Application of a mesoscale atmospheric dispersion modeling system to the estimation of SO 2 concentrations from major elevated sources in Southern Florida

Abstract

Estimates of maximum ground-level concentrations of SO 2 due to anthropogenic emissions have been made for two National Park Service management areas in southern Florida as part of an interdisciplinary biological effects study for these areas. The nearest major sources of SO 2 are located at least 60 km away on the southern Florida coast so that mesoscale atmospheric transport must occur for the receptor areas to be affected by these sources. A mesoscale atmospheric dispersion modeling system consisting of a three-dimensional mesoscale meteorological model and a three-dimensional Lagrangian particle dispersion model were employed to make the estimates for a realistic worst-case summer meteorological scenario. The temporal and spatial variations of the meteorological fields resulting from the interaction of sea and land breezes with the synoptic flow were simulated with the meteorological model for the southern Florida peninsula. The dispersion characteristics of plumes emitted from four major elevated point sources were then evaluated using the Lagrangian particle model 1. (i) by means of particle dispersion plots and 2. (ii) by computing the 3-h-average ground-level SO 2 concentrations. A comparison was made with concentrations estimated using a plume-trapping formulation and the TVA σ y curves. The study results illustrate the complexity of the dispersion patterns which can occur for travel distances on the order of 100 km in a coastal area due to diurnal effects and mesoscale circulations, and demonstrate the potential of the mesoscale atmospheric dispersion modeling system for studies of air quality in complex terrain.