Water vapour profile retrievals from SSM/T-2 data constrained by infrared-based cloud parameters

An algorithm has been developed for the retrieval of water vapour profiles from passive microwave observations near 183GHz. The algorithm treats clouds explicitly and can incorporate cloud information from other sources. As a test, the algorithm has been configured to use data from the SSM /T-2 on the DMSP polar orbiting satellite series. Cloud top temperature and phase information have been derived from the AVHRR on the NOAA polar orbiting satellite series. Obtaining suitable coincidences between the SSM /T-2 and the AVHRR is challenging but two reasonable cases have been found. In one case, a liquid cloud injected into the retrieval results in significant improvement in the accuracy and vertical resolution in the neighbourhood of the cloud top. A cloud base is a by-product of the algorithm, but its validity has yet to be established. In the other case, a cirrus cloud injected into the algorithm resulted in little change in the retrieval which indicates that the algorithm was performing well in the cloud top vicinity (400mb).