CALIPSO-measurement of clouds

The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) will be part of the “A-Train” constellation of Earth Observing satellites. CALIPSO will provide cloud and aerosol profiles, data important for climate research and the prediction of future climates. CALIPSO will carry its own laser light source as part of its instrument called Lidar. Lidar, is an acronym for Light Detection And Ranging, which is the optical analog of Radar. It has become a powerful technique for measuring atmospheric constituents like aerosols, clouds, and gases. CALIPSO will make elastic backscatter measurements in three channels; 1064 nm and 532 nm wavelengths, and a depolarization channel at 532 nm. The depolarization measurements of CALIPSO will help determine if clouds contain liquid droplets or ice crystals.

Future spaceborne lidars will use the Differential Absorption Lidar (DIAL) technique to make gaseous measurements, for example, by using wavelengths on and off absorption features of gases like water vapor. Over the last 40 years, lidars have contributed important measurements in chemical and biological detection and identification, due to their specificity, accurate range and real-time remote sensing detection capabilities. In Earth orbit, lidars permit measurements with high vertical resolution in the troposphere.