We have developed a global, atmospheric chemistry model that includes both a prognostic troposphere and stratosphere. The model, named IMPACT, can be driven either by assimilated meteorological fields or meteorological fields from a general circulation model. The model includes the necessary physics and chemistry to realistically simulate emissions, chemical transformation, deposition, advection, convection, and other processes.

Here we use assimilated meteorological fields from the NASA/DAO office to simulate the time period April 1 to October 31, 2001. We compare ozone fluctuations to observations. By analyzing the upwind and overhead influence we investigate the amount of ozone that is formed locally (in-situ) photochemically versus that transported in either vertically (from the upper troposphere/lower stratosphere) or horizontally (from upwind locations). We further investigate the sensitivity of ozone levels in Phoenix to a variety of factors.