A Concept for Measuring Liquid Water Path from Microwave Attenuation along Satellite-Earth Path
Chen Hongbin(Laboratory for Middle Atmosphere and Global Environmental Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029)
To measure cloud liquid water path (LWP) which is an important parameter in the cloud physics and meteorology, various techniques have been developed. However, because of the observational difficulties related to high variability of clouds in space and time, all measurement techniques cannot yield global datasets of LWP to meet the needs in numerical weather prediction, precipitation enhancement, and climate change studies. The author presents a concept to determine LWP from cloud microwave attenuation along the satellite-earth surface path. An investigation has been conducted on the optimal choice of channels and mode of observations. Analysis of errors relevant to the method has also been done. The results show that (a) in principle, the proposed method can provide LWP measurements with much higher accuracy than the available (passive) satellite remote sensing; (b) the method with dual- or triple-channel combination can simultaneously observe atmospheric precipitable water (PW), LWP, and ice water path (IWP); and (c) if combined with the available satellite remote sensing techniques, it will more efficiently yield global datasets of LWP, PW, and IWP.