Numerical simulation of meteorology for the July 26-30, 1990 ozone episode in the San Joaquin Valley

One of the largest air quality field studies in the United States was conducted in Central California during the summer of 1990. During the intensive measurement periods of this study, meteorological measurements were made at 165 surface and 49 upper air stations. Air quality measurements were made at 150 surface stations as well as from aircraft. Data obtained from this study were analyzed and one of the five captured ozone episodes (August 3-6, 1990) was simulated earlier using MM5. The results of the model were used for the analysis of meteorological fields and inputs to air quality models. In this study, a second episode (July 26-30, 1990) was simulated using the same model with and without the use of FDDA. In addition, two boundary layer processes (TKE and Blackadar) were tested. The model results were evaluated against the rich database of the San Joaquin Valley Air Quality Study. Special attention was given to the predictive capability of the model for the unique meteorological features of the area such as the low-level-jet, Fresno eddy, sea breeze circulation, and slope flows. These meteorological features are believed to play an important role in the formation of elevated ozone concentrations. The results obtained from these simulations were compared with the results obtained from the simulation of the August 3-6, 1990 ozone episode. The meteorological model outputs were also used to prepare meteorological inputs for the SARMAP Air Quality Model.