Influence of the temperature of the lower subtropical stratosphere on the Antarctic polar vortex dynamics
V.V. Zuev1, I.V. Borovko2,3, V.N. Krupchatnikov2,3,4, E.S. Savelieva1
1Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia
2Institute of Computational Mathematics and Mathematical Geophysics of the Siberian Branch of the RAS, Novosibirsk, Russia
3Siberian Regional Hydrometeorological Research Institute, Novosibirsk, Russia, Novosibirsk, Russia
4National Research Novosibirsk State University, Novosibirsk, Russia
Keywords: антарктический полярный вихрь, субтропическая стратосфера, полярные озоновые аномалии, Antarctic polar vortex, subtropical stratosphere, polar ozone depletion
Abstract
The stratospheric polar vortex persistence in the winter-spring period is one of key factors of the duration and extent of stratospheric ozone depletion in a polar region. The Arctic polar vortex reaches its peak intensity in winter, whereas the Antarctic vortex usually strengthens in early spring. As a result, the strong ozone depletion is observed every year from August to November over the Antarctic, while short-term ozone loss occasionally occurs over the Arctic from January to March. In this work, we examine the reason for the high strength and persistence of the Antarctic polar vortex in the winter-spring period. Based on the ERA-Interim reanalysis data, we show a high agreement between the seasonal variations in the temperature in the lower subtropical stratosphere and zonal wind in the subpolar and polar lower stratosphere in the Southern Hemisphere. The results of numerical simulations using PlaSim-ICMMG-1.0 show acceleration of zonal wind in the subpolar region with an increase in the temperature of the subtropical stratosphere. Thus, the winter-spring strengthening of the Antarctic polar vortex occurs due to an increase in the stratospheric equator-to-pole temperature gradient as a result of the seasonal temperature growth in the lower subtropical stratosphere in this period.
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