Surface Wind and Wave Interactions in Tropical Cyclones

This study will investigate the interaction of ocean surface waves and surface winds in tropical cyclones in order to understand the implications on remotely sensed surface winds. Over the past several years, the Wide-Swath Radar Altimeter (WSRA) has been collecting surface wave spectra data in coincidence with Stepped-Frequency Microwave Radiometer (SFMR) surface brightness temperature (T_B) measurements on one of NOAA’s WP-3D hurricane hunter aircraft in tropical cyclones. The wave spectra data from the WSRA will be analyzed to gain a better understanding of the surface wave field in different regions of tropical cyclones. The results of the surface wave field analysis will then be compared to the coincident SFMR T_B measurements and surface wind measurements from GPS drowpwindsondes. Different combinations of wind and wave directions will impart different magnitudes of wind stress on the ocean surface for a given wind speed. Changes to the surface wind stress on the surface will modify the wave breaking and thus the white-water coverage on the surface. The T_B measured by the SFMR is related to the amount of white-water on the surface and a wind speed estimate is obtained through the use of a radiative transfer model and inversion algorithm. In order to retrieve accurate wind speed estimates with the SFMR, it is important that the relationship between the surface wind and waves is understood.