Correlating an Upwind Source-Footprint with Urban Emissions Data Using the MM5/MCIP/CALPUFF Modeling System

A modeling system has been developed relying on plume diffusion theory to yield the upwind source area and emissions responsible for a measured downwind concentration. Three steps comprise this modeling strategy. Application of the MM5 meteorological model to yield a regional wind field, processing of the wind field through the Models-3/CMAQ meteorological processor (MCIP), inversion of the resulting wind field, and finally application of the CALPUFF puff dispersion model to the inverted wind field. In this manner, plume dispersion theory is applied to map the upwind pollutant source area (source-footprint) for a measured downwind concentration. This method has been applied to the Boston, MA area for a period in May of 1999 when the Urban Respiration and Trace Gas Metabolism project was conducting field studies in the south Boston area. An emission inventory was obtained from the Massachusetts Department of Environmental Quality and correlated with the inverted CALPUFF plume to yield the fractional source contribution of the downwind sources to a receptor in urban Boston, MA. The data indicate that 92% of the impacting emissions come from within a radius of 30 km and that over a 5 hour period emissions from Connecticut and Rhode Island also influenced the Boston area.