Global distribution of cirrus clouds from CloudSat/Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) measurements
Global distribution of cirrus clouds from CloudSat/Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) measurements
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DOI：
10.1029/2008jd009972
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发表时间：
2008-10-31
影响因子：
4.4
通讯作者：
Liu, Dong
中科院分区：
文献类型：
--
作者：
Sassen, Kenneth;Wang, Zhien;Liu, Dong
对流层上部的卷云分布在全球各地，是地球-大气系统辐射平衡的重要调节器，因此也是气候的重要调节器。尽管卷云分布广泛，但是，从卫星辐射测量或分散的地面观测站点很难研究卷云，因为它们可以作为多层云系统的一部分出现，并且具有光学薄的特征。因此，需要更好地描述卷云的全球分布情况，这是CloudSat和CALIPSO卫星编队飞行的主要理由，这两颗卫星分别支持云雷达和偏振激光雷达。这些主动遥感器的测量结果，在经过适当的算法分析后，有能力识别和准确测量这类云的位置和高度。本研究中使用的CloudSat/云气溶胶激光雷达和红外探路者卫星观测（CALIPSO）数据卷云算法旨在识别那些可能被地面天气观测者归类为卷云的云：它是基于以前使用多个遥感器方法的经验，以及从大量的地面激光雷达和雷达观测中收集的知识，这些观测是在最小的先验假设我们报告卷云的全球和季节性频率，以及在最初1年收集的数据中获得的高度和厚度。我们发现卷云出现的全球平均频率为16.7%。这些新的结果与其他卷云气候学进行了比较，并解释了当地卷云形成机制和负责的全球天气现象。
The cirrus clouds of the upper troposphere are globally widespread and are important regulators of the radiative balance, and hence climate, of the Earth-atmosphere system. Despite their wide distribution, however, cirrus are difficult to study from satellite radiance measurements or from scattered ground observing sites because they can occur as part of multilayered cloud systems and are characteristically optically thin. The need to better characterize the global distribution of cirrus clouds was therefore a major justification for the formation flying of the CloudSat and CALIPSO satellites, which support a cloud radar and polarization lidar, respectively. Measurements by these active remote sensors, when analyzed by appropriate algorithms, have the ability to identify and accurately measure the locations and heights of this category of clouds. The combined CloudSat/Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data cirrus cloud algorithm used in this study is aimed at identifying those clouds that would likely be classified as cirrus by a surface weather observer: it is based on previous experience with multiple remote sensor approaches and knowledge gleaned from extensive surface lidar and radar observations of visually identified cirrus clouds with a minimum of a priori assumptions. We report on the global and seasonal frequencies of cirrus clouds, and on their heights and thicknesses obtained over the initial 1 year of data collected. We find a global average frequency of cirrus cloud occurrence of 16.7%. These new results are compared with other cirrus cloud climatologies and are interpreted in terms of local cirrus cloud formation mechanisms and the responsible global weather phenomena.