RELATING METEOROLOGICAL VARIABLES AND TRENDS IN MOTOR-VEHICLE EMISSIONS TO MONTHLY URBAN CARBON-MONOXIDE CONCENTRATIONS

A model which quantifies the relationship between the monthly time ser ies for CO emissions, the monthly time Series in ambient CO concentrat ion, and meteorologically driven dispersion was developed. Fifteen cit ies representing a wide range of geographical and climatic conditions were selected. An eight-year time series (1984-1991 inclusive) of mont hly averaged data were examined in each city. A new method of handling missing ambient concentration values which is designed to calculate c ity-wide average concentrations that follow the trend seen at individu al monitor sites is presented. This method is general and can be used in other applications involving missing data. The model uses emissions estimates along with two meteorological variables (wind speed and mix ing height) to estimate monthly averages of ambient air pollution conc entrations. The model is shown to have a wide range of applicability; it works equally well for a wide range of cities that have very differ ent temporal CO distributions. The model is suited for assessing long- term trends in ambient air pollutants and can also be used for estimat ing seasonal variations in concentration, estimation of trends in emis sions, and for filling in gaps in the ambient concentration record. Co pyright (C) 1996 Elsevier Science Ltd