Abstract
The life time of TRMM is only three years. This is mainly because of the fuel consumption. The three year life time is not enough to observe interannual variation of the monsoon activity. Thus, TRMM follow-on mission has been discussed for several years. The main objectives of TRMM follow-on are : (1) to extend the TRMM rain observation, (2) to observe with wider coverage up to near 60 degree latitude, and (3) to observe vertical structure of rain. Since the diurnal variation of the precipitation exists even in the mid and high latitude, non-sun synchronous orbit is required to avoid the bias. Good sensitivity and capability to discriminate rain and snow are required for the observation in mid- and high latitude regions. The vertical structure is very important to study the precipitation process and the latent heat release. It is also important to bridge to microwave radiometer estimations. To meet the objectives, the candidates of the core sensors are a dual-wavelength precipitation radar and a TMI-like microwave radiometer. A VIRS-type visible infrared radiometer and LIS are also desirable.
