Expanding the horizons of the Visibility Assessment Scoping Model (VASM)

摘要

The Visibility Assessment Scoping Model (VASM) has successfully simulated seasonal distributions of hourly visual impairment, or haziness, that compare favorably with observations for both relatively polluted eastern sites and relatively pristine western sites in the US. The VASM approach combines regional modeling of seasonal mean concentrations of key anthropogenic particle species with Monte Carlo statistical techniques using past monitoring data and relative humidity (RH) climatology. The Monte Carlo method requires as input the seasonal geometric mean and standard deviation of daily concentrations of six particle species: sulfate, nitrate, organic carbon, elemental carbon, and dust in the fine particle mode, and dust in the coarse particle mode. In addition, the Monte Carlo method uses inter-species seasonal correlations of daily concentrations, RH climatology (seasonal means, standard deviations of daily averages, and typical diurnal patterns), and predicted future mean seasonal concentrations for one or more particle species.