Air Quality: EPA's Integrated Science Assessments (ISAs)
Seasonal Modeling of the Export of Pollutants from North America Using the Multi-Scale Air Quality Simulation Platform (MAQSIP)
Attention in recent years has focused on the trans-boundary transport of ozone and fine particulate matte between the United States and Mexico and Canada and across state boundaries in the United States. In a similar manner, but on a larger spatial scale, the export of pollutant emissions from North America also can be expected to exert an influence on atmospheric chemistry, especially over the North Atlantic Ocean and even on Europe. The importance of long-range transport to air quality in the United States has been documented in a number of cases. Examples include: the transport of dust from northern Africa, the transport of dust from the Gobi and Taklamakan Deserts in Asia; the transport of smoke from biomass fires in central America and southern Mexico: and the transport of ozone, its precursors and persistent organic pollutants from Asia. Many of these phenomena occur periodically for short periods of time and could be modeled on an episodic basis
However, a thorough evaluation of transport from polluted areas requires analysis for time periods much longer than those required for analysis of episodes associated with specific synoptic situations. For this study, the outflow of pollutants (O3, Nox, and CO) from North American was calculated from May 15 through September 11, 1995, based on simulations performed with MAQSIP is a comprehensive chemistry-transport modeling system that simulates atmospheric chemical phenomena from the urban scale to the hemispheric scale. Meteorological fields obtained from the MM5 mesoscale model were used to calculate transport; the Carbon Bond mechanism (version 4.2) was used to calculate chemical production and destruction terms; and national emissions inventories were used to calculate anthropogenic and natural emissions. A comparison of ground level ozone concentrations calculated by MAQSIP with observed values in the eastern United States for this period, given in Kasibhatla and Chameides (2000) demonstrates the reasonableness of the model's results. Fluxes of O3, Nox, and CO normal to the eastern boundary of MAQSIP's domain for the entire simulation will be presented . Relations between these fluxes and synoptic patterns will be discusses.