Global analysis of ice microphysics from CloudSat and CALIPSO: Incorporation of specular reflection in lidar signals
Global analysis of ice microphysics from CloudSat and CALIPSO: Incorporation of specular reflection in lidar signals
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DOI：
10.1029/2009jd013383
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发表时间：
2010-11
影响因子：
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通讯作者：
H. Okamoto;Kaori Sato;Y. Hagihara
中科院分区：
文献类型：
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作者：
H. Okamoto;Kaori Sato;Y. Hagihara
[1] 我们开发了一种新的雷达激光雷达算法，可应用于 CloudSat 和云气溶胶激光雷达以及红外探路者卫星观测 (CALIPSO) 数据来检索冰微物理。该算法分析了 CALIPSO 经常观测到的具有大后向散射系数和小去偏振比的激光雷达信号的镜面反射。我们以前的雷达激光雷达算法对 CloudSat 和 CALIPSO 数据的分析表明，当存在镜面反射时，检索冰云微物理存在问题。我们为水平方向的板实现了额外的查找表。雷达激光雷达算法中的镜面反射模式可以极大地改善检索结果。除了 532 nm 处的雷达反射率因子和后向散射系数之外，新的雷达激光雷达算法还需要 CALIPSO 测量的去偏振比。我们对检索结果进行了几项敏感性研究。结果证明，非球形性是最大的不确定性来源。对 CloudSat-CALIPSO 重叠区域的冰微物理进行了全局分析。有效半径随着高度的增加而减小。镜面反射的有效半径范围为100至300μm。冰水含量 (IWC) 范围为每立方米 10−4 到十分之几克。有效半径和 IWC 都随着海拔（温度）降低（增加）而增加。取向颗粒的最大混合比发生在-20℃至-5℃之间。 IWC 在热带地区有两个最大值，分别是 15 公里以上和 5 公里左右。我们还研究了陆地和海洋冰微物理的差异。陆地和海洋上的有效半径相似，但陆地上的 IWC 往往更大。
[1] We developed a new radar-lidar algorithm that can be applied to CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data to retrieve ice microphysics. The algorithm analyzes the specular reflection of lidar signals often observed by CALIPSO with large backscattering coefficients and small depolarization ratios. Analyses of CloudSat and CALIPSO data by our former radar-lidar algorithm showed problems retrieving ice cloud microphysics when specular reflection was present. We implemented additional look-up tables for horizontally oriented plates. A specular reflection mode in the radar-lidar algorithm could drastically improve retrieval results. The new radar-lidar algorithm requires depolarization ratios measured by CALIPSO, in addition to the radar reflectivity factor and backscattering coefficient at 532 nm. We performed several sensitivity studies to retrieval results. Nonsphericity turned out to be the largest source of uncertainties. Global analyses of ice microphysics for CloudSat-CALIPSO overlap regions were performed. The effective radius decreased as the altitude increased. The effective radius in the specular reflection ranged from 100 to 300 μm. The ice water content (IWC) ranged from 10−4 to several tenths of a gram per cubic meter. Both effective radius and IWC increased as the altitude (temperature) decreased (increased). The largest mixing ratio of oriented particles occurred between −20 and −5°C. The IWC had two maxima in the tropics above 15 km and around 5 km. We also examined the differences in ice microphysics over land and ocean. The effective radius was similar over land and ocean, but the IWC tended to be larger over land.