American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article    Cited by

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 98, NO. D12, PAGES 23,013–23,027, 1993

Large-Scale Isentropic Mixing Properties of the Antarctic Polar Vortex From Analyzed Winds

Kenneth P. Bowman

Climate System Research Program, Department of Meteorology, Texas A&M University, College Station


Abstract

Winds derived from analyzed geopotential height fields are used to study quasi-horizontal mixing by the large-scale flow in the lower stratosphere during austral spring. This is the period when the Antarctic ozone hole appears and disappears. Trajectories are computed for large ensembles of particles initially inside and outside the main polar vortex. Mixing and transport are diagnosed through estimates of finite time Lyapunov exponents and Lagrangian dispersion statistics of the tracer trajectories. At 450 K and above prior to the vortex breakdown: Lyapunov exponents are a factor of 2 smaller inside the vortex than outside; diffusion coefficients are an order of magnitude smaller inside than outside the vortex; and the trajectories reveal little exchange of air across the vortex boundary. At lower levels (425 and 400 K) mixing is greater, and there is substantial exchange of air across the vortex boundary. In some years there are large wave events that expel small amounts of vortex air into the mid-latitudes. At the end of the spring season during the vortex breakdown there is rapid mixing of air across the vortex boundary, which is evident in the mixing diagnostics and the tracer trajectories.

Received 29 March 1993; accepted 27 August 1993.

Read Full Article    Cited by

Citation: Bowman, K. P. (1993), Large-Scale Isentropic Mixing Properties of the Antarctic Polar Vortex From Analyzed Winds, J. Geophys. Res., 98(D12), 23,013–23,027.