机载微波辐射计反演云液水含量的云物理方法  

Retrieval Method of Path-Integrated Cloud Liquid Water Content for Airborne Upward-Looking Microwave Radiometer Using a Cloud Model

作　　者：周珺[1] 雷恒池[1] 魏重[1] 胡朝霞[1] 杨军[2] 嵇磊[2] 

机构地区：[1]中国科学院大气物理研究所,北京100029 [2]南京信息工程大学,南京210044

出　　处：《大气科学》2008年第5期1071-1082,共12页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金资助项目40537034;中国科学院知识创新工程重要方向项目KZCX3SW225

摘　　要：用一维层状云模式产生云样本,通过统计回归求得机载对空微波辐射计测云中路径积分液态水含量的反演系数,与用历史探空统计资料作相对湿度诊断产生云样本的反演方法进行了比较,并通过因素分析、数值模拟检验等方法对机载微波辐射计的探测误差进行估计。对2001年7月8日的个例分析表明,用云模式得到的统计样本,由于加入了对层状云物理过程的考虑,较为符合当天的实际天气情况,在一定程度上减小了由于背景大气条件、云温、云内含水量的垂直分布等的不确定性所引起的反演误差。对反演精度的数值模拟检验表明,各高度层的均方根相对误差在9.5%-12.7%之间,反演精度在所有高度上都高于原方法。对探测误差的因素分析表明,与仪器漂移及背景场引起的误差相比,由云液水垂直分布的不确定所引起的误差是不可忽略的。因此为进一步提高反演精度,根据实际宏观观测资料,对云模式产生的大量样本进行筛选,从中选取与实际云况较为符合的云样本进行拟合,结果表明,采用这一措施可以使反演精度得到进一步改善。A new retrieval method for deducing path-integrated cloud liquid water content （LWC） by airborne upward-looking microwave radiometer is introduced in this paper. The coefficients of retrieval equation are obtained through the statistic regression method like the former method, but the statistical samples are produced by the onedimensional stratiform cloud model. The new method is compared with the former one in which historic radiosonde data are employed to determine the vertical distribution of LWC by testing relative humidity above some threshold value. Besides, the detection errors are estimated through factor analysis and numerical simulation tests. The case on 8 July 2001 in Jilin Provence shows that the retrieval errors are diminished to some extent because the new statistical samples are consistent with the synoptic observations compared with the former method. The numerical simulation results indicate that the statistical relative errors decrease to 9. 5%- 12. 7% and the retrieval accuracy is better than the former method at all altitudes. The factor analysis indicates that the errors caused by the uncertainty of the vertical distribution of LWC cannot be ignored, compared with the errors caused by the background and the instrument drift errors. In order to improve the retrieval accuracy, the authors use selected cloud samples which are supplied by a cloud model to regress retrieval coefficients according to the synoptic observation. The numerical simulation tests indicate that the retrieval accuracy can be improved at all altitudes.

关 键 词：机载微波辐射计 云中垂直路径的液态水含量 反演方法 一维层状云模式 辐射传输模式 

分 类 号：P426[天文地球—大气科学及气象学]