Posts tagged Ice
![The figure above is a [very] simple model displaying isostatic rebound of Greenland if its ice sheet were not present. The Greenland ice sheet (GISh) is 2,500 km north-south, 1,000 km east-west, 3 km thick, and covers almost 2 million square kilometers (or 80% of the island). Because of the weight of GISh, the continental lithosphere is depressed in an elastic motion. If the GISh were to be removed, the lithosphere would rise in reaction. This rebounding process is known as isostasy and in case of ice sheets, glacial rebound.
Underneath any vast ice sheet is a land surface not unlike any other ice-free surface on earth. It has valleys, hills, plains, etc. Therefore, we see that in Greenland the underlying topography, the Bedrock (or simply the Bed), is shaped as a concave, and with the removal of the ice sheet it rises and assumes a less curved form.
PS: Please note that this is purely for visualization purposes and not to be used in scientific analysis.](http://27.media.tumblr.com/tumblr_ltdut3Ejs91qff4ofo1_400.jpg)
The figure above is a [very] simple model displaying isostatic rebound of Greenland if its ice sheet were not present. The Greenland ice sheet (GISh) is 2,500 km north-south, 1,000 km east-west, 3 km thick, and covers almost 2 million square kilometers (or 80% of the island). Because of the weight of GISh, the continental lithosphere is depressed in an elastic motion. If the GISh were to be removed, the lithosphere would rise in reaction. This rebounding process is known as isostasy and in case of ice sheets, glacial rebound.
Underneath any vast ice sheet is a land surface not unlike any other ice-free surface on earth. It has valleys, hills, plains, etc. Therefore, we see that in Greenland the underlying topography, the Bedrock (or simply the Bed), is shaped as a concave, and with the removal of the ice sheet it rises and assumes a less curved form.
PS: Please note that this is purely for visualization purposes and not to be used in scientific analysis.
NASA Operation IceBridge Returns to Antarctica
satellite image acquired October 5, 2011
download large image (5 MB, JPEG)
download GeoTIFF file (42 MB, TIFF)
For the third consecutive October, NASA research aircraft are flying over Antarctica in search of clues about the health and dynamics of the frozen continent’s massive ice sheets and shelves. Part of the NASA-funded IceBridge mission, planes carry instruments to measure the thickness of snow and ice, as well as the shape of the land andseafloor beneath the ice.
On October 5, 2011, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this clear view of the Antarctic Peninsula, the Larsen Ice Shelf, and the sea ice covered waters around the region. The Peninsula stands out as the raised terrain amidst the ice from the lower left to upper middle of the image.
On October 12, 2011, NASA’s DC-8 aircraft flew from Punta Arenas, Chile, across the Antarctic Peninsula and Weddell Sea, and back to Chile—making two 1,700-kilometer transects from east to west across the region. Several early flights in the 2011 campaign will take the team over sea ice near the Antarctic Peninsula before too much of it melts in the southern spring. Scientists are trying to understand why sea ice in the Southern Hemisphere is not following the steady decline of sea ice thickness and extent observed in the Arctic.
Operation IceBridge is designed to continue critical ice sheet measurements for the next few years between the end of the ICESat I mission and the launch of ICESat II in 2016. Researchers make instrumented flights to Greenland and the Arctic each March through May, and over Antarctica each October and November. Many flight lines retrace previous ICESat-1 tracks or future ICESat-2 tracks. Some also align with current observations made by the European Space Agency’s CryoSat-2 satellite.
The overlapping flight lines and satellite tracks help scientists improve the accuracy of their data. Scientists are concerned about how quickly key glaciers and ice shelves are thinning. Better understanding this type of change is crucial to projecting impacts like sea-level rise.
NASA image provided courtesy of Jeff Schmaltz, MODIS Rapid Response team. Caption by Michael Carlowicz and Patrick Lynch.
- Instrument: Aqua - MODIS
Permafrost is ground that is at or below the freezing point of water (0 °C or 32 °F) for two or more years. Ice is not always present, as may be in the case of nonporous bedrock, but it frequently occurs. Most permafrost is located in high latitudes (i.e. land close to the North and South poles), but alpine permafrost may exist at high altitudes in much lower latitudes. Permafrost exists in 24% of exposed land in the Northern Hemisphere.
