激光雷达和毫米波雷达的卷云微物理特性的联合反演方法

Joint inversion method of cirrus physical properties using both Lidar and millimeter wave radar

联合激光雷达和毫米波雷达对卷云观测可以得到更全面的卷云特性信息,是卷云观测的一种发展趋势。使用美国大气辐射观测(Atmospheric Radiation Measurement,ARM)计划中卷云观测数据,将激光雷达和毫米波雷达反演的云边界信息相结合,得到更为准确的卷云边界信息。提出卷云微物理特性的激光雷达和毫米波雷达联合反演算法,该联合反演算法能在激光雷达不能穿透或毫米波不能识别卷云的情况下,反演出整个卷云的冰水含量、光学厚度。使用联合反演算法对一次卷云过程进行反演,其中激光不能穿透的区域冰水路径含量反演精度提高24%,毫米波雷达无法识别的区域冰水路径含量反演精度提高48%。在正确反演冰水含量的基础上,利用冰水含量、粒径分布与光学厚度的关系得到卷云过程的光学厚度,克服了由于卷云对激光雷达强衰减导致的光学厚度观测的困难。

Joint observation using Lidar and millimeter wave cloud radar （MWCR） from which more comprehensive properties of cirrus can be retrieved is the main trend of cirrus observation. Combining the information of cirrus boundary from Lidar and MWCR of ARM project, more accurate boundary of cirrus was obtained. Joint inversion method for retrieving cirrus microphysical properties was presented. Both ice water content and optical depth can be inverted accurately even in cases when the cirrus can＇t be penetrated by Lidar or can＇t be sensed by the MWCR through this method. The joint method was applied to a cirrus case, the results showed the accuracy of ice path content increased by 24% when the Lidar can＇t penetrate the cirrus and 48% when the MWCR can＇t sense the cirrus. Based on the accurate inversion of ice water content, the optical depth of cirrus was obtained using the relationship between ice water content, size distribution and optical depth. The inversion method of optical depth can overcome the difficulty arise from the attenuation of cirrus to Lidar.