COMPARING PREDICTIONS FROM THE CAL3QHCR AND AERMOD MODELS FOR HIGHWAY APPLICTIONS

摘要

Presented is a comparison of three modeling procedures – CAL3QHCR, AERMOD area, andAERMOD volume – for predicting pollutant concentrations near highways. All are based on theGaussian dispersion equations and are evaluated by contrasting the trends in model predictions.Model trends are depicted for a variety of conditions related to atmospheric stability, wind anglewith respect to the highway, and near-road downwind distances. The models tested providewidely differing prediction trends. Predictions by the CAL3QHCR model at the roadway edgefor crosswind conditions are independent of atmospheric stability; whereas, AERMODpredictions vary significantly by atmospheric stability. AERMOD produced the highestconcentrations at roadside using an area source configuration and the lowest using a volumesource configuration. AERMOD predicts a wider range of concentrations across unstable tostable atmospheric conditions when contrasted with CAL3QHCR. The concentration decaypredicted by AERMOD for convective conditions is virtually identical across a wide range ofatmospheric scaling (Monin-Obukhov lengths of -6.9 to -8888 m).