One of the critical components of the Earth's hydrological cycle is precipitation. Rainfall is essential for providing the fresh water that sustains life. The only currently available precipitation radar in space is provided by the Tropical Rainfall Measuring Mission (TRMM). TRMM is a joint space project between NASA and the Japanese Aerospace Exploration Agency (JAXA). TRMM is designed to measure precipitation and its variation from a low-inclination orbit combining a suite of sensors to overcome many of the limitations of remote sensors previously used for such measurements from space. The TRMM satellite has been launched November 27 in 1997 and the mission has recently been extended to 2009. The observatory for rainfall observations consists of precipitation radar, a multi-frequency microwave radiometer and a visible and infrared (VIS/IR) radiometer. Several data products are available ranging from the raw orbital products with a ground resolution of approximately 5 km to near real-time completely satellite based precipitation estimates and monthly calibrated products based on precipitation observations with ground resolutions of around 25 km.
The TRMM data products are available at near realtime and used to force the drought monitoring system. Some examples of TRMM derived annual precipitation for the Iberian Peninsula are shown below.
TRMM 2003 (wet year)
TRMM 2005 (dry year)
