Statistics of vertical backscatter profiles of cirrus clouds
Statistics of vertical backscatter profiles of cirrus clouds
复制标题
卷云垂直后向散射剖面统计
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
T. Maestri
中科院分区：
文献类型：
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作者：
P. Veglio;T. Maestri
抽象的。对云气溶胶激光雷达和红外探路者卫星观测搭载的 CALIOP 激光雷达收集的卷云垂直反向散射和消光剖面进行了近乎全球的统计分析。提供了卷云总体属性的出现频率和分布统计数据，以及首次仅提供水平均匀（5 公里视场）卷云的统计数据。计算水平均匀 cirri 的年度和季节性反向散射剖面 (BSP)。在白天/夜间情况以及中纬度和热带地区发现的差异是根据它们所源自的云的平均物理参数进行研究的。研究了云物理参数（光学深度、几何厚度和温度）与 BSP 形状之间的关系。研究发现云几何厚度是影响平均CALIOP BSP形状的主要参数。具体来说，几何厚度较小的卷云在云顶附近的平均 BSP 曲线上显示出最大值。随着云几何厚度的增加，BSP 最大值向云底移动。云光学深度和温度对 CALIOP BSP 的形状影响较小。一般来说，随着云温和光学深度的增加，观察到 BSP 最大值略有增加。为了拟合平均 BSP，作为云层内几何厚度和位置的函数，提供了多项式函数。评估了沿云垂直维度使用恒定冰含量 (IWC) 或从 BSP 拟合函数导出的 IWC 剖面时对红外光谱中卫星辐射传输模拟的影响。事实上，事实证明，在现实的假设下，平均 BSP 与 IWC 轮廓成线性比例。
Abstract. A nearly global statistical analysis of vertical backscatter and extinction profiles of cirrus clouds collected by the CALIOP lidar, on-board of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation, is presented. Statistics on frequency of occurrence and distribution of bulk properties of cirrus clouds in general and, for the first time, of horizontally homogeneous (on a 5-km field of view) cirrus clouds only are provided. Annual and seasonal backscatter profiles (BSP) are computed for the horizontally homogeneous cirri. Differences found in the day/night cases and for midlatitudes and tropics are studied in terms of the mean physical parameters of the clouds from which they are derived. The relationship between cloud physical parameters (optical depth, geometrical thickness and temperature) and the shape of the BSP is investigated. It is found that cloud geometrical thickness is the main parameter affecting the shape of the mean CALIOP BSP. Specifically, cirrus clouds with small geometrical thicknesses show a maximum in mean BSP curve located near cloud top. As the cloud geometrical thickness increases the BSP maximum shifts towards cloud base. Cloud optical depth and temperature have smaller effects on the shape of the CALIOP BSPs. In general a slight increase in the BSP maximum is observed as cloud temperature and optical depth increase. In order to fit mean BSPs, as functions of geometrical thickness and position within the cloud layer, polynomial functions are provided. The impact on satellite radiative transfer simulations in the infrared spectrum when using either a constant ice-content (IWC) along the cloud vertical dimension or an IWC profile derived from the BSP fitting functions is evaluated. It is, in fact, demonstrated that, under realistic hypotheses, the mean BSP is linearly proportional to the IWC profile.