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Sterks

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Re: The 2019 melting season
« Reply #4500 on: July 25, 2019, 12:47:34 AM »
The models do predict continuous interchange of heat with the continents. That’s scorching heat .

A repetition of the (thermally) protective vortex of the last 10 days is not probable at least until August.

Clear indications of snow/surface refreezing in CAB and even in Beaufort from Worldview, see sequence.
https://go.nasa.gov/2JZDyEc
« Last Edit: July 25, 2019, 12:54:18 AM by Sterks »

F.Tnioli

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Re: The 2019 melting season
« Reply #4501 on: July 25, 2019, 12:47:51 AM »
i'd say we can safely settle on very approximate range of ~180...300 W/m2 absorbed at the surface under clear skies (high pressure systems) for late July / early August
So about 5-9 cm of ice per day might be melting under the clear skies of the big high pressure system soon to arrive in the CAB.

Reason: it takes about 35 W/m^2 to melt each centimeter of ice per day:

Energy flux to melt 1 cm thickness of ice per day [in units of W/m^2] = 1 cm x (10^4 cm^2/m^2) x (334 J/g latent heat of melt) x (0.9 g/cm^3 density) / ( 3600x24 seconds/day)
= 35 W/m^2
(Uses the definition W = J/s)

DISCUSSION POINT
Doesn't that seem a bit high?
...
Understandable confusion. What you miss in the basic picture of the process - is basics about how absorption works. You assume that all 180...300 W/m2 goes into melting the ice. In reality it does not: like already mentioned above, some of that energy is lost via evaporation (mostly from liquid water at the surface, but even dry ice actually evaporates slowly).

Further, whenever there is any noticeable open water - most of those 180...300 W/m2 gets absorbed at significant depth of downwards water column, since you know, water is a transparent thing. Noticeable amounts of light are present even at ~200 meters depth if my memory serves, - that's basically how deep significant fraction of absorption happens.

Same effect also happens to a lesser degree through the ice itself whenever there is no snow cover on it, increasingly so when the ice getting thinner: much sunlight simply goes through it and into water column below it, since ice is often significantly transparent, itself.

With water density being the highest at +4 Celcius iirc, a layer of colder melt water often remains near remaining ice, with warmer water sinking down as it's a bit heavier (though this much depends on water column mixing factors present at the location), which is another "sink" for some absorbed heat. "Sink" if we talk immediate insolation effects on ice thickness, of course - but in the same time, often it's also "delayed bottom melt" if we look further into melt season, as quite often large masses of warmer water from below end up getting near the surface and doing said bottom melt to still-remaining ice at a later date. This effect gets really nasty whenever some layers of water end up much warmer then 4C, thus losing density and starting to go up "themselves", without any water current forcing.

Yet one more heat sink which "steals" much of absorbed energy - is IR re-radiation. We know that in the absense of sunlight, Arctic ocean under clear skies cools down quickly and freezes into thick ice, during polar night. Why? Because it loses its surface heat, much via IR radiation right up into near-Earth space. Well, if you'd think about it, then you'd realize that this process is STILL happening summer-time, continuously, removing significant fraction of absorbed energy from the surface in short order. The intensity of this heat loss is not anyhow dependant on insolation, it's merely a function of surface temperature and emissivity of surface matherial. It's just that insolation brings in significantly more energy per second than amount lost via IR emissivity of the surface.

So, if you start to crunch 'em numbers of cm/day of ice lost, you can't neglect this and other heat loss mechanisms, if you want to arrive to anyhow realistic figures. Sadly, this kind of calculations takes more than a single small napkin. But one can try, of course. It's just that this topic is not quite the place to delve deeper into this, i suspect.

P.S. Neven, if you're going to snip this post, i'll understand... But IMHO it's better to achieve understanding about this among gentlemen here, which all the above helps to do in pretty short form, given relative complexity of described processes.
« Last Edit: July 25, 2019, 01:06:49 AM by F.Tnioli »
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bbr2314

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Re: The 2019 melting season
« Reply #4502 on: July 25, 2019, 12:55:25 AM »
The smoke from the Siberian firestorm now covers an area that's approximately the size of the continental US. Oh, and it is now getting entrained into the Laptev low -- I anticipate a very major portion will end up being deposited into the sea ice (or open water).


Rich

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Re: The 2019 melting season
« Reply #4503 on: July 25, 2019, 01:14:30 AM »
The dipole has arrived. But it does not come with a lot of heat.

The SST's are very warm around the edges, but in no rush to invade the CAB.

2019 leads in some categories, but area losses are skipping, suggesting lost momentum.

The wind remains impressive, but mostly cold and pointed away from Fram. Some compaction, some dispersion, some export. Nothing record breaking.

The ice is in crap condition, but it won't disappear w/o good reason. Especially from the CAB.
 
I'm rooting for a record and anything else that might occur in the short term that will jolt the world ioward the necessary urgent response to AGW.

Second place doesn't make headlines. That where it looks like we're headed.

F.Tnioli

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Re: The 2019 melting season
« Reply #4504 on: July 25, 2019, 01:18:05 AM »
I saw couple signs that say that you're absolutely correct about the CAA part, lately. And very true about extent and area, too. Apart from (often difficult, uncertain, or not available) measurements of current ice volume / thickness, i'd say small dips in concentration % could sometimes be one useful hint about such processes. I wonder if you use that as one of quick things to check, yourself.

Well, hints like that help, certainly. One of the challenges, of course, is determining how to section off areas for analysis. That's why I tend to focus on just the Sverdrup Islands, rather than wider areas like the Queen Elizabeth Islands or the whole of the CAA.

Even a small change in one of the satellite-discernible metrics (area, concentration, extent) for the Sverdrups alone is likely to be significant. But changes of similar magnitude for the whole of the CAA are potentially just noise. For example, the CAA's conventional boundaries include the North Water Polynya, at least in part. The CAA also includes smaller areas of continuously (or nearly so) open water, including at the west end of James Sound (at North Kent Island) and in the general vicinity of Bailie-Hamilton Island. Even absent significant regional melt or fragmentation, the exact boundaries of these open water phenomena can easily swamp the signal of more concerning events when considering the region broadly.
Definitely just noise for the whole of CAA, yes. Indeed i meant small dips in concentration detectable for a single "mechanically" region - i.e. an area which has all the ice in it moving in practically same direction (if any), affected by one and same water current under it (if any), and practically same wind direction, speed, precipitation kind/amount above it (if any). And i meant eye-balling it (sats photos) much more than using any processed concentration data, too.

P.S. Pleasure to read your posts. You definitely know what you're doing. I wish you good luck with your further work, sir.
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bbr2314

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Re: The 2019 melting season
« Reply #4505 on: July 25, 2019, 01:18:18 AM »
The dipole has arrived. But it does not come with a lot of heat.

The SST's are very warm around the edges, but in no rush to invade the CAB.

2019 leads in some categories, but area losses are skipping, suggesting lost momentum.

The wind remains impressive, but mostly cold and pointed away from Fram. Some compaction, some dispersion, some export. Nothing record breaking.

The ice is in crap condition, but it won't disappear w/o good reason. Especially from the CAB.
 
I'm rooting for a record and anything else that might occur in the short term that will jolt the world ioward the necessary urgent response to AGW.

Second place doesn't make headlines. That where it looks like we're headed.

What are you smoking? The impending heights and 850 temps are all-time highs as projected by EURO. I also think that the tempering of area losses is due to cloud interference but this is more conjecture on my part. We shall see.

pearscot

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Re: The 2019 melting season
« Reply #4506 on: July 25, 2019, 01:21:44 AM »
Others have mentioned it today, so I figured I would take a look at it myself - just north of Greenland four massive icebergs (not really sure what to call them since they are/were part of the "central" pack are now floating (I use the term central, not in terms of geographic area, rather central insofar as I've never seen this region break away from the rest). The scale of this boggles the mind, with it copied/pasted above for reference. Is this rare or has this happened before? I just don't know, but I always considered this region to be more 'steadfast' as opposed to the others. 
pls!

F.Tnioli

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Re: The 2019 melting season
« Reply #4507 on: July 25, 2019, 01:30:34 AM »
The dipole has arrived. But it does not come with a lot of heat.

The SST's are very warm around the edges, but in no rush to invade the CAB.

2019 leads in some categories, but area losses are skipping, suggesting lost momentum.

The wind remains impressive, but mostly cold and pointed away from Fram. Some compaction, some dispersion, some export. Nothing record breaking.

The ice is in crap condition, but it won't disappear w/o good reason. Especially from the CAB.
 
I'm rooting for a record and anything else that might occur in the short term that will jolt the world ioward the necessary urgent response to AGW.

Second place doesn't make headlines. That where it looks like we're headed.

What are you smoking? The impending heights and 850 temps are all-time highs as projected by EURO. I also think that the tempering of area losses is due to cloud interference but this is more conjecture on my part. We shall see.
Now this is one interesting question for sure, bbr - what is he smoking? Well, based on such a peaceful part of his post - "Some compaction, some dispersion, some export. Nothing record breaking" - i dare suspect it's labrador joint. It makes one really peaceful, see? :D
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Rod

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Re: The 2019 melting season
« Reply #4508 on: July 25, 2019, 01:44:54 AM »
“The dipole has arrived. But it does not come with a lot of heat.”  🤔

bbr2314

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Re: The 2019 melting season
« Reply #4509 on: July 25, 2019, 01:45:40 AM »
“The dipole has arrived. But it does not come with a lot of heat.” 🤔
As I said, he is clearly smoking something, the alternative is he is blatantly lying.

RoxTheGeologist

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Re: The 2019 melting season
« Reply #4510 on: July 25, 2019, 01:51:03 AM »
The dipole has arrived. But it does not come with a lot of heat.

The SST's are very warm around the edges, but in no rush to invade the CAB.

2019 leads in some categories, but area losses are skipping, suggesting lost momentum.

The wind remains impressive, but mostly cold and pointed away from Fram. Some compaction, some dispersion, some export. Nothing record breaking.

The ice is in crap condition, but it won't disappear w/o good reason. Especially from the CAB.
 
I'm rooting for a record and anything else that might occur in the short term that will jolt the world ioward the necessary urgent response to AGW.

Second place doesn't make headlines. That where it looks like we're headed.

SSTs in the ice pack are buffered at 0°C or thereabouts by melting ice. You don't see the SST increase until all the ice is melted. You can't tell how much ice is melting by looking at SSTs until all the ice is gone.

Rich

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Re: The 2019 melting season
« Reply #4511 on: July 25, 2019, 01:54:16 AM »

What are you smoking? The impending heights and 850 temps are all-time highs as projected by EURO. I also think that the tempering of area losses is due to cloud interference but this is more conjecture on my part. We shall see.

I'm curious. What is the altitude where those record 850 hpa temps are being set? Is the ice going to float up there?




be cause

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Re: The 2019 melting season
« Reply #4512 on: July 25, 2019, 02:00:25 AM »
I can vouch that it's not by smoking anything worthwhile that Rich gets his notions but clearly he is a wiser man than Zack Labe .  .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

bbr2314

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Re: The 2019 melting season
« Reply #4513 on: July 25, 2019, 02:01:14 AM »
I can vouch that it's not by smoking anything worthwhile that Rich gets his notions but clearly he is a wiser man than Zack Labe .  .. b.c.
So it's meth? That makes sense, especially after reading his follow up comment. LOL. Or maybe Krokodil?

Freegrass

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Re: The 2019 melting season
« Reply #4514 on: July 25, 2019, 02:08:35 AM »
Others have mentioned it today, so I figured I would take a look at it myself - just north of Greenland four massive icebergs (not really sure what to call them since they are/were part of the "central" pack
I guess you could call it an ice shelf? Or as others call it here; "Fast Ice"?

Quote
The scale of this boggles the mind
It surely does. I measured the big piece (3) at 100 km long. That's immense! I guess it stays in tact as a large piece because it's very old, and therefore very strong ice?

Luckily the wind is blowing from east to west, so I think that these large pieces of ice will remain in the ice pack, although the big piece on the right (4) has been drifting towards the fram, and has started to break up.
« Last Edit: July 25, 2019, 02:21:26 AM by Freegrass »
If every 8 year old in the world is taught meditation, we will eliminate violence from the world within one generation.

Rich

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Re: The 2019 melting season
« Reply #4515 on: July 25, 2019, 02:16:13 AM »

SSTs in the ice pack are buffered at 0°C or thereabouts by melting ice. You don't see the SST increase until all the ice is melted. You can't tell how much ice is melting by looking at SSTs until all the ice is gone.

So, I went back and checked the thread to see if anyone posted an image of 2M temps this year in the ESS while it was still covered in ice.

Check post #2368. It's showing 4-5C 2M temps over the ESS while it was still covered in ice. Please explain how that was possible.
« Last Edit: July 25, 2019, 02:27:15 AM by Rich »

Rod

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Re: The 2019 melting season
« Reply #4516 on: July 25, 2019, 02:41:02 AM »
These discussions are getting tiring!

He was responding, in a nice way, to your comment about SSTs.

You changed the subject to 2m temps over the ice covered ESS, and post #2368 is talking about temps on Wrangel Island. 

Nothing you ever say supports your position. It is like you just want to argue for the sake of arguing.


« Last Edit: July 25, 2019, 02:57:55 AM by Rod »

Sam

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Re: The 2019 melting season
« Reply #4517 on: July 25, 2019, 02:41:51 AM »
I feel a bit like I jumped forward a decade or two in a time machine.  Or if certain models were right - more like 40 years.

The Northern Seaway is open and has been for awhile now. That would have been headline news here a decade ago. Not any more.

All of the ice is gone around Novaya Zemlya.

The PIOMAS projections all but certainly project a record low volume this year. Only two prior year loss tracks suggest anything other than a record.

Now we have the enormous icebergs breaking off of the northern coast of Greenland and heading for the Nares not the Fram.

At the same time, the breakup off the northeast coast of Greenland would be stunning in other years.

Then on the opposite side of the arctic we have wide swaths of trash ice everywhere that looks ready to go poof at the slightest hint of a high pressure zone.

What a year. The next two months are shaping up to be historic.

Sam

F.Tnioli

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Re: The 2019 melting season
« Reply #4518 on: July 25, 2019, 02:45:15 AM »

SSTs in the ice pack are buffered at 0°C or thereabouts by melting ice. You don't see the SST increase until all the ice is melted. You can't tell how much ice is melting by looking at SSTs until all the ice is gone.

So, I went back and checked the thread to see if anyone posted an image of 2M temps this year in the ESS while it was still covered in ice.

Check post #2368. It's showing 4-5C 2M temps over the ESS while it was still covered in ice. Please explain how that was possible.
You've been told about SST and you're checking 2M temps. Do you know "SST" means "sea surface temperature"? Are you aware 2M is 2 meters above said sea surface? Do you know how much length 2 meters is? And do you realize that sea surface is ice/water, while 2M above it - is only air? Do you know that given air thermal conductivity, the idea of 4-5C air 2 meters above ~0C ice/water is nothing unusual?

I'm just curious where exactly that joint made you slip, you see. Peace. ;)
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FishOutofWater

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Re: The 2019 melting season
« Reply #4519 on: July 25, 2019, 03:03:56 AM »
A stunning amount of heat is forecast to affect the American side of the Arctic ocean. It's apparent in the ECMWF 850mb progs and it's apparent on the GFS 2m progs. Some folks here just don't get that an icewater system doesn't have big thermal anomalies near the surface because it sucks up heat like a huge sponge.

Larger anomalies are possible on the Siberian side of the Arctic in late June and early July after all the snow is gone in Siberia. It's a warm air advection off of land thing.

A main cause of Arctic amplification is water vapor and warm clouds advected from the north Atlantic and north Pacific, but northern Siberia when it gets warm and wet in late June and early July is another potential source of OutgoingLongwaveRadiation reducing water vapor and clouds.

Rich

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Re: The 2019 melting season
« Reply #4520 on: July 25, 2019, 03:05:06 AM »
The SST's and 2M temps are separate points.

When I commented that the dipole was not bringing a lot of heat, I was commenting on the 2M temps.

If you at the rapid melt situations we've had this far this year, they've been accompanied by high 2M temps over the ice prior to the rapid melt.

Neven's gif from post 573 is a nice example of high 2M temps over ice.

Look at the 2M temp forecast today. 1C average? Not much.

Completely different issue than SST. I saw that Rox referred to SST and thought she made a mistake which I did not correct.

If someone wants to know where I get my "crazy notions".... they come from this melting season. All of the rapid melt this year has been preceded by high 2M surface temperatures (not SST's).

SST's don't show positive until after the ice has melted. LOL.


FishOutofWater

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Re: The 2019 melting season
« Reply #4521 on: July 25, 2019, 03:12:55 AM »
Rich, you clearly are not tuned into the calendar. It is normally above freezing in late July but the amount of solar energy is declining in the Arctic and subarctic. Thermal anomalies are not as large in late July because of these factors. Moreover, most melt ponds have drained by late July so ice is exposed at the surface. I don't think you are smoking anything good. I think that you need to go back and watch some of those old movies from the north pole observatory before Trump and his cabal cut funding for monitoring the ice.

Rich

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Re: The 2019 melting season
« Reply #4522 on: July 25, 2019, 03:52:12 AM »
I do understand the difference between an anomaly and absolute temperature.

I also get that advection from adjacent land may account for warm 2M temps in some locations (Siberia) and not others (CAB).

So, will the massive influx of solar energy be accompanied by a rapid decrease in CAB area? Will there be an observable increase in momentum?

Coffee Drinker

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Re: The 2019 melting season
« Reply #4523 on: July 25, 2019, 03:58:34 AM »
I have to agree with rich. Temperature anomalies (2m) are at best marginally positive (1979-2000 base). There were years where the whole arctic basin was dark red on those anomaly maps. Pretty much the whole Siberian coast is below average in the forecast.
https://climatereanalyzer.org/wx/fcst_outlook/

Also we have to keep in mind that the 1979-2000 base belongs already to a long gone climate. So to get ahead with melting, average or marginally above temps don't cut it anymore.

What we need would be hot continental air (30C at surface) being driven over the ice either from Siberia or North America. Like what happened earlier this year when the Siberian coast or Alaska was at 30C and more.

Rod

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Re: The 2019 melting season
« Reply #4524 on: July 25, 2019, 04:20:02 AM »
I have to agree with rich. Temperature anomalies (2m) are at best marginally positive (1979-2000 base).

It is a good thing you and Rich got this figured out!  Otherwise, I might be a little worried about all of that ice north of Wrangel and in the Beaufort. 

Rich

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Re: The 2019 melting season
« Reply #4525 on: July 25, 2019, 04:26:21 AM »
I'm off to the Stupid Questions thread to try and narrow down the variables here.

DrTskoul

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Re: The 2019 melting season
« Reply #4526 on: July 25, 2019, 04:26:40 AM »
Somebody need to spend time up north near a frozen lake during summer and just observe. Arm chairs are nice...

sark

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Re: The 2019 melting season
« Reply #4527 on: July 25, 2019, 04:31:17 AM »
On the matter of how impactful this incursion will be, I think simple, just look to the heat this wave brings to France tomorrow.  42C / 107.6F with their own model. 

https://twitter.com/khaustein/status/1154144648199364608

I'm more interested in the potential temperature at 1000mb.  But with records falling every day everywhere around the world, you guessed right.


This is making fools of us.

I am not a scientist

Pragma

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Re: The 2019 melting season
« Reply #4528 on: July 25, 2019, 04:37:42 AM »
On the matter of how impactful this incursion will be, I think simple, just look to the heat this wave brings to France tomorrow.  42C / 107.6F with their own model. 

https://twitter.com/khaustein/status/1154144648199364608

I'm more interested in the potential temperature at 1000mb.  But with records falling every day everywhere around the world, you guessed right.


This is making fools of us.

I haven't got a clue as to what it is you are trying to say.

Anyone speak gibberish?

Coffee Drinker

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Re: The 2019 melting season
« Reply #4529 on: July 25, 2019, 04:39:32 AM »
Somebody need to spend time up north near a frozen lake during summer and just observe. Arm chairs are nice...

It totally depends on the wind direction. I grew up at the Baltic Sea which is freezing in spring. Wind blowing from the land and there is basically no difference temperature wise between the beach and 50km inland. Same at the arctic coast. 30C air blowing over the ice from Siberia is entirely possible. How far the heat can travel over the ice largely depends on the speed of the wind and how sustained the heat transfer is. The statement that temperature is "locked" at 0C over the ice is simply wrong.

bbr2314

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Re: The 2019 melting season
« Reply #4530 on: July 25, 2019, 04:40:55 AM »
On the matter of how impactful this incursion will be, I think simple, just look to the heat this wave brings to France tomorrow.  42C / 107.6F with their own model. 

https://twitter.com/khaustein/status/1154144648199364608

I'm more interested in the potential temperature at 1000mb.  But with records falling every day everywhere around the world, you guessed right.


This is making fools of us.

I haven't got a clue as to what it is you are trying to say.

Anyone speak gibberish?
It isn't gibberish, you are the stupid one. The heat over France is bound for the Arctic by way of the record setting block now forming over Scandinavia. Models show it lifting into the ATL front and Greenland and merging with the existing Arctic block which is now getting underway.

DrTskoul

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Re: The 2019 melting season
« Reply #4531 on: July 25, 2019, 04:43:17 AM »
Both of you cut it out!! Enough with the name calling children.....

Rich

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Re: The 2019 melting season
« Reply #4532 on: July 25, 2019, 04:49:27 AM »
Somebody need to spend time up north near a frozen lake during summer and just observe. Arm chairs are nice...

It would be nice if the people who had spent time in front of that frozen lake had the command of science and the English language necessary to explain what they observed.

Feel free to come by the Stupid Questions thread and explain the factors which determine the 2M temperature over ice.

So far we have the ice itself and warm air advection over land. Neither of those explain why the current 10 day forecast has a higher day max 2M temp at 90N than 85N.

Appreciate FOW at least making an effort to engage

Alphabet Hotel

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Re: The 2019 melting season
« Reply #4533 on: July 25, 2019, 04:50:11 AM »
I found images of the same floe from July 12 and July 24. It's about 27 km long. What a difference 12 days makes! There's a lot of detail so I didn't scale it, just adjusted the white balance and red hue (auto white balance, red hue +18)

I only remembered to save a link to the July 12 image:

https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=72.55254276510199&lng=-128.34365844726562&zoom=11&preset=CUSTOM&layers=B01,B02,B03&maxcc=31&gain=1.0&gamma=1.0&time=2019-01-01%7C2019-07-12&atmFilter=&showDates=false&evalscript=cmV0dXJuIFtCOEEqMixCMDMqMSxCMDIqMV0%3D&showImage


sark

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Re: The 2019 melting season
« Reply #4534 on: July 25, 2019, 04:53:50 AM »
Ahhh the Earth's northern Polar Cell.  She reflects the division within us by splitting entirely herself.

HEY!  Hey "Polar Cell". *wobbles wobbles rips in half repeatedly*

Go back to the Arctic and form a polar vortex, would you?  Repeatedly subjecting this forum to such unthinkable desperate acts is shameful & sad.

I don't hear about bad ideas.  I'm interested in GOOD ONES
I am not a scientist

FishOutofWater

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Re: The 2019 melting season
« Reply #4535 on: July 25, 2019, 05:00:36 AM »
I suspect that melt ponds lasted later in July before the year 2000. The thick multiyear ice would have kept its below -1.5C temperatures longer into the melt season supporting melt ponds later into the year.

I think that explains the paradox of 80N temperatures being lower after Y2k than prior to it. Melt ponds support warmer surface temperatures. An saltwater ice mixture supports negative 1.5 C temperatures at the surface.  The effects of solar heating and atmospheric heat may lead to a higher 2m temperature. The paradox is that melt ponds over thick ice support higher 2m temperatures than drained melt ponds over ice that's almost melted out.

Observe that there has been a significant dip in temperatures the past few days, but 80N to the pole is still above freezing on average.



Yes, I'm sitting in a dining room chair in North Carolina. It has been sweltering here but today we got relief from a cold front that passed through. I am very frustrated by the paucity of data out of the Arctic. I know that my hypotheses could be wrong and would like more data.
« Last Edit: July 25, 2019, 05:31:59 AM by FishOutofWater »

F.Tnioli

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Re: The 2019 melting season
« Reply #4536 on: July 25, 2019, 05:16:59 AM »
...
If someone wants to know where I get my "crazy notions".... they come from this melting season. ...
Huh? Is there "this melting season" weed on the market these days, and you're smoking it? Because that's the only way the statement can be believable, to me (and quite few others i bet).

Jokes aside, Rich, you either can't or don't want to do non-biased discussion here, it seems. Whichever the case, in my experience such manner of posting will not be tolerated by this forum's administration forever, especially not in this topic. Just personal opinion of mine though.

Take care.
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subgeometer

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Re: The 2019 melting season
« Reply #4537 on: July 25, 2019, 05:34:25 AM »
The dipole has arrived. But it does not come with a lot of heat.

The SST's are very warm around the edges, but in no rush to invade the CAB.




This looks like heat to me - Within 3 days almostthe whole basin will be empty of anything like freezing air up to some altitude, and stay that way for a few days, I've attached windys 850hPa EC forecast for 850hPa on Sunday. Anywhere there is wind that heat will transfer to the surface.

Unfortunately Windy have removed or obscured their 3D interface, so I've attached 2 distorted strips to show the whole basin(to 85N)

Over the Beaufort Sea the freezing altitude will be like 3km for the next few days, and the region will be totally cloudfree over the open water and dispersed ice, so SSTs will get a kick along

GoSouthYoungins

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Re: The 2019 melting season
« Reply #4538 on: July 25, 2019, 05:54:12 AM »
The statement that temperature is "locked" at 0C over the ice is simply wrong.

So ya, kinda...at smallish scale. But over 100km from shore, it is true. And the arctic is huge.
big time oops

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DrTskoul

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Re: The 2019 melting season
« Reply #4540 on: July 25, 2019, 06:06:36 AM »
Nice hole....

Rich

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Re: The 2019 melting season
« Reply #4541 on: July 25, 2019, 06:17:46 AM »

Jokes aside, Rich, you either can't or don't want to do non-biased discussion here, it seems.

What's the perceived bias?

If I'm not convinced that 850 hpa temps are more important than 2M temps, is that reflective of some kind of bias?

The 850 hpa temps are at altitude. There are variables which determine the transport of heat from altitude to the surface. I'm clearly not an expert in that and trying to understand what they are. But at the end of the day, it seems that the heat at / near the surface will determine the melt, not the heat 1,000 feet up.

The common weather forecast available to any layperson such as the GFS provides a 2M temperature forecast and for most of the ice covered areas in the Arctic that is hovering around 1C.

If I express that as being not a lot of heat, that's not an outlandish statement by any means.

If someone wants to prove that the current weather means high melt, I'm certainly not stopping them. I'd welcome that. I've asked the question as to what evidence we should look for to verify.

Try to focus on the substance of the conversation and not on the name calling from the peanut gallery. We're discussing the difference between 2M temps and temps at much higher altitude.

F.Tnioli

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Re: The 2019 melting season
« Reply #4542 on: July 25, 2019, 06:22:14 AM »
Rich, i am not going to answer your questions since you did not answer mine, above. Instead, would you kindly read the last line of this recent post of yours, aloud, to yourself, a few times? Perhaps this will reveal what's going on here, to you. ;)

Been some good fun, feel free to drop another bucket of bolts in response, but i'm not game anymore, as long as you keep at what you're doing last couple pages. Cheers.
« Last Edit: July 25, 2019, 06:28:45 AM by F.Tnioli »
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Freegrass

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Re: The 2019 melting season
« Reply #4543 on: July 25, 2019, 06:28:11 AM »
Nice hole....
Yes, and looking at this image, it looks like the ice in that area will be gone in a few days from now. I guess that's more than 10% of the total sea ice extent that will be gone?  :'(
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bluice

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Re: The 2019 melting season
« Reply #4544 on: July 25, 2019, 06:37:37 AM »
Rich, you are derailing the main thread. Please stop doing that.

slow wing

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Re: The 2019 melting season
« Reply #4545 on: July 25, 2019, 06:44:45 AM »
What you miss in the basic picture of the process - is basics about how absorption works. You assume that all 180...300 W/m2 goes into melting the ice. In reality it does not: like already mentioned above, some of that energy is lost via evaporation (mostly from liquid water at the surface, but even dry ice actually evaporates slowly).

Further, whenever there is any noticeable open water - most of those 180...300 W/m2 gets absorbed at significant depth of downwards water column, since you know, water is a transparent thing. Noticeable amounts of light are present even at ~200 meters depth if my memory serves, - that's basically how deep significant fraction of absorption happens.

Same effect also happens to a lesser degree through the ice itself whenever there is no snow cover on it, increasingly so when the ice getting thinner: much sunlight simply goes through it and into water column below it, since ice is often significantly transparent, itself.

With water density being the highest at +4 Celcius iirc, a layer of colder melt water often remains near remaining ice, with warmer water sinking down as it's a bit heavier (though this much depends on water column mixing factors present at the location), which is another "sink" for some absorbed heat.

...

Sadly, this kind of calculations takes more than a single small napkin.

Yes, I assumed the bolded part as an approximation: that the heat absorbed by the ice goes predominantly into melting the ice.

 I've further speculated that -- before even reaching the ice -- a significant fraction of the solar insolation incident at the top of the atmosphere (at an elevation angle of only about 20 degrees above the horizon, remember) may have already been lost through absorption or scattering in the atmosphere before it gets to reach the ice, and that applies even in what appears to be 'clear sky' conditions.


But back to considering only that part of the insolation that has already been absorbed by the ice...

Someone else already suggested an alternative mechanism -- namely, heating of the ice up to zero degrees C -- that may use some fraction of the energy. I already posted the back-of-the-envelope calculation for the size of that, and shown that it should indeed be much smaller than melting.

Now you've suggested several further mechanisms where heat that's already been absorbed by the ice might be lost or absorbed elsewhere, rather than melting the ice. (Likewise, I've assumed all of those to be fractionally much smaller than melting.)

I do invite you to bring out your napkin as calculations on envelopes and napkins are used all the time in science with complicated processes, in trying to assess what is relevant or important and what is not.

So which one of your stated mechanisms do you think is the most important in competing with direct melting to use up the solar energy absorbed by the ice? I suggest you pick one and then do a back-of-the-napkin calculation to estimate the fraction of absorbed solar energy that is lost to your chosen process instead of melting the ice.

I'm skeptical that any of them are important but it will be interesting to see which of the other processes you suggest, if any, are comparable in energy scale to the energy that goes into melting the ice.

Rich

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Re: The 2019 melting season
« Reply #4546 on: July 25, 2019, 07:04:03 AM »
Rich, you are derailing the main thread. Please stop doing that.

I made a comment that the dipole is not bringing a lot of heat to the Arctic.

That's main thread material. You can agree or disagree. All of the comments about me smoking weed or having bias or your comment....that is derailing the thread.

I'm content to move on.
« Last Edit: July 25, 2019, 07:20:37 AM by Rich »

F.Tnioli

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Re: The 2019 melting season
« Reply #4547 on: July 25, 2019, 07:14:55 AM »
Slow Wing, here's a simple line from this page, which is about actual measurements of insolation at Barrow (which is quite far from the Pole, but still should be good enough to solve your doubts about how much reaches the surface):

"... maximum daily incident solar radiation (330-360 W m-2) at the surface".

P.S. And just to be safe, note that monthly mean insolation for July at Barrow, given on the same page - is appropriately low 120-130 W/m2 at the surface, as it includes all the cloudy days, which for July at Barrow is ~75% days of the month (source). This also well demonstrates how dramatic is the difference between clear skies and clouds in terms of insolation.
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slow wing

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Re: The 2019 melting season
« Reply #4548 on: July 25, 2019, 07:29:23 AM »
it seems that the heat at / near the surface will determine the melt, not the heat 1,000 feet up.

It's a fair question. The short answer is that the air near the surface holds hardly any heat energy because it's a gas and so it contains hardly any mass per unit volume.



In more detail, these 3 points are relevant:

1) If we are just looking at the air temperature then we are ignoring water vapor, which can be important. (The dew point shows how much water vapor is in the air.) But now considering just dry air...

2) The temperature at 2 meters is not representative of the amount of heat in the air column as it is somewhat tied to the ~0 degrees temperature just below it.

3) The (dry) air in the meters just above the ice is carrying very little energy and so can melt only a negligible depth of ice. To get significant melt, a significant fraction of the heat in the air column has to be transported somehow into melting the ice (water vapor, infrared radiation, convection...)




To illustrate point 3, consider how much warm air would be required to melt, e.g., a 1 cm thickness of ice.

 (We assume some quasi-static conditions where the air column above the ice causes the melt directly below it - with the caveat that this is not normally a very good assumption.)


To melt, e.g.,  a 1 cm depth of ice requires (334 J/g specific heat of melt) x 0.9 g/cm^3 = 300 J/cm^2.

So 300 J would need to be supplied by the air column above each square cm of ice.

But the specific heat of air is only 1 J/g.(degree C) and the mass of air in the entire column all the way up into space is only about 1000 g/cm^2 (i.e one atmosphere) What average loss of air temperature, dT_air, would be needed to supply the 300 J/cm^2 to melt a 1 cm thickness of ice?

Require:

dT_air[Celsius] x 1.0 J/g.[degree C] x 1000 g/cm^2 = 300 J/cm^2

=> dT_air = 0.3 degrees C.


So THE ENTIRE COLUMN OF AIR UP INTO SPACE would need to lose 0.3 degrees C to melt a 1 cm depth of ice. Obviously, the air just directly above the ice can't melt much ice at all.

oren

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Re: The 2019 melting season
« Reply #4549 on: July 25, 2019, 07:39:58 AM »
I would ask to move the scientific background discussions (insolation, joules, centimeters and so on) to one of the science threads, for example the recently opened insolation discussion. These subjects are not appropriate in the melting season thread, IMHO, and they will soon get lost here while the science threads may be revisited by readers months and even years later.