Total ozone and tropopause zonal asymmetry during the Antarctic spring

Analysis of zonal anomalies in total ozone and thermal tropopause height shows that ozone depletion during austral spring has a strong influence on the height and sharpness of the tropopause over West Antarctica. The seasonal change of tropopause peak height occurs between 9 km (summer and autumn) and 13-14 km (winter and spring) over the Weddell Sea region, and in the range of 9-10 km at opposite longitudes in the Australian sector. Elevation of the tropopause is explained by low stratospheric temperature due to the seasonal temperature minimum in winter and ozone losses in spring. Accordingly, tropopause zonal asymmetry is determined by strong east-west asymmetry of the surface temperatures in the winter and total ozone asymmetry in spring. Lowering of the elevated tropopause over the boundary of the Antarctic continent is explained by the influence of the cold continental troposphere both in winter and spring. Overall, this work reports some details of relative contribution of radiative (strong cooling of the lower stratosphere and continental troposphere) and dynamical (quasi-stationary planetary wave 1 in total ozone) processes to the Antarctic tropopause formation. The sloping meridional profile of the tropopause and widening of the transition layer between the troposphere and stratosphere over West Antarctica suggest the possibility of enhanced air mixing not only vertically but also horizontally. This may contribute to the east-west asymmetry in Antarctic climate change.