Motivation, Design and Highlights of the 2007 Border Air Quality and Meteorology Study

Southwestern Ontario is significantly impacted by both long-range trans-boundary flow and local sources of air pollutants leading to O3 and PM2.5 concentrations that are consistently the highest in Canada. The Great Lakes enclose the region on three sides and have a considerable influence on the meteorology and pollutant behaviour with the highest O3 near the shores of Lake Huron and Lake Erie. Cool lake waters and lake breezes contribute to the development of these high concentrations and are also known to influence the formation of convective storms. These complexities present challenges in forecasting O3 and PM2.5 and severe weather as well as in devising strategies to improve air quality. To improve on these issues there is a need to better understand the role of the lakes in the movement of pollutants, the formation of secondary pollutants and the interaction of multiple lake breeze fronts. The Border Air Quality and Meteorology Study was undertaken in the summer of 2007 for this purpose. The study involved enhanced meteorological and O3 monitoring for June, July and August and an intensive campaign from June 20 to July 9. During the 3 months, monitoring was enhanced with ~15 km resolution meteorological measurements and O3 over the domain, including points over Lake Erie on an island and from a ferry boat, and an additional meteorological buoy in Lake St. Clair. The intensive involved 3 enhanced surface sites, a mobile lab moving through the domain as well as an aircraft flying several paths at multiple heights below ~3000 m and as low as ~50m over water. Meteorological (GEM) and air quality models (AURAMS) run in forecast mode were a key part of the study guiding mobile lab and aircraft deployment which in turn provided real time feedback regarding model success. The resulting dataset provides an unprecedented opportunity to test several overarching hypotheses: (1) The relative importance of local emissions is enhanced by the lakes due to both a chemical and a dynamical influence; (2) Diagnosing and modelling the magnitude and spatial distribution of vertical motions induced by lake breeze circulations and other surface features will improve understanding and forecasting of pollutants and the initiation of thunderstorms; (3) The accuracy of air quality forecasting in southern Ontario is significantly impacted by how the model and data assimilation are treating the processes over the Great Lakes. This presentation will provide background information, an overview of the study design and highlights of the observations while subsequent presentations will include specific details on scientific findings to date.