Validation Testing of New Mechanisms with Outdoor Chamber Data. Volume 2: Analysis of VOC Data for the CB4 and CAL Photochemical Mechanisms

摘要

Ambient hydrocarbon data were analyzed to derive hydrocarbon speciation for use with the Carbon Bond Four (CB4) and the Carter, Atkinson, Lurmann (CAL) mechanisms. A total of 66 city-years of detailed surface-layer hydrocarbon data (comprising 773 individual analyses) was available. A total of 56 hydrocarbon samples collected aloft was also added to the data base. These data were speciated into the carbon fractions for hydrocarbon species in the CB4 and CAL mechanisms. Fractions for each mechanism are reported for each city-year, for five clusters of city years with similar internal composition, and for the total. The five clusters were determined using two forms of cluster analysis. Multiple regression was also used to confirm the overall average carbon fractions. Four analyses of automobile exhaust from the UNC autoexhaust smog chamber study were also speciated. Recommendations for the default carbon fractions for OZIPM4 are given. Selected simulations for both mechanisms are used to demonstrate the effects of HC composition on ozone predictions.