Analysis of Wave Breaking on Gaofen-3 and TerraSAR-X SAR Image and Its Effect on Wave Retrieval

The main purpose of our work is to investigate the performance wave breaking and its effect on retrieval in data acquired from Chinese Gaofen-3 (GF-3) synthetic aperture radar (SAR) at C-band German TerraSAR-X (TS-X) X-band. SAR images available for this study included 140 GF-3 quad-polarization strip (QPS) mode 50 dual-polarized (vertical-vertical (VV) horizontal-horizontal (HH)) TS-X stripmap (SM) mode. Moreover, these were collocated with waves simulated by numeric WAVEWATCH-III (WW3) (version 5.16) model HYbrid Coordinate Ocean Model (HYCOM) current. In particular, a few covered moored buoys monitored National Data Buoy Center (NDBC) Oceanic Atmospheric Administration (NOAA). comparison between WW3-simulated results significant heights (SWHs) European Centre Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA-5) showed that correlation coefficient (COR) was 0.4–0.6 root mean squared error (RMSE) about 0.2 m SWHs 0–4 m. winds inverted using VV-polarized geophysical functions (GMFs), e.g., CSARMOD-GF XMOD2 images. Bragg resonant roughness normalized cross section (NRCS) backscattering SAR-derived wind, parameters, HYCOM Then, contribution non-polarized (NP) estimated NRCS, HH-polarized polarization ratio (PR) co-polarized components NRCS. Because NRCSs have poor results, due saturation wind speeds greater than 20 m/s, analysis excluded such conditions. revealed signal more sensitive Interestingly, had linear speed. variation bias (inverted SWH minus WW3 simulation) increased as speed (>8 m/s) whitecap coverage (>0.005) increased. Following rationale, during tropical cyclones should consider influence breaking.