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University of Oklahoma: "Classification of the Gulf of Mexico return flow regimes during the cool season"

Final Report

The return flow event in the Gulf of Mexico first came to the attention of research meteorologists in the late 1970s. The challenging forecast problems associated with these events in the cool season were discussed at a workshop held at the National Severe Storms Laboratory (NSSL) in early 1987. Based on recommendations coming from this workshop, a field program was planned and carried out in Feb.- Mar. 1988. The research conducted under this Partners Project was based on some of the preliminary study results. The researchers had realized that a key observational platform in the experiment was the DMSP polar orbiting satellite and the SSMI (microwave retrieval) data it collected. This instrument retrieves the total precipitable water over oceanic regions and, in the data-sparse Gulf, proved to be extremely valuable in following the evolution of moisture transport in the return flow episodes.

The objective of this research was to examine other return flow situations that would complement those studied during the special experiment in 1988. Since the data requires special processing, the expertise for which resides at the Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison, it was necessary to link a scientist from SSEC with a Southern Region forecaster so that appropriate return flow cases could be examined with the benefit of SSMI data processed at the SSEC. Dr. Robert Rabin and Mr. Alan Johnson collaborated on the study of return flows using SSMI data for several cases in 1989-1991. The backdrop for the SSMI studies was a yearly climatology of return flow events collected by Southern Region forecasters since 1989. The emphasis is on using precipitable water estimates and wind speed from the SSMI to determine moisture depth and to forecast short-term changes in moisture near the Gulf Coast. An MS thesis, two journal articles, and two workshops grew out of this research.