Accuracy of ozone air quality forecasts in the Baltimore Metropolitan area

Current photochemical model results suggest that large emissions reductions will be required to meet the National Air Quality Standard (NAAQS) for ozone (03) in the northeastern United States. One approach to achieving these reductions is by instituting episodic controls during forecasted high 03 events. In order to be successful, these episodic controls must be accompanied by a viable forecasting program. This paper reports O3 forecasting results from the 1994 and 1995 summer seasons in the Baltimore metropolitan area. The forecasts are based on a meteorological regression algorithm using surface and upper air measurements and subjective forecaster analyses. The results show that short range (12-24 h) forecasts are successful in predicting multi-day severe high 03 events and low 03 cases but is less successful in forecasting isolated (single day) high 03 events. Uncertainty in the forecasts are related to poor forecasts of sky conditions, local wind conditions and lack of knowledge of boundary advection of 03 and its precursors.