Frequency of tropical precipitating clouds as observed by the Tropical Rainfall Measuring Mission Precipitation Radar and ICESat/Geoscience Laser Altimeter System
Frequency of tropical precipitating clouds as observed by the Tropical Rainfall Measuring Mission Precipitation Radar and ICESat/Geoscience Laser Altimeter System
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DOI：
10.1029/2007jd008468
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发表时间：
2007-07
影响因子：
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通讯作者：
S. Casey;A. Dessler;C. Schumacher
中科院分区：
文献类型：
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作者：
S. Casey;A. Dessler;C. Schumacher
[1]热带地区的对流云可以分为三类：云顶高度接近地面2公里的浅云，云顶高度接近0°C的中层浓云，以及被对流层顶覆盖的深对流云。这种三峰分布在冰、云和陆地高程卫星（ICESat）上携带的地球科学激光高度计系统（GLAS）的云数据中以及热带降雨测量使命（TRMM）降水雷达（PR）的降水数据中都是可见的。分数面积覆盖率（FAC）数据计算在三个级别的每一个，以描述如何经常看到光学厚云或降水在每个级别。通过将TRMM PR观测到的降水的FAC除以GLAS/ICESat观测到的厚云的FAC，我们得到了降水云的分数。我们发现，热带平均降水云分数是低的：3.7%的浅云，6.5%的中层云，和24.1%的深云。
[1] Convective clouds in the tropics can be grouped into three categories: shallow clouds with cloud top heights near 2 km above the surface, midlevel congestus clouds with tops near the 0°C level, and deep convective clouds capped by the tropopause. This trimodal distribution is visible in cloud data from the Geoscience Laser Altimeter System (GLAS), carried aboard the Ice, Cloud, and land Elevation Satellite (ICESat), as well as in precipitation data from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR). Fractional areal coverage (FAC) data is calculated at each of the three levels to describe how often optically thick clouds or precipitation are seen at each level. By dividing the FAC of TRMM PR-observed precipitation by the FAC of thick GLAS/ICESat-observed clouds, we derive the fraction of clouds that are precipitating. We find that the tropical mean precipitating cloud fraction is low: 3.7% for shallow clouds, 6.5% for midlevel clouds, and 24.1% for deep clouds.