IV.2 NASA-TRMM

The objective of this proposal is to improve satellite precipitation estimation using multiple instruments on TRMM and other satellites for the preparation of developing knowledge and techniques suitable for transfer to the next-generation constellation-based Global Precipitation Measurement (GPM) mission. Three research topics crucial to GPM’s goal of providing improved global precipitation data for climate and hydrologic applications are selected for study in this proposal, as follows:

1. Stratiform rainfall and snow identification and quantification using TRMM/GPM radar and microwave radiometers. Because the GPM mission extends measurements of precipitating clouds from tropical to the much higher latitude regions, stratiform rain and snow estimation becomes a critical issue for global climate and hydrology;
   
2. Systematic study of techniques combining TRMM/GPM superior precipitation sampling with geosynchronous infrared precipitation estimation. Although the goal of GPM is to improve the quality of precipitation measurements, as well as the sampling frequency and intensity, there remains a spatial-temporal resolution gap between the GPM data and the demands of meteorological and hydrological studies. Therefore, effectively taking the merits of different instruments from TRMM/GPM and geosynchronous satellites provides a promising approach for improvement of satellite global precipitation estimation; and
   
3. Cloud-type analyses using patterns and dynamic variations of cloud patches monitored from geosynchronous infrared imagery and the vertical structural profiles retrieved from the TRMM/GPM instruments.
   

NASA TRMM and GPM programs

1. TRMM Satellite
   The accurate measurement of the spatial and temporal variation of tropical rainfall around the globe remains one of the critical unsolved problems of meteorology. TRMM provide the first detailed and comprehensive dataset on the four dimensional distribution of rainfall and latent heating over vastly undersampled oceanic and tropical continental regimes. Combined with concurrent measurement of the atmosphere's radiation budget, estimates of the total diabatic heating will be realized for the first time ever on a global scale. Link: NASA Tropical Rainfall Measurement Mission (TRMM).
2. GPM Strategy
   An objective for the Global Precipitation Measurement (GPM) project is the production of 3-hour global precipitation products. To achieve this temporal coverage on a global basis will require a constellation of satellites with the appropriate instruments. It is anticipated that at least eight satellites will be needed in a constellation to provide the desired 3-hour global precipitation product. Link: NASA Global Precipitation Measurement (GPM).