A Preliminary View of Tropical Cirrus from the CALIPSO Satellite Mission

Tropical cirrus clouds play an important role in the climate system by reducing incoming sunlight from reaching the Earth's surface and by absorbing upwelling infrared radiation emitted by the surface and lower atmosphere. The effects of cirrus extend from local to large scales and can affect the global circulation and the large-scale water budget. Understanding the evolution and the effects of cirrus, however, requires a detailed knowledge of several factors including cloud fraction, height and thickness linked to key environmental variables. The successful launch of the CALIPSO satellite on April 28, 2006, and its subsequent insertion into the A- Train satellite constellation, offers a bold new opportunity to examine the distribution and properties of cirrus. The CALIPSO payload includes a two-wavelength polarization-sensitive lidar, a 3-channel infrared imager tailored for cirrus studies and a visible wide field-of-view camera. This paper will present a preliminary analysis of tropical cirrus observations from the CALIPSO lidar system. Comparisons will be made with passive sensor measurements and retrievals (e.g., MODIS) and other satellite data sets including lidar observations from ICESAT.