Wet Tropospheric Correction Methods for Wide-Swath Altimeters

Wet troposphere path delay (WPD) is a crucial error source for wide-swath altimeters with high-resolution observations. This study generated a simulated wide-swath through the nadir microwave radiometer (MWR) track and evaluated four wide-swath wet tropospheric correction (WTC) methods based on multisource data from 2017 with strict spacetime windows. The numerical weather model (NWM) method can provide a basic correction for the wide-swath altimeter. The MWR method, based on the extension of nadir one-beam MWR, could not provide a reliable correction. The residual error increased rapidly after deviating from the nadir profile. The overall root-mean-square error (RMSE) of the combination method was approximately 0.58 cm and had high uniformity within the swath. Even at the far end of the swath, the correction was better than that on the NWM and MWR methods. The objective analysis (OA) method using linear spatiotemporal OA had the best result among the four correction methods. The overall RMSE was only 0.49 cm, which was 34% lower than the NWM method. High consistency was maintained at each cross-track position of the swath. The last two wide-swath WTC methods provided in this study had high performance. For the wide-swath altimeter, the combination method is a scheme worthy of consideration, as it can provide WTC results conveniently, quickly, and accurately. Although the operation of the OA method is complex and depends on multisource observation data, it promises to be a high-quality scheme for the wide-swath altimeter WTC when a more accurate WTC value is required.