Emission Inventory Preparation and Air Quality Modelling in the Pacific Northwest

In recent years, considerable effort has been spent creating comprehensive, sub-regional emission inventories in the Pacific Northwest for use in policy reviews, planning and decision-making, and numerical modelling. Although part of an ongoing project for Environment Canada which involves a number of first-time innovations, the focus of this paper is on the steps undertaken to integrate these sub-regional data into a consistent, model-ready format. Emission processing was performed using the Sparse Matrix Operating Kernel Emission (SMOKE v1.3) modelling system and the Community Multi-scale Air Quality modelling (CMAQ) system using the RADM2 chemical mechanism. The Pacific Northwest study area covers about 700,000 km2 and extends from central Oregon to central British Columbia, and from the Pacific Ocean west of Vancouver Island to western Idaho. Emissions, spatial surrogates, temporal factors, biogenic inputs, etc. were obtained from numerous groups and agencies, including: Environment Canada; Greater Vancouver Regional District; US EPA; States of Washington, Oregon, and Idaho; University of Washington; among others. Newly developed emission data, often varying in detail and resolution, were created, combined, and converted to SMOKE-ready format. Software tools (SMOKE-In and EI-View) developed by the authors were used to perform data compilation, processing, and QA/QC checks. Comprehensive CMAQ model evaluations for ozone and PM2.5 show very good agreement between the modelled and observed in terms of magnitude, and temporal and spatial trends