Advances in satellite passive microwave remote sensing of cloud liquid water

Great progress has been made on the satellite passive remote sensing of cloud liquid water in recent two or three decades. The advances in satellite passive remote sensors and the significant improvement in detecting precision offered both technique and data support for the satellite passive remote sensing of cloud liquid water, based on which some statistical retrieval methods and physical retrieval methods have been developed and improved. Some important retrieval methods developed in various periods of time are briefly reviewed here. Key techniques related to these retrieval methods are summarized, and the merits and limitations of each method are evaluated. Due to different radiative characteristics of ocean and land surface, the statistical and physical retrieval methods over ocean and over land are outlined seperately and then compared with each other. Some surveys and discussion are also made on the emissivity of land, which is a bottleneck restriction for the development of the retrieval technique of cloud liquid water over land.