Assessment of Sea-Surface Wind Retrieval from C-Band Miniaturized SAR Imagery

Synthetic aperture radar (SAR) has been widely used for observing sea-surface wind fields (SSWFs), with many scholars having evaluated the performance of SAR in SSWF retrieval. Due to the large systems and high costs of traditional SAR, a tendency towards the development of smaller and more cost-effective SAR systems has emerged. However, to date, there has been no evaluation of the SSWF retrieval performance of miniaturized SAR systems. This study utilized 1053 HiSea-1 and Chaohu-1 miniaturized SAR images covering the Southeast China Sea to retrieve SSWFs. After a quality control procedure, the retrieved winds were subsequently compared with ERA5, buoy, and ASCAT data. The retrieved wind speeds demonstrated root mean square errors (RMSEs) of 2.42 m/s, 1.64 m/s, and 3.29 m/s, respectively, while the mean bias errors (MBEs) were found to be -0.44 m/s, 1.08 m/s, and -1.65 m/s, respectively. Furthermore, the retrieved wind directions exhibited RMSEs of 11.5 & DEG;, 36.8 & DEG;, and 41.7 & DEG;, with corresponding MBEs of -1.3 & DEG;, 2.4 & DEG;, and -8.8 & DEG;, respectively. The results indicate that HiSea-1 and Chaohu-1 SAR satellites have the potential and practicality for SSWF retrieval, validating the technical indicators and performance requirements implemented during the satellites' design phase.