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GREENLAND-SPRING
A handout photo provided on July 9, 2013 by the NASA Earth Observatory and taken on June 21, using Landsat 8 data from the US Geological Survey, shows springtime in southwest Greenland. Pools of blue water begin to dot the surface of the ice sheet as the top layer of snow and ice melts. The ponds provide an important indicator of how much the ice sheet is melting in a given year. In 2013, melt ponds were initially slow to appear along the edge of the ice. The first pools were visible in Landsat 8 images in early June. Meltwater accumulates as pools in depressions in the ice, and the extent and depth of these ponds and the rate at which they grow and shrink tells scientists how quickly the ice is melting. Despite the late start, melting in 2013 has been rapid, occurring at a faster pace than the 1981-2010 average. The satellite is likely to become a critical tool for assessing ice sheet melting because it can measure light in two narrow wavelength bands–deep blue and blue (0.43–0.45 micrometers). These wavelengths of visible light penetrate pure water more deeply than others, and they also reflect off of the lakebed. Landsat observations of reflected blue light allow scientists to estimate the extent and depth of melt pond, as well as the purity of the water. AFP PHOTO / NASA EARTH OBSERVATORY / Jesse Allen and Robert Simmon
RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / NASA EARTH OBSERVATORY / Jesse Allen and Robert Simmon" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS
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Detalii fotografie |
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-, GREENLAND |
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AFP / Mediafax Foto |
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| Fotograf: |
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Jesse Allen/Robert Simmon |
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| Data: |
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9 Iulie 2013 |
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2709 x 1818 (1.06 MB) |
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