Abstract. A new free modular software package is described for tracking tropopause
polar vortices (TPVs) natively on structured or unstructured grids. Motivated
by limitations in spatial characterization and time tracking within existing
approaches, TPVTrack mimics the expected dynamics of TPVs to represent their
(1) spatial structure, with variable shapes and intensities, and (2) time
evolution, with mergers and splits. TPVs are segmented from the gridded flow
field into spatial objects as restricted regional watershed basins on the
tropopause, described by geometric metrics, associated over time by overlap
similarity into major and minor correspondences, and tracked along major
correspondences. Simplified segmentation and correspondence test cases
illustrate some of the appeal, sensitivities, and limitations of TPVTrack,
including effective representation of spatial shape and reduced false
positive associations in time. Tracked TPVs in more realistic historical
conditions are consistent in bulk with expectations of life cycle and mean
structure. Individual tracks are less reliable when discriminating among
multiple overlaps. Modifications to track other physical features are
possible, with each application requiring evaluation.