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Peter Ellis

That cloud is almost certainly ice fog forming over the new cracks in the shattered area. The now-exposed water evaporates and then condenses as it hits the colder overlying air.

Glacierchange.wordpress.com

Great stuff appears almost everyday in your examination. Having observed calving events on this glacier before, this is still astounding the size of it. Just inland of the rifting and current terminus is a bedrock high. As the glacier thins this will produce a greater weakening of the ice as it flow over. The rift formed directly downstream of this. I have annotated the NASA image and posted for your use . I note this location as point A. What is fascinating is the speed at which the glacier surface below A at C was transformed from an ordinary set of transverse crevasses to the chaotic scene typically indicative of an area of rapid acceleration and failure of seracs, those walls betweens crevasses. The glacier has had a profound response to the rift. The area of crevasse transformation is an indication of the connection of this area of the glacier to action at the terminus. The area around C is a zone of weakness to watch for further appearance of rifting. The area in front of the bedrock high is clearly not a place for the terminus to stabilize. The bedrock high itself could well be.

Neven

Thanksa lot , Mauri! I have updated the post with your image and explanation.

logicman

Neven: this is an excellent article which I shall soon be linking in my blog. Your animation captures the shift of melange nicely.

Ice breaks when the built up mechanical forces exceed its strength. At that time, the energy which caused the breaking is converted instantly into heat energy. This heat causes the formation of ice smoke, or where there is a lot of activity: a fog bank.

This glacier has now retreated past the union of two streams. That should cause further acceleration.

Neven

Thanks, logicman. I first learned of those ice smoke fog banks on your blog. :-)

Call me crazy but doesn't this mean there was another (large) retreat yesterday? Why would the ice smoke appear 5 days after the retreat between the 6th and 7th? I've been looking at the animation for the past 5 minutes and it certainly looks to me as if the dark patch on the right side, just above the bigger, lower red circle has shifted very far to the right implying a huge calving off.

But maybe I'm just seeing things here, it could just be the shadow of the fog cloud. Let's see if the Aqua satellite has made a new picture of the area yet.

Neven

Here is the latest picture: http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r02c02.2010193.aqua.250m

Now there are some regular clouds blocking the view, but I'm not seeing that huge calving off anymore. That's what you get with those low-resolution images... ;-)

Neven

I might have found something else to wet my alarmist appetite though: a second rift in the Petermann Glacier, halfway between the big rift and the terminus. If I have time I will look at it tonight. If true, the glacier will calve off spectacularly as soon as that sea ice in front of it gets washed away.

Neven

Not the terminus, the ice front.

Peter2010

Newsflash -
Web cam 2 reporting 19.5c temp inside its box, prior high was 13.5c - ave 11.5c.
bright sun and seems like ice fog or steam on the camera..

http://psc.apl.washington.edu/northpole/webphotos/noaa2.jpg

Neven

Good catch, Pete. It looks like a hot spa now.

Neven

That rift in Petermann Glacier is not a new feature. Sigh. Sometimes I get tired of myself... ;-)

Nick Barnes

A bit of sea ice is surely not going to exert a significant backforce on the glacier.

Neven

You're right, Nick. I'm having one of my silly days.

Glacierchange.wordpress.com

The fog is intriguing, but I would hesitate to jump to conclusions about why it formed. This area does have frequent fog forming by the usual means. We cannot even see the height of the cloud bank well. Down glacier winds are higher down the Jakobshavn too.

Artful Dodger

Does anyone know which buoy number is pictured in the NOAA NetCam2 shot? Perhaps the sea ice has drifted south into a warmer area.

MODIS metadata shows lots of clear sky near the pole at 20:30 UTC

http://rapidfire.sci.gsfc.nasa.gov/realtime/single.php?T101932030

Peter Ellis

http://psc.apl.washington.edu/northpole/DriftTrackMap.html
http://psc.apl.washington.edu/northpole/PAWS_atmos_recent.html
http://psc.apl.washington.edu/northpole/POPS13_atmos_recent.html

Camera 2 is currently furthest north, at (88.141°N 10.986°W) compared to (86.839°N 1.812°W) for Camera 1. Camera 1 hasn't returned any pictures for almost a week.

Lord Soth

The loose ice near the pole in the MODIS imagery appears to be expanding and has mainitain itself for for about five days now. Enviornment Canada shows the sea ice temperture in that area as plus 2 as of yesterday. We now have a serious possibility of a polynya developing near or at the pole.

http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r04c04.2010194.terra

I would really like to see a PIOMAS update, as sea ice extent is really failing us as a tool in determining the actual ice loss. Even NSIDC which does a five day averaging, has done a hockey stick on us; indicating that sea ice extent is several deviations away from reality.

Lord Soth

I was checking the grid size for NSIDC, and they count any cell with at least 15% coverage as sea ice for there calculations. Their grid size is 25km. Thats 625 sq km of ice per cell that can be misclassified per cell, and is obvious is, from the graph shown.

http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png

I could find no info on the grid size for IJIS. Does anybody have info on this?

The IJIS slide show ( I set mine for July 1 to July 12) shows that the real action is occuring in the pack.

http://www.ijis.iarc.uaf.edu/cgi-bin/seaice-monitor.cgi?lang=e

You will need to set the dates in the slide show yourself as it is not built into the link.

Lord Soth

It appears that Cryosphere Today is running amok.

http://arctic.atmos.uiuc.edu/cryosphere/iphone/

The sea ice map has not been updated since July 7, yet the sea ice anomaly keeps declining every day. The ipod image is time stamped July 10, but looks like it is from June..

They should be posting a "Stay Tuned, We are having technical difficulties" message; as certain groups of people will take what is showing as a statement of fact.

Anu

I could find no info on the grid size for IJIS. Does anybody have info on this?
-- Lord Soth | July 13, 2010 at 13:15

IARC-JAXA says "SIC (sea ice concentration) data of JAXA’s AMSR-E standard products are used for this purpose "
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

They give a paper with details:
http://sharaku.eorc.jaxa.jp/AMSR/products/pdf/alg_des.pdf
Table 2 implies that they grid the data for sea ice concentration into 25 km, and also 12.5 km, data products. This grid size is a finer resolution than the measurements at 6.9 and 10.7 GHz (which actually give data at 58 and 37 km resolution). But the 89 GHz channel, for example, samples at 5km x 5km.

In other words, they don't really say :-)
Probably the 25 km grid.

Glacierchange.wordpress.com

Another problem for Jakobshavn this year is the high snowline from the comparatively warm temperatures as evident in the June 17th snowline from Landsat compared to other years. The image is at the end of the post.

fredt34

NASA has selected Jakobshavn Glacier as their Image of the Day, http://earthobservatory.nasa.gov/IOTD/view.php?id=44625&src=eorss-iotd

Excerpt : "In the winter of 2010, Jakobshavn’s ice front did not re-advance as it usually does, so it began the 2010 melt season in the same location as the 2009 summer melt season. As a result, the glacier had the potential to experience significant retreat during the summer of 2010. The breakup in early July 2010 occurred on the northern tributary to Jakobshavn Glacier. The southern tributary actually drains a larger portion of Greenland’s central ice sheet, so a retreat there could lead to a more substantial ice discharge."

Neven

Great link, Fred!

Werther

Hi Neven,
Since I noticed your blogsite I check each day... This time I may have crossed something interesting while checking on todays Modis. Look at Kangerlussuaq glacier, King Christian IX land (straigt to the other side refering to J.Isbrae). You see the large swath of melting water ( 20x8 km)? Where did that come from... nothing there a day ago. Any opinions?

Neven

Hello, Werther, thanks for being here! I find it amazing that you notice such a thing. I will put up an animation today and then perhaps someone else can tell us what's going on.

John Christensen

Hi Neven, Is this article still open for comments? Have you considered the link between NAO and retreating of the Jacobshavn glacier? Even intuitively, when the NAO is strongly negative, warm air and low pressures will come from the south accelerating the retreat of the glacier (together with general retreat of Arctic sea ice), while the positive phase of NAO should act to conserve sea ice and Greenland glaciers. The last two winters we have experienced extremely strong negative phases of NAO, which ties well with the lack of gain of the glacier, but here's the test; since we have seen a consistent positive NAO since Nov 2011, has the glacier been able to grow since then?

Neven

Hi John, of course this article is still open for comments! There's another Jakobshavn post I wrote in April 2011: Flushing out the Fjord (+ part 2).

I always knew the NAO had an influence, but no more than that. I was reminded of it when reading an article on Diablobanquisa about the effects of the NAO in the Baltic Sea.

We'll see what the effect of this winter's mainly positive NAO will be. Thanks for suggesting the link.

Peter Ellis

Should point out that so far as I'm aware, we can't know anything until the melt season. The glacier doesn't calve at all during the winter, so the floating tongue spends several months growing outwards undisturbed. Once the melt starts, it's a question of whether (and how fast) the calving front retreats back to the previous summer's line, or whether it'll stop short of that.

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