This study describes a multi-satellite/multi-sensor retrieval algorithm designed to obtain the atmospheric water budget over the open ocean. To accomplish this, a combination of datasets derived from the GOES-8 5-channel Imager and the DMSP passive microwave instrument suite (SSM/I, SSM/T, SSM/T2) have been acquired for the Gulf of Mexico-Caribbean Sea basin. Whereas the methodology is being tested over this basin, the algorithm is being designed for portability to any open-ocean region.
Algorithm modules using the different data sources to retrieve individual geophysical parameters needed in the water budget equation are designed in a manner that takes advantage of the high temporal resolution of the GOES-8 measurements as well as their physical relationships to the SSM/I passive microwave signals for water vapor, cloud liquid water, and rainfall. The methodology consists of retrieving the precipitation, surface evaporation, and the vapor-cloud water storage terms in the atmospheric water balance equation from satellite techniques, while the water vapor advection term is obtained as a residual in the balance equation. Thus, we seek to develop a purely satellite-based method for deriving the full set of terms in the atmospheric water budget equation without requiring information on the wind velocity profile.
The algorithm is to be validated by comparing the water vapor transports into the targeted basin diagnosed from the satellite algorithm, with those obtained from a network of land-based upper air stations that uniformly surround the basin. Preliminary budget results will be presented, obtained from combining an array of different algorithm modules found in the scientific literature, for the retrieval of the different terms in the water balance equation. Future research will concentrate on optimizing the selection of algorithm modules needed to obtain the time-evolution of an open-ocean atmospheric water budget and to conduct detailed analysis of an annual cycle over the Gulf of Mexico-Caribbean Sea region.