Lagrangian tracer homogenization and dispersion in a simplified atmospheric GCM

Lagrangian transport in the atmosphere is numerically studied by using a si mplified general circulation model (SGCM) with Newtonian cooling and Raylei gh friction. Long-term Lagrangian behaviour is analyzed by determining hemi spheric and global homogenization times and by studying the time evolution of tracer distributions. At short times, the properties of absolute dispers ion are considered. The tracer dynamics reveals the presence of transport b arriers associated with slow inter-hemispheric and troposphere-stratosphere exchanges, and with a slow crossing of the boundary between the Ferrel and Hadley cells.