This data set includes ground-based radar observations carried out at the Fraser Experimental Forest Headquarters, Colorado, USA (39.95 N, 105.9 W), between 17-26 February and 26-30 March 2003. Truck-mounted L- and Ku-band scatterometers were used to collect fully polarimetric backscattering coefficients of snow. The calibrated radar systems measured the amplitude and phase of backscattered signal ... over a relatively wide bandwidth at L-band (1.1-1.4 GHz) and Ku-band (15.25-15.75 GHz). Backscatter measurements of an open snow pack were collected at three different incidence angles (20, 35, and 50 degrees) several times a day. This data set is part of the NASA Cold Land Processes Field Experiment (CLPX). The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.