Hurricane Winds Retrieval from C Band Co-pol SAR

Abstract

Since the beginning of modern radar technology, the co-polarization (copol) mode has been predominantly used for marine navigation, target detection, ocean and atmospheric monitoring etc. In remote sensing of ocean surface winds, co-pol is operationally used in satellite scatterometer missions and some of SAR winds demonstration projects. Compared to cross-polarization modes, co-pol radar measurements have much stronger backscattered intensity and signal to noise ratio; thus, cross-pol measurements could sense atmospheric and oceanic processes which could affect small scale waves on the ocean surface. Co-pol measurements also have stronger sensitivity to wind direction than cross-pol, which made it suitable for monitoring ocean surface wind direction as well as wind speed. However, due to the different radar configuration of cross-pol SAR and the complicated dynamical processes that develop under hurricane conditions, wind monitoring under hurricane forces has formidable challenges. These include the demands for wind direction a priori, saturation of radar backscattered signals, speed ambiguity with decreased radar NRCS response under high wind speeds in low incidence angles. This chapter will summarize some recent progress in these fields. The demands for combining the advantages of both co-pol and cross-pol measurements and appropriate data assimilation methodology to ingest SAR winds into marine and hurricane numerical weather forecasting will also be discussed.