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Large-scale isentropic mixing properties of the Antarctic polar vortex from analyzed windsWinds 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.
Document ID
19950049222
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Bowman, Kenneth P.
(Texas A & M University College Station, TX, United States)
Date Acquired
August 16, 2013
Publication Date
December 20, 1993
Publication Information
Publication: Journal of Geophysical Research
Volume: 98
Issue: D12
ISSN: 0148-0227
Subject Category
Meteorology And Climatology
Accession Number
95A80821
Funding Number(s)
CONTRACT_GRANT: NAGW-992
Distribution Limits
Public
Copyright
Other

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