The effect of rain on radiative fluxes and heating rates is a process that is neglected in most of the large scale atmospheric models used for weather forecasting or climate prediction. Yet to our knowledge, the magnitude of the resulting radiative bias remains unquantified. This study aims to quantify the rain radiative effect (RRE) at a range of temporal and spatial scales, as a step toward determining whether the radiation schemes in these models should include rain. Using off‐line radiative transfer calculations with input from an ensemble of cloud resolving model simulations, we find that rain has a negligible effect on global mean radiative fluxes (less than 0.2 W m⁻²). Weekly mean RREs at specific locations may be larger (less than 4 W m⁻²). At the finest temporal and spatial resolutions, the RRE can occasionally be much larger again (greater than 100 W m⁻²), but values exceeding 10 W m⁻² occur in less than 0.1% of cases. Using detailed analysis of case studies we demonstrate that the magnitude and direction of the RRE depend on the rain water path, its vertical location with respect to cloud, and, for longwave radiation, the temperature at which it occurs. Large RREs generally only occur when the rain water path is large and the cloud water path is small. These cases are infrequent and intermittent. As the RREs are generally small, we conclude that this missing process is unlikely to be important for large scale atmospheric models.

中文翻译：

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使用云解析模拟全局集合表征雨的辐射效应

降雨对辐射通量和加热速率的影响在用于天气预报或气候预测的大多数大型大气模型中都被忽略。然而据我们所知，所产生的辐射偏差的大小仍未量化。这项研究旨在在一定的时间和空间尺度上量化雨水的辐射效应（RRE），以此作为确定这些模型中的辐射方案是否应包括雨水的步骤。使用离线辐射传输计算和来自云解析模型模拟的集成输入，我们发现降雨对整体平均辐射通量（小于0.2 W m ^-2）的影响可忽略不计。特定位置的每周平均RRE可能更大（小于4 W m ^-2）。在最佳的时间和空间分辨率下，RRE有时可能会再次大得多（大于100 W m ^-2），但在不到0.1％的情况下会出现超过10 W m ^-2的值。通过对案例研究的详细分析，我们证明了RRE的大小和方向取决于雨水路径，其相对于云的垂直位置以及对于长波辐射而言，其发生的温度。通常，大的RRE仅在雨水路径较大而云水路径较小时发生。这些情况很少见，而且断断续续。由于RRE通常较小，因此我们得出结论，对于大型大气模型，这种缺失的过程不太重要。