Laminar cirrus observed near the tropical tropopause by LITE

The Lidar In-space Technology Experiment (LITE) provided near-global observations of optically thin clouds during a 10-day Space Shuttle mission in September 1994. We report here on layers of cirrus occurring in thin sheets, which we refer to as 'laminar' cirrus, observed near the tropical tropopause. The layers were observed to have thicknesses generally between a few hundred meters and one kilometer and to be unusually homogeneous in the horizontal, with extents of up to 2700 km. Layers were observed near and possibly above the mean tropical tropopause, both in clear air and above intense tropical thunderstorms, but only in the tropics (35 degrees N to 20 degrees S). Thin layers near the tropopause were found to be common, but not pervasive, throughout the tropics including regions characterized by large scale subsidence in the middle troposphere.