greater than the 2010's average AND the 2000's average.

I think much of that is down to the Atlantic side of the Arctic. In the last few years before 2019 that ice age has been pushed back well over the edge of the continental slope. This year the ice remained in contact with Svalbard for the whole season. Perhaps it's correlated with the Nares strait not closing? If more Atlantic water is being diverted around Greenland that would explain less melting around Svalbard.

53
Arctic sea ice / Re: Accuracy of poll predictions
« on: September 23, 2019, 11:08:52 PM »

My typical method is to pick the bin above the median.




54
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 20, 2019, 10:53:29 PM »
Neven, are you reopening the refreezing thread today or tomorrow?  ;)

The fat lady has finally sung...

Great job Gerontocrat and Juan C. Garcia, thank you both 8) 8) You have earned a very well deserved rest now :)

Are you sure - 2018 had a big drop today, and without increases the 5 day average is still going down thanks to the century break a couple of days ago

55
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 20, 2019, 09:52:39 PM »

And from me too. Thank you for all the excellent data and analysis.

56
Arctic sea ice / Re: "Stupid" Questions :o
« on: September 20, 2019, 09:49:36 PM »
As kindly suggested I apply to those of you who 'get it' here: Why should there be any connection between ocean depth and surface ice. The assumption that deep water in the CAB should somehow protect the ice keeps popping up, but why should that be the case?
...
- There is a mixed layer, top 50 m. This layer is called mixed because, thanks to the action on the surface by winds, waves, etc., the mechanical input is able to mix differences in temperature and salinity by induced turbulence. It is strong enough to keep stratified layers from forming. Curiously the mixed layer has an increased salinity in most oceans except in the Arctic Ocean, which mixed layer is much fresher than at higher depths. The mixed layer ends by an abrupt salinity increase called halocline.

What makes the water of Arctic ocean mixed layer "fresh" and cold relatively? I think it's rivers, and the fact that the halocline comes before the increase of temperature, deeper under the halocline. So thanks to this strong stratification layer, the heat from beneath won't reach the mixed layer, staying relatively cold, and relatively fresh. I think there's a physical explanation for the halocline coming at lower depth than the temperature increase from deep waters, but I don't remember it. If it was not the case, there would not be Arctic ice, probably.
...
PS. Wikipedia page of the Arctic brings some interesting facts...

Thanks for that explanation. As Uniquorn points out, it is not as "idealized" as what you explain or the halocline/thermocline description in Wikipedia, but it seems THE factor: given the conditions of the Arctic Ocean, the halocline exists wherever the ocean is DEEP, inhibits mass and heat transport from the SUNK Atlantic and Pacific waters beneath, BUT the protective effect of the halocline has no room in SHALLOW shelves (peripheral seas of the Arctic proper). Temperature changes happen mostly UNDER the halocline, which helps BIG TIME the survival of the CAB in summer.

I think it is a rational explanation linking DEEP waters and SURVIVING ice.

The relationship between sea ice and bathymetry is well understood, particularly on the Atlantic side of the ocean. The warm salty waters from the Atlantic sink below the fresher Arctic waters from the Atlantic waters in under the Nansen basin. On the Pacific side the warmer Pacific waters in the Chukchi sea form the deeper waters under the Beaufort Gyre. The ice edge closely tracks the edge of the continental shelf in the summer on the Atlantic side of the Arctic.

The Freshwater cap on the Arctic is replenished by freshwater from melting ice and from the rivers, (I think about 50/50 from what I have read. The Siberian shallow seas are freshened because of the distance from the oceans and the big rivers that drain onto the shelf.

The mixed layer depth varies seasonally. In the summer it becomes shallow, there is little mixing and lots of input of freshwater causing stratification. In the winter as freezing starts the formation of ice expels dense brine that causes convection in the upper layers, and the mixed layer deepens, perhaps all the way to the halocline.

57
Permafrost / Re: Northern Hemisphere Winter 2019-2020 Snowcover / Misc Obs
« on: September 18, 2019, 06:48:46 PM »

Hmm... Won't snow act to trap heat in the ground? I think the best analogy is when you burn yourself. The first thing you want to do is run lots of cold water over the burn.

Heat flow of a spike on the surface (say summer insolation) is best reduced by applying lots of cold to the the surface as quickly and for as long as possible. Having a nice snow cover reduces the heat loss dramatically compared to emissive heat loss from the ground itself. You have to conduct that heat through all those nice insulating air bubbles in the snow rather than just through a couple of meters of soggy ground.

Of course it depends on the timing, but I think there would be a good thermodynamic argument that deep and early snow cover is really bad for permafrost and sea ice retention. Snow on sea ice effectively reduces the FDDs buy elevating the temperature of the ice compared to having no snow. That snow cover persisting into the high insolation months has the opposite effect. Raising albedo when the sun should be warming the ground has the opposite effect.

As the Earth warms, perhaps we will go through a phase of increased snowfall as the amount of water in the atmosphere increases, but that snow will melt out faster in the spring. The worst of both worlds for ice and permafrost.

58
Arctic sea ice / Re: The 2019 melting season
« on: September 18, 2019, 06:25:46 PM »
And what is the approximate area of Arctic Ocean with depth>100m ?
That simple thought has more meat from a physics point of view than the 07 12 16 19 thing (cute signature though).
Of course the Arctic resists melting because warm water sinks at the shelves breaks. The core is not only atmospherically more protected, it does not get ocean heat at all either!
But my feeling is that a summer with a very ice-dispersive weather like 2016 will eventually melt most of it.

Although it sounds compelling, I've never really been convinced by the bathymetry argument, i.e. that deeper waters somehow protect surface ice.

The main objections I have are as follow:

1) Warm water does not sink


If the warm water is more saline it does.

59
Arctic sea ice / Re: The 2019 melting season
« on: September 17, 2019, 07:14:03 PM »
It is interesting to note that there is a pattern to the very bad years of 2007, 2012, 2016, and 2019.

The first "bad" year was 2007. It took five years for 2012 to happen. It took four years for 2016 to happen. It took three years for 2019 to happen.

Perhaps it is nonsense, but that would put 4M KM^2 minimum as "normal" come 2021 (two years after 2019, and then we are down to one year separating these instances, i.e. it becomes each and every year), with each year thereafter likely to achieve a max under 2019, 2016, and 2007.

It should also be noted the last minimum above 5M KM^2 looks to be 2009. That is potentially about 11 years between the last minimum above 5M KM^2 and the last minimum above 4M KM^2 (using the step-trend above, that year would be 2020, or it may have already occurred).

We cannot say whether the remaining decline will follow on the same gradual continuum. Below 4M KM^2, the area / volume discrepancy inherently favors massive drops in area relative to volume as 0 is approached. I would think that there will not be another 11 years between the last 4M KM^2 min and the last 3M KM^2 min.

Does that mean we are approaching an asymptote at 4 M?
Maybe temporarily but I think the volume decline means it will not hold. Maybe it is a situation of once the asymptote is breached twice consecutively it cannot recover and spirals to near 0. Until it happens two years in a row, or rather until now, there has been sufficient momentum for temporary recoveries. As we can see in the year over year charts that momentum has been fading.

I suspect the total insolation above 80°N (from observation) is too little to melt the ice that forms on a yearly basis. The ice will have to be thinner, so less FDD days or more export. That equates to warmer and wetter weather for 9 months of the year. That or some good big storms to mix the ice with the warmer water below the halocline or in the adjoining seas during the summer.

The area within 80°N is 3883031 km2 (please someone correct that math if I'm wrong!) so perhaps that is where we will asymptote, give or take a little due to land masses causing local patterns. That may persist until we build up enough imbalance between the polar and equatorial temperatures to drive additional heat into the Arctic in the form of big warm storms.



 

60
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 16, 2019, 07:24:12 PM »
...or the correlation might break down completely :)
Same data on a chronological chart:

It'd be worth looking at the coherence of the data, and figure out at what frequencies the correlation is strong.

61
Arctic sea ice / Re: The 2019 melting season
« on: September 16, 2019, 06:37:45 PM »
JAXA/ViSHOP extent has now fallen below the 2016 minimum:

http://GreatWhiteCon.info/2019/09/the-2019-arctic-sea-ice-metric-minima/#Sep-16

Only 2012 left to beat!

That's quite a big gap. Perhaps not this season. I'm just hoping it drops another 7k so the result drops into the correct bin. By correct I mean the one I voted for.

62
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 15, 2019, 07:22:53 PM »

Whenever a curve or line is fitted to a graph it is to illustrate a correlation; such a correlation is the decline in sea ice volume over the last few decades. I'm no expert in sea ice modelling but, there is a fundamental need to understand how one would apply a model to be able to predict future conditions.

To understand a correlation a model is built. The model can perhaps take the starting data and then show how sea ice has changed on a year to year basis (hind casting). It can then be used to predict the future, and it's skill tested by it's ability to do so. Models are only as good as the test conditions applied. Hindcasting can be tricky as there is the temptation to model fit the data.

Obviously models based on a line fit are incorrect, they can be trivial disproved by projecting backwards in time and showing that there wasn't that much ice 10000 years ago. I hear the 'but there wasn't GHG emissions" so immediately the model has to include global warming from GHG gases. Assumptions are disproved, the model improves. If a model can effectively hind cast current sea ice from pre industrial times, then we perhaps have a chance of predicting more accurately what the future holds.

At least correlate global temperatures with sea ice volume, that seems like a better starting point than time.




63
Arctic sea ice / Re: The Freezing Season For Dummies
« on: September 15, 2019, 07:00:27 PM »
The freezing season is about to start again and we need to give space to the professionals that don't like us amateurs messing up their thread. That's why I created this "thread for dummies" (aka people without a scientific background) that are concerned about the climate and want to discuss it without being bitched by the "professionals".
bitched by the "professionals" ?

ooooo! miaow

I can bitch! Does that make me a professional too?


64
Greenland and Arctic Circle / Re: Iluliagdlup Tasia
« on: September 15, 2019, 06:40:28 PM »
Wow! Does it drain every year?

65
Arctic sea ice / Re: The 2019 melting season
« on: September 15, 2019, 06:35:09 PM »
The more scientifically inclined amongst us might be interested in taking a look at this news received via Don Perovich:

https://www.cryosphereinnovation.com/data

At long last some more ice mass balance buoys are "awaiting deployment" across the Arctic Ocean, including four at the MOSAiC expedition.

We might get data to back up our varied theories. Lets hope there are a lot of them, and the data is immediately available to all. It's really excellent news.

66
Arctic sea ice / Re: The 2019 melting season
« on: September 12, 2019, 11:55:14 PM »

This makes a big assumption - that system behavior will be consistent as we reach that limit.

Based on the surprising end of season slowdown this year, I'm not sure that's safe. I'm still mulling hypotheses for what we are seeing and why the dynamics are not falling more in line with your assumptions. 

"Blue Ocean" is a boundary condition, and the retreat of the ice to where it stands now - post 2007 - suggests to me that the dynamics for the ice north of 80 are significantly different from those of the peripheral seas, which is were most significant visible changes in the Arctic have unfolded.


This is my thought too; that there isn't enough insolation to melt the ice N of 80°N with the current FDD thickness increase, even in a sunny year. To melt the ice there has to be less FDDs. Increased oceanic heat isn't going to effect the high Arctic sea ice while vertical mixing is prohibited by the halocline. The latter isn't likely to disappear completely because of the input of fresh water from rivers and ice melt. Mixing can occur during big storms, but they seem to be rare in the summer. If that's the case, then seeing the high Arctic ice free is likely to require a warm, cloudy winter as well as a bright summer.

Did I just state the obvious?


67
Arctic sea ice / Re: The 2019 melting season
« on: August 23, 2019, 06:49:54 PM »
At this time of the year, I'd expect calm, cloudy, and snowy weather to be the most detrimental to the longevity of ice in the Arctic. All three work to trap heat in the ocean and atmosphere.

 If the Arctic isn't losing heat as effectively then the Earth is just going to warm up faster. This melt season seems to have been particularly bad. Lots of insolation with blue skys to soak up heat, and now plenty of cloud and some snow to start trapping that heat; extra water vapor in the atmosphere from warm seas surrounding the ice providing the proverbial 'icing' on the cake. There isn't going to be a new minimum, but this is worse.

68
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: August 21, 2019, 07:35:07 PM »
Quote
Earth gravity variations will not affect anything that floats over a iso-potential surface because these variations have already been accounted for in the level variations of the iso-surface. Nothing that lies in this iso-potential surface will feel gravitational pull parallel to the iso-potential surface. BECAUSE BY DEFINITION THE GRAVITATIONAL FORCE IS PERPENTICULAR TO THIS SURFACE.
Umm the shouty bits do not make it more true.
The mass of the Greenland ice sheet is above your theoretical surface.
The ice sheet has a gravitational pull perpendicular to its mass .
When the ice is gone the gravitational effects in the local area change.
Lowering  the surface of the water nearby.
The same effect will happen in antarctic resulting  the polar sea levels falling and higher seas  the nearer you get to the equator.

http://sealevelstudy.org/sea-change-science/whats-in-a-number/attractive-ice-sheets

You are both right! SIS is correct, as are you. All things being equal water follows an equipotential surface  that is perpendicular to the gravity field. As ice melts, mass is redistributed and the shape of the surface changes, and be inference, water level. I think it's confusing as we think of things flowing up and down 'hills' but in reality, in terms of the 'hills' on the geoid, the hills are flat....

69
Arctic sea ice / Re: The 2019 melting season
« on: August 21, 2019, 07:02:32 PM »

isn't early season snow good for slowing ice loss but increases long term heat retention?

70
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: August 19, 2019, 11:23:03 PM »
Back to the problem of ice being lovely attracted to Greenland. From first principles (Newtonian):

Gravitation: a conservative force from which a potential energy field can be derived.
Ideally, water fills the oceans following a constant iso-potential surface. It will be almost horizontal, but in some places with more gravitational pull, the level will be depressed, and in others, will be higher than average.
This is a static effect. Earth gravity variations will not affect anything that floats over a iso-potential surface because these variations have already been accounted for in the level variations of the iso-surface. Nothing that lies in this iso-potential surface will feel gravitational pull parallel to the iso-potential surface. BECAUSE BY DEFINITION THE GRAVITATIONAL FORCE IS PERPENTICULAR TO THIS SURFACE. And in the case of an ice block, this is balanced by buoyancy force due to the water being denser than ice.
Same happens with earth inertial centrifugal force, proportional to the distance to the earth axis. It can be derived from a potential field, which combined, distorts a little bit the gravitational iso-potential surfaces.

Coriolis inertial force, however, is the tricky one, since this cannot be made a conservative force, it depends on the relative velocity of the ice block with respect to the Earth.

The coriolis force appears in all kinds of interesting problems of the Arctic. I would recommend to read about it rather than quantum mechanics (in the context of the Arctic). It's less attractive to discuss while smoking a joint and looking at your gin-tonic ice cubes sticking at the sides than, say, quantum mechanics paradoxes and dragons.

The geoid is a map of the equipotential surface, represented as a departure from a reference ellipsoid (the mathematical approximation for the earth). The equipotential surface includes rotational effects. It is changing slowly, from ongoing PGR and ice melt. As sis says, since it is an equipotential surface by definition gravity is always perpendicular to a tangent to the surface.

71
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: August 19, 2019, 11:13:24 PM »
Oh, this should be here too...

Ups and downs from PGR

72
Greenland and Arctic Circle / Re: What's new in Greenland?
« on: August 19, 2019, 11:10:01 PM »

Here's a map of the ups and downs.

73
Arctic sea ice / Re: The 2019 melting season
« on: August 19, 2019, 05:43:33 PM »
My theory is that Greenlands mass pulls the ice towards it.

I like your theory, it makes a lot of sense.

You can look at what the surface of the ocean would like like given the effects of gravity and the rotation of the earth, it's the equipotential surface - the geoid

74
Arctic sea ice / Re: The 2019 melting season
« on: August 13, 2019, 08:27:26 PM »
Can somebody with better skills that I have with Sentinel, try to verify if we just lost a few Km
of glacierer here:
https://www.dropbox.com/s/yakmbopak5c0syj/Screenshot%202019-08-13%2020.16.01.png?dl=0

This thread?

https://forum.arctic-sea-ice.net/index.php/topic,400.0.html

75
Consequences / Re: Laurentide II
« on: August 13, 2019, 07:56:44 PM »

I posted a question on stupid questions noting that early and heavy snowfall is probably a good way to heat up the planet as it does a very good job of insulating against heat loss that would otherwise have been going on.

76
Arctic sea ice / Re: "Stupid" Questions :o
« on: August 13, 2019, 07:55:14 PM »

Hmm -- question about late season bottom melt.

Assuming that the ice isn't moving over water heated by insolation.
And assuming the surface of the ice isn't being covered in seawater.

Where is the heat stored to create bottom melt? Is it in the ice itself, and by the slow transfer of heat through the ice from the 0°C surface?

Bottom melt continues until the whole of the ice thickness is at -1.8°C (or whatever the interface melting temperature is at the base of the ice), as that heat will gradually be used to melt the base (if its not lost to the atmosphere).

1) If that is the case, does it make sense that until the average surface temperature drops below -1.8°C (on average, as the daily variations are damped as they propagate through the ice), bottom melt will continue? A meter of ice at 0°C contains enough heat to melt around 2.16cm (enthalpy of fusion is 83x the specific heat capacity) of the base. If we see 0°C on the map, that is promoting bottom melt, but it takes a while for that heat to move through the ice, depending on it's thickness, thicker ice has more insulation between the 0°C surface and the -1.8°C base.

2) Does it also means that thin ice has the most capacity to refreeze? The seawater has little insulation when the temperature above the ice falls. Open water has all that mixing going on, probably causing conviction as the surface chills and bringing warmer saltier water to the surface

3) Snowfall on ice will insulate the top of the ice, preventing the ice from losing heat. Early and heavier freeze season snowfall will trap more heat, perhaps prolonging bottom melt and slowing down heat loss. As a note I'd guess that heavier snowfalls are therefore really bad news for cooling the planet. It's a bit like putting a blanket over the heat exchanger of your fridge.


77
Arctic sea ice / Re: The 2019 melting season
« on: August 13, 2019, 06:06:22 PM »

It would be interesting to know how much ice the Barnes Ice Cap lost this yet. It seems to have been under blue sky for most of July and August.

A remnant of the last ice age. It will not survive to see the next.


Next ?


100,000 years from now

We are STILL in an ice age. What we are experiencing is the Earth's climate transitioning from a interglacial to a hothouse state. My guess is it'll take a few million years to switch back to icehouse. Go on; Prove me wrong.

78
Arctic sea ice / Re: The 2019 melting season
« on: August 13, 2019, 05:50:40 PM »

...
Here you are:
...

Thank you Espen! I didn't realize you read this part of the forum ...



79
Arctic sea ice / Re: The 2019 melting season
« on: August 12, 2019, 11:16:26 PM »

It would be interesting to know how much ice the Barnes Ice Cap lost this yet. It seems to have been under blue sky for most of July and August.

80
Arctic sea ice / Re: When will the Northwest Passage "open" in 2019?
« on: August 12, 2019, 10:06:28 PM »
Looks cold.  (Yes, I live in Florida.)

Everywhere looks cold from Florida.

And dry.

81
Arctic sea ice / Re: When will the Northwest Passage "open" in 2019?
« on: August 12, 2019, 04:12:36 PM »

Jim, oh great thread arbitrator, are you accepting bribes?

82
New CESM2 runs are indicating that the most likely value for ECS is 5.3C:

Oh S**t.

83
Arctic sea ice / Re: The 2019 melting season
« on: August 12, 2019, 01:37:20 AM »
I am amazed how easily the human is deceived and can "see" patterns with minimal data....

Canals on Mars.

84
Arctic sea ice / Re: When will the Northwest Passage "open" in 2019?
« on: August 08, 2019, 11:45:42 PM »

....

Right now I fear that we shall have a similar race like not too long ago with the opening between beaufort and chucki that was kind of a matter of hours in favor of the later slot.

Yes, and I definitely got that one a few hours two early, darn it. Grrr... That little stringer of ice.

Lets hope for the same again :)

85
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: August 08, 2019, 06:57:04 PM »
Hear hear...

Hmm, I think we better start taking our gin in tea, I don't think the ice is going to be there much longer. Is that too quintessentially British?

86
Arctic sea ice / Re: When will the Northwest Passage "open" in 2019?
« on: August 08, 2019, 06:54:02 PM »
I think the ice to the north will migrate south once the southernmost ice melts, delaying the opening of the passage through Bellot Strait.

I like your analysis, Oren; maybe because I voted for the 2nd half of August.

Please can someone get out there and push some flows south??

87
Heavy action in Jøkelbugt (Glacier Bay) notice how the calved icebergs in front or Zachariae Isstrøm are sucked away from the sea ice movements further out:

I guess there is substantial amounts of meltwater flowing out of the glacier, would that help move the icebergs?

88
Arctic sea ice / Re: "Stupid" Questions :o
« on: August 05, 2019, 12:43:12 AM »
Q. Can it? My response to this statement on the 2019 Melting Thread.

There is more than enough heat in the deep water to melt the ice and keep the arctic ice free year round. 

However, the heat can not move upwards through the halocline. 

The halocline is 50 meters thick (at least) and is very difficult to breach.  If it ever happens, look out!   The arctic will be a completely different place.


I've often wondered if/why the thermal conductivity of seawater is insufficient for significant melting of the ice just by thermal conduction, when the halocline is stable.

So let's see...


Consider the year-round loss of ice thickness due to thermal conduction from a 1-degree-C-warmer layer at a 50 meter depth.


ASSUMPTIONS & PROPERTIES:




CALCULATIONS:

Upwards heat flux = (temperature gradient) x (thermal conductivity) = 2e-2 K/m x 0.6W/mK = 1.2e-2 W/m^2

Thermal energy added to ice in 1 year = (Upwards heat flux) x (time in 1 year) = 1.2e-2 W/m^2  x 3.1e7 s = 3.7e5 J/m^2; multiply by 1e-4 m^2/cm^2 = 37 J/cm^2

Depth of ice melted = thermal energy added / (heat of melting x density)
= 37 J/cm^2 / (334 J/g x 0.9 g/cm^3) = 0.12 cm depth



CONCLUSIONS

So the thickness of ice melted over a year in the above scenario is only of order a millimeter.

Indeed, the thermal conductivity of seawater is insufficient to provide significant melting from deep layers of warmer, saltier water below the ice.

The layer down to the halocline is typically mixed as the ice freezes. Cold briny water is formed from expulsion, sinks and the upper layer becomes mixed.

The strong stratification in the melt season is unlikely to allow much heat to propagate by conduction. I'd expected much more heat to be transferred as ice freezes, and to stop it thickening as quickly throughout the freeze.



89
Arctic sea ice / Re: The 2019 melting season
« on: August 02, 2019, 09:05:18 PM »
My hunch is because the 2012 GAC did a lot to release heat that was entrained in deeper waters, 2013 and 2014 had less melt.

Very interesting point that I hadn't considered before.

The thin ice on the Greenland coast may also be indicative of heat building in deep waters. It's far north, and we have had plenty of Pacific to Atlantic drift this year, so why isn't it thick as usual? The only reason I can see for it being thinner is that the water is warmer! It strikes me that it's likely to be representative of the increasing heat build up in the intermediate waters. I'd say it would take a long time for extra heat to impact the surface, as it has to conduct through the halocline. If it is driven by conduction we wont be able to observe it with SST or salinity changes, so to test the theory we would have to have consistent buoy records going back a decade at least.


90
Arctic sea ice / Re: The 2019 melting season
« on: August 02, 2019, 08:35:22 PM »
I still can't make up my mind which one looks worse: 2012 or 2019, but 2019 is more fearsome.

To my eye (and most graphs), on this day 2019 looks worse. But given that the 2012 GAC was this week, it won't be for long. Unless...

My hunch is because the 2012 GAC did a lot to release heat that was entrained in deeper waters, 2013 and 2014 had less melt. 2019 looks like it is on trend, and that 'normal' conditions are getting close to 2012. I wont hold my breath for 'recovery' years in 2020 and 2021.

91
Arctic sea ice / Re: The 2019 melting season
« on: August 02, 2019, 08:20:16 PM »
Here's Neven's year-to-year comparison maps for Arctic sea ice on 1 August.


2019 definitely appears to be one of the worst years on this date. How bad will this melt season end up compared to previous worst years? Too early to tell?

What's really noticeable is the difference on the CAA and Greenland side of the Arctic, compared to all other years (except, perhaps, 2016). There appears to be thinner ice extending hundreds of KMs offshore where the store of MYI used to be.

92
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: July 31, 2019, 10:06:31 PM »
Just some incredible skew-ts. A few others with freeze levels above 4000m.

This is a subtropical airmass. I've found myself saying this a few times over the past couple of years, but this doesn't belong north of the Arctic circle -- virtually ever.

Thank you for your professional and, therefore, even more terrifying analysis.

93
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: July 31, 2019, 10:03:30 PM »

It's looking VERY blue in NE Greenland

94
Arctic sea ice / Re: The 2019 melting season
« on: July 31, 2019, 09:54:58 PM »
It's probably a good idea to take a break from posting for a couple of days (or more if you can). ;)
Here are unihamburg amsr2-uhh september minimums from 2012-2018 overlaid onto noaa bathymetry. I leave it to the viewer to discern the level of correlation between ice location and ocean depth, only pointing out the obvious discrepancies over the Beaufort/CAB and the ESS/CAB.

Question. Is the late melting in the ESS, despite the southerly location, due to lower salinity, stronger ice, permafrost ~30m below, pacific and atlantic ocean currents causing compaction or other (your suggestion)?

tech note: osi saf is estimated over the previous 3 days so, while extremely useful, should probably be considered as historic.

I would say its down to the distance from the Atlantic and Pacific oceans. The freshwater input, the depth, and the surface salinity are similar. Any incursions of warm water from the pacific are deflected along the Alaskan coast, and the Atlantic waters have already sunk below the halocline before they reach the Laptev, never mind the ESS. On average weather systems that can carry humid air from the Pacific or Atlantic have to cross more ice before reaching the ESS, The air will be on average cooler and dryer, and transfer less energy to the ice.
yep, likely. And this years hole at the end of the atlantic current?

Guessing again. Shoaling (i need to check the bathymetry) or simply consistent wind patterns opening up a polynya.
I'm more concerned that the opening up of the Greenland coast is showing what a few decades of entraining extra heat into the Halocline is going to do. Thinner ice more susceptible to melt from shoaling of warm saline deep waters. Going out on a limb It also suggests that the Nares might not close again.

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Arctic sea ice / Re: The 2019 melting season
« on: July 31, 2019, 09:35:37 PM »
It's probably a good idea to take a break from posting for a couple of days (or more if you can). ;)
Here are unihamburg amsr2-uhh september minimums from 2012-2018 overlaid onto noaa bathymetry. I leave it to the viewer to discern the level of correlation between ice location and ocean depth, only pointing out the obvious discrepancies over the Beaufort/CAB and the ESS/CAB.

Question. Is the late melting in the ESS, despite the southerly location, due to lower salinity, stronger ice, permafrost ~30m below, pacific and atlantic ocean currents causing compaction or other (your suggestion)?

tech note: osi saf is estimated over the previous 3 days so, while extremely useful, should probably be considered as historic.

I would say its down to the distance from the Atlantic and Pacific oceans. The freshwater input, the depth, and the surface salinity are similar. Any incursions of warm water from the pacific are deflected along the Alaskan coast, and the Atlantic waters have already sunk below the halocline before they reach the Laptev, never mind the ESS. On average weather systems that can carry humid air from the Pacific or Atlantic have to cross more ice before reaching the ESS, The air will be on average cooler and dryer, and transfer less energy to the ice.

96

I think if you really want to know where we are heading with emissions you simply have to follow the money, and investment banks have yet to actually stop funding oil, coal and gas infrastructure, and we have yet to control deforestation and industrial farming. It's not looking good.

That infrastructure has a long lead time to spend the money, 2 years or so, and then usually has a ROI over 10 years and thereafter it makes money. If the money is still flowing towards oil and gas how can we expect emissions to stop growing?

97
Arctic sea ice / Re: The 2019 melting season
« on: July 30, 2019, 04:02:46 PM »
Still a little extreme.
Yes, it sure is weird. I also checked SST, and they show an increase all over the place. 4°C may be some exaggeration from me, but the temperature went from -1.5°C to above freezing in most places, and the winds are blowing the ice straight into all that hot water. If you look at the winds in the coming days, it looks like a giant hand is pushing the entire pack away from Greenland, straight into hot water...

https://earth.nullschool.net/#2019/07/31/1200Z/wind/isobaric/1000hPa/orthographic=-44.09,94.09,1829/loc=-45.617,84.295

I thought satellites could only measure the top 1/10 mm of the ocean. Perhaps a still warm day with little mixing?

98
Arctic sea ice / Re: Arctic Image of the Day
« on: July 29, 2019, 09:32:06 PM »

One is a picture of a floating iceberg in front of the boat. It could have come from anywhere. Find an old picture of an iceberg then take a picture without an iceberg there.

99
Arctic sea ice / Re: Arctic Image of the Day
« on: July 29, 2019, 08:06:59 PM »

The image is off a ice berg, and rather deceptive

100
Arctic sea ice / Re: The 2019 melting season
« on: July 29, 2019, 08:02:01 PM »
That overlaid bathymetry map shows the impacts of the subduction of heat in the Beaufort sea and the Nansen basin. The "Atlantification" of the Nansen basin is one of the major changes that has been taking place in the Arctic over the past 15 years. The new and very disturbing thing we're seeing this summer is the collapse of thick ice north of Ellesmere Island and in the Lincoln sea. I've looked on Worldview back as far as I could go and this summer is far worse around Ellesmere than any other year. It's hard to predict what this area will look like in September because this situation is like nothing we've seen before.

Perhaps seeing the effects of more heat in the Atlantic waters finally making it all the way around the Nansen Basin? It would be hard to prove as the salinity will be the same and the surface temperature pinned at that of melting ice.

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