This study presents results from a multi-satellite/multi-sensor retrieval algorithm used to obtain the atmospheric water budget over the Gulf of Mexico and Caribbean Sea basin over one semiannual cycle. To accomplish this, a combination of datasets derived from the GOES-8 5-channel Imager and the DMSP passive microwave instrument suites (SSM/I) were acquired for the Gulf of Mexico and Caribbean Sea basin for the time period consisting of the months of October 1997, January, April, July, and October 1998, and January 1999. Whereas the methodology was developed over this basin, the algorithm was 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 were designed in a manner that takes advantage of their physical relationships to the SSM/I passive microwave signals for water vapor, cloud liquid water, and rainfall as well as the high temporal resolution of the GOES-8. The methodology consisted of retrieving the precipitation, surface evaporation, and the vapor-cloud water storage terms in the atmospheric water balance equation from satellite techniques, while the divergence of the vertically integrated horizontal water vapor transport was obtained as a residual in the balance equation. Thus, a purely satellite-based methodology for deriving the full set of terms in the atmospheric water budget equation was developed without requiring information on the wind velocity profile. The algorithm was built by combining an array of different modules found in the scientific literature for the retrieval of the different terms in the water balance equation.

Total columnar atmospheric water budget results will be presented for the period of study. The analysis was aimed at studying the seasonal characteristics of the Gulf of Mexico and Caribbean Sea basin water budget for one semiannual cycle. Also, results from inter-comparisons done among different algorithm modules tested to retrieve the water budget terms will also be presented. These inter-comparisons were conducted with the idea of finding out the best combination of algorithms suites to carry out the study. Finally, the algorithm was validated by comparing the divergence of the vertically integrated horizontal water vapor transports in 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.