Research On Cloud Liquid Water Retrieval Over Land

The TRMM Microwave Imager (TMI) 85.5GHz channel vertical polarization brightness temperature and vertical atmospheric properties ( including temperature, pressure and humidity)are used to calculate the surface emissivity in clear day with the VDISORT model and numerical method improved in this paper. The amount of non-precipitation cloud liquid water (CLW) over detecting area on cloudy day is retrieved using an iteration method and the VDISORT model.The emissivity of Henan area on 6 March 2005 is calculated by means of the improved numerical method, and then the amount of cloud liquid water (CLW) over Henan area on 21 and 16 March 2005 is retrieved by means of iteration method. The improved numerical method calculating surface emissivity shows more efficiency. The surface emissivity calculated by the improved numerical method and the amount of CLW retrieved by means of iteration method are evaluated by comparing with FY-2 Satellite images and Henan physiognomy map. The retrieved CLW distribution shows improvements comparing with the CLW data from TRMM 2A12 products in the same time and the CLW data from NCEP data in the near period. And comparisons are made between the retrieved CLW on 16 March 2005 and aircraft detecting data in situ in Henan province, it is shown that the retrieved CLW shows some agreement with CLW values estimated by aircraft detecting data.The retrieved amount of non-precipitation CLW over ocean is more reliable due to the relatively simple radiation characteristics of the ocean surface. An area covering both land and ocean (115°E～125°E, 30°N～40°N) is particularly selected to meet the case study on the cloud over the mixed area on 2 March 2005. The amount of CLW over land is retrieved by the above method, and the amount of CLW over ocean is retrieved by linear regression method. With the help of FY-2C Satellite images, we demonstrated and discussed the feasibility of the CLW retrieve method used in this paper.