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Mesosphere–stratosphere transport during Southern Hemisphere autumn deduced from MIPAS observations
Author(s) -
Lahoz W.A.,
Orsolini Y.J.,
Geer A.J.,
Choi W.,
Allen D.R.
Publication year - 2009
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.397
Subject(s) - stratosphere , mesosphere , atmospheric sciences , atmospheric sounding , environmental science , northern hemisphere , latitude , southern hemisphere , climatology , sudden stratospheric warming , methane , depth sounding , atmospheric methane , polar vortex , geology , geodesy , chemistry , organic chemistry , oceanography
Mesosphere – stratosphere transport during Southern Hemisphere autumn (March–June 2003) is studied using a pole‐centred approach of along‐orbit sequences of vertical profiles of methane observations from the Envisat MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) instrument suppl1emented by meteorological analyses from ECMWF and the Met Office. We hypothesize that the methane distribution can be explained as a combination of two transport processes: (1) isentropic transport in the lower mesosphere and upper stratosphere of methane‐rich air from low/mid latitudes to high latitudes during early autumn, and (2) diabatic descent at high latitudes of methane‐poor air from the lower mesosphere during autumn. Calculations of stratospheric effective diffusivity provide broad support for this hypothesis. The along‐orbit data are shown to provide more information than studies using spatial and temporal averages of the same MIPAS methane data, and to explain anomalous features in the methane distribution, where the vertical gradient is reversed, reported by studies using MIPAS and ILAS‐II data. Copyright © 2009 Royal Meteorological Society