Variability of Black Carbon mass concentration in surface snow at Svalbard.

Black Carbon (BC) is a significant forcing agent in the Arctic, but substantial uncertainty remains to quantify its climate effects due to the complexity of the different mechanisms involved, in particular related to processes in the snow-pack after deposition. In this study, we provide detailed and unique information on the evolution and variability of BC content in the upper surface snow layer during the spring period in Svalbard (Ny-Ålesund). Two different snow-sampling strategies were adopted during spring 2014 and 2015, providing the refractory BC (rBC) mass concentration variability on a seasonal/daily and daily/hourly time scales. The present work aims to identify which atmospheric variables could interact and modify the mass concentration of BC in the upper snowpack, the snow layer which BC particles affects the snow albedo. Despite the low BC mass concentrations, a relatively high daily variability was observed. Atmospheric, meteorological, and snow-related physico -chemical parameters were considered in a multiple statistical model to separate the factors determining observations. Precipitation events were the main drivers of the BC variability. Snow metamorphism and activation of local sources during the snow melting periods appeared to play a non-negligible role (wind resuspension in specific Arctic areas where coal mines were present). The BC content in the snow resulted in being statistically decoupled from the atmospheric BC load. [ABSTRACT FROM AUTHOR]