A climatology of Black Carbon properties in the Arctic, from a decade of spring and summertime aircraft measurements

Abstract A key driving factor behind rapid Arctic climate change is black carbon (BC), the atmospheric aerosol that most efficiently absorbs sunlight. Our knowledge about BC properties and distribution in the Arctic is scarce, and mainly limited to long-term measurements of a few ground stations and snap-shots by aircraft observations. Here, we combine observations from aircraft campaigns performed over nine years, and present a vertically resolved climatology of average BC properties. Model calculations indicate that these geographically restricted measurements could be well representative for the European and Canadian Arctic. A factor of 4 higher BC mass concentration, and a much higher inter-annual and geographic variability was found in spring compared to the stable situation in summer. Unexpectedly, the BC particle size distributions remain constant between seasons. A comparison between observations and BC concentrations simulated by a global model shows notable discrepancies, highlighting the need for further model developments and intensified measurements.