The observations of ozone and ozone precursors by the NCAR Electra aircraft and at the LaPorte ground site during the TEXAQS-2000 field program are used in this study to diagnose the emissions and photochemistry within a photochemical forecast model. This model is the coupled MM5 mesoscale and RADM2 photochemical model, and is able to capture important meteorological features at 1.7 km horizontal resolution. The emissions inventory and its impact on ozone production are evaluated by comparing the observations with the model photochemical forecasts for a limited number of emission scenarios.