The GPM Ground Validation NASA S-Band Dual-Polarimetric (NPOL) Doppler Radar Wallops Flight Facility (WFF) dataset consists of rain rate, reflectivity, Doppler velocity, and other radar measurements obtained from the NPOL doppler radar positioned at the Wallops Flight Facility (WFF) in support of the Global Precipitation Mission (GPM). NPOL was developed by scientists at WFF and is a fully transportable and self-contained S-band (10 cm), scanning dual-polarimetric Doppler research radar that was placed near Newark, Maryland between GPM GV missions. Data files are available from December 6, 2013 thru April 28, 2017 in Universal Format (UF), with browse files in PNG format containing images of corrected radar reflectivity, differential reflectivity, specific differential phase, co-polar correlation, and Doppler velocity images. Data are tarred into daily collections of files and zipped for storage and quick download.