Problem Statement: Significant progress has been made over the past decade in satellite precipitation product development. However biases and uncertainties are common among precipitation products and an obstacle exists in quickly gaining knowledge of product quality, biases and behavior at a local or regional scale, namely user defined areas or points of interest. Current online operational inter-comparison and validation services have not addressed this issue adequately. To expedite the use of satellite precipitation products, the obstacle needs to be removed. We have developed a TRL-7 prototype ( in the TRMM Online Visualization and Analysis System (TOVAS) to address this issue (Liu et al. 2009). Despite its limited functionality and datasets, users can use this tool to generate customized plots within the United States for 2005. In addition, users can download customized data for further analysis, e.g. comparing their gauge data. Analysis Method: To meet increasing demands, we propose to integrate community recognized IPWG (International Precipitation Working Group) Validation Algorithms/statistics into the TRMM Online Visualization and Analysis System (TOVAS), allowing users to generate customized plots and data. In addition, we will expand the current coverage from the United States to global. TRMM monthly, other precipitation products and their derived climatology products will be added as well. Whenever an algorithm team changes their product version number, users would like to know the differences between the new and the old by inter-comparing both versions of products in their areas of interest. Making this service available to users will help them to better understand associated changes, such as, biases, which is particularly important to application users. We plan to implement this inter-comparison in all TRMM Level-3 monthly standard products. Significance: Precipitation is hard to measure and difficult to predict. Each year droughts and floods cause severe property damages and human casualties around the world. Accurate measurement and forecast are important for mitigation and preparedness efforts. The proposed additions will complement and accelerate the existing and ongoing validation activities in the community and enhance existing data services for TRMM and the future Global Precipitation Mission (GPM). Relevance to the Program Element: The proposed additions response to the 3rd focus of the program for tool development. This proposal directly addresses NASA’s Earth Science Division research themes by providing estimating, validating and conveying measurement differences between sensors, in merged data products (e.g. 3B42, 3B43), and in long-term Earth system science data records. The proposed IPWG algorithms have been widely used and recognized by the precipitation community.

Project PI: Zhong Liu/GES DISC DAAC and George Mason University, NASA Goddard Space Flight Center

GMU/DAAC, NASA/GSFC, Code 610.2, Greenbelt, MD 20771



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Started: Apr 01, 2011

Last Activity: Apr 01, 2011


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