Evaluation of a Data Assimilation Technique for a Mesoscale Meteorological Model Used for Air Quality Modeling

Abstract

Abstract An observational data assimilation (ODA) technique was evaluated based on both its direct effect on meteorological model fields and its indirect effect on the results of two air quality models that input these meteorological fields: a Lagrangian particle model (LPM) and a photochemical model, the variable-grid version of the Urban Airshed Model (UAM-V). The purpose was to investigate the model performance improvements that are derived from using field-study observations with an ODA technique. The ODA technique, based upon Newtonian relaxation, was incorporated into the Colorado State University Regional Atmospheric Modeling System (RAMS). The technique was applied with rawinsonde, profiler, and sodar observations of winds, temperature, and moisture from an intensive field campaign during 3–7 August 1990 over the San Joaquin Valley in California. The RAMS meteorological fields, produced with and without the use of the ODA technique, and the results from the two air quality models using these two f...