As we move from the TRMM to GPM era, more emphasis will be placed on precipitation in mid- and high-latitudes. In these areas, a large and highly variable portion of the total annual precipitation is snow. During the winter of 2006-2007, NASA GPM Ground Validation program joined a field campaign designed to measure winter precipitation for the Canadian Cloudsat/CALIPSO validation program (C3VP). GPM's participation was aimed at improving satellite-based snowfall detection and retrieval algorithms. Intensive observations of snowfall using airborne and ground-based instrumentation were conducted centered on the Centre of Atmospheric Research Experiments (CARE) site near Egber, Ontario, Canada (about 80km north of Toronto). In this paper, we will present the progress towards developing a winter precipitation algorithm over land using current satellite observations from AMSU/MHS and CloudSat, and C3VP field campaign data. In addition, we will examine the microwave retrievals of surface emissivity spectra from AMSU and AMSR-E in the summer and winter months under clear sky conditions over C3VP site. The cloud-free atmospheric contribution is calculated from AIRS temperature and humidity profiles, and NWP model reanalysis from GDAS and ECMWF. The land surface temperature from MODIS, GDAS and ECMWF are used for comparison purposes. The differences in the atmospheric contribution due to different inputs of temperature and humidity profiles along with the effect of surface temperature are discussed. The relationship between the land surface emissivity, surface temperature and snow water equivalent in the winter months is also analysed. The potential for using microwave emissivity for precipitation retrievals over land is discussed.