Retrieval of water vapor profiles using SSM/T-2 and SSM/I data

A physically based retrieval algorithm ia presented that retrieves water va por profiles from Special Sensor Microwave/Temperarure-2 (SSM/T-2) passive microwave brightness temperature measurements. This method can use SSM/T-2 data alone or in conjunction with data from the Special Sensor Microwave/Im ager (SSM/I). Several SSM/I channels, as well as total integrated water vap or (TIWV) retrieved from SSR-VI, are tested to see if they add value to the retrieval. In the retrieval process, TIWV is formally treated as a separat e channel. It is found that using the SSM/I TIWV increases the yield of the retrieval (the percentage of retrieved profiles whose brightness temperatu res agree with the observations, on average, to within the noise level of t he instrument), as well as reduces the average normalized brightness temper ature error. Also, use of the TIWV allows the: omission of the SSM/T-2 150- GHz channel data without a significant impact on results. It is shown that by using the SSM/I TIWV, retrievals can be made further into areas of preci pitation and heavy clouds than when using data from only the SSM/T-2. Examp les of retrieved profiles are shown to agree with the general features of p rofiles from radiosondes and the European Centre for Medium-Range Weather F orecasts analyses.