ESA Satellite Measures Greenland Ice Sheet
Researchers are analyzing data on Greenland’s ice sheets that has been aquired over the last decade from the European Space Agency’s ERS satellites. These satellites are able to measure elevations on the Earth’s surface to within 2 centimeters!
ERS radar altimeters work by sending 1800 separate radar pulses down to Earth per second then recording how long their echoes take to bounce back 800 kilometres to the satellite platform. The sensor times its pulses’ journey down to under a nanosecond to calculate the distance to the planet below to a maximum accuracy of two centimetres.
The result is a mixed picture, with a net increase of 6.4 centimetres per year in the interior area above 1500 metres elevation. Below that altitude, the elevation-change rate is minus 2.0 cm per year, broadly matching reported thinning in the ice-sheet margins. The trend below 1500 metres however does not include the steeply-sloping marginal areas where current altimeter data are unusable.
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