To estimate the impact of biomass burning on the concentration of BC and other pollutants, we had conducted model simulations over the Pan-Arctic region using a regional chemical transport model (WRF-Chem). The initial and lateral boundary conditions for the meteorology and chemical species were taken from NCEP-GFS and MOZART-4/GEOS-5, respectively. RACM and GOCART modules were used for the gaseous and aerosol chemistry, respectively. Anthropogenic emissions were based on EDGAR 4.3, and the biomass burning were based on the near-real-time version of FINN for each day. A pyro-convection process was also considered for the estimation of vertical profiles of biomass burning emissions. Biogenic emissions of VOCs were estimated by MEGAN 2.1 which is included in the model to use the meteorology and radiation calculated in the model for every 20 minutes. Calculation was conducted from August to October 2016, when the Siberian forest fire were estimated to be quite active in the NCAR FINN inventory. To estimate the impact of biomass burning, we have conducted two calculations; 1) full emissions (anthropogenic, biogenic, and biomass burning) and 2) without biomass burning emissions (anthropogenic and biogenic). Meteorological field was compared with the observational data from the ship-based observation on R/V Mirai at the Arctic Ocean and Bering Sea, and model succeeded to reproduce the general variations of meteorological field such as the passage of low pressure systems. BC concentration at the surface level was increased over the Bering Sea after 25 September, and the main cause of the increase was estimated to be the biomass burning at around the Lake Baikal in late September. Backward-trajectory calculation using WRF-FLEXPART was also conducted for the estimation of source region, and the results imply that the major plume was released at the height of around 2.5 km above the ground.
Air Pollution in the Arctic: Climate, Environment and Societies