Lobe dynamics applied to barotropic Rossby-wave breaking

• Main Authors: Koh, Tieh Yong., Plumb, R. Alan.
• Format: Article
• Language: English
• Published: 2012
• Subjects: DRNTU::Science::Geology
• Online Access: https://hdl.handle.net/10356/94017; http://hdl.handle.net/10220/8223
• Institution: Nanyang Technological University

We applied the methods of lobe dynamics to the problem of transport across the edge of a barotropic vortex patch. The model used captures the essential dynamics of filament shedding in the wintertime stratospheric polar vortex. Two approaches were adopted for the problem: (1) the dominant periodic component of the vortical flow was identified and conventional lobe dynamics methods for periodic dynamical systems were applied to it; (2) the full aperiodic, dynamically consistent flow was retained and a modified brand of lobe dynamics was used to quantify the transport. Our results show that in the periodic case, much reversible transport occurs across the lobe dynamical boundary due to overlapping intruding and extruding lobes. In the aperiodic case, a small amount of intrusion was noted, contrary to the well-established fact that potential vorticity shedding in barotropic vortices is uniquely outwards. In our discussion, we argue that while lobe dynamics provides a rigorous framework for quantifying transport across the lobe dynamical boundary, this boundary may not be appropriate for quantifying transport across internal transport barriers, such as the stratospheric polar vortex edge.