LAMINAR CIRRUS OBSERVED NEAR THE TROPICAL TROPOPAUSE BY LITE

The Lidar In-space Technology Experiment (LITE) provided near-global o bservations of optically thin clouds during a 10-day Space Shuttle mis sion in September 1994. We report here on layers of cirrus occurring i n thin sheets, which we refer to as 'laminar' cirrus, observed near th e tropical tropopause. The layers were observed to have thicknesses ge nerally between a few hundred meters and one kilometer and to be unusu ally homogeneous in the horizontal, with extents of up to 2700 km. Lay ers 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 t ropopause were found to be common, but not pervasive, throughout the t ropics including regions characterized by large scale subsidence in th e middle troposphere.