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Nonlinear Processes in Geophysics An interactive open-access journal of the European Geosciences Union

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Nonlin. Processes Geophys., 24, 379-392, 2017
https://doi.org/10.5194/npg-24-379-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
25 Jul 2017
Insights into the three-dimensional Lagrangian geometry of the Antarctic polar vortex
Jezabel Curbelo1,2, Víctor José García-Garrido1, Carlos Roberto Mechoso3, Ana Maria Mancho1, Stephen Wiggins4, and Coumba Niang1,5 1Instituto de Ciencias Matemáticas, CSIC-UAM-UC3M-UCM. C/ Nicolás Cabrera 15, Campus de Cantoblanco UAM, 28049 Madrid, Spain
2Departamento de Matemáticas, Facultad de Ciencias, Universidad Autonóma de Madrid, 28049 Madrid, Spain
3Department of Atmospheric and Oceanic Sciences, University of California at Los Angeles, Los Angeles, California, USA
4School of Mathematics, University of Bristol, Bristol BS8 1TW, UK
5Laboratoire de Physique de l'Atmosphere et de l'Ocean Simeon Fongang, Ecole Superieure Polytechnique, Universite Cheikh Anta Diop, 5085, Dakar-Fann, Senegal
Abstract. 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.

Citation: Curbelo, J., García-Garrido, V. J., Mechoso, C. R., Mancho, A. M., Wiggins, S., and Niang, C.: Insights into the three-dimensional Lagrangian geometry of the Antarctic polar vortex, Nonlin. Processes Geophys., 24, 379-392, https://doi.org/10.5194/npg-24-379-2017, 2017.
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Short summary
Lagrangian coherent structures have supported the description of transport processes in fluid dynamics. In this work we use the M function to provide new insights into the 3-D Lagrangian structure of the southern stratosphere. Dynamical systems concepts appropriate to 3-D, such as normally hyperbolic invariant curves, are discussed and applied to describe the vertical extension of the stratospheric polar vortex and its evolution.
Lagrangian coherent structures have supported the description of transport processes in fluid...
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