Seasonal evolution of winds, atmospheric tides, and Reynolds stress components in the Southern Hemisphere mesosphere-lower thermosphere in 2019

Gunter Stober, DIego Janches, Vivien Matthias, Dave Fritts, John Marino, Tracy Moffat-Griffin, Kathrin Baumgarten, Wonseok Lee, Damian Murphy, Yong Ha Kim, Nicholas Mitchell, Scott Palo

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15 Citations (SciVal)

Abstract

In this study we explore the seasonal variability of the mean winds and diurnal and semidiurnal tidal amplitude and phases, as well as the Reynolds stress components during 2019, utilizing meteor radars at six Southern Hemisphere locations ranging from midlatitudes to polar latitudes. These include Tierra del Fuego, King Edward Point on South Georgia island, King Sejong Station, Rothera, Davis, and Mc- Murdo stations. The year 2019 was exceptional in the Southern Hemisphere, due to the occurrence of a rare minor stratospheric warming in September. Our results show a substantial longitudinal and latitudinal seasonal variability of mean winds and tides, pointing towards a wobbling and asymmetric polar vortex. Furthermore, the derived momentum fluxes and wind variances, utilizing a recently developed algorithm, reveal a characteristic seasonal pattern at each location included in this study. The longitudinal and latitudinal variability of vertical flux of zonal and meridional momentum is discussed in the context of polar vortex asymmetry, spatial and temporal variability, and the longitude and latitude dependence of the vertical propagation conditions of gravity waves. The horizontal momentum fluxes exhibit a rather consistent seasonal structure between the stations, while the wind variances indicate a clear seasonal behavior and altitude dependence, showing the largest values at higher altitudes during the hemispheric winter and two variance minima during the equinoxes. Also the hemispheric summer mesopause and the zonal wind reversal can be identified in the wind variances.

Original languageEnglish
Pages (from-to)1-29
Number of pages29
JournalAnnales Geophysicae
Volume39
Issue number1
DOIs
Publication statusPublished - 7 Jan 2021

Bibliographical note

Funding Information:
Financial support. Diego Janches was supported by the NASA He-liophysics ISFM program. TDF’s operation is supported by NASA SSO, NESC assessment TI-17-01204, and NSF grant AGS1647354. For Nicholas Mitchell and Tracy Moffat-Griffin, this work was supported by the Natural Environment Research Council (grant 25 nos. NE/R001391/1 and NE/R001235/1). Yong Ha Kim and Wonseok Lee are financially supported by the Korea Polar Research Institute. Operation of the Davis meteor radar was supported under the Australian Antarctic Science project. The momentum flux retrievals were developed as part of the ARISE design study (http://arise-project.eu, last access: October 2020) funded by the European Union’s Seventh Framework Programme for Research and Technological Development. Gunter Stober is a member of the Oeschger Center for Climate Change Research.

Funding Information:
Acknowledgements. Gunter Stober acknowledges the helpful discussions within the DFG research unit MS-GWaves. The authors appreciate the invaluable support of the EARG personnel with the operation of TDF. We thank the two anonymous reviewers for their helpful comments.

Publisher Copyright:
© 2021 BMJ Publishing Group. All rights reserved.

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Geology
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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