Ozone and water vapour in the austral polar stratospheric vortex and sub-vortex

Abstract

Abstract. In-situ measurements of ozone and water vapour, in the Antarctic lower stratosphere, were made as part of the APE-GAIA mission in September and October 1999. The measurements show a distinct difference above and below the 415 K isentrope. Above 415 K, the chemically perturbed region of low ozone and water vapour is clearly evident. Below 415 K, but still above the tropopause, no sharp meridional gradients in ozone and water vapour were observed. The observations are consistent with analyses of potential vorticity from the European Centre for Medium Range Weather Forecasting, which show smaller radial gradients at 380 K than at 450 K potential temperature. Ozone loss in the chemically perturbed region above 415 K averages 5 ppbv per day for mid-September to mid-October. Apparent ozone loss rates in the sub-vortex region are greater, at 7 ppbv per day. The data support, therefore, the existence of a subvortex region in which meridional transport is more efficient than in the vortex above. The low ozone mixing ratios in the sub-vortex region may be due to in-situ chemical destruction of ozone or transport of ozone-poor air out of the bottom of the vortex. The aircraft data we use cannot distinguish between these two processes.

Morphology of the tropopause layer and lower stratosphere above a tropical cyclone: a case study on cyclone Davina (1999)

“…with masses equivalent to spherical diameters greater that 1.5 µm. Water vapour was measured by the FLASH instrument, an aircraft version of an instrument already deployed on balloons (Yushkov et al, 1998;Peet et al 2004). While outside of clouds the two instruments give the same result, comparison of the two instruments in clouds gives the amount of condensed water.…”