This study presents a comparative evaluation of prognostic mesoscale meteorological and of photochemical gas/aerosol air quality model predictions with data from the North East Oxidant and Particle Study (NE-OPS) research program over Phildelphia, PA. Model simulations are performed for a two week period from 11th July 1999 00 UTC to 25th July 1999 11 UTC. The MM5 model is applied with 14 layers in the vertical direction and the results are compared with aircraft, wind profiler and RASS data collected during the NE-OPS program. Comparisons with aircraft data indicate that while the temperature values are successfully reproduced by the model, the same cannot be said of the relative humidity values. The virtual temperature profiles predicted by the model compare very well with RASS data while the wind components calculated by the model are only in partial agreement with the wind profiler data.

US EPA's Community Multiscale Air Quality (CMAQ) model, a component of the Models-3 system, and MCNC's Multiscale Air Quality SImulation Platform (MAQSIP) are used to simulate gaseous and aerosol phase air quality dynamics for the same domain. The modal aerosol model included as part of the current release of CMAQ is used in the CMAQ simulations while the dynamic sectional aerosol model developed at the University of Delaware (UDAERO) is adopted in the MAQSIP simulations. The emissions data were processed from the National Emissions Trends (NET) inventory using MCNC's Sparse Matrix Operator Kernel Emissions (SMOKE) modeling system. Fourteen layers in the vertical direction and three levels of nested domains are used, with grid resolution of 36km for the outmost domain, 12km for the intermediate domain and 4km for the innermost domain. The model predictions are compared with chemically and temporally resolved pollutant concentration measurements obtained through the NEOPS study to evaluate the performance of the models in capturing the 3-dimensional regional scale dynamics of ozone and particulate matter.