The project will develop quantitative tools to analyze the large-scale tracer transport in both models and the atmosphere. Numerical models of atmospheric chemistry and transport are being increasingly used to understand the interactions between various atmospheric regions, e.g., between troposphere and stratosphere, and the Tropics and midlatitudes. Since trace gases do not directly impact atmospheric motion, they reveal the movement of air parcels. The climatological pathways of the air parcels and the dynamical mechanisms determining the pathways are not known with great certainty at this time. Dr. Bowman will develop a diagnostic tool for analyzing tracer transport, by estimating the Green's (or influence) function for the tracer conservation equation. Dr. Bowman will construct this function from particle trajectories computed from observed (reanalysis) and NCAR Community Climate Model simulated winds. Bowman's project is unique in view of its focus on transport dynamics of the troposphere (as opposed to the stratosphere).