Long-range Transport of Natural and Anthropogenic Pollutants to the Arctic in Summertime

Model simulations of an intensive field campaign conducted over the Canadian high Arctic during the summer of 2014 were carried out using an online regional air quality model (GEM-MACH). Model results were compared with in-situ measurements from multiple platforms. The model captured the regional sources and transport to the Canadian Arctic well; the vertical structure of the lower atmosphere was well simulated by the model. The model results indicate that under transient conditions during summer, the Canadian high Arctic can be impacted by long-range transported pollutants from both anthropogenic and natural (e.g., biomass burning) sources in southern regions, including western and central Canada, as well as eastern North America. In this study, further analysis was carried out focussing on two cases during the campaign: 1) an elevated plume reaching the Arctic influenced by both biomass burning (over western Canada) and anthropogenic (over central Canada) sources, where biomass burning aerosols being scavenged during the transport is evident; and 2) transport of biomass burning plume at low altitudes over cold Arctic water channels when elevated plume may be bought down due to descending motion (over Labrador sea and Baffin Bay).