Spatial variability of light-absorbing impurities in the seasonal snowpack of the Nordic Arctic

Quantifying light-absorbing impurities in snow is a critical parameter needed when evaluating snow albedo. Black carbon (BC) is the most effective impurity in reducing snow albedo by mass, and it has been shown to negatively affect the albedo in various regions of the globe, for example the Himalayas and the Arctic. Within the Arctic, the Scandinavian sector is a region where models have estimated high concentrations of BC in the seasonal snowpack compared to the rest of the Arctic. In this work, ambient snow samples were collected in 2012, 2013 and 2014 to examine the spatial variability of BC particles in the Scandinavian Arctic (Finland, Norway, and Sweden). Some of the sampling sites were revisited on consecutive years, during winter and spring conditions. Samples were analyzed for their elemental carbon (EC) content using a filter-based thermal-optical method (EC used as a proxy of BC). Samples collected in 2013 and 2014 were also analyzed with the single particle soot photometer. During the winter of 2013, BC concentrations increased with longitude, i.e. reflecting higher BC concentrations in samples closer to the Russian boarder. Air pollution (including BC particles) originating from the Kola Peninsula has been suggested to contribute to the higher BC concentrations. Similar spatial trends were found in samples collected in 2012.