Collins modified the NCAR Community Climate Model to simulate the Nimbus-7 radiometers, and produced a set of model calculations he could compare with the satellite observations. The Nimbus-7 cloud matrix data set provided daily and monthly mean distributions of cloud amount and cloud type. (Image courtesy of JSC Digital Image Collection). By subtracting the near-infrared from the broadband, Collins partitioned the radiation reflected from the Earth between near-infrared and visible.Ĭlouds over the Pacific. Information included data from one wide-field-of-view radiometer that measured reflected sunlight over all wavelengths, both visible and near-infrared, while a second wide-field-of-view radiometer measured the reflected sunlight in near-infrared wavelengths. The radiation data sets from NASA's Atmospheric Science Data Center (ASDC) provided Collins nine years of global observations collected from 1979 to 1987. His goal was to determine whether there were any discrepancies between the model and the observations under cloudy skies. "I realized that there were observations made on the Nimbus class of platforms, specifically Nimbus-7, that would be ideal for this kind of study." Collins divides his work at NCAR between the Climate and Global Dynamics Division and the Mesoscale and Microscale Meteorology Division.Ĭollins compared the Nimbus-7 satellite observations of visible and near-infrared radiation reflected by the oceans and atmosphere with a general circulation model (GCM). "I wanted to scale this investigation to the entire globe," said William Collins, a climate scientist at the National Center for Atmospheric Research (NCAR). But aircraft measurements are limited in their geographic scope.
To investigate whether or not clouds absorb more sunlight than models predict, some investigators compare model calculations to aircraft measurements of reflected sunlight.
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