This sequence of three images in northern Colorado was taken by NASA's Airborne Synthetic Aperture Radar (AirSar) for the joint NASA-National Oceanic and Atmospheric Administration Cold Land Processes Experiment. The images were produced from data acquired on February 19, 21 and 23, 2002 (top to bottom), and demonstrate the effects of snow on the radar backscatter at different frequencies. The images are centered at 40 degrees north latitude and 106 degrees west longitude, 12 kilometers (7.5 miles) west of the town of Fraser. The colors red, green and blue indicate the relative total power of the radar backscatter at P-, L-, and C-bands, respectively.

The top image was acquired before snowfall; the middle image was acquired the morning after the snow. When the snow melted, the most prominent changes were visible and can be seen in the bottom image. In this image, melting snow allows less of the radar signal to backscatter and some features appear darker.

The Cold Land Processes Experiment is a multi-year experiment to study how snow processes work and how snow-covered areas affect weather and climate. Fraser, Colo., is one of three study areas in northern Colorado and southern Wyoming providing ideal natural laboratories for snow research.

AirSar flies aboard a NASA DC-8 based at NASA's Dryden Flight Research Center, Edwards, Calif. Built, operated and managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., AirSar is part of NASA's Earth Science Enterprise program. JPL is a division of the California Institute of Technology in Pasadena.