Tropical Cyclone Wind Estimation Using Synthetic Aperture Radar

We have investigated various SAR images of tropical cyclones, which were acquired by the SAR aboard the satellites ENVISAT and RADARSAT-1 at different polarizations and incidence angles, using a similar approach as suggested by Horstmann et al., 2005 [1]. The resulting SAR-retrieved wind fields are compared to results of high-resolution numerical models as well as in situ measurements collected by aircrafts and buoy data. Uncertainty estimates are retrieved with respect to the local wind as well as imaging geometry. Furthermore, limitations of SAR wind retrieval at high wind speeds, in particular of the geophysical model functions (GMF) for retrieving wind speeds, will be addressed and discussed. These investigations show the influence of sea state (in particular of swell) and heavy rain on the NRCS and therefore on the wind speed retrieval as well as the limitations due to sensors.