Arctic ice

[SnowBear]

One thing I have noticed on those two images GW, and it is important if we are to figure out if the camera has moved, or if the objects in the back ground have moved, is that it seems to me the camera itself has moved in relation to its own platform. If you look at the lettering top left, on one image the photo edge lines up almost with what I think is a D, lower image its half a character to the left. If the camera has slewed slightly, which to me it looks like it has, it would give what we are seeing in those images. Also, when analysing these images and trying to see how high ice is, or how long a ledge is, whether something has moved...which it will do considering the drift rate of the North Pole, we have to compare images taken at the same time of the day as shadows and effects from the sun at low angles as at the North Pole could produce various optical effects.

I do also wonder if we know the exact position of that camera now? The drift rate of the ice could be taking the instruments into an area which melted last year. Does this camera now give a good idea of the true North Pole?

This post has nothing to do with whether I think the Pole will melt or not, its to do with image analysis and making sure what we are seeing is from the true North Pole.

Edited July 8, 2008 by SnowBear

[trevw]

just something Chris had pointed out earlier. There is a difference from having a 'pool' of water on top of the ice to a hole through the ice and a broken pack.

The two photo's above are separated by a few days but look at the height of the snow above the water in the second. The ice has risen up.

At the same time we had noted 'differences' in camera position.

Could the pack now have fractured and the 'settling out' of the floes be responsible for both the lower water line and the camera 'jiggling'?

They gave it a 50/50 chance of being ice free by late Aug and here we are with broken pack in early July! Do you think we'll be getting amended forecasts with our July update?

Must admit I feel the images are definitely interesting, if not necessarily indicative of the state of the entire arctic, they do give an interesting insight to the conditions.

Is it just the light or has there been abit of snowfall in the second pic?

I was also wondering if there were other mechansims that could drop the water level... All the pools seem to have dropped by the same amount - which is I expect not as much as the level would drop if the pools went all the way down to see level, this seems to imply that either the solid surface has been raised generally (snow fall?) or perhaps evaporation has outpaced melt for a period? My reasoning for this is that I would expect the deeper pools to melt through first and once they did for them to empty very quickly..

[SnowBear]

Looking closer, I think it is new snow fall which has brought the ice level up, rather than the water level dropped.

[Devonian]

Isn't the Arctic an 'ice desert'? Snowfalls of any depth are unusual?

[SnowBear]

Seem to remember seeing on one the pages where those webcam images come from they talk of snowfall, and that a lot of the melt ponds are from yearly snowfall melting in the summer.

Found it..

What is happening to all the images from the North Pole? The North Pole is starting to cool down for the winter, and it's darker now because the sun is lower in the sky. You can see the cold temperature of the camera housing on the lower left corner of each image. There is snow fall, and apparently, blowing snow or ice has covered the camera lens. There is still a bit of possible sunlight left in the season, and the melting from that sunlight, or sublimination by dry winds, may serve to remove the snow from the camera lens, so it is possible we may get more images. However, it is also possible that with the onset of winter, the camera may remain snow covered. At the Autumn Equinox, approximately September 21, the sun sinks below the horizon at the North Pole, and the Pole is in twilight until early October, after which it is in full darkness for the Winter.

http://www.arctic.noaa.gov/np2002/gallery_np_tour.html

[Chris Knight]

Must admit I feel the images are definitely interesting, if not necessarily indicative of the state of the entire arctic, they do give an interesting insight to the conditions.

Is it just the light or has there been abit of snowfall in the second pic?

I was also wondering if there were other mechansims that could drop the water level... All the pools seem to have dropped by the same amount - which is I expect not as much as the level would drop if the pools went all the way down to see level, this seems to imply that either the solid surface has been raised generally (snow fall?) or perhaps evaporation has outpaced melt for a period? My reasoning for this is that I would expect the deeper pools to melt through first and once they did for them to empty very quickly..

Interesting, and not indicative of the whole Arctic, I agree. There must be a good thickness of ice (in April) to deploy an unmanned buoy station like this in the first place. Ice up to 2m thick is commonly used to ensure the longevity of the instruments. The bottom ice grows down into ocean water at -1.5 deg C or colder, the upper ice is provided by precipitation falling from above, and is therefore pretty salt-free, melting at 0 deg C. There is therefore a temperature difference between the top, middle and base of the ice floe. Between the melt pools the snow is slushy, the surface refreezes, often when the sky is clear and the sun is shining, but the pools tend to warm under sunlight, due to their greater albedo, and that they are mostly fresh water, so up to 4 deg C warmer near the bottom of the bigger pools, than at the top.

Water is denser than ice, so as the pool deepens, the level drops by about 1cm for every 10 cm of ice melted.

The pools are not commonly found in the Antarctic, which is mostly annual ice:

http://www.nature.com/nature/journal/v408/...0F80BCA48AE7B11

Here is a lot of information on sea Ice:

http://www.gi.alaska.edu/~eicken/he_teach/...cenom_intro.htm

I don't know what the current situation up there is, apart from what we can see, but this old paper mentions pools 1-2 feet deep in July and August on Ice Island T-3(?), and 1-4 feet from Russian NP4 and NP6 polar manned stations in 1956 and 1957. So they are nothing new:

http://pubs.aina.ucalgary.ca/arctic/Arctic14-3-188.pdf

Edited July 8, 2008 by Chris Knight

[trevw]

Water is denser than ice, so as the pool deepens, the level drops by about 1cm for every 10 cm of ice melted.

Hadn't considered that effect, thanks.

I also realized that I was (rather naively) thinking of the arctic ice 'perched' on top of the sea and so was expecting to see huge holes once the bottom melted out. After a couple of seconds of actual thought (which I find painful these days) I realise that the 'distance' between sea level and ice surface will be related to the ratio of the densities of the ice and water. I think about 80-90% should be below the level of the water so you would only expect 20-40cm of drop?

[Chris Knight]

Hadn't considered that effect, thanks.

I also realized that I was (rather naively) thinking of the arctic ice 'perched' on top of the sea and so was expecting to see huge holes once the bottom melted out. After a couple of seconds of actual thought (which I find painful these days) I realise that the 'distance' between sea level and ice surface will be related to the ratio of the densities of the ice and water. I think about 80-90% should be below the level of the water so you would only expect 20-40cm of drop?

Sounds about right to me, depending on the thickness of the ice floe. Apparently the bottom of the ice in contact with the ocean continues to grow downwards even during the summer, insulated from above by the ice above.

As the ice at the bottom of the pool melts, the latent heat of fusion (80 calories/gram ice melted) is taken from the water, cooling 80 ml by 1 deg C, for every gram of ice melted, and this heat must be replaced by solar, and/or longwave IR from 1) the (GHGs in the) atmosphere and 2) reflected by clouds, for the melt to continue. If that heat is not replaced, the pool starts to refreeze, first at the surface, and later from ice crystals from the edges of existing ice, and finally from the bottom, leaving microscopic channels of concentrated liquid brine which percolate down through the ice at subzero temperatures, leaving less briny multiyear ice.

[BARRY]

Sounds about right to me, depending on the thickness of the ice floe. Apparently the bottom of the ice in contact with the ocean continues to grow downwards even during the summer, insulated from above by the ice above.

As the ice at the bottom of the pool melts, the latent heat of fusion (80 calories/gram ice melted) is taken from the water, cooling 80 ml by 1 deg C, for every gram of ice melted, and this heat must be replaced by solar, and/or longwave IR from 1) the (GHGs in the) atmosphere and 2) reflected by clouds, for the melt to continue. If that heat is not replaced, the pool starts to refreeze, first at the surface, and later from ice crystals from the edges of existing ice, and finally from the bottom, leaving microscopic channels of concentrated liquid brine which percolate down through the ice at subzero temperatures, leaving less briny multiyear ice.

at last constructive opinions instead DOOM,DOOM,DOOM

[The PIT]

Isn't the Arctic an 'ice desert'? Snowfalls of any depth are unusual?

Yup because the air is so cold it can't hold much moisture.

[SnowBear]

Yup because the air is so cold it can't hold much moisture.

In the depth of winter maybe, but not spring through to autumn, it can and does snow at the North Pole.

[Chris Knight]

Isn't the Arctic an 'ice desert'? Snowfalls of any depth are unusual?

Yup because the air is so cold it can't hold much moisture.

In the depth of winter maybe, but not spring through to autumn, it can and does snow at the North Pole.

Some bits seem to have less than 250mm precipitation, like Svalbard airport!

(from "Long-term variations in

temperature and precipitation

in the Svalbard area" by

Inger Hanssen-Bauer, met.no

“Hydrology in the Arctic”, Longyearbyen, Svalbard

June 16-18 2008)

Also Northern Greenland interior, but it can be difficult to measure snowfall when the winds are greater than 7m/sec, so there are under-recording biases. NP weather stations didn't bother to measure snowfall for this reason, AFAIK. Snow depth measurement is also problematical due to wind in subzero temperatures.

Much of the Arctic is estimated to have precipitation similar to the various tundra regions surrounding the Arctic.

I think Dev was thinking about the Antarctic interior when he wrote that.

[Nick L]

Yeah I thought it was the Antarctic that was the desert. I have heard some parts receive only a few cm of snowfall per year. Still more than the Midlands

[SnowBear]

Some bits seem to have less than 250mm precipitation, like Svalbard airport!

I was always lead to believe that 1" of forecast rain would give 4" of snow if it fell as snow.

Even that 250mm at Svalbard is 1 metre if it falls as snow?

The thing is with the Arctic is there is moisture around from the surrounding ocean and also from the areas that do melt back in the warmer months. The Antarctic is all land and ice and very dry due to the distances involved to open water.

The two cannot be compared really.

[bluecon]

They gave it a 50/50 chance of being ice free by late Aug and here we are with broken pack in early July! Do you think we'll be getting amended forecasts with our July update?

Maybe but the change in forecast will be for more ice than predicted.

Looks like the ice melt is falling far behind last year.

http://igloo.atmos.uiuc.edu/cgi-bin/test/p...=08&sy=2008

[Gray-Wolf]

We have spashdown!

Couldn't get an image update yesterday but cam 2 had

either a very big dumping on the snow surface or a lot of 'reduction' due to melt don't cha' think?

Maybe but the change in forecast will be for more ice than predicted.

Looks like the ice melt is falling far behind last year.

http://igloo.atmos.uiuc.edu/cgi-bin/test/p...=08&sy=2008

This isn't a race bluecon, pretty serious stuff if you ask me.

The sight of Kilimanjaro without it's snowy peak was bad enough but what is an ice free pole going to mean (like any of us can know).

[doctormog]

The sight of Kilimanjaro without it's snowy peak was bad enough but what is an ice free pole going to mean (like any of us can know).

For further information on the Kilimanjaro situation and its use as a marker of climate change see below...

http://www.geotimes.org/aug07/article.html...ilimanjaro.html

Not sure of the relevance to a webcam in the Arctic, which is incidentally not currently melting at the dire rates predicted by some earlier in the year, although that could change in coming months).

Surely we should all be please about every day that passes when the situation is more "icy" than last year's record breaker? The current data speaks for itself i.e. below the long term mean but not nearly as "bad" as last year.

That's not a forecast or an opinion just an observation of the current situation. As ever the next few months will prove interesting.

The current NSIDC picture suggests c. 0.5 to 1 million sq km more ice than at the same stage last year:

http://nsidc.org/data/seaice_index/images/..._timeseries.png

Will the rate of loss remain constant, accelerate or possibly even slow in coming weeks? Levels, according to the above data, seem to have remained fairly consistently in the range of c. 0.5 m sq km below the long term average over recent months.

[jethro]

Being a picky, pedantic mare......

Less snow on Kilimanjaro has been caused by felling of trees and land clearance lower down the slopes; previously the trees created a micro climate which increased moisture content of the atmosphere and thus precipitation on the top of the mountain. Nowt to do with warming temperatures melting snow, or it being too warm to snow - entirely due to a dryer atmosphere.

That snow in the Arctic looks pretty clean to me, reckon it's a new fall.

Beat me to it doc...

Edited July 9, 2008 by jethro

[Gray-Wolf]

Being a picky, pedantic mare......

Less snow on Kilimanjaro has been caused by felling of trees and land clearance lower down the slopes; previously the trees created a micro climate which increased moisture content of the atmosphere and thus precipitation on the top of the mountain. Nowt to do with warming temperatures melting snow, or it being too warm to snow - entirely due to a dryer atmosphere.

That snow in the Arctic looks pretty clean to me, reckon it's a new fall.

Beat me to it doc...

?

So man can do in 'micro climates' but doesn't 'do in' macro climates???

From what I can see of the 'Russian' side of things the ice has melted back from the coasts and if things occur like last year then we can expect the open water pack (which is well fragmented) to rotate clockwise with the ice melting as it passes Bering straights (as it did last year).

If I remember correctly the melt of the ice whilst it rotated was the 'fastest spurt' of ice decay in last seasons record melt and consitions seem just right for that to occur again now the Alaskan sector is clear of all ice.

2 weeks and check again I'd say

Edited July 9, 2008 by Gray-Wolf

[jethro]

?

So man can do in 'micro climates' but doesn't 'do in' macro climates???

We can do both, it's just citing Kilimanjaro as an example of warmer temps creating melting snow is inaccurate, like I said, born a pedant....

[jethro]

The postman's just delivered a brochure from Quark expeditions full of wonderful cruises to the Arctic and Antartica

www.quark-expeditions.co.uk

It all looks amazing but can't help but wonder, if the ice is so fragile, is it such a good idea to have ice breakers cruising back and forth?

[doctormog]

The postman's just delivered a brochure from Quark expeditions full of wonderful cruises to the Arctic and Antartica

www.quark-expeditions.co.uk

It all looks amazing but can't help but wonder, if the ice is so fragile, is it such a good idea to have ice breakers cruising back and forth?

Sorry, totally off-topic but if you decide to go on one say hi to my sister-in-law's dad who amongst other things works for them

http://www.quarkexpeditions.com/our-people...s/laurie-dexter

[laserguy]

It all looks amazing but can't help but wonder, if the ice is so fragile, is it such a good idea to have ice breakers cruising back and forth?

I'd love to go,but my occasionally fragile constitution probably wouldn't withstand the rigours of such cold and besides,I really don't fancy getting stuck in the ice like that pleasure boat did recently - y'know,the one full of tourists who'd gone to see the non-existant ice .

[picog]

We have spashdown!

Couldn't get an image update yesterday but cam 2 had

either a very big dumping on the snow surface or a lot of 'reduction' due to melt don't cha' think?

This isn't a race bluecon, pretty serious stuff if you ask me.

The sight of Kilimanjaro without it's snowy peak was bad enough but what is an ice free pole going to mean (like any of us can know).

Camera 2 seems to be showing fresh, new snow to me — quite a bit of it. The melt water also looks semi-frozen too.

[SnowBear]

I agree picoq, I think its new snow, and it definitely looks like the ponds have new ice. If you look at the sky its a typical snow laden sky that wouldnt look out of place in the UK when we get a good snow storm.

The landscape has taken on a "puffy" look too.

New snow for me!