The GPM Ground Validation NASA Micro Rain Radar (MRR) GCPEx dataset was collected by a Micro Rain Radar (MRR), which is a vertically pointing Doppler radar which provides measurements of vertical velocity, drop size distribution, rainfall rate, attenuation, liquid water content, and reflectivity factor obtained during the GPM Cold-season Precipitation Experiment (GCPEx), which took place in Canada during Winter 2011-2012. GCPEx addressed shortcomings in the GPM snowfall retrieval algorithm by collecting microphysical properties, associated remote sensing observations, and coordinated model simulations of precipitating snow. The MRR is a frequency-modulated continuous wave (FMCW) vertically pointing Doppler radar, which operates at 24.24GHz, and it is the second generation of the instrument manufactured by METEK (http://metek.de/product/mrr-2/). NASA MRR data was collected from late October 2011 through March 2013. Version 2 of the dataset became active on 13-May-2015.