GPM Validation Network Data and Analysis Resources for Multiple Applications

The Global Precipitation Measurement (GPM) Mission Validation Network (VN) was developed as a prototype and proof-of-concept using similar ground-based radar and space-based radar and radiometer datasets available from the Tropical Rainfall Measuring Mission (TRMM) satellite, prior to GPM launch in February, 2014. The VN became operational with the first release of public products from GPM in September, 2014. The GPM VN collects and archives Level 2 GPM Dual-Frequency Precipitation Radar (DPR) and Level 1 (calibrated brightness temperatures; Tbb) and Level 2 (rain rate) GPM Microwave Imager (GMI) and GPM constellation satellite microwave imager data products, and time- and space-matched, quality-controlled ground radar (GR) data from operational weather radar networks and research radars in numerous U.S. and international locations. The ground and space-based radar measurements, and derivatives thereof (e.g., rain rates, hydrometeor types, drop size distributions) are analyzed through a process of volume matching, and the resulting volume matched and original resolution data are used to evaluate the instrument performance and characteristics of the direct and derived GPM measurements, primarily as they relate to the GPM mission requirements (see Petersen et. al., these proceedings). To date, over 7000 precipitation events sampled coincidentally by ground and space-based radar among 86 distinct ground radar locations have been identified and analyzed for the GPM DPR in the VN data set, for locations ranging from the tropics to Alaska, using the GPM Version 4 (V04A) release. The complete dataset for GPM Version 5 (V05A) is expected to be available and analyzed by the date of this conference. In addition to the GPM-specific data set, the prototype data set of approximately 6600 coincident rain events between TRMM and 22 southeastern U.S. ground radars is available for analysis in the VN database, beginning in August, 2006 through decommissioning of TRMM in mid-2014. A reprocessing of TRMM Precipitation Radar (PR) and TRMM Microwave Imager (TMI) data using GPM-compatible algorithms is expected in 2017, and will become part of the VN data archive at that time. All VN satellite and ground radar data, both original and volume-matched product types, are publically available for download. All VN-era operational versions (6 and 7 for TRMM, V04A for GPM) are available in the archive. A pair of VN Data User’s Manuals (at https://pmm.nasa.gov/science/ground-validation) describes the full contents and volume-match product formats for the prototype and operational VN data sets. VN data and accompanying analysis tools have been used for a variety of applications, including direct validation of GPM instrument measurement requirements, evaluation of effects of GPM algorithm changes in development of new algorithm versions, determination of ground radar calibration and stability within radar networks, and evaluation of GPM’s abilities to detect light and/or shallow precipitation, both rain and snow. The data and available tools support analysis and comparison of radar reflectivity, rain rate, and drop size distribution (DSD) parameters, at time and space scales ranging from individual radar range gates or microwave imager footprint measurements up through summary statistics over the entire data set. This paper will present an updated overview of the GPM Validation Network data sets, the available data analysis and visualization tool set, and access to these data and analysis tools. Examples of the outputs from the various analysis tools will be presented. Comparisons of the original (V04A) and current (V05x) operational data versions and the effects of the GPM DPR V05x recalibration on the DPR comparisons to ground radar will also be shown and summarized.