A Test of the Simulation of Tropical Convective Cloudiness by a Cloud-Resolving Model
A Test of the Simulation of Tropical Convective Cloudiness by a Cloud-Resolving Model
复制标题
云解析模型模拟热带对流多云的试验
DOI：
10.1175/2008jcli2272.1
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发表时间：
2009
影响因子：
4.9
通讯作者：
T. Kubar
中科院分区：
文献类型：
--
作者：
M. Lopez;D. Hartmann;P. Blossey;R. Wood;C. Bretherton;T. Kubar
描述了一种通过与地球轨道卫星对云和降水的观测进行比较来测试模型对热带对流云的模拟的方法。云分为代表对流核心的几类：中等厚的砧云和薄的高云。这些云的丰度分数是根据降雨率的函数计算的。三维模型具有热带太平洋对流区域的稳定强迫特征，并将模型云与同一区域的卫星观测进行比较。该模型很好地模拟了降水率与代表对流核心的光学厚冷云之间的关系。观测结果显示，砧云数量较多，对降雨率的依赖性很强，但模型产生的砧云太少，约为 4 倍，且对降雨率的依赖性非常弱。观测结果还显示了出射长波辐射（OLR）和反照率的概率密度函数，其最大值对应于扩展的上层冷云，而模型却没有。使用二维模型探讨了砧云模拟对模型参数的敏感性。研究了云物理参数和平均风切变效应。通过调整模型中的云物理参数以产生更多的冰云和更少的液态水云，可以在保持对光学厚云的良好模拟的同时改进砧云的模拟。
A methodology is described for testing the simulation of tropical convective clouds by models through comparison with observations of clouds and precipitation from earth-orbiting satellites. Clouds are divided into categories that represent convective cores: moderately thick anvil clouds and thin high clouds. Fractional abundances of these clouds are computed as a function of rain rate. A three-dimensional model is forced with steady forcing characteristics of tropical Pacific convective regions, and the model clouds are compared with satellite observations for the same regions. The model produces a good simulation of the relationship between the precipitation rate and optically thick cold clouds that represent convective cores. The observations show large abundances of anvil cloud with a strong dependence on rain rate, but the model produces too little anvil cloud by a factor of about 4 and with a very weak dependence on the rain rate. The observations also show probability density functions for outgoing longwave radiation (OLR) and albedo with maxima that correspond to extended upper-level cold clouds, whereas the model does not. The sensitivity of the anvil cloud simulation to model parameters is explored using a two-dimensional model. Both cloud physical parameters and mean wind shear effects are investigated. The simulation of anvil cloud can be improved while maintaining a good simulation of optically thick cloud by adjusting the cloud physics parameters in the model to produce more ice cloud and less liquid water cloud.