Unusual quasi 10‐day planetary wave activity and the ionospheric response during the 2019 Southern Hemisphere sudden stratospheric warming

Wang, J.C.; Palo, S.E.; Forbes, J.M.; Marino, J.; Moffat-Griffin, T. ORCID: https://orcid.org/0000-0002-9670-6715; Mitchell, N.J.. 2021 Unusual quasi 10‐day planetary wave activity and the ionospheric response during the 2019 Southern Hemisphere sudden stratospheric warming. Journal of Geophysical Research: Space Physics, 126 (6), e2021JA029286. https://doi.org/10.1029/2021JA029286

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Abstract/Summary

An unusual sudden stratospheric warming (SSW) event occurred in the Southern Hemisphere in September 2019. Ground-based and satellite observations show the presence of transient eastward- and westward-propagating quasi-10 day planetary waves (Q10DWs) during the SSW. The planetary wave activity maximizes in the mesosphere and lower thermosphere region approximately 10 days after the SSW onset. Analysis indicates that the westward-propagating Q10DW with zonal wave number s = 1 is mainly symmetric about the equator, which is contrary to theory which predicts the presence of an antisymmetric normal mode for such planetary wave. Observations from microwave limb sounder and sounding of the atmosphere using broadband emission radiometry are combined with meteor radar wind measurements from Antarctica, providing a comprehensive view of Q10DW wave activity in the Southern Hemisphere during this SSW. Analysis suggests that the Q10DWs of various wavenumbers are potentially excited from nonlinear wave-wave interactions that also involve stationary planetary waves with s = 1 and s = 2. The Q10DWs are also found to couple the ionosphere with the neutral atmosphere. The timing of the quasi-10-day oscillations (Q10DOs) in the ionosphere are contemporaneous with the Q10DWs in the neutral atmosphere during a period of relatively low solar and geomagnetic activity, suggesting that the Q10DWs play a key role in driving the ionospheric Q10DOs during the Southern SSW event. This study provides observational evidence for coupling between the neutral atmosphere and ionosphere through the upward propagation of global scale planetary waves.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1029/2021JA029286
ISSN:	2169-9380
Date made live:	12 Jun 2021 06:10 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/530499

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