Airborne Empty Microwave Radiometer Measurements Of Cloud Liquid Water Containing The Inversion Method

Cloud liquid water content is always one of the most important quantities in many subjects and operations,particularly in modification weather the conditions of cloud liquid water and supercooled liquid water content are the predetermination conditions of seeding clouds. At present, the measuring methods are not enough and these known methods are in all kinds of shortages. So the Institude of Atmospheric Physics,Chinese Academy of Sciences cooperate with Jilin Weather modification Office,Changchun consigning the Institude of Geograpy , Changchun to develop the airborne up-looking microwave radiometer for the first time in China. With a new instrument, a new retrieving method must been developed .But at present,there are almost no papers about the airborne up-looking microwave radiometer. The retrieving method apt to the new instrument is introduced in this paper.The fundamentals and method of deducing path-integrated cloud liquid water content (L)by an airborne up-looking microwave radiometer are introduced in this paper. Based on historic radiosonde data of Changchun city,Jilin Province and Xian city.Shanxi Province and on the typical model of profiles of cloud liquid water content for stratiformis, the coefficients of retrieval equation are obtained as the functions of height for each month from April to July in the two cities. Furthermore, we explore the internal physics signification of retrieval coefficients'distributing according to every month and have comparisons between the two cities. Then the numerical simulation tests of the accuracy of retrieval results are given: the statistical relative deviation of retrieved values of L to the simulated 'trues' on the ground is 15-25% and that ataltitude of 6km is 5-10%,that means the retrieval method and implementation of the method are applicable to processing measurements of an airborne radiometer made in China recently. Besides, the information on actual height of lowest cloud base is used in constructing of cloud liquid water profile by using radiosonde profiles, that makes an improvement of relative accuracy of retrieved value of L at almost all altitudes by 5-20% according to numerical simulation comparison.The lower the altitude is,the more the accuracy is improved. Application the retrieval coefficients of the city of Changchun in April to a field experiments in Jilin Province, on April 22 demonstrate the airborne up-looking microwave radiometer can detect cloud liquid water and supercooled liquid water content . The conclusions show that the airborne up-looking microwave radiometer is practical and operational.