The cryosphere has a global reach, extending beyond the polar regions. It consists of those parts of the Earth’s surface where water is found in solid form, including areas of snow, sea ice, glaciers, permafrost, ice sheets, and ice bergs. NASA Earth observing satellites are providing scientists with unparalleled insight into how the cryosphere behaves, how it is changing, and what implications those changes have on the Earth’s global system, including weather and climate.
Satellite observations are particularly useful for monitoring changes in polar ice shelves and glaciers. Landsat-7 ETM+ and Terra ASTER data from different years show a significant retreat of the Jakobshavn Glacier calving front (where ice bergs “calve” off into Jakobshavn Fjord) over the period 2002-2004. MODIS imagery shows a before and after view of the Larsen-B Ice Shelf collapse in early 2002. Satellite data acquired over Antarctica in recent years have greatly expanded our knowledge of that ice covered continent. Knowledge of changes occurring there is of critical importance since so much of the world’s water is locked up in Antarctic ice. The MODIS mosaic of Antarctic reveals detailed features on the ice sheet, ice shelves, and ice flows [More recent observations from satellites not discussed here have yielded the most accurate map of Antarctica’s topography (from ICESat) and estimates of net ice mass loss over the continent (from GRACE)].
Microwave radiometers such as SSM/I have observed polar sea ice for many years, monitoring changes in Arctic Ocean sea ice cover from season to season and from year to year. These observations show there has been a net loss in sea ice cover there over the last two decades. A map of minimum sea ice cover (that occurs in September of each year) is shown for 2004, along with the average minimum sea ice cover for the period 1978-2002. The most extreme minima have occurred in the past few years. The shrinkage of sea ice is important from a climate standpoint, in that more open ocean is available to absorb more heat, whereas ice reflects most incident radiation back into space.
MODIS observations of snow provide information on available water resources. This is particular important in the American West where mountain snowpacks store significant amounts of water. The risk for drought, wildfires, and flooding in the spring and summer depends on the amount of snow falling the previous winter. MODIS daily snow cover and MODIS land cover data are combined in an image of the western U.S. Back to poster
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