This document provides a basic set of documentation for the data products available from the GPM Ground Validation System (GVS) Validation Network (VN). In the GPM era the VN performs a direct match-up of GPM’s space-based Dual-frequency Precipitation Radar (DPR) data with ground radar data from the U.S. network of NOAA Weather Surveillance Radar-1988 Doppler (WSR-88D, or “NEXRAD”). Ground radar networks from international partners are also part of the VN. The VN match-up will help evaluate the reflectance attenuation correction algorithms of the DPR and will identify biases between ground observations and satellite retrievals as they occur in different meteorological regimes. Volume 2 of the Validation Network Data User’s Guide describes the GPM core and constellation VN data set. 

An earlier version  of the VN capability performed a match-up of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) data with ground-based radar (GR) measurements from a subset of the WSR-88D sites now included in the GPM-era VN operational radar data network. Legacy TRMM data and their matching GR observations will continue to be part of the VN operations in the GPM era.  Refer to Volume 1 of the Validation Network Data User’s Guide for a description of the legacy TRMM-specific VN data set.

The transition from the Tropical Rainfall Measuring Mission (TRMM) data products to the Global Precipitation Measurement (GPM) mission products has begun. This document specifically addresses the multi-satellite products, the TRMM Multi-satellite Precipitation Analysis (TMPA), the real-time TMPA (TMPA-RT), and the Integrated Multi-satellitE Retrievals for GPM (IMERG).

TRMM is out of fuel and slowly descending. As well, there are some battery issues. The actual demise of TRMM is not the substantive issue. On 7 November 2014 the satellite descended to an altitude that precluded useful TRMM Precipitation Radar data, although the TRMM Microwave Imager (TMI) will function alone, with slowly changing characteristics until the decommissioning, forecast to be in early 2015. The TMI will continue to be used as one of the input satellite data sets for the TMPA and TMPA-RT, but if quality issues arise, its loss would not be a fatal diminution of the microwave data content.

This 17 page flyer provides an overview of the GPM Mission. It describes the technologies used to measure precipitation and the missions scientific goals and societal applications.

Excerpt:

"The Global Precipitation Measurement (GPM) mission is an international partnership co-led by NASA and the Japan Aerospace Exploration Agency (JAXA). The mission centers on the deployment of the GPM Core Observatory and consists of a network, or constellation, of additional satellites that together will provide next-generation global observations of precipitation from space. The GPM Core Observatory will carry an advanced radar/radiometer system and serve as a reference standard to unify precipitation measurements from all satellites that fly within the constellation."

Table of Contents:

• Precipitation Measurement Science
• Global Precipitation Measurement Mission
• GPM Core Observatory
• GMI: GPM Microwave Imager
• DPR: Dual-frequency Precipitation Radar
• Spacecraft Design
• Ground System and Data
• GPM Mission Applications: A Global Understanding for a Better Future

This excerpt from the NASA Earth Observer publication provides and in-depth summary of the Midlatitude Continental Convective Clouds Experiment (MC3E), which took place from April 22nd - June 6th 2011 in central Oklahoma. The overarching goals of the field effort were to provide a complete three-dimensional characterization of precipitation microphysics in the context of improving the reliability of GPM precipitation retrievals over land, and to advance understanding of the primary physical components that form the basis for models that simulate convection and clouds.