Comparison of RAM model estimates with 1976 St. Louis RAPS measurements of sulfur dioxide

Comparisons of model estimates from the model RAM with SO₂ measurements from 13 Regional Air Pollution Study sites in St. Louis for the year 1976 were made with emphasis on 2nd highest concentrations for the 1-h, 3-h and 24-h averaging times, and also the top 5% of the distribution for 24-h concentrations. Although there is considerable scatter in the comparison of the 2nd highest concentrations, only 9 of 39 data points are outside the bounds of a factor of two and no overall bias is seen, although as the averaging time increases there is more underestimation by the model. Exponential distribution fit the top 5 % of the 24-h concentration distributions for all stations for both estimated and measured concentrations. The distributions for estimated and measured concentrations were judged to match at eight of the thirteen sites.