Seminars

Lecturer: Simon Alexander, Australian Antarctic Division
Date: 2012-09-27 10:30
Place: Aniara

Interactions between dynamics and clouds in the polar UTLS

Data from a suite of instruments located at Davis, Antarctica (69S, 78E) enable a detailed investigation of dynamics and thin clouds in the upper troposphere and lower stratosphere (UTLS). A vertically-pointing Rayleigh lidar provides observations of tropospheric cirrus clouds and (wintertime) polar stratospheric clouds (PSCs); a Very High Frequency radar resolves the year-round radar tropopause; and vertically-resolved ozone profiles are available from co-located ozonesonde launches. Using these data, I will discuss the sub-diurnal structure and the seasonal variability of the Antarctic radar tropopause. Optically thin cirrus clouds near the tropopause are observed at Davis with the lidar. I will present a case study to illustrate the behaviour of these clouds in relation to the dynamical and chemical structure of the UTLS during a tropopause fold. Orographic gravity waves drive the formation of significant quantities of PSCs in both polar regions above major mountain ranges. Using various satellite data (CALIPSO, MLS, COSMIC), I will illustrate this and demonstrate how a quantification of their effects on increasing PSC occurrence may be made.

Created 2012-08-16 10:24:14 by Uwe Raffalski
Last changed 2012-08-16 10:24:14 by Uwe Raffalski