| Summary: | Elemental carbon (proxy for black carbon) consentrations in the upper 5 cm of the snow pack. Each snow sample was collected from the upper 5 cm of the snow (1–2 L, unmelted), in a glass jar. The snow samples were kept frozen until being rapidly melted in a microwave oven, and then the melted water (typically about 0.5 L) was filtered through quartz substrate using a small vacuum pump. The filters were analyzed with a thermo-optical method, using the Thermal/Optical Carbon Aerosol Analyzer (Sunset Laboratory Inc., Forest Grove, USA), and a temperature protocols (before 2009 the NIOSH 5040 and after 2009 the EUSAAR_2 protocol [Birch, 2003; Cavalli et al., 2010; Forsström et al., 2009]) to obtain the elemental carbon concentrations in the snow.
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