Classification of clouds over the western equatorial Pacific Ocean using combined infrared and microwave satellite data
Classification of clouds over the western equatorial Pacific Ocean using combined infrared and microwave satellite data
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DOI：
10.1029/95jd00823
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发表时间：
1995-07
影响因子：
--
通讯作者：
Guosheng Liu;J. Curry;Rong-shyang Sheu
中科院分区：
文献类型：
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作者：
Guosheng Liu;J. Curry;Rong-shyang Sheu
提出了一种新的云分类方案，结合红外和微波卫星数据。由于微波辐射可以深入云层，因此该方案能够确定薄云和深云的特征。此外，新方案可以提供传统红外可见光云分类方案无法提供的降水信息。建议的云分类方案利用从红外测量获得的云顶温度和微波指数，包括发射和散射信号。定义了暖非降水云、暖降水云、中顶非降水云、中顶降水云、薄高顶非降水云、深高顶非降水云、砧状层状降水云和深对流降水云等8种云类。利用热带海洋-全球大气耦合海气响应试验的飞机雷达资料对分类方案进行了验证。用新的云分类方案对1992年11月至1993年2月赤道西太平洋暖池区的云进行了研究，首次获得了云覆盖和降水分布随云型变化的谱。分析表明，该地区的大部分云量与温暖的非降水云有关。闪烁像素仅占总云像素的约15%。在降水像素中，约50%的云顶温度高于-40 °C。利用微波卫星资料获得的降雨率，研究了每种降水云类型的相对贡献。云顶温度高于−40°C的降水云至少贡献了总降水量的23%，而其余77%的降水几乎被层状降水云和深对流降水云平分。
A new cloud classification scheme is presented that combines infrared and microwave satellite data. Because microwave radiation can penetrate deep into the cloud layer, this scheme is able to determine characteristics for both thin and deep clouds. Additionally, the new scheme can provide information on precipitation, which traditional infrared-visible cloud classification schemes have been unable to. The proposed cloud classification scheme utilizes the cloud top temperature obtained from infrared measurements and a microwave index that includes both emission and scattering signals. The following eight cloud classes are defined: warm nonprecipitating cloud, warm precipitating cloud, midtop nonprecipitating cloud, midtop precipitating cloud, thin high-top nonprecipitating cloud, deep high-top nonprecipitating cloud, anvil with stratiform precipitating cloud, and deep convective precipitating cloud. The classification scheme is validated by aircraft radar data obtained from Tropical Ocean-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment. The new cloud classification scheme is used to investigate the clouds in the western equatorial Pacific Ocean warm pool region for the period from November 1992 to February 1993, allowing us to obtain for the first time the spectra of cloud coverage and precipitation distribution as a function of cloud types. The analysis shows that most of the cloudiness in this region is associated with warm nonprecipitating clouds. Precipitating pixels comprise only about 15% of total cloud pixels. Of the precipitating pixels, about 50% have cloud top temperatures warmer than −40°C. Using rainfall rates obtained from microwave satellite data, the relative contribution by each precipitating cloud type is investigated. It is found that the precipitating clouds with cloud top temperature warmer than −40°C contribute at least 23% of the total rainfall amount, while the remaining 77% of total precipitation is divided almost equally by anvil with stratiform precipitating cloud and the deep convective precipitating cloud.