Air-Sea Coupling Mechanisms in Tropical Cyclones

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9714885 Shay The U.S. Weather Research Program (USWRP) is an interagency activity designed to perform and implement the research necessary to improve the delivery of weather services to the nation. Under this Program, the National Science Foundation, the National Oceanic and Atmospheric Administration (NOAA), the National Aeronautics and Space Administration (NASA) and the Office of Naval Research are jointly evaluating and supporting research of high priority to the USWRP. One of the primary goals of the USWRP is to perform the research necessary to improve track and intensity forecasts of hurricanes. The goal of this research effort is to improve understanding of the role of air- sea interactions in modifying the near-surface wind structure of tropical cyclones. Of particular importance is to understand the role of these interactions as tropical cyclones pass over warm oceanic features that surround the United States Eastern Seaboard and the Gulf of Mexico states. Specific research objectives are: (a) Determine locations and heat content of warm core oceanic eddies; (b) Examine the forcing of warm ocean features on enhanced surface stresses, fluxes and waves in the APBL and the role of the OPBL feedback on the APBL; and (c) Quantify the roles of mixing and horizontal advection of SST and salinity gradients including the mass, heat and salt budgets in the OPBL. Research approach involves an ocean monitoring program based on satellite remote sensing to detect warm, mesoscale oceanic features during the summer months. These features will be monitored using the analyzed sea-surface height anomalies derived from the NASA TOPEX and Geosat Follow On missions to determine their locations relative to the forecast storm track. Sea surface temperatures will be monitored from Advanced Very High Resolution Radiometer. Additionally, as part of the NOAA Hurricane Research Division experimental field program, a coupled atmospheric and oceanic ob servational program will be conducted from an NOAA aircraft. Observations will include measurement of upper ocean current, temperature and density structure using airborne expendable profilers. Concurrent observations of the turbulent fluxes of momentum, heat and moisture in the APBL during these oceanographic deployments; and remote-sensing of surface winds and stresses using the Stepped Frequency Microwave Radiometer and airborne C-Band Scatterometer, and possibly 2-dimensional directional wave spectra from the NASA Scanning Radar Altimeter will be acquired during reconnaissance and research missions. Successful completion of this research will lead to a better understanding of the role of warm upper oceanic features on surface wind variations. This may lead to improved boundary layer parameterizations and improved hurricane intensity forecasts. ***