Stratospheric background aerosol and polar cloud observations by laser backscattersonde within the framework of the European project "Stratospheric Regular Sounding"

摘要

The Stratospheric Regular Sounding projectwas planned to measure regularly the vertical profiles of several tracers likeozone, water vapor, NO_x, ClO_x and BrO_xradicals, aerosol, pressure and temperature, at three latitudes, to discriminatebetween the transport and photochemical terms which control their distribution.As part of this project, the "Istituto di Fisica dell'Atmosfera"launched nine laser backscattersondes (LABS) on board stratospheric balloons tomake observations of background aerosol and PSCs. LABS was launched with anoptical particle counter operated by the University of Wyoming. Observationshave been performed in the arctic, mid-latitudes and tropical regions indifferent seasons. Polar stratospheric clouds have been observed in areas insideand outside the polar vortex edge. A background aerosol was observed both inmid-latitudes and in arctic regions with a backscattering ratio of 1.2 at 692nm. Very stratified aerosol layers, possibly transported into the lowerstratosphere by deep convective systems, have been observed in the lowerstratosphere between 20 and 29 km in the tropics in the Southern Hemisphere.Key words. Atmospheric composition and structure(aerosols and particles; middle atmosphere – composition and chemistry;instruments and techniques)