Diagnosing Tropical Cyclone Surface Wind Fields from SAR

Synthetic aperture radar (SAR) can provide images of ocean surface radar backscatter at pixel sizes as small as a few hundred meters. This backscatter can be related to various air-sea interaction parameters of interest, including ocean surface wind and ocean surface waves. For wind speeds less than ~20 m/s, there are useful model functions that relate the surface wind speed and relative direction between the wind and the radar beam to the backscatter. However, the inverse problem of estimating surface wind from backscatter is more challenging. The challenge is even greater in the high wind regime in and around tropical cyclones. We apply our surface pressure retrieval methodology to SAR images of tropical cyclones as a method to check existing wind retrieval methodologies. We further examine its potential to address the high wind regime Cal/Val problem through the use of surface pressure observations.