Abstract
This paper deals with the present status of active microwave remote sensing for rainfall measurement from space by rain radar. About 60% of the global rainfall is concentrated in the tropical region and it is presumably the principal driving force of the global climate system. This paper outlines the Tropical Rainfall Measuring Mission (TRMM) which is the first observation project with an active array rain radar in space. France is also planning the BEST project to observe tropical energy budget by measuring tropical rain and wind. Plans of rain radars on the manned space station of both USA (TRAMAR) and Japan (rain radar on JEW) are also introduced.
