Preprints
https://doi.org/10.5194/acp-2021-676
https://doi.org/10.5194/acp-2021-676

  10 Sep 2021

10 Sep 2021

Review status: this preprint is currently under review for the journal ACP.

Evolution of the stratospheric polar vortex edge intensity and duration in the Southern hemisphere over the 1979–2020 period

Audrey Lecouffe, Sophie Godin-Beekmann, Andrea Pazmiño, and Alain Hauchecorne Audrey Lecouffe et al.
  • LATMOS/IPSL, UVSQ, Sorbonne Université, CNRS, Paris, France

Abstract. The intensity and position of the Southern Hemisphere stratospheric polar vortex edge is evaluated as a function of equivalent latitude over the 1979–2020 period on three isentropic levels (475 K, 550 K and 675 K) from ECMWF ERA-Interim reanalysis. The study also includes an analysis of the onset and breakup dates of the polar vortex, which are determined from wind thresholds (e.g. 15.2 m.s−1, 20 m.s−1and 25 m.s−1) along the vortex edge. The vortex edge is stronger in late winter, over September–October – November with the period of strongest intensity occurring later at the lowermost level. A lower variability of the edge position is observed during the same period. Long-term increase of the vortex edge intensity and break-up date is observed over the 1979–1999 period, linked to the increase of the ozone hole. Long-term decrease of the vortex onset date related to the 25 m.s−1wind threshold is also observed at 475 K during this period. The solar cycle and to a lower extent the quasi-biennal oscillation (QBO) and El Niño Southern Oscillation (ENSO) modulate the inter-annual evolution of the strength of the vortex edge and the vortex breakup dates. Stronger vortex edge and longer vortex duration is observed in solar minimum (minSC) years, with the QBO and ENSO further modulating the solar cycle influence, especially at 475 K and 550 K: during West QBO (wQBO) phases, the difference between vortex edge intensity for minSC and maxSC years is smaller than during East QBO (eQBO) phases. The polar vortex edge is stronger and lasts longer for maxSC/wQBO years than for maxSC/eQBO years. ENSO has a weaker impact but the vortex edge is somewhat stronger during cold ENSO phases for both minSC and maxSC years.

Audrey Lecouffe et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-676', Anonymous Referee #1, 08 Oct 2021
  • RC2: 'major revisions required', Anonymous Referee #2, 20 Oct 2021

Audrey Lecouffe et al.

Audrey Lecouffe et al.

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Short summary
This study uses a model developped in France at LATMOS to analyse the behavior of the Antarctic polar vortex from 1979 to 2020. We have found that the edge intensity of the polar vortex is higher at the end of the winter, while its edge position is less extended during this period. The polar vortex is stronger and last longer during solar maximum years. Breakup date of the vortex is link to the ozone hole and maximum wind speed.
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