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Alexander555

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Re: "Stupid" Questions :o
« Reply #1450 on: June 13, 2018, 07:41:30 PM »
Somebody posted the first pic a couple weeks ago. Is that the positive anomaly we see between Indonesia and Ecuador ?

Istari

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Re: "Stupid" Questions :o
« Reply #1451 on: June 14, 2018, 12:00:20 AM »
Been lurking here on an off over a few years, I though about it already last year, but never asked, so do it this year: Why are the ice in the Faxe Basin (North of Hudson) showing greyish in worldview ?

Peter Ellis

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Re: "Stupid" Questions :o
« Reply #1452 on: June 14, 2018, 10:40:46 PM »
Melt ponding

FredBear

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Re: "Stupid" Questions :o
« Reply #1453 on: June 15, 2018, 08:50:58 AM »
Raised question about Foxe Basin last year (under "Stupid" Q), got a couple of responses (nos. 1155, 1156.). I had noticed the ice turns to a creamy mush on the sat. images each year but still takes forever to melt out. Don't think it is melt ponds   .   .   
Very obvious cream colour in the Basin on arctic.io June 14 2018 image.
« Last Edit: June 15, 2018, 08:59:14 AM by FredBear »

oren

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Re: "Stupid" Questions :o
« Reply #1454 on: June 15, 2018, 12:00:38 PM »
Raised question about Foxe Basin last year (under "Stupid" Q), got a couple of responses (nos. 1155, 1156.). I had noticed the ice turns to a creamy mush on the sat. images each year but still takes forever to melt out. Don't think it is melt ponds   .   .   
Very obvious cream colour in the Basin on arctic.io June 14 2018 image.
Looking at Worldview, I think you are right. Melt ponds can be seen on fast ice around the image - top left, top right, bottom left, with the familiar bluish tinge. However ice in the basin itself is indeed gray, while the snow on the land around is white.
Perhaps ice in the basin is subject to compression and ridging due to prevailing currents, winds or tides and is therefore not flat? This way, when the snow melts it becomes darker, but no ponds form. This would also explain why the ice lasts longer, due to its effective thickness.
Now someone with real knowledge about Foxe Basin needs to step in...

Edit: Wikipedia to the rescue.
Quote
During much of the year, landfast ice dominates in the north, while pack ice prevails towards the south. Foxe Basin itself is rarely ice-free until September, open pack ice being common throughout the summer. Vigorous tidal currents and strong winds keep the ice pack in constant motion and contribute to the numerous polynyas and shore leads which are found throughout the region. This same motion, combined with the high sediment content of the water makes the sea ice of Foxe Basin dark and rough, easily distinguishable from other ice in the Canadian Arctic.
« Last Edit: June 15, 2018, 12:58:23 PM by oren »

Andreas T

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Re: "Stupid" Questions :o
« Reply #1455 on: June 15, 2018, 06:15:45 PM »
Have a look on sentinel playground where you can see much higher resolution images
https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=68.21848500761313&lng=-79.178466796875&zoom=9&preset=1_NATURAL_COL0R&layers=B01,B02,B03&maxcc=99&gain=0.4&gamma=1.0&time=2015-01-01%7C2018-06-14&atmFilter=&showDates=false&showImage
I have noticed before that Foxe basin in the summer has a turquoise colour in many places which suggests  sediment stirred up along the shallow island coasts. That may explain darker, dirty ice?
I looked for images of freezing which may explain the rounded floes but it gets dark before refreeze it seems

Dharma Rupa

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Re: "Stupid" Questions :o
« Reply #1456 on: June 17, 2018, 08:46:38 PM »
How much does the sea level rise caused by melt in Antarctica effect the Arctic?  (and in what ways?)


gerontocrat

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Re: "Stupid" Questions :o
« Reply #1457 on: June 21, 2018, 09:45:58 PM »
"My stupid question that belongs to me". Too long-winded but it is late.

There is much discussion of the importance of cloud cover. In the winter clouds keeping the Arctic Ocean surface warmer, at this time of year restricting insolation reaching the ground to melt the ice. Indeed, it is said that this was a reason for the 2017 minimum being so unexpectedly(?) high.

If you look at the images  on the 2018 melting season one can see that the satellites up there have no problem in recognising clouds, and I suspect little problem in determining the transparency /thickness thereof. I also assume that there are generally accepted algorithms to estimate the reduction in insolation reaching the ground due to clouds. As the position of the sun is known spatially at any time this would also provide a measure of actual insolation reaching the surface.

So the question is, is there a database of quantitative estimates of what happened , is happening and what is forecast to happen regarding insolation reaching the surface ? Or am I totally off my trolley asking the question?
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Sebastian Jones

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Re: "Stupid" Questions :o
« Reply #1458 on: June 22, 2018, 05:59:57 AM »
How much does the sea level rise caused by melt in Antarctica effect the Arctic?  (and in what ways?)


At first I thought that this was an exceptionally stupid question- obviously if the sea level rises the ice will float higher.....but if you are asking how ocean currents will change and how that will affect arctic ice stability....I dunno.

sidd

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Re: "Stupid" Questions :o
« Reply #1459 on: June 22, 2018, 06:48:22 AM »
if ice melts off antarctica, the level drops around antarctica and rises in the arctic, all else remaining the same (ha!)

if it melts off greenland, the reverse.

sidd

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Re: "Stupid" Questions :o
« Reply #1460 on: June 22, 2018, 10:50:58 AM »
How much does the sea level rise caused by melt in Antarctica effect the Arctic?  (and in what ways?)
The primary effect will to make the various water channels into and out of the arctic deeper and wider. This could be as much as 4km wider in the Bering strait This will make it easier for warmer water to move into the  Arctic from both the Atlantic and Pacific thus hastening the end. The channels through the Canadian archipelago, and Nares Strait would also  widen and deepen making it harder for ice to form and quicker for it  to disappear.
« Last Edit: June 24, 2018, 10:40:26 AM by DavidR »
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Dharma Rupa

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Re: "Stupid" Questions :o
« Reply #1461 on: June 22, 2018, 01:58:24 PM »
How much does the sea level rise caused by melt in Antarctica effect the Arctic?  (and in what ways?)
The primary effect will to make the various water channels into and out of the arctic deeper and wider. This cold be as much as 4km wider in the Bering strait This will make it easier for warmer water to move into the  Arctic from both the Atlantic and Pacific thus hastening the end. The channels through the Canadian archipelago, and Nares Strait would also  widen and deepen making it harder for ice to form and quicker for it  to disappear.

That seems to make sense.  What about the weather?  (Also, anything that might be predictable about currents?)

Stephan

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Re: "Stupid" Questions :o
« Reply #1462 on: June 22, 2018, 10:13:46 PM »
How much does the sea level rise caused by melt in Antarctica effect the Arctic?  (and in what ways?)
When larger portions of ice (close to a coast) melt then their weight does not exist anymore. In fact, scientists have calculated that due to a bigger loss on the WAIS (which will lead to a higher sea level worldwide) the sea level at the Amundsen Sea coast will drop because of the smaller gravity of the ice sheet. In addition (this was on news today here in Germany) the smaller weight of the ice pack will cause a rebound of the bedrock. Around Amundsen Sea there is a rise of up to 41 mm/year which adds up to the (smaller) sea level depletion caused by the smaller gravity of the molten ice.
The same is obviously true for Greenland. There also sea levels should fall slightly because of these two effects. I have no idea whether this small sea level change will effect the Arctic itself.
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Dharma Rupa

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Re: "Stupid" Questions :o
« Reply #1463 on: June 22, 2018, 11:40:15 PM »
How much does the sea level rise caused by melt in Antarctica effect the Arctic?  (and in what ways?)
When larger portions of ice (close to a coast) melt then their weight does not exist anymore. In fact, scientists have calculated that due to a bigger loss on the WAIS (which will lead to a higher sea level worldwide) the sea level at the Amundsen Sea coast will drop because of the smaller gravity of the ice sheet. In addition (this was on news today here in Germany) the smaller weight of the ice pack will cause a rebound of the bedrock. Around Amundsen Sea there is a rise of up to 41 mm/year which adds up to the (smaller) sea level depletion caused by the smaller gravity of the molten ice.
The same is obviously true for Greenland. There also sea levels should fall slightly because of these two effects. I have no idea whether this small sea level change will effect the Arctic itself.

Actually, it was basically this which led me to ask the question in the first place, though I am more interested in what might happen to the currents.  A lot of the currents are directed by surface phenomena, and I don't really have a clue in what way.

The heat balance is a different confounding factor than the mass balance and sea level rise...I was trying to understand those.  The heat balance, I expect, will show itself in more and nastier storms.


Alexander555

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Re: "Stupid" Questions :o
« Reply #1464 on: June 25, 2018, 09:35:30 PM »
Tor, i will ask the question here. Otherwise i'm probably going too far off-topic. But is that cold blob there the entire year ? Because if you look at that pic of the Canadian rivers, you see that a big part of the meltwater in Canada ends up south of Greenland. Everything east of the middle of that  mountain range you see in West-Canada. That's a lot of snow, and when that snow is gone the melting of Greenland starts.  And some of the rivers in the north end up in the Beaufort Sea. But there is no meltwater from Greenland as soon as the snow  is gone. So probably that cold blob is there the entire year, is that correct ?

And do you maybe know how much snow there was in Canada, in lets say the last 8 years. Was it more or less than the average ?

Sebastian Jones

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Re: "Stupid" Questions :o
« Reply #1465 on: June 25, 2018, 11:48:13 PM »
... is that cold blob there the entire year ?
The cold blob you identify appears to be on a temperature anomaly map. There fore it cannot be there all the time, else it would be normal....
Having said that, this part of the Labrador sea is colder than areas to the east, because the West Greenland current flows N to S, bringing cool water - and icebergs- south .

Alexander555

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Re: "Stupid" Questions :o
« Reply #1466 on: June 26, 2018, 12:23:03 AM »
I understand , but in general these anomaly maps compare to a periode further in the past. Like 1971-2000. So if something would change in the last few years, it can show up the entire year. For example, if there would be more snow because the planet is warming ( more evaporation). There will be more meltwater. And normaly it should be in the area of Canada. Further south there should be less snow. That's why i asked how snowfall was  in Canada in the last few years.

LDorey

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Re: "Stupid" Questions :o
« Reply #1467 on: June 26, 2018, 03:59:48 PM »
Basic Info on the blob... there's lots out there...

https://en.wikipedia.org/wiki/Cold_blob_(North_Atlantic)

RoxTheGeologist

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Re: "Stupid" Questions :o
« Reply #1468 on: June 28, 2018, 06:25:29 PM »
Okay: How does Bottom melt happen under an ice pack?

I figure there are at least two answers
1) sunlight warms the ocean below the ice when it becomes transparent and albedo drops
2) the ice gets mixed with warmer ocean on the edges of the pack, creating convection and mixing.

Can it happen any other way?

Tor Bejnar

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Re: "Stupid" Questions :o
« Reply #1469 on: June 28, 2018, 07:02:37 PM »
I think Ekman Pumping is another way to get warm sea water in contact with broad expanses of sea ice.  See the old thread: Arctic ice divergence/compaction and Ekman Transport

Also, use the "Search" tool (upper right corner of this page, but search after clicking on "Arctic Sea ice : Forum" just below "Home   Help   Search   Profile ...") and search for "Ekman". 

(I'm not an expert on Ekman pumping; I've just read the term.)

Edit:  Here is a snipit from a 2015 post by TerryM:
Quote
An Ekman Spiral occurs whenever wind blows across the water, however, when combined with our knowledge that the wind in a low pressure system moves in an anti-clockwise direction this 90 degree diversion explains why warm, deeper waters are drawn upward in the center as surface ice is dispersed.

While all the details of Ekman Transportation and all the effects of Coriolis forces on Arctic ice & water are far to complex for me. Familiarity with Ekman Spirals and the resulting pumping/suction have helped me to understand some of what I've been witnessing as the Arctic continues it's warming.
« Last Edit: June 28, 2018, 07:15:06 PM by Tor Bejnar »
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Richard Rathbone

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Re: "Stupid" Questions :o
« Reply #1470 on: June 28, 2018, 09:40:53 PM »
Okay: How does Bottom melt happen under an ice pack?

I figure there are at least two answers
1) sunlight warms the ocean below the ice when it becomes transparent and albedo drops
2) the ice gets mixed with warmer ocean on the edges of the pack, creating convection and mixing.

Can it happen any other way?

3) Seawater is salty.
This creates a different, and lower, melting point at the base, so if the rest of the ice gets warm enough to melt, so does the base, and as the ice cools at the end of the summer, the bottom is the last place in the floe to get cold enough to stop melting.

The major effects are from heating the water, but unless a floe is thick enough to keep the winter's cold inside it all summer, if the top melts, the bottom must because it happens at a lower temperature.

johnm33

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Re: "Stupid" Questions :o
« Reply #1471 on: June 28, 2018, 10:22:32 PM »
Bottom melt?
Take a look at the thickness animation from beaufort, i think there's more to 'get' if you watch it from start-up .  What i think i'm seeing is a series and build up of internal waves clashing beneath the ice. That is where two parallel waves approach from opposite directions warmer deep water is forced upwards, you'll have to decide for yourself if they're bouncing off the shelves, but it seems to me the shallows are largely unaffected. The clash of waves builds up to a cacophony which causes them to dissipate, leaving the ice thinner and weaker,  bear in mind there's now plenty of fresh water ready to refreeze, so which way it goes depends on local conditions.
What caused it? i first suspected a tidal surge entering over the Lomonosov ridge by ESAS then less likely a slide from the shelf into the Amerasian basin, but now think probably the low that traversed the Arctic from the 7th onwards. nullschool 


Occasionally, it appears to me, you can see this sort of bottom melt at either end of the eurasian basin too.
added space
« Last Edit: June 29, 2018, 01:26:34 PM by johnm33 »

DavidR

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Re: "Stupid" Questions :o
« Reply #1472 on: June 29, 2018, 09:36:11 AM »
Bottom melt?
Take a look at the thickness animation from beaufort, i think there's more to 'get' if you watch it from start-up .

What I'm seeing in that video is an awful lot of rapidly thinning ice across the Beaufort, Chukchi and Laptev all of much the same thickness suggesting that something of a plunge is in the offing if this continues.  My thought is that the dispersion of the ice is allowing water much closer to the pole to be affected by insolation.  With the smaller floes, more warm water may be getting under the ice from all sides. Rather similar to the difference between solid cloud cover and a lot of small clouds with sunny breaks between them.
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binntho

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Re: "Stupid" Questions :o
« Reply #1473 on: June 29, 2018, 09:51:32 AM »
Not that I pretend to understand how this works ... but it seems to me that bottom melt will happen simply because the ocean under the ice is much warmer than the air above at all times.

Yes, there is a layer of colder water under the ice, but heat does spread and there will be a gradient from the warmer deeper waters towards the surface of the ice. During winter the air is cold enough that the bottom of the ice falls well below freezing, so bottom freeze.

When the air temperatures rise, the ice starts warming up from above and below, until the lower surface rises above the freezing threshold, and bottom melt starts, even before surface melt gets going.

This should presumably happen without direct sunlight - but sunlight that reaches through the ice causes bottom melt as well.
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oren

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Re: "Stupid" Questions :o
« Reply #1474 on: June 29, 2018, 10:05:02 AM »
This is way above my pay grade, but add another factor: saline water gets denser as it cools, so as the ice cools the top of the water, that water sinks and is replaced by warmer water. So indeed unless the ice core temp is very low so as to cause bottom freeze, bottom melt will happen even before top melt.

binntho

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Re: "Stupid" Questions :o
« Reply #1475 on: June 29, 2018, 10:28:11 AM »
As well as the salt-freezer effect (as used e.g. in old-fashioned hand-cranked ice cream machines). If a lump of ice has two "interfaces", one salty and the other fresh, the salty side will melt and the fresh side will freeze.

So bottom melt may possibly cause top-freeze, even when air temperature are above freezing ...
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Daniel B.

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Re: "Stupid" Questions :o
« Reply #1476 on: June 29, 2018, 03:22:49 PM »
As well as the salt-freezer effect (as used e.g. in old-fashioned hand-cranked ice cream machines). If a lump of ice has two "interfaces", one salty and the other fresh, the salty side will melt and the fresh side will freeze.

So bottom melt may possibly cause top-freeze, even when air temperature are above freezing ...

Yes, and it will created a slushy combination.  When the melting ice meets the colder seawater, it will lead to a partial refreeze (slush) of the ice melt.  The melt will also be fresher than the seawater, so it will stay above the seawater, due to its lower density.  On the salty side, the warmer ice melt will prevent the seawater from freezing.

RoxTheGeologist

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Re: "Stupid" Questions :o
« Reply #1477 on: June 29, 2018, 06:05:31 PM »
Okay: How does Bottom melt happen under an ice pack?

I figure there are at least two answers
1) sunlight warms the ocean below the ice when it becomes transparent and albedo drops
2) the ice gets mixed with warmer ocean on the edges of the pack, creating convection and mixing.

Can it happen any other way?

3) Seawater is salty.
This creates a different, and lower, melting point at the base, so if the rest of the ice gets warm enough to melt, so does the base, and as the ice cools at the end of the summer, the bottom is the last place in the floe to get cold enough to stop melting.

The major effects are from heating the water, but unless a floe is thick enough to keep the winter's cold inside it all summer, if the top melts, the bottom must because it happens at a lower temperature.

That makes a lot of sense. Thank you. The ice heats up and effectively conducts the heat to the base where it melts. Hmmm, but as the ice melts, you'll end up with a boundary of low salinity water. That water will insulate the base of the ice, but if it's below 25 PSU then it will become less dense as it cools, so you'd expect some convection and mixing. I need to go and read more!

Dharma Rupa

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Re: "Stupid" Questions :o
« Reply #1478 on: July 02, 2018, 04:09:29 PM »
Is there anyplace that tries to measure Total Ice Edge (down to some pixel size, of course)?

I was looking at the Worldview for July 1 at a single spot for various years, and it seemed to me that in general the average size of the "larger" flows was getting smaller (especially sometime after about 2007).   So I was going to ask about the average flow size, but couldn't come up with an accurate way to describe the question.  On the other hand, Total Ice Edge would probably capture the same metric pretty well, and I can at least imagine an algorithm for computing it from declouded pictures.

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Re: "Stupid" Questions :o
« Reply #1479 on: July 02, 2018, 07:44:30 PM »
Steam (water vapor) is the strongest GHG. From my studies in chemistry many years ago, I seem to remember that burning of fossile fuels create humidity. The primary products of complete combustion of e.g. kerosene or propane are carbon dioxide and water. Something like 15-20% of what goes up the flue on gas furnaces is steam. A lot of it is, however, condensed immediately in cooling towers.

My question is: How many gigatonnes of steam are created yearly from burning FF (net), and for how long does that additional steam remain in the atmosphere?

Stephan

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Re: "Stupid" Questions :o
« Reply #1480 on: July 02, 2018, 10:40:34 PM »
Steam (water vapor) is the strongest GHG. From my studies in chemistry many years ago, I seem to remember that burning of fossile fuels create humidity. The primary products of complete combustion of e.g. kerosene or propane are carbon dioxide and water. Something like 15-20% of what goes up the flue on gas furnaces is steam. A lot of it is, however, condensed immediately in cooling towers.

My question is: How many gigatonnes of steam are created yearly from burning FF (net), and for how long does that additional steam remain in the atmosphere?
If you just assume, that oil is represented by octane (C8H18), then its burning will create carbon dioxide and water according to the formula below (mole weights multiplied with the numbers of molecules in brackets)
C8H18 (114) + 12,5*O2 (400) → 8*CO2 (352) + 9*H2O (162)
According to Wikipedia.de in 2016 a total of 4,384 Gt oil was produced worldwide. If this would have been completely combusted to CO2 and water this would sum up to an enormous amount of 4,384*162/114 = 6,23 Gt.

Water has a very short life in the atmosphere as it likely forms clouds and precipitates. So this increase will not be significant compared to the amount of water in the atmosphere.

A comparable calculation applies for natural gas.
CH4 (16) + 2*O2 (64) → CO2 (44) + 2*H2O (36)
Around 2,53 Gt were produced in 2015 (Wikipedia.de). This adds up to 2,53*36/16 = 5,69 Gt of water worldwide (a 100% combustion to water and CO2 assumed).

Another idea: This water also sums up to Global Sea Level Rise. 100 Gt lifts the oceans up by about 1 0,28 mm (corrected 3.7.2018). The two figures are around 12 Gt, meaning that the 360 Gt (= 1 mm) are reached within a 3 decades (corrected 3.7.2018).
« Last Edit: July 03, 2018, 10:09:24 PM by Stephan »
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Hyperion

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Re: "Stupid" Questions :o
« Reply #1481 on: July 03, 2018, 12:35:52 PM »
Bottom melt?
Take a look at the thickness animation from beaufort, i think there's more to 'get' if you watch it from start-up .  What i think i'm seeing is a series and build up of internal waves clashing beneath the ice. That is where two parallel waves approach from opposite directions warmer deep water is forced upwards, you'll have to decide for yourself if they're bouncing off the shelves, but it seems to me the shallows are largely unaffected. The clash of waves builds up to a cacophony which causes them to dissipate, leaving the ice thinner and weaker,  bear in mind there's now plenty of fresh water ready to refreeze, so which way it goes depends on local conditions.
What caused it? i first suspected a tidal surge entering over the Lomonosov ridge by ESAS then less likely a slide from the shelf into the Amerasian basin, but now think probably the low that traversed the Arctic from the 7th onwards.
Wow! That is son scary animation. I've trimmed it down so it will play on here. It really does look like the last of the fresh Beaufort lid being flushed out of the channels of the CAA, and then strong winds from off Siberia, in the last week helping the surge of Atlantic water that's been building for months to flood across the basin towards Canada and Alaska. Surface waters do move a lot faster under wind impetus than floes. And upwelling is caused by winds blowing off a shelf.
But hang on... The last week is a forecast in that animation. Maybe it won't happen.
But wait.... That's from the US Navy.
 So my stupid question would have to be:
Ain't them the guys with an immense network of new HAARP equipped ships sub's and underwater bases, so powerful that its lethal to go on deck of one while its making and guiding low pressure systems? And doesn't the political elite really really want the Arctic open for business? Bet Putin's got HAARP systems too,   and him and Trumpet have the whole season ordered up like a spit roasted polar bear er? Probably staying with that Palin woman in Alaska so they can watch it through her binoculars huh?
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Re: "Stupid" Questions :o
« Reply #1482 on: July 04, 2018, 01:35:32 AM »
start-up .
Wow! That is one scary animation. ... It really does look like the last of the fresh Beaufort lid being flushed out of the channels of the CAA, ...
If the rate of melt shown in that clip continues for the next two weeks we will see most of the Beaufort, Chukchi and a fair swath of the CAB adjacent to those seas melting out. Combined with the 500K km^2 of late melt  in the Hudson and Kara, that will also contribute to a big loss in July, we could be in for a wild ride in July. The CAB is already low in both area and extent and typically  it doesn't start to plummet until August however this pattern of melt could start the process early.
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Hefaistos

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Re: "Stupid" Questions :o
« Reply #1483 on: July 04, 2018, 10:46:14 AM »
Steam (water vapor) is the strongest GHG. From my studies in chemistry many years ago, I seem to remember that burning of fossile fuels create humidity. The primary products of complete combustion of e.g. kerosene or propane are carbon dioxide and water. Something like 15-20% of what goes up the flue on gas furnaces is steam. A lot of it is, however, condensed immediately in cooling towers.

My question is: How many gigatonnes of steam are created yearly from burning FF (net), and for how long does that additional steam remain in the atmosphere?
If you just assume, that oil is represented by octane (C8H18), then its burning will create carbon dioxide and water according to the formula below (mole weights multiplied with the numbers of molecules in brackets)
C8H18 (114) + 12,5*O2 (400) → 8*CO2 (352) + 9*H2O (162)
According to Wikipedia.de in 2016 a total of 4,384 Gt oil was produced worldwide. If this would have been completely combusted to CO2 and water this would sum up to an enormous amount of 4,384*162/114 = 6,23 Gt.

Water has a very short life in the atmosphere as it likely forms clouds and precipitates. So this increase will not be significant compared to the amount of water in the atmosphere.

A comparable calculation applies for natural gas.
CH4 (16) + 2*O2 (64) → CO2 (44) + 2*H2O (36)
Around 2,53 Gt were produced in 2015 (Wikipedia.de). This adds up to 2,53*36/16 = 5,69 Gt of water worldwide (a 100% combustion to water and CO2 assumed).

Another idea: This water also sums up to Global Sea Level Rise. 100 Gt lifts the oceans up by about 1 0,28 mm (corrected 3.7.2018). The two figures are around 12 Gt, meaning that the 360 Gt (= 1 mm) are reached within a 3 decades (corrected 3.7.2018).
Thanks. Googled the following facts: About 12,900 km3 of water, mostly in the form of water vapor, is in the atmosphere at any one time. If it all fell as precipitation at once, the Earth would be covered with only about 1 inch of water.

1 km3 of water is 1 Gt, so the yearly 12 Gt of steam from FF burning amounts to only 1 per mille of the total amount in the atmosphere.

Sebastian Jones

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Re: "Stupid" Questions :o
« Reply #1484 on: July 04, 2018, 05:51:16 PM »
I regularly check Gerontocrat's sea ice area and extent posts- dedicated posters such as this help make the forum a great resource. I do not understand why peripheral seas such as the Gulf of St. Lawrence continue to show a small amount of sea ice. Is it an artifact of interpretation? Is it real? I'm prepared to believe that there is some lingering ice in sheltered nooks of the Bering sea, and in the Okhotsk sea, but the St. Lawrence is a long way south of the closest "real" ice. Thanks in advance!

gerontocrat

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Re: "Stupid" Questions :o
« Reply #1485 on: July 04, 2018, 06:17:44 PM »
I do not understand why peripheral seas such as the Gulf of St. Lawrence continue to show a small amount of sea ice. Is it an artifact of interpretation? Is it real? I'm prepared to believe that there is some lingering ice in sheltered nooks of the Bering sea, and in the Okhotsk sea, but the St. Lawrence is a long way south of the closest "real" ice. Thanks in advance!

Oren reckons it is mostly an artifact that winks on and off - limitations of the satellite instrument.

But some of it is real.  Here is proof (from Canadian Ice Service) - a little bit tucked up in Saglek Bay, Labrador. (Click on the map to see all of it).

ps:- if you feel energetic, have a root around https://www.canada.ca/en/environment-climate-change/services/ice-forecasts-observations/latest-conditions.html
pps: That site says on average the last bit of ice on the East Coast finally melts out in the week beginning 16 July (this year about two weeks ahead of average).
« Last Edit: July 04, 2018, 06:35:50 PM by gerontocrat »
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Re: "Stupid" Questions :o
« Reply #1486 on: July 09, 2018, 04:15:05 PM »
Is there any evidence that the melting season lasts longer now than it has in the past?
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gerontocrat

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Re: "Stupid" Questions :o
« Reply #1487 on: July 09, 2018, 07:10:31 PM »
Is there any evidence that the melting season lasts longer now than it has in the past?

I did some graphs on ice-free days sea by sea- examples attached.
It seemed to me that the length of time without ice was more significant than how long the melting season lasted.
« Last Edit: July 09, 2018, 07:15:57 PM by gerontocrat »
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sinocentric

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Re: "Stupid" Questions :o
« Reply #1488 on: July 09, 2018, 09:32:58 PM »
Hey gerontocrat, first of all, thanks for all the posting that you do! I've been lurking on here for a while, and I follow the arctic melting thread pretty regularly. It's awesome to see you guys breaking down that data, I hadn't really followed that until this year. And the graphs you just posted are interesting too - I hadn't seen that data before.

Just to be clear, the reason I was asking that question wasn't to cast doubt on the fact that the arctic is melting or anything like that. I only ask because there is at least some evidence that summers are becoming longer, Here is an article from the Jereusalem post discussing a study that indicates the summer will be 6 months long in Israel by 2100:   https://www.jpost.com/HEALTH-SCIENCE/Study-Global-warming-to-nearly-double-length-of-Israeli-summer-by-2100-545093

In your posts discussing the daily ice loss, I've noticed that you put the average number of days of melting left. I'm just wondering if it's possible that this year would have a longer melting season than, say, what would be expected in 1980, and if that would effect the eventual ice loss total. I haven't seen that discussed anywhere before.

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Re: "Stupid" Questions :o
« Reply #1489 on: July 09, 2018, 10:33:23 PM »
SC, here's a Science Daily article from 2014 worth reading:

Quote
Arctic melt season lengthening, ocean rapidly warming

The length of the melt season for Arctic sea ice is growing by several days each decade, and an earlier start to the melt season is allowing the Arctic Ocean to absorb enough additional solar radiation in some places to melt as much as four feet of the Arctic ice cap's thickness, according to a new study by National Snow and Ice Data Center (NSIDC) and NASA researchers.
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sinocentric

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Re: "Stupid" Questions :o
« Reply #1490 on: July 10, 2018, 01:36:47 AM »
Thanks Neven, that's what I was looking for. I guess it is lengthening overall...crazy stuff.

oren

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Re: "Stupid" Questions :o
« Reply #1491 on: July 10, 2018, 03:07:49 AM »
sinocentric, first I should say that summer in Israel already feel like it's 6 months long... but to your point, I think the melting season is lengthening but IMHO more on the spring side than on the fall side. Remember that the melting season is location-dependent, as the Bering Sea melting and freezing seasons, for example, are not the same as those at the North Pole. But if you look at overall NH sea ice extent, I think max extent is affected by the poor refreeze and melt onset at the periphery, growing warmer every year, while min extent is demarcated by the sun setting on the inner Arctic Ocean and causing a big shift in the heat equation. There comes along a day around mid-September where large swaths of the inner CAB surface refreeze, and that day is usually the day of min extent (or at least of min area). I think it will be easy to achieve lower mins, but very hard to move the min date further out, say to October. Eyeballing the JAXA chart decadal averages I can't see any serious shift of the minimum. So I wouldn't count on this melting season having a later min date, beyond the normal random variation.
BTW, 2012 did have a late minimum, which helped it achieve its record, and 2007 an even later minimum, while 2016 which was a serious contender for min area was stopped short by an early freeze onset in the region around the pole.

johnm33

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Re: "Stupid" Questions :o
« Reply #1492 on: July 18, 2018, 11:35:38 AM »
When you make ice cream you add salt to ice, the physics involved then cool the ice, assuming 0c, to about -21c . When we see flash melts followed by almost immediate refreeze how often is that caused by airborne salt being distributed over the area?

binntho

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Re: "Stupid" Questions :o
« Reply #1493 on: July 18, 2018, 01:20:32 PM »
When you make ice cream you add salt to ice, the physics involved then cool the ice, assuming 0c, to about -21c . When we see flash melts followed by almost immediate refreeze how often is that caused by airborne salt being distributed over the area?

This doesn't sound quite right. An old-fashioned ice cream maker has an inner bowl of liquid placed in a bowl of ice. When salt is added to the ice in the outer bowl it starts to melt chemically and the phase change involved draws energy from the surroundings, including the still-remaining ice and the liquid in the inner bowl which eventually freezes if things are done correctly.

I think it would be difficult to reach -21 degrees using this method, although I guess it could be done with enough salt.

Spreading ice on an ice floe would have the same effect, i.e. some of the ice would melt, cooling the remaining ice and the surrounding water/atmosphere. But I can't imagine this being on any significant scale.

In this interesting video an ice/liquid mixture in a small plastic glass reaches melting point (0 degrees C) and then, by adding a substantial amount of salt, the temperature is shown to drop to around -11 degrees C  (the experiment starts at 2:20).

http://marshallbrain.com/science/ice-cream.htm
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Peter Ellis

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Re: "Stupid" Questions :o
« Reply #1494 on: July 18, 2018, 02:35:01 PM »
I think it would be difficult to reach -21 degrees using this method, although I guess it could be done with enough salt.

"Enough" here is around 1/3 sate to ice by weight. Unless the airborne salt is a layer several centimetres thick (hint: no) then it's not relevant in this context.

Dharma Rupa

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Re: "Stupid" Questions :o
« Reply #1495 on: July 23, 2018, 07:03:36 PM »
How much of the "fresh" water in the Arctic is consumed with the Fall and Winter Freeze?  Put another way, how much does the thermocline rise during the Winter?

JamesW

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Re: "Stupid" Questions :o
« Reply #1496 on: July 25, 2018, 10:36:02 PM »
Hello all. I have been watching the melt season now over the the last few seasons with interest. This is my first post so thought apt to start at the stupid questions page  ;)

One thing I am interested and wanting to know more right now is the wind/wave/pressure action on the ice. I am getting a good grip on most of the good information here overall. So thanks to all of the committed writers who contribute.

From this season so far the early cyclone in June seemed somewhat to preserve the ice with cloud cover screening it from the sun and also as the ice was more compact wind/wave/pressure action appeared to have less effect than it would of done otherwise if it came a little later in the melt season with a more broken pack. Apart from the fact it did appear to draw in warmer air off the continent. So l am looking at early melt season wind/wave/pressure effects to late melt season wind/wave/pressure effects on the ice during melt season atm.

Whats more of interest to me now is how with a more fragmented pack how wind/wave action interacts with the ice along with low pressure. I am looking for a more scientific viewpoint on

1. Using the Beaufort wind scale and how it would effect fragmented ice as wind speed gets higher?
2. Its effects would they be different on how broken up the ice is? And is there any information out there that shows these effects on ice say at 20% - 80% fragmented like it shows on NSIDC concentration etc?
3. How high up the Beaufort scale would wind need to be, to cause upwelling/mixing to take place and how much low air pressure might relate to this?

If someone could point me in the right direction with some scientific papers PDF's or some qualified comment I would highly appreciate it.

I have posted a small copy of Beaufort for information on Beaufort action on ice free open seas.

0    Calm - 0  - Sea like a mirror.

1-3    Light winds - 19 km/h or less    - Small wavelets, ripples formed but do not break: A glassy appearance maintained.

4    Moderate winds - 20 - 29 km/h - Small waves - becoming longer; fairly frequent white horses.

5    Fresh winds - 30 - 39 km/h - Moderate waves, taking a more pronounced long form; many white horses are formed - a chance of some spray.

6    Strong winds - 40 - 50 km/h - Large waves begin to form; the white foam crests are more extensive with probably some spray.

7    Near gale - 51 - 62 km/h - Sea heaps up and white foam from breaking waves begins to be blown in streaks along direction of wind.

8    Gale    63 - 75 km/h - Moderately high waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks along the direction of the wind.

9    Strong gale - 76 - 87 km/h - High waves; dense streaks of foam; crests of waves begin to topple, tumble and roll over; spray may affect visibility.

10    Storm - 88 - 102 km/h - Very high waves with long overhanging crests; the resulting foam in great patches is blown in dense white streaks; the surface of the sea takes on a white appearance; the tumbling of the sea becomes heavy with visibility affected.

11    Violent storm - 103 -117 km/h - Exceptionally high waves; small and medium sized ships occasionally lost from view behind waves; the sea is completely covered with long white patches of foam; the edges of wave crests are blown into froth.

12+    Hurricane - 118 km/h or more    64 knots or more    Very rarely experienced. The air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affected
« Last Edit: July 26, 2018, 12:03:22 AM by JamesW »

oren

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Re: "Stupid" Questions :o
« Reply #1497 on: July 26, 2018, 03:08:59 AM »
Hi JamesW, these questions are above my pay grade and perhaps should have been posted in the smart questions thread had such existed... but I just want to say welcome. The first post is always the hardest.

JamesW

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Re: "Stupid" Questions :o
« Reply #1498 on: July 26, 2018, 07:41:34 PM »
Hi JamesW, these questions are above my pay grade and perhaps should have been posted in the smart questions thread had such existed... but I just want to say welcome. The first post is always the hardest.

Thanks Oren for your reply. I have found this study on wave ice action concluded July 2016 by the American Meteorological Society (AMS) which is mainly studying wind/wave effects on ice August/September when the arctic has more open seas. Basically positive wind wave ice feedback action has not yet been quantified as yet fully it appears, although it is stated it should be so models in the future are portrayed more accurately. So renders my question a little in to the unknown, although this paper if anyone has a spare half an hour does give quite a bit of insight in to what is happening in the arctic regards climate change and its effects in the arctic on wave/wind ice action feedbacks changes during August/September....i.e. decadal averages increases/decreases in wave heights etc. which is helpful when looking at certain seas and why they are possibly changing faster than others during the melt season. Among all the other feedbacks changes etc etc...

For example 'The maximum positive trends of wave height (0.3–0.4 m decade−1) appeared in the Laptev Sea, followed by trends of ~0.3 m decade−1 north of the Alaskan coast. It also has tonnes of side data if anyone wants to delve deeper in to specific areas of the report as highlighted within it.

It has some very interesting points showing that wind/wave mechanical strain is enough to break iceshields of between 0.5 - 0.6m and then to propagate the ice quickly for melt. This would help realise ice thickness as it breaks up quickly would generally be less than 0.6m. So some simple and good information to gain among the more sophisticated areas of the report.

I hope this detail enlightens peoples knowledge a little to help understand more of how the chaotic system is altering.

I also thought this would be helpful as we are about to enter August where this report is relevant.

https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-16-0219.1
« Last Edit: July 26, 2018, 08:11:56 PM by JamesW »

RoxTheGeologist

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Re: "Stupid" Questions :o
« Reply #1499 on: July 26, 2018, 08:10:10 PM »

Help! Does anybody know of a published sea surface density map, or is there a way I can extrapolate one from Salinity and Temperature using a numerical formula I found?