Long-range transport of Siberian wildfire smoke to British Columbia: Lidar observations and air quality impacts

In July and August 2012, a combination of dry weather and record-breaking temperatures led to an unusually intense wildfire season in Boreal Asia. Based on model results and satellite observations it is thought that a portion of the smoke output from these fires was carried across the Pacific to North America in quantities sufficient to adversely affect air quality in southwestern British Columbia. CORALNet lidar observations taken in Vancouver during these months revealed aerosol layers in the free troposphere followed by relative increases in backscatter ratio within the boundary layer peaking on July 7–10 and again on August 9–15. Depolarization ratios in the boundary layer and for layers in the free troposphere during this period were consistent with high concentrations of smoke. Throughout July and August, Total Suspended Particulate (TSP) monitors throughout the lower Fraser Valley of British Columbia revealed several days with a significant increase in PM2.5 concentrations and nine of the twenty highest daily average PM2.5 concentrations of 2012 coincide with increases in backscatter in the lidar observations indicating that these events were accompanied by a substantial increase in particulate concentrations near the surface.