The radiative effect on microphysics (REM) plays an important role in the dew/frost formation near the surface. How REM impacts cirrus clouds is investigated in this study, using bin microphysical model simulations and coincident data of the CloudSat and Global Precipitation Measurement (GPM) satellites. REM affects ice crystal spectrum with two types: radiative cooling and warming. Radiative cooling, as predicted by the bin‐model simulations, favors the formation of horizontally oriented ice crystals (HOICs), but radiative warming does not. Hence, a test of REM can be transformed to a test of HOICs, because HOICs can be measured by the microwave polarization observations of the GPM Microwave Imager (GMI) at 166 GHz. To analyze the GMI data for their HOIC distribution, clouds are sorted into four groups with different optical depth and altitude, based on the radiative cooling/warming ratio (or eta) computed with satellite‐retrieved ice water content. Their HOIC distributions (e.g., the midlevel thick clouds have more HOICs than the high‐level ones) agree well with those predicted by the bin‐model simulations. The general agreement between the GMI observations and bin‐model simulations suggests that REM is common in cirrus clouds and impacts cirrus clouds significantly.

中文翻译：

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利用卫星观测模拟卷云对微物理的辐射效应

微观物理学的辐射效应（REM）在地表附近露水/霜冻形成中起着重要作用。在这项研究中，使用bin微物理模型模拟以及CloudSat和全球降水量测量（GPM）卫星的重合数据，研究了REM如何影响卷云。REM影响冰晶光谱的类型有两种：辐射冷却和加热。正如bin模型模拟所预测的那样，辐射冷却有利于水平取向冰晶（HOIC）的形成，但辐射增温则不然。因此，REM的测试可以转换为HOIC的测试，因为可以通过GPM微波成像仪（GMI）在166 GHz的微波极化观测来测量HOIC。为了分析GMI数据的HOIC分布，将云分为光学深度和高度不同的四组，基于用卫星获取的冰水含量计算得出的辐射冷却/升温比（或eta）。它们的HOIC分布（例如，中层厚云的HOIC数量多于高层云的数量），与bin模型模拟预测的结果一致。GMI观测值与二元模型模拟之间的总体一致表明，REM在卷云中很常见，并且会严重影响卷云。