Prediction of daily ozone concentration maxima in the urban atmosphere

Abstract

A model for the prediction of daily O 3 concentration maxima several hours in advance is reported. The model is developed for an urban area of warm oceanic climate and can be easily integrated with automatic pollution and meteorological stations. It provides a basis for issuing advance warnings to the public before O 3 peaks are reached. It also affords straightforward interpretation of the processes leading to O 3 level changes as the predicted O 3 concentrations are directly related to variables with physical meaning. The correlations between O 3 concentrations and other pollutants, e.g. CO, NO, NO 2, SO 2, suspended particles as well as meteorological variables, e.g. wind speed, temperature, relative humidity, rainfall, solar radiation, cloud cover and light intensity, were evaluated prior to the selection of variables for the model. Multiple linear regression with forward stepwise method has defined seasonal, photochemical and persistence components that account for the seasonal influence of O 3 production, the relations between O 3 and NO x , and previous day O 3 levels, respectively. The model was calibrated using data collected over a period of two years and its performance for prediction was evaluated by calculation of the daily O 3 concentration maxima over the subsequent two years and comparing the predictions to measured values.