Study on Ocean Wind Vector Retrieval from ERS‐2 SAR Image

Abstract

AbstractSAR (Synthetic Aperture Radar) wind retrieval is a hot research topic in current Remote Sensing field. In this paper the principle of space borne SAR ocean wind retrieval and three related retrieval algorithms are introduced firstly. Then, the flowchart of the retrieval procedures is provided. As an example, ERS‐2 SAR image covering Hong Kong region acquired on May 7, 2002 is used for wind vector retrieval. The classic SAR Wind Direction Algorithm ‐ spectral method is improved, and applied for the retrieval. The wind direction thus estimated is however with 180º ambiguity. Buoy data collected by the Hong Kong Observatory are then used to resolve the uncertainty. Finally, the GMF (Geophysical Model Function)‐CMOD4 is adopted to estimate the wind speed at the height of 10 m above sea level. Compared with the data recorded by Hong Kong Observatory, the error in the wind direction and average wind speed are very small. The results show that accurate ADC (Analog to Digital Converter) compensation and image calibration, together with improved SWDA and CMOD4 algorithms, could offer high quality wind vector.