Global Change

Global change, land use changes and population growth are interrelated forces that can cause significant changes in future air quality in the U.S. 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 U.S. Much of the research done in LAR is driven by questions related to future air quality conditions.

Impact of Global Change on U.S. Air Quality

Through and EPA STAR grant, LAR is currently researching the impact of global change on U.S. air quality by employing a multi-scale numerical modeling system, which is comprised of global scale and nested regional models. On the global scale we employ the National Center for Atmospheric Research (NCAR)/Department of Energy (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 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).

Current ozone concentration Future ozone concentration

This work will continue through 2010 with support from a new EPA STAR grant (see March 2008 report to EPA). The overall goal for the continued work is to answer questions, as posed from our current project, related to the effects of global change on continental and regional air quality AND to include quantitative estimates of uncertainties as part of the answers to our research questions. We will employ an ensemble modeling approach with three specific objectives: 1) to develop a quantitative measure of the uncertainty in our modeling framework using ensemble modeling methods in comparison to current 1990-1999 observations; 2) to project these uncertainties into the future for the period 2045-2054 and quantitatively address the uncertainties that accompany projections of future emissions, both global and U.S., including changes in land cover, urbanization, biogenic emissions, and fire emissions; and 3) to continue to address our research questions that will determine the consequences of global change upon U.S. air quality.