In this work, we study the Lagrangian footprint of the planetary
waves present in the Southern Hemisphere stratosphere during the exceptional
sudden Stratospheric warming event that took place during September 2002. Our
focus is on constructing a simple kinematic model that retains the
fundamental mechanisms responsible for complex fluid parcel evolution, during
the polar vortex breakdown and its previous stages. The construction of the
kinematic model is guided by the Fourier decomposition of the geopotential
field. The study of Lagrangian transport phenomena in the ERA-Interim
reanalysis data highlights hyperbolic trajectories, and these trajectories are
Lagrangian objects that are the kinematic mechanism for the observed
filamentation phenomena. Our analysis shows that the breaking and splitting
of the polar vortex is justified in our model by the sudden growth of a
planetary wave and the decay of the axisymmetric flow