This data set consists of measurements of GPS signals reflected from the Earth's surface and collected on an airborne platform. A modified GPS Delay Mapping Receiver (DMR) tracks and measures the direct, line-of-sight, right hand circulary polarized (RHCP) signal of a GPS satellite. It also simultaneously measures the delayed, Earth-reflected, near-specular, LHCP GPS signal. These measurements are ... a form of bistatic radar. The measurements can be used to estimate the surface scattering coefficient and path delays between the direct and reflected GPS signals. Over land, scattering coefficients can be used to estimate changes in surface soil moisture. Over water surfaces, the reflected pulses can be used to sense roughness and derive wind speeds. The bistatic range measurements can also be used to estimate the receiver height above the surface in a form of aircraft altimetry. Data were collected throughout each Meso-cell Study Area (MSA) within the Cold Land Processes Field Experiment (CLPX) Small Regional Study Area (SRSA, 39.5 N-41 N, 105 W-107.5 W). Spatial resolution of these data is variable depending on airborne height and scattering regime (specular or rough). Data were collected 19 and 21 February 2002, and 22-24 February and 25, 30, 31 March 2003. Data are available via FTP.