Stratosphere-troposphere mass exchange estimated from advection-diffusion of a tracer

Isentropic cross-tropopause exchange of mass is diagnosed using a numerically synthesized PV-like tracer that undergoes advection-diffusion driven by meteorological winds. Unlike particle advection methods, this new technique quantifies instantaneous, irreversible mass flux associated with tropopause folds. This eliminates ambiguity in the fluxes associated with the residence time of particles. Furthermore, the technique allows partitioning of the fluxes into two opposing directions. We will describe the distribution of mass fluxes on various isentropic levels in the "middle world" as a function of time (season) and equivalent latitude. The results will be compared with the estimates based on the particle advection methods.