Preprints
https://doi.org/10.5194/wcd-2021-70
https://doi.org/10.5194/wcd-2021-70

  19 Oct 2021

19 Oct 2021

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

Characteristics of long-track tropopause polar vortices

Matthew T. Bray and Steven M. Cavallo Matthew T. Bray and Steven M. Cavallo
  • School of Meteorology, University of Oklahoma, 120 David L Boren Blvd., Norman, OK

Abstract. Tropopause polar vortices (TPVs) are closed circulations centered on the tropopause that form and predominately reside in high latitudes. Due to their attendant flow, TPVs have been shown to influence surface weather features, and thus, a greater understanding of the dynamics of these features may improve our ability to forecast impactful weather events. In this study, we focus on the subset of TPVs which have lifetimes of longer than two weeks (the ninety-fifth percentile of all TPV cases between 1979 and 2018); these long-lived vortices offer a unique opportunity to study the conditions under which TPVs strengthen and analyze patterns of vortex formation and movement. Using ERA-Interim data, along with TPV tracks derived from the same reanalysis, we investigate the formation, motion, and development of these long-lived vortices. We find that these long-track TPVs are significantly stronger, occur more often in the summer, and tend to remain more poleward than an average TPV. Similarly, these TPVs are shown to form at higher latitudes than average. Long-lived TPVs form predominately by splitting from existing vortices, but a notable minority seem to generate via dynamic processes in the absence of pre-existing TPVs. These non-likely split genesis events are found to occur in select geographic regions, driven by Rossby wave growth and breaking. Notable differences emerge between the lifecycles of long-lived vortices in the summer and winter, specifically with regards to equatorward progression and amplitude. These long-lived TPVs also appear as likely as any TPV to exit the Arctic and move into the mid-latitudes, though this often occurs late in the vortex lifetime, immediately preceding vortex lysis in most cases.

Matthew T. Bray and Steven M. Cavallo

Status: open (until 02 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Matthew T. Bray and Steven M. Cavallo

Matthew T. Bray and Steven M. Cavallo

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Short summary
Tropopause polar vortices (TPVs) are a high-latitude atmospheric phenomenon that impact weather inside and outside of polar regions. Using a set of long-lived TPVs to gain insight into the conditions that are most supportive of TPV survival, we describe patterns of vortex formation and movement. In addition, we analyze the characteristics of these TPVs and how they vary by season. These results help us to better understand TPVs which, in turn, may improve forecasts of related weather events.