| GPM's Precipitation Processing System (PPS) is one of the first measurement-based processing systems approved by NASA Headquarters. A measurement-based system employs a recognized scientific measurement, and provides continuity between data from previous and future satellite missions. The PPS is an evolution of the highly successful Tropical Rainfall Measuring Mission (TRMM) Science Data and Information System (TSDIS). The PPS implementation removes the single-point nature of TSDIS and migrates the system to portable software, making it easy and cost effective to add processing capabilities for the multiple satellites and data streams GPM will require. PPS will be NASA's contribution to the distributed ground system for the GPM mission. The PPS will integrate data from GPM's multiple satellites and multiple partner data streams. It will also provide key tools for use by the GPM science algorithm developers. In support of GPM, PPS will produce three distinct types of products. The first is a continually updated rain map that will serve as an important GPM outreach product. The second is near-real-time data generated from the precipitation radar and the various radiometers in the mission, as well as a three-hour global merged product that will combine radar, radiometer and infrared data. The final type consists of the standard research products that are established by the precipitation measurement missions science team. Thus far, the PPS team has held two demonstrations (in 2003 and 2004) in which precipitation scientists, NASA Headquarters personnel, TRMM project personnel, and GPM project personnel participated. These demonstrations showed the current iteration of PPS processing TRMM data and GPM-like simulated data. In addition, portions of the PPS software have been demonstrated running on a variety of different platforms. Prototyped portions of the PPS Service Oriented Architecture (SOA) have also been demonstrated to the PPS review team. On November 16-17, 2005, PPS Build 1 will be reviewed at GSFC by the PPS review panel. This review will focus on the first operational use of the PPS software—TRMM version 7 (v7) reprocessing (also considered GPM version 0 processing). TRMM v7 reprocessing is anticipated to begin in late 2007 or early 2008. The use of PPS in this undertaking is an important risk mitigation opportunity that will greatly enhance PPS readiness to support GPM. Also to be reviewed in November are GPM-focused PPS services such as the flexible science data toolkit, dynamic subsetting of data, submission of user algorithms into the PPS processing stream, etc. In addition, portability will once again be substantiated by demonstrating a new hardware platform upon which PPS software will run. In practice, PPS may be called upon to formulate products using information from radiometers whose data is not generated by PPS. To simulate such a situation, the PPS team—in cooperation with a group at the Colorado State University—created a concept for generating this type of product. The team developed a common logical format for radiometer data and translated it into a physical Hierarchical Data Format Release 4 (HDF4) output. PPS software will be used to generate this product at the November PPS review. From 2002 through 2007, the bulk of PPS funding has been provided directly from NASA Headquarters and the science team. In 2007, the GPM project will provide the necessary funding to complete the evolution of PPS for GPM-specific mission objectives such as partner data integration, algorithm development, geolocation toolkit development, Mission Operations Center ingest, etc. PPS is currently on track for supporting an early 2010 launch of GPM satellites. By Erich Stocker/GPM Data Processing Manager |