Abstract. The impacts of black carbon (BC) and particulate matter with aerodynamic
diameters less than 2.5 µm (PM2.5) emissions from different
source sectors (e.g., transportation, power, industry, residential, and
biomass burning) and geographic source regions (e.g., Europe, North America,
China, Russia, central Asia, south Asia, and the Middle East) to Arctic BC
and PM2.5 concentrations are investigated through a series of annual
sensitivity simulations using the Weather Research and Forecasting – sulfur
transport and deposition model (WRF-STEM) modeling framework. The simulations
are validated using observations at two Arctic sites (Alert and Barrow
Atmospheric Baseline Observatory), the Interagency Monitoring
of Protected Visual Environments (IMPROVE) surface sites over the US, and
aircraft observations over the Arctic during spring and summer 2008.
Emissions from power, industrial, and biomass burning sectors are found to be
the main contributors to the Arctic PM2.5 surface concentration, with
contributions of ∼ 30 %, ∼ 25 %, and ∼ 20 %,
respectively. In contrast, the residential and transportation sectors are
identified as the major contributors to Arctic BC, with contributions of
∼ 38 % and ∼ 30 %. Anthropogenic emissions are the most
dominant contributors (∼ 88 %) to the BC surface concentration over
the Arctic annually; however, the contribution from biomass burning is
significant over the summer (up to ∼ 50 %). Among all geographical
regions, Europe and China have the highest contributions to the BC surface
concentrations, with contributions of ∼ 46 % and ∼ 25 %,
respectively. Industrial and power emissions had the highest contributions to
the Arctic sulfate (SO4) surface concentration, with annual
contributions of ∼ 43 % and ∼ 41 %, respectively. Further
sensitivity runs show that, among various economic sectors of all geographic
regions, European and Chinese residential sectors contribute to
∼ 25 % and ∼ 14 % of the Arctic average surface BC
concentration. Emissions from the Chinese industry sector and European power
sector contribute ∼ 12 % and ∼ 18 % of the Arctic surface
sulfate concentration. For Arctic PM2.5, the anthropogenic emissions
contribute > ∼ 75 % at the surface annually, with
contributions of ∼ 25 % from Europe and ∼ 20 % from
China; however, the contributions of biomass burning emissions are
significant in particular during spring and summer. The contributions of each
geographical region to the Arctic PM2.5 and BC vary significantly with
altitude. The simulations show that the BC from China is transported to the
Arctic in the midtroposphere, while BC from European emission sources are
transported near the surface under 5 km, especially during winter.