blt
Cartographer
Reged: 01/25/03
Posts: 638
Loc: Santa Cruz, Ca
|
|
I was looking at the high res images of the breakup and noticed something I've always wanted to see. Which is what does the iceberg look line under the under the sea?
Take a look at the labeled iceberg. About 90% of it is blue and 10% is white. I'm speculating that its a slice of the tabular icesheet that has flipped on its side exposing the ice normally below sealevel. I expect that the blue color may mark the region previously below seawater. If the floating bergs are 25 m high, the depth below sea level would be about 200m making the whole berg about 225 m thick.
|
Pragueimp
Explorer
Reged: 02/20/08
Posts: 193
Loc: Prague
|
|
Well spotted blt! That is really fascinating.
So, how much of the iceberg is now underwater?! Still 200m? And why did it flip on it's side? It can't have been top heavy? Some interesting physics there...
--------------------
Mark
Environmental English
www.envenglish.com
|
satcom15
Tourist
Reged: 06/16/07
Posts: 151
|
|
Quote:
I was looking at the high res images of the breakup and noticed something I've always wanted to see. Which is what does the iceberg look line under the under the sea?
Take a look at the labeled iceberg. About 90% of it is blue and 10% is white. I'm speculating that its a slice of the tabular icesheet that has flipped on its side exposing the ice normally below sealevel. I expect that the blue color may mark the region previously below seawater. If the floating bergs are 25 m high, the depth below sea level would be about 200m making the whole berg about 225 m thick.
If this is true, the edges of the white ice (above water part) of the ice berg on the right don't seem to match the edges of the icerberg on the left. Could the iceberg calved from the ice sheet in the foreground, flipped on its side, then rotated 90 degrees? At least from the perspective of the image this seems like it might have happened. I agree the blue of the ice could have been the sub water ice. And the proportions of Above to Below water ice look reasonable. Also the iceberg on the left does not have the same look to it as the one on the right and its top surface is higher. Sure seems plausible doesn't it. Interesting. Regardless, that the ice sheet shattered as it did is still pretty amazing.
Cheers
|
blt
Cartographer
Reged: 01/25/03
Posts: 638
Loc: Santa Cruz, Ca
|
|
The Wilkins Ice Shelf continues to disintegrate (from Science News)
Quote:
Wilkins Ice Shelf has experienced further break-up with an area of about 160 km² breaking off from 30 May to 31 May 2008.
Wilkins Ice Shelf, a broad plate of floating ice south of South America on the Antarctic Peninsula, is connected to two islands, Charcot and Latady. In February 2008, an area of about 400 km² broke off from the ice shelf, narrowing the connection down to a 6 km strip; this latest event in May has further reduced the strip to just 2.7 km. ...
According to Dr Matthias Braun from the Center for Remote Sensing of Land Surfaces, Bonn University, and Dr Angelika Humbert from the Institute of Geophysics, Münster University, who have been investigating the dynamics of Wilkins Ice Shelf for months, this break-up has not yet finished. "The remaining plate has an arched fracture at its narrowest position, making it very likely that the connection will break completely in the coming days," Braun and Humbert said.
You can read more in a new article by Mauri S Pelto on the break-up of Antarctic Ice Shelves on Real Climate
June 9, 2008
March 2008
|
Hill
Master Guide
Reged: 10/31/04
Posts: 8852
Loc: Los Angeles
|
|
National Geographic has an animated view of the break-up and more information here.
--------------------
Translate text
"Eternity is a very long time, especially towards the end" Stephen Hawking (quoting Woody Allen) 
"There are all kinds of interesting questions that come from a knowledge of science, which only adds to the excitement and mystery and awe of a flower." Richard Feynman
Iraq war and occupation costs
|
kakasucai
First Post
Reged: 06/18/08
Posts: 1
|
|
we should think about our world
--------------------
Download Free 3d midels
|
Hill
Master Guide
Reged: 10/31/04
Posts: 8852
Loc: Los Angeles
|
|
The ice shelf continues to break up, even in austral mid-winter:
Quote:
10 July 2008
The Wilkins Ice Shelf is experiencing further disintegration that is threatening the collapse of the ice bridge connecting the shelf to Charcot Island. Since the connection to the island in the image centre helps to stabilise the ice shelf, it is likely the break-up of the bridge will put the remainder of the ice shelf at risk.
This animation, comprised of images acquired by Envisat’s Advanced Synthetic Aperture Radar (ASAR) between 30 May and 9 July 2008, shows the break-up event which began on the east (right) rather than the on west (left) like the previous event that occurred last month. By 8 July, a fracture that could open the ice bridge was visible.
According to the image acquired on 7 July 2008, Dr Matthias Braun from the Center for Remote Sensing of Land Surfaces at Bonn University estimates the area lost on the Wilkins Ice Shelf during this break-up event is about 1350 km² with a rough estimate of 500 to 700 km² in addition being lost if the bridge to Charcot Island collapses.
This break-up is puzzling to scientists because it has occurred in the Southern Hemispheric winter and does not have characteristics similar to two earlier events that occurred in 2008, which were comparable to the break-up of the Larsen-A and -B ice shelves.
The full story is here at the European Space Agency website.
--------------------
Translate text
"Eternity is a very long time, especially towards the end" Stephen Hawking (quoting Woody Allen)
"There are all kinds of interesting questions that come from a knowledge of science, which only adds to the excitement and mystery and awe of a flower." Richard Feynman
Iraq war and occupation costs
|
satcom15
Tourist
Reged: 06/16/07
Posts: 151
|
|
The speed and continued breakup of Wilkins Ice shelf even during the winter is astounding. Thanks for the posts Hill. I wonder, if arctic and antarctic ice melting/disintegrating are accelerating seems like this would result in more open water with less reflection of solar radiation in the polar regions. By themselves, events such as the Wilkens and Larson iceshelf losses of solar radiation reflectance are fairly small in scale. However, do they have a small but postive feedback, growing effect over time? If there is more solar radiation absorbed and reemitted by open water, what does that mean for polar and eventually global temperatures? Will cloud cover increase over the polar regions because of higher atmospheric moisture content? Will the break-up of the iceshelf permit acceleration of antarctic icestreams and thus increases of fresh water in the ocean? What does that mean with respect to ocean salinity and water density in those regions? Do or can these events have consequences with respect to global ocean currents? What is happening under the West Antarctic Ice sheet? Is there erosion of the ice by underlying water? So many questions with no clear cut answers. My fear is that we have embarked on a human caused "experiment" in climate change with no desirable outcome.
|
Hill
Master Guide
Reged: 10/31/04
Posts: 8852
Loc: Los Angeles
|
|
Various reports I've read speak of varied responses to open ocean vs. ice cover. In the North polar region for instance, open ocean will likely result in more precipitation in that area. Several studies point to a likelihood of the greater flow southward of cold fresher water in the vicinity of Greenland stopping the Gulf Stream's flow and thus its moderating influence on European climate. The British Isles, sitting at the same latitude as southern/central Canada may end up with a climate approximating.
Global warming is the prognosis for the Earth as a whole, but some localities may actually end up colder, at least initially.
Here is one report from Woods Hole Oceanographic Institution that is a bout 5 years old. Things are progressing much faster than was though possible even 5 years ago. Illustrations and captions are from the report.
THE GLOBAL OCEAN CONVEYOR—The global ocean circulation system, often called the Ocean Conveyor, transports heat throughout the planet. White sections represent warm surface currents. Purple sections represent deep cold currents. (Illustration by Jayne Doucette, WHOI)
DRAMATIC CHANGES IN THE NORTH ATLANTIC—Subpolar seas bordering the North Atlantic have become noticeably less salty since the mid-1960s, especially in the last decade. This is the largest and most dramatic oceanic change ever measured in the era of modern instruments. This has resulted in a freshening of the deep ocean in the North Atlantic, which in the past disrupted the Ocean Conveyor and caused abrupt climate changes. (B. Dickson, et. al., in Nature, April 2002)
--------------------
Translate text
"Eternity is a very long time, especially towards the end" Stephen Hawking (quoting Woody Allen)
"There are all kinds of interesting questions that come from a knowledge of science, which only adds to the excitement and mystery and awe of a flower." Richard Feynman
Iraq war and occupation costs
|
ysb45
Tourist
Reged: 04/06/08
Posts: 2
|
|
Who Cares - there i8s no such thing as global warming
|
Previous
Index
Next
Threaded
[Re: 
Edit
Reply
Quote
