The GPM Ground Validation Airborne Second Generation Precipitation Radar (APR-2) GCPEx dataset was collected during the GPM Cold-season Precipitation Experiment (GCPEx), which occurred in Ontario, Canada during the winter season of 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 Second Generation Airborne Precipitation Radar (APR-2) is a dual-frequency (13 GHz and 35 GHz), Doppler, dual-polarization radar system. It has a downward looking antenna that performs cross track scans, covering a swath that is +/- 25 degrees to each side of the aircraft path. Additional features include: simultaneous dual-frequency, matched beam operation at 13.4 and 35.6 GHz (same as GPM Dual-Frequency Precipitation Radar), simultaneous measurement of both like- and cross-polarized signals at both frequencies, Doppler operation, and real-time pulse compression (calibrated reflectivity data can be produced for large areas in the field during flight, if necessary). The APR-2 flew aboard the NASA DC-8 for the GPM Cold-season Precipitation Experiment (GCPEx) from 11 January to 25 February, 2012.