Validating the California Puff (CALPUFF) Modelling System Using an Industrial Area in Accra, Ghana as a Case Study

The performance of the California Puff (CALPUFF) modelling system has been evaluated using a case study in Ghana. The performance evaluation consisted of a quantitative comparison of dispersion simulation results of SO2 and NO2 with measurements at the Tema Oil Refinery, and meteorological simulation results with observations from the Tema Meteorological Station, both in the Greater Accra region of Ghana. Four statistical indicators—Index of Agreement (IOA), Fractional Bias (FB), Normalized Mean Square Error (NMSE) and the Pearson correlation coefficient(R) employed in the assessment indicate sufficient reliability of both CALPUFF and its meteorological simulator, CALMET. IOA values of 0.73 and 0.67 and FB values of 1.65 and 1.42 were obtained for SO2 and NO2 respectively. IOA between measured and modelled emissions were 0.72 and 0.69 for SO2 and NO2 respectively. The correlations between the simulated and observed emission were 0.66 and 0.08 for SO2 and NO2 respectively. An IOA value of 0.66 was obtained for both wind speed and wind direction with correlations of 0.29 and 0.58 in comparison with observations from the meteorological station.