HR: 0830h
AN: A31C-0051    [PDF]
TI: Tracer Transport in the Atmosphere
AU: * Khushalani, B
EM: bharat@usc.edu
AF: University of Southern California, Dpt of Aerospace Engg, Rapp Research Building,, Los Angeles, CA 90089-1191 United States
AB: Atmospheric tracer transport governed by large scale weather systems in the troposphere and the stratosphere determines global distribution of chemical tracers, ozone and water vapour. Identification of barriers to transport such as tropopause is important to enable understanding of different concentrations of such tracers in different parts of the atmosphere. Understanding the exchange of fluid and transport of fluid particles across oceanic eddies on the other hand is essential for an assessment of distribution of fluid properties such as temperature and salinity. Intergyre transport is dominated by coherent eddies which trap fluid and carry it along with them. The effect of such atmospheric eddies on transport of tracers can be analyzed from geometric point of view offered by dynamical systems theory to study Lagrangian particle dynamics. Point vortex system on a sphere appears as finite dimensional approximation to vorticity evolution, equations of motion of which are derived by substituting delta functions into the vorticity equation. This Hamiltonian system acts as a dynamical model for the motion of concentrated regions of vorticity on a sphere. Stable and unstable manifolds of hyperbolic points are obtained from numerical simulations and KAM tori representing barriers to fluid transport can be identified. We will investigate sharing of fluid by vortex rings and effect of coherent vortices in mesoscale transport in such a three-dimensional geometry and show that transport in this vortex model depends on topology of streamlines. Topology of the advected boundary is governed by time-dependence of advecting flow which is distinguished by isolated regions of closed streamlines bounded by separatrices.
DE: 3220 Nonlinear dynamics
DE: 3230 Numerical solutions
DE: 3399 General or miscellaneous
DE: 4520 Eddies and mesoscale processes
DE: 4808 Chemical tracers
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting