Influence of Global Change and Asian Emissions on Regional Air Quality in the Pacific Northwest

Global climate change, land use changes and population growth are interrelated forces that can cause significant changes in future air quality in the US. In the Pacific Northwest, air quality now and in the future can also be exacerbated by the impact of polluted air masses transported from Asia across the Pacific to the US. In this work we address the issue of what role current Asian emissions play on air quality in the Northwest, and how global change might influence the impact of future Asian emissions. To do this we employ a multi-scale numerical modeling system, which is comprised of global scale and nested regional models. On the global scale we employ the NCAR/DOE Parallel Climate Model (PCM) and the NCAR MOZART-2 chemical transport model. The MM5/SMOKE/CMAQ regional modeling system is used to refine the global scale model outputs to regional scale air quality. Global and regional model simulations are conducted for a future period (2045 - 2055) and compared to base case simulations of contemporary climate conditions (1990 - 2000). For contemporary simulations, US anthropogenic emissions are based on the National Emissions trend 1999 (NEI99) dataset, while future year anthropogenic emissions are projected using emission growth factors from EPA's the Economic Growth Analysis System (EGAS) along with IPCC scenarios. Biogenic emissions are treated using the new biogenic emissions Model of Emissions of Gases and Aerosols from Nature (MEGAN). In this paper, we present a preliminary analysis of the results of contemporary, long term simulations in terms of the impact of Asian emissions on Northwest air quality, and we examine the results of MOZART global simulations in terms of changes in boundary conditions for regional simulations in the Northwest for future periods.