Retrieving microphysical properties near the tops of potential rain clouds by multispectral analysis of AVHRR data
Retrieving microphysical properties near the tops of potential rain clouds by multispectral analysis of AVHRR data
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DOI：
10.1016/0169-8095(94)90096-5
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发表时间：
1994-06-20
影响因子：
5.5
通讯作者：
Gutman, Garik
中科院分区：
文献类型：
--
作者：
Rosenfeld, Daniel;Gutman, Garik
潜在的降水云顶的属性检索从发射和反射的辐射，由NOAA-11卫星上的高级甚高分辨率辐射计（AVHRR）测量。只有在可见光波段光学厚度大并充满视野的云才被认为是降水的候选者。因此，完全避免了来自云层下方的发射和反射辐射的影响，这在半透明或破碎的云层中很重要。通过将测量的辐射亮度与具有各种微物理性质的云的理论计算的辐射亮度进行比较来进行检索。降水形成过程的可能性，然后估计和验证对降水的实际观测，使用天气雷达。结果表明，反演粒子有效半径大于约14 μ m的光学厚云与雷达回波区域对应良好，表明存在降水大小的粒子。这一结果与以下事实是一致的，即在具有相对温暖的顶部的云中，通过暖雨过程以及冰增殖过程的机制，有效的降水形成需要半径至少为12 μ m的水滴的存在。
Properties of potentially precipitating cloud tops are retrieved from the radiances emitted and reflected from them, as measured by the Advanced Very High Resolution Radiometer (AVHRR) onboard the NOAA-11 satellite. Only clouds that are optically thick in the visible wave band and filling the field of view are considered as candidates for precipitation. Therefore, effects of emitted and reflected radiation from below the clouds, which is important in semi-transparent or broken clouds, are avoided altogether. The retrieval is done by comparing the measured radiance to the theoretically calculated radiance from clouds having various microphysical properties. The likelihood for precipitation formation processes is then estimated and verified against actual observations of precipitation, using a weather radar. It was shown that optically thick clouds with retrieved particle effective radius greater than about 14 mu m correspond well to areas with radar echoes, indicating the existence of precipitation size particles. This result is consistent with the fact that existence of drops having a radius of at least 12 mu m is required for efficient precipitation formation in clouds with relatively warm tops, by the mechanisms of warm rain processes as well as ice multiplication processes.