Aircraft observations of thin cirrus clouds near the tropical tropopause

摘要: This work describes aircraft-based lidar observations of thin cirrus clouds at the tropical tropopause in central Pacific obtained during Tropical Ozone Transport Experiment/Vortex Experiment (TOTE/VOTE) December 1995 and February 1996. Thin were found on each four flights which penetrated within 15° equator 200–210 east longitude. South 15°N, detected above aircraft about 65% time that data available. The altitudes these exceeded 18 km times. could be divided into two basic types: quasi-laminar wisps thicker, more textured structures. On basis trajectory analyses temperature histories, types usually formed respectively by (1) situ cooling both a synoptic scale mesoscale (2) recent (a few days) outflow from convection. There is evidence one case thicker can also cooling. actual presence or absence was consistent with convective histories derived back calculations. Notably, any given time, only relatively small portion (at most 25%) west has been influenced convection previous 10 days. structures some strongly resembled long-wavelength (500–1000 km) gravity waves observed nearly simultaneously ER-2 flights. Comparison water vapor profiles made NASA provide observational support for hypothesis play an important role dehydrating tropospheric air as it enters stratosphere.