Analysis of the effects of wildfires upon US air quality for current and future climate conditions

As large, intermittent sources of primary particulates and secondary aerosol and ozone precursors, wildfires can have an important impact on regional air quality. As part of an ongoing analysis on the effects of global change upon US air quality, we report results for current and future decade simulations of the inter-relationship among climate change, wildfires and air quality for specific regions of the US. Meteorological fields, downscaled using WRF from the ECHAM5 global climate model for the IPCC A1B scenario were used to drive the MEGAN biogenic emissions model, the SMOKE emissions processing tool, and the CMAQ chemical transport model to predict ozone and aerosol concentrations for representative years within the current (1995-2004) and a future decade (2045-2054). Simulations were completed for two nested domains covering most of the northern hemisphere from eastern Asia to North America at 220 km horizontal resolution (hemispheric domain) and covering the continental US at 36 km resolution (CONUS). Sensitivity studies were conducted using current decade historical fire occurrence data and using a stochastic fire occurrence model driven by regional meteorological conditions. Results are reported for the Northwest, Southwest, and Central Rockies regions of the US in terms of the effects of different fire emission treatments and in terms of the effects of climate change upon fire occurrence and fire plume transport and fate.