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Five years of atmospheric aerosol data are available as global aerosol maps from NASA's Multi-angle Imaging SpectroRadiometer (MISR). These images show the seasonal-average distribution of atmospheric aerosol amount across Africa and the Atlantic Ocean; such global maps are also available for all other parts of the planet, and for monthly as well as seasonal time increments. The measurements capture airborne particles in the entire atmospheric column, for sub-visible sizes ranging from tiny smoke particles to "medium" dust (about 0.5 to 2.5 microns). Such particles are produced by forest fires, desert winds, volcanoes, breaking ocean waves, and urban and industrial pollution sources.
MISR retrieves aerosol amount with high accuracy at mid-visible wavelengths, even over urban areas and bright desert source regions, in addition to obtaining some information about particle size and shape, from the varying scene brightness over nine different view angles and four wavelengths. These maps were generated from data acquired between March 2000 and November 2004, and show column-integrated aerosol optical depth (also known as optical thickness) averaged over half-degree by half-degree grid cell areas (about 60 kilometer rectangles at low latitudes). The color scale indicates the range of optical depths, from relatively clear skies in blue and purple, to hazier atmospheres in red, orange, yellow or green. Black pixels indicate missing results due to persistent seasonal cloud cover. The MISR aerosol algorithm uses both stereoscopic and spectral brightness techniques to identify and screen out cloudy pixels.
To view the MISR data and learn more about this mission, click here: http://www-misr.jpl.nasa.gov/gallery/galnew.html
Posted: Mar 02, 2005 9:22AM by Joe
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