Improving Coastal SWOT Wide-Swath Wet Tropospheric Correction Using Objective Analysis
Abstract
Accurate wet tropospheric correction (WTC) is essential for sea surface height (SSH) retrieval from the surface water and ocean topography (SWOT) wide-swath altimetry, especially in coastal regions where onboard microwave radiometer (MWR) observations are affected by land contamination. This letter quantifies the coastal degradation of MWR-derived WTC using real SWOT observations from the one-day calibration phase and the 21-day science phase, and evaluates a multisource objective analysis (OA) configuration for coastal full-swath WTC reconstruction. Validation against coastal Global Navigation Satellite System (GNSS) stations shows that the MWR–GNSS root-mean-square error (RMSE) increases from 1.16/1.47 cm offshore to 1.86/2.25 cm within 30 km of the coast for the one-day and 21-day phases, respectively. Evaluated within 100 km of the coast, the OA correction achieves the lowest SSH anomaly (SSHA)-difference variance among the tested MWR, numerical weather model (NWM), and OA corrections, reducing the variance by 21.7%/23.2% relative to MWR and by 18.2%/8.9% relative to NWM for the two phases, respectively. These results indicate that the OA configuration provides a more continuous and cross-track-stable WTC field for coastal SWOT SSH retrieval.