南半球中高纬度区域不同类型云的辐射特性

利用CloudSat的2B-CLDCLASS-LIDAR云分类产品和2B-FLXHR-LIDAR辐射产品4 a（2007-2010年）的数据，定量分析了单层云（高云、中云、低云）和3种双层云（如:高云与中云共存、高云与低云共存以及中云与低云共存）在南半球中高纬度（40°-65°S）的云量、云辐射强迫和云辐射加热率。其中云辐射加热率定义为有云时的大气加热率廓线与晴空大气加热率廓线的差值。结果表明:研究区域盛行单层低云和单层中云，其云量分别为44.1%和10.3%。并且，中云重叠低云在双层云中云量也是最大（8.7%）。不同类型云的云量也显著影响着其云辐射强迫。单层低云在大气层顶、地表以及大气中的净云辐射强迫分别是-64.8、-56.5和-8.4 W/m2，其绝对值大于其他类型云。虽然单层的中云在大气层顶和地表的净辐射强迫也为负值，但其在大气中的净云辐射强迫为正值（2.3 W/m2）。最后，讨论了不同类型云对大气中辐射能量垂直分布的影响。所有类型云的短波（或长波）云辐射加热率都随高度升高表现为由负值转为正值（或由正值转为负值）。对于大部分云，其净云辐射加热率主要由长波云辐射加热率决定。这些研究结果旨在为模式中云重叠参数化方案在区域的适用性评估及改进提供观测依据。 

Radiative characteristics of various cloud types over southern mid-high latitudes

A quantitative analysis of cloud fraction, cloud radiative forcing (CRF), and cloud radiative heating rate (CRH) of three single-layered cloud types (include high clouds, middle clouds and low clouds) and three two-layered cloud types (high clouds overlapping middle clouds or low clouds and middle clouds overlapping low clouds) is presented, based on the 2B-CLDCLASS-LIDAR and 2B-FLXHR-LIDAR products (covering four years from 2007 to 2010) over the southern mid-high latitudes (40°-65°S). The CRH at a given atmospheric level is defined as the cloudy minus clear-sky radiative heating rate. The statistical results show that regionally averaged cloud fractions of the single-layered low clouds and single-layered middle clouds are 44.1% and 10.3% respectively indicating their prevalence over studied region. Moreover, among two-layered cloud types middle clouds overlapping low clouds also show largest cloud fraction (8.7%). Significantly, cloud fractions of various cloud types affect their CRFs. The regionally averaged net CRF induced by the single-layered low clouds at the top and bottom of the atmosphere (TOA and BOA) and in the atmosphere are -64.8, -56.5, and -8.4 W/m², respectively, whose absolute values are largest among all cloud types. Although net CRFs at the TOA and BOA induced by single-layered middle clouds are also negative, its net CRF in the atmosphere is positive with a value of 2.3 W/m². Ultimately, impacts of different cloud types on the atmospheric vertical distributions of radiation energy are also presented. The shortwave CRHs (or the long wave CRHs) of all cloud types similarly transform from negative to positive (or from positive to negative) with increasing altitude. For most cloud types, their net CRHs is dominated by associated long wave CRHs. These results are designed to provide the observational basis for the applicability of the regional assessment and improvement in the cloud parameterization schemes of the model.