Abstract SARAL carried onboard a radar altimeter that provides very precise measurements of the sea surface height (SSH). Like other altimetric missions, SARAL carries a passive microwave radiometer (PMR) for wet tropospheric correction to SSH. In the present study, new algorithms are developed for the retrieval of cloud liquid water (CLW) and total precipitable water vapor (TPW) over the global oceans from PMR measurements of the brightness temperatures. A radiative transfer and genetic algorithm based retrieval scheme is proposed for the estimation of CLW and TPW from SARAL PMR. The comparisons of CLW from PMR with independent measurements from GPM-GMI and SSMIS within and outside ±40° latitudes show correlation (R) of 0.86 and 0.83, bias of 0.7 and −3.61 mg/cm2, and root mean square error (RMSE) of 8.42 and 8.07 mg/cm2, respectively. Similarly, TPW from PMR with GPM-GMI and SSMIS show R of 0.99 and 0.98, bias of −0.04 and −0.03 g/cm2 and RMSE of 0.17 and 0.17 g/cm2, respectively. The retrieval accuracy of CLW and TPW from the new algorithms is compared with these parameters provided in the SARAL geophysical data records as finished products, which showed substantial improvement in the quality of the parameters from the new algorithm.

中文翻译：

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从 SARAL 微波辐射计观测中测量总可降水量和云状液态水的改进算法

摘要 SARAL 搭载了雷达高度计，可提供非常精确的海面高度 (SSH) 测量值。与其他高度测量任务一样，SARAL 携带一个被动微波辐射计 (PMR)，用于对 SSH 进行湿对流层校正。在本研究中，开发了新算法，用于从亮温的 PMR 测量值中反演全球海洋上空的云液态水 (CLW) 和总可降水水汽 (TPW)。提出了一种基于辐射传输和遗传算法的检索方案，用于从 SARAL PMR 估计 CLW 和 TPW。来自 PMR 的 CLW 与来自 ±40° 纬度内外的 GPM-GMI 和 SSMIS 的独立测量值的比较显示相关性 (R) 为 0.86 和 0.83，偏差为 0.7 和 -3.61 mg/cm2，以及均方根误差 (RMSE)分别为 8.42 和 8.07 mg/cm2。相似地，来自具有 GPM-GMI 和 SSMIS 的 PMR 的 TPW 显示 R 为 0.99 和 0.98，偏差分别为 -0.04 和 -0.03 g/cm2，RMSE 分别为 0.17 和 0.17 g/cm2。将新算法中CLW和TPW的检索精度与SARAL地球物理数据记录中作为成品提供的这些参数进行了比较，表明新算法的参数质量有了实质性的提高。