Rainfall estimates from spaceborne microwave radiometers form the foundation of global precipitation data sets. Since the beginning of the satellite microwave rainfall estimation era in the 1980s, the primary signature leveraged over land for these estimates has been the brightness temperature (TB) depression due to ice particle scattering. Contrary to this practice, time series analyses based on observations from two spaceborne radars and two spaceborne radiometers reveal a TB increase at H19 due to raindrop emission as the primary cloud particle signature over desert terrain. Low surface emissivity supports the use of liquid raindrop emission as the primary signature over desert surfaces. In these regions, the surface rain rate better correlates with the liquid raindrop emission signal than with the scattering induced by ice further aloft, suggesting a new potential for improving rainfall estimation over deserts by exploiting the liquid raindrop emission signature.

中文翻译：

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微波辐射计在沙漠上的雨滴签名

来自星载微波辐射计的降雨量估算值构成了全球降水数据集的基础。自从1980年代卫星微波降雨估算时代开始以来，在陆地上进行这些估算的主要特征是由于冰粒散射造成的亮度温度（TB）下降。与这种做法相反，基于来自两个星载雷达和两个星载辐射计的观测结果进行的时间序列分析显示，由于雨滴的散发是沙漠地形上主要的云粒子特征，因此H19的TB增加。低表面发射率支持使用液体雨滴发射作为沙漠表面的主要特征。在这些地区，地表降雨速率与液态雨滴排放信号的相关性更好，而不是与更高处的冰引起的散射相关，