Document Type

Article

Publication Date

2013

DOI

10.5194/acpd-13-729-2013

Publication Title

Atmospheric Chemistry and Physics Discussions

Volume

13

Pages

729-763

Abstract

Observations of the mesospheric semi-annual oscillation (MSAO) in the equatorial region have been reported dating back several decades. Seasonal variations in both species densities and airglow emissions are well documented. The extensive observations available offer an excellent case study for comparison with model simulations. The broad range of measurements is summarised with emphasis on the 80 to 100 km region. Photochemical model simulations are described for near-equinox and near solstice conditions, the two lines with notable differences in the observed MSAO parameters. Diurnal tides are included in order to facilitate comparisons of observations made at different local times. The roles of water vapour as the "driver" species and ozone as the "response" species are examined to test for consistency between the model results and observations. The model simulations suggest the interactions between eddy mixing and background vertical advection play a significant role in the MSAO phenomenon. At the equator, 90km altitude, the derived eddy mixing rate is approximately 1X 106cm2s-1 and vertical advection 0.8 cms-1. For April the corresponding values are 4 X 105cms-1 and 0.1 cms-1.

Rights

© 2013 The Authors.

Published under the terms of a Creative Commons Attribution 3.0 Unported (CC BY 3.0) License.

Original Publication Citation

Gattinger, R. L., Kyrölä, E., Boone, C. D., Evans, W. F. J., Walker, K. A., McDade, I. C., Bernath, P. F., & Llewellyn, E. J. (2013). Water vapour and the equatorial mesospheric semi-annual oscillation (MSAO). Atmospheric Chemistry and Physics Discussions, 13, 729-763. https://doi.org/10.5194/acpd-13-729-2013

ORCID

0000-0002-1255-396X (Bernath)

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