Water Vapor Profile Retrievals at 183 GHz: Land vs. Ocean and Clear vs. Cloudy,
ATMOSPHERIC AND ENVIRONMENTAL RESEARCH INC CAMBRIDGE MA
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This report summarizes the results of an initial study to investigate the retrieval of water vapor profiles over land from several combinations of millimeter wave frequency channels, to compare the results obtained over land to performance expected over the ocean, and to assess the feasibility of obtaining cloud information from 183 GHz measurements. Brightness temperatures were simulated for four hypothetical millimeter wave moisture sounders using a recently developed sensor simulation model. Channel frequency selecton was investigated by comparing results from individual instrumental channel sets. In performing these simulations atmospheric data sets consisting of 400 radiosonde temperature and moisture profiles obtained over both land and ocean were used. The effect of beam-filling cloud on brightness temperatures was evaluated by incorporating physical cloud submodles. For representative cloud types within the simulation algorithm. Retrievals of vertical moisture profiles were accomplished by implementing a general statistical regression method which minimizes the mean square of interest. Retrieval statistics evaluated from a dependent subset of channel brightness temperatures and vertical water vapor profiles were applied subsequently to infer water vapor profiles from an independent set of brightness temperatures.