The GPM Ground Validation Environment Canada (EC) Precipitation Occurrence Sensor System (POSS) GCPEx dataset is comprised of data gathered during the GPM Cold-season Precipitation Experiment (GCPEx), which took place in Ontario, Canada, January 15 - March 1, 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 POSS is a bi-static X-band Doppler radar designed by Environment Canada. The POSS measures a signal whose frequency is proportional to the particle Doppler velocity and whose amplitude is proportional to the particle scattering cross-section. Its measurements can be used to provide information regarding precipitation occurrence, type, rate, and raindrop size distribution.