Interannual Variability of the 12-hr Tide in the Mesosphere and Lower Thermosphere in 15 Years of Meteor-Radar Observations Over Rothera (68°S, 68°W)

Shaun M. Dempsey, Phoebe E. Noble, Corwin J. Wright, Nicholas J. Mitchell, Tracy Moffat-Griffin

Research output: Contribution to journalArticlepeer-review

1 Citation (SciVal)


The solar tides of the mesosphere and lower thermosphere (MLT) show great variability on time scales of days to years, with significant variability at interannual time scales. However, the nature and causes of this variability remain poorly understood. Here, we present measurements made over the interval 2005–2020 of the interannual variability of the 12-hr tide as measured at heights of 80–100 km by a meteor radar over Rothera (68°S, 68°W). We use a linear regression analysis to investigate correlations between the 12-hr tidal amplitudes and several climate indices, specifically the solar cycle (as measured by F10.7 solar flux), El Niño Southern Oscillation (ENSO), the Quasi-Biennial Oscillation (QBO) at 10 and 30 hPa and the Southern Annular Mode (SAM). Our observations reveal that the 12-hr tide has a large amplitude and a clearly defined seasonal cycle with monthly mean values as large as 35 m s−1. We observe substantial interannual variability, with monthly mean 12-hr tidal amplitudes at 95 km exhibiting a two standard-deviation range (2σ) in spring of 13.4 m s−1, 11.2 m s−1 in summer, 18.6 m s−1 in autumn, and 7.0 m s−1 in winter. We find that F10.7, QBO10, QBO30, and SAM all have significant correlations to the 12-hr tidal amplitudes at the 95% level, with a linear trend also present. Whereas we detect very minimal correlation with ENSO. These results suggest that variations in F10.7, the QBO and SAM may contribute significantly to the interannual variability of 12-hr tidal amplitudes in the Antarctic MLT.

Original languageEnglish
Article numbere2022JD036694
JournalJournal of Geophysical Research: Atmospheres
Issue number22
Early online date6 Nov 2022
Publication statusPublished - 27 Nov 2022

Bibliographical note

Funding Information:
SMD and PEN are supported by a NERC GW4+ Doctoral Training Partnership studentship from the Natural Environment Research Council (Grant for SMD: NE/L002434/1 and PEN: NE/S007504/1) and are thankful for the support and additional training provided. TMG, CJW, and NJM are supported by the UK Natural Environment Research Council (Grants NE/R001391/1 and NE/R001235/1) and Royal Society University Research Fellowship URF\R\221023.


  • interannual variability
  • MLT tides

ASJC Scopus subject areas

  • Geophysics
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


Dive into the research topics of 'Interannual Variability of the 12-hr Tide in the Mesosphere and Lower Thermosphere in 15 Years of Meteor-Radar Observations Over Rothera (68°S, 68°W)'. Together they form a unique fingerprint.

Cite this