Insights into the three-dimensional Lagrangian geometry of the Antarctic polar vortex

In this paper we study the three-dimensional (3-D) Lagrangian structures in the stratospheric polar vortex (SPV) above Antarctica. We analyse and visualize these structures using Lagrangian descriptor function M. The procedure for calculation with reanalysis data is explained. Benchmarks are compute...

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Bibliographic Details
Published in:Nonlinear Processes in Geophysics
Main Authors: Curbelo, Jezabel, García-Garrido, Víctor José, Roberto Mechoso, Carlos, Maria Mancho, Ana, Wiggins, Stephen, Niang, Coumba
Format: Article in Journal/Newspaper
Language:English
Published: 2017
Subjects:
Online Access:https://hdl.handle.net/1983/aae187b9-ff68-4eec-92c3-a1012f6a9c6b
https://research-information.bris.ac.uk/en/publications/aae187b9-ff68-4eec-92c3-a1012f6a9c6b
https://doi.org/10.5194/npg-24-379-2017
https://research-information.bris.ac.uk/ws/files/144067798/Full_text_PDF_final_published_version_.pdf
Description
Summary:In this paper we study the three-dimensional (3-D) Lagrangian structures in the stratospheric polar vortex (SPV) above Antarctica. We analyse and visualize these structures using Lagrangian descriptor function M. The procedure for calculation with reanalysis data is explained. Benchmarks are computed and analysed that allow us to compare 2-D and 3-D aspects of Lagrangian transport. Dynamical systems concepts appropriate to 3-D, such as normally hyperbolic invariant curves, are discussed and applied. In order to illustrate our approach we select an interval of time in which the SPV is relatively undisturbed (August 1979) and an interval of rapid SPV changes (October 1979). Our results provide new insights into the Lagrangian structure of the vertical extension of the stratospheric polar vortex and its evolution. Our results also show complex Lagrangian patterns indicative of strong mixing processes in the upper troposphere and lower stratosphere. Finally, during the transition to summer in the late spring, we illustrate the vertical structure of two counterrotating vortices, one the polar and the other an emerging one, and the invariant separatrix that divides them.