Interannual variability of winds in the Antarctic mesosphere and lower thermosphere over Rothera (67°S, 68°W) during 2005-2021 in meteor radar observations and WACCM-X

Phoebe E. Noble, Neil P. Hindley, Corwin James Wright, Chihoko Y. Cullens, Nicholas Pedatella, Scott England, Nicholas J. Mitchell, Tracy Moffat-Griffin

Research output: Contribution to journalArticlepeer-review

Abstract

The mesosphere and lower thermosphere (MLT) plays a critical role in linking the middle and upper atmosphere. However, many General Circulation Models do not model the MLT and those that do remain poorly constrained. We use long-term meteor radar observations (2005–2021) from Rothera (67°S, 68°W) on the Antarctic Peninsula to evaluate the Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCM-X) and investigate interannual variability. We find some significant differences between WACCM-X and observations. In particular, at upper heights, observations reveal eastwards wintertime (April–September) winds, whereas the model predicts westwards winds. In summer (October–March), the observed winds are northwards but predictions are southwards. Both the model and observations reveal significant interannual variability. We characterize the trend and the correlation between the winds and key phenomena: (a) the 11-year solar cycle, (b) El Niño Southern Oscillation, (c) Quasi-Biennial Oscillation and (d) Southern Annular Mode using a linear regression method. Observations of the zonal wind show significant changes with time. The summertime westwards wind near 80 km is weakening by up to 4–5 ms−1 per decade, whilst the eastward wintertime winds around 85–95 km are strengthening at by around 7 ms−1 per decade. We find that at some times of year there are significant correlations between the phenomena and the observed/modeled winds. The significance of this work lies in quantifying the biases in a leading General Circulation Model and demonstrating notable interannual variability in both modeled and observed winds.
Original languageEnglish
Article numbere2023JD039789
JournalJournal of Geophysical Research : Atmospheres
Volume129
Issue number4
Early online date21 Feb 2024
DOIs
Publication statusPublished - 28 Feb 2024

Data Availability Statement

Data for F10.7 is provided by (Government of Canada, 2022). Data for ENSO comes from Nino 3.4 index, Trenberth (2022). QBO indices from ERA5 reanalysis, Copernicus Climate Change Service (2022), and the SAM from Marshall (2018). The meteor radar data used in this work is from Mitchell (2021). The WACCM-X data is available alongside the code and processed meteor radar data at Noble (2023).

Keywords

  • Antartica
  • linear regression
  • long term
  • mesosphere
  • meteor radar
  • remote sensing

ASJC Scopus subject areas

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

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