A model to estimate mixing height and its effects on ozone modeling

A mixing height estimation model (PMH) whose output can be used in air quality models, especially the Urban Airshed Model (UAM-IV), is developed. The evaluation of the performance of the PMH shows that the predictions match the observations very well. The average geometric mean of the predicted to observed hourly mixing height ratios is equal to 0.99. The outputs of the PMH along with those of the mixing height model incorporated in the UAM-IV package (RAMMETX) are used in the UAM-IV to simulate hourly average concentrations of tropospheric ozone (O3) in the Indianapolis metropolitan statistical area (MSA). A comparative study performed to assess the effects of mixing height shows that the UAM-IV performs better when the mixing height fields are from the PMH. For example, the episodic mean of the average normalized bias and the average normalized absolute bias of predicted to observed O3 concentrations are 1.2% and 18.6%, respectively, when the mixing height fields are from the PMH. They are 6.6% and 20.1%, respectively, when the mixing height fields are from RAMMETX.