Satellite-borne microwave radiometers provide wet tropospheric correction (WTC) for altimetry observations, which is critical to high-accuracy sea surface height (SSH) measurements. However, it was reported that the Haiyang-2A (HY-2A) calibration microwave radiometer (CMR) experienced abrupt 18.7 GHz band failure. The global navigation satellite system (GNSS) can provide (near) real-time accurate WTC with high temporal resolutions. In this study, GNSS observations of 132 global coastal sites from January 2017 to February 2018 are used for CMR validation and calibration. In addition, the European Centre for Medium-Range Weather Forecasts (ECMWF) products during the same period are also used for comparison. After calibration with GNSS observations, the root-mean-square (RMS) of the WTC differences between CMR and ECMWF decreases from 2.53 to 1.66 cm. After calibration with ECMWF products, the RMS of the WTC differences between ECMWF-calibrated CMR and ECMWF is 1.54 cm. Moreover, different processing strategies of WTC are applied to SSH measurements. The mean sea level anomaly (SLA) values of SSH obtained with ECMWF-calibrated CMR are comparable to those obtained with GNSS-calibrated CMR WTC and with ECMWF WTC. In addition, compared to the SLAs of Jason-3, the SLAs of HY-2A obtained with ECMWF WTC show the smallest differences of 7.79 cm in RMS, which are 0.1 cm smaller than those obtained with ECMWF-calibrated CMR WTC and 0.23 cm smaller than those obtained with GNSS-calibrated CMR WTC. The SLAs obtained with original CMR WTC are reduced by approximately 0.8 cm in RMS after using GNSS-calibrated CMR WTC. Therefore, even with the known limitations of ground-based GNSS (non-collocated measurements over land instead of over ocean), it can indeed serve as a valuable WTC source for radiometer calibration due to the lower latency of GNSS observations.

星载微波辐射计为测高观测提供湿对流层校正 (WTC)，这对于高精度海面高度 (SSH) 测量至关重要。然而，据报道，海洋二号A（HY-2A）校准微波辐射计（CMR）在18.7 GHz频段突然出现故障。全球导航卫星系统 (GNSS) 可以提供具有高时间分辨率的（近）实时准确的 WTC。在本研究中，2017 年 1 月至 2018 年 2 月对 132 个全球沿海站点的 GNSS 观测用于 CMR 验证和校准。此外，欧洲中期天气预报中心（ECMWF）同期的产品也用于比较。使用 GNSS 观测校准后，CMR 和 ECMWF 之间的 WTC 差异的均方根 (RMS) 从 2.53 减小到 1.66 cm。使用 ECMWF 产品校准后，ECMWF 校准的 CMR 与 ECMWF 之间的 WTC 差异的 RMS 为 1.54 cm。此外，将 WTC 的不同处理策略应用于 SSH 测量。使用 ECMWF 校准的 CMR 获得的 SSH 的平均海平面异常 (SLA) 值与使用 GNSS 校准的 CMR WTC 和 ECMWF WTC 获得的值相当。此外，与 Jason-3 的 SLA 相比，使用 ECMWF WTC 获得的 HY-2A 的 SLA 的 RMS 差异最小，为 7.79 cm，比 ECMWF 校准的 CMR WTC 获得的 SLA 小 0.1 cm，小 0.23 cm比使用 GNSS 校准的 CMR WTC 获得的数据。使用 GNSS 校准的 CMR WTC 后，使用原始 CMR WTC 获得的 SLA 在 RMS 中减少了大约 0.8 厘米。所以，