Vertical cloud properties in the tropical western Pacific Ocean: Validation of the CCSR/NIES/FRCGC GCM by shipborne radar and lidar
Vertical cloud properties in the tropical western Pacific Ocean: Validation of the CCSR/NIES/FRCGC GCM by shipborne radar and lidar
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DOI：
10.1029/2008jd009812
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发表时间：
2008-12
影响因子：
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通讯作者：
H. Okamoto;T. Nishizawa;T. Takemura;Kaori Sato;H. Kumagai;Y. Ohno;N. Sugimoto;A. Shimizu;I. Matsui;T. Nakajima
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文献类型：
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作者：
H. Okamoto;T. Nishizawa;T. Takemura;Kaori Sato;H. Kumagai;Y. Ohno;N. Sugimoto;A. Shimizu;I. Matsui;T. Nakajima
[1]这项研究利用95 GHz雷达和激光雷达数据，对热带西太平洋上空的垂直云结构进行了研究。这些数据是在2001年9月至12月，在MIRAI科考船的MR01-K05巡航期间观测到的。云的垂直结构在6~10公里范围内比较均匀，最大云出现率为20%，位于12公里处。1公里处平均降水量为11.5%。利用东京大学气候系统研究中心、国家环境研究所和全球变化前沿研究中心(CCSR/NIES/FRCGC)的大气环流模式(GCM)的输出，模拟了Mirai巡航轨道上的云量、雷达反射率因子和激光雷达后向散射系数。最初的输出显示最大云量在15公里处；然而，在考虑了雷达的衰减和最小灵敏度后，最大云量移到了12公里处。该模型高估了8公里以上的云量，模拟云量是观测云量的两倍多。该模式高估了到达12公里以上高空大气的深对流频率。此外，它高估了降水频率。在整个高度范围内，模拟的雷达反射率被低估了，而模拟和观测的激光雷达后向散射与亚网格尺度处理在12公里以上符合得很好。40μm的冰有效半径和冰水含量在薄云中是合理的，而在其他地区则被低估了。模拟的液态水含量被高估了。
[1] This study examined the vertical cloud structure over the tropical western Pacific Ocean using 95-GHz radar and lidar data observed from September to December 2001 during the MR01-K05 cruise of the research vessel Mirai. The cloud vertical structure was homogeneous between 6 and 10 km, and the maximum cloud occurrence was 20% and located at 12 km. The mean precipitation occurrence was 11.5% at 1 km. The cloud fraction, radar reflectivity factor, and lidar backscattering coefficient were simulated along the Mirai cruise track using the output from the Center for Climate System Research, University of Tokyo; National Institute for Environmental Studies; and Frontier Research Center for Global Change (CCSR/NIES/FRCGC) general circulation model (GCM). The original output showed the maximum cloud fraction at 15 km; however, after considering attenuation and the minimum sensitivity of the radar, the maximum shifted to 12 km. The model overestimated the cloud fraction above 8 km, with the simulated fraction more than twice as large as the observed fraction. The model overpredicted the frequency of deep convection reaching the upper atmosphere above 12 km. Further, it overestimated precipitation frequency. Simulated radar reflectivity was underestimated throughout the entire altitude range, whereas simulated and observed lidar backscattering were in good agreement above 12 km with subgrid-scale treatment. The ice effective radius of 40 μm and ice water content were reasonable in thin clouds, but the radius was underestimated in other regions. The simulated liquid water content was overestimated.