Elemental and water-insoluble organic carbon in Svalbard snow: a synthesis of observations during 2007-2018

Light-absorbing carbonaceous aerosols emitted by biomass or fossil fuel combustion can contribute to amplifying Arctic climate warming by lowering the albedo of snow. The Svalbard archipelago, being near to Europe and Russia, is particularly affected by these pollutants, and improved knowledge of their distribution in snow is needed to assess their impact. Here we present and synthesize new data obtained on Svalbard between 2007 and 2018, comprising measurements of elemental (EC) and water-insoluble organic carbon (WIOC) in snow from 37 separate sites. We used these data, combined with meteorological data and snowpack modeling, to investigate the variability of EC and WIOC deposition in Svalbard snow across latitude, longitude, elevation and time. Overall, EC concentrations (C-snow(EC)) ranged from < 1.0 to 266.6 ng g(-1), while WIOC concentrations (C-snow(WIOC)) ranged from < 1 to 9426 ng g(-1), with the highest values observed near Ny-Alesund. Calculated snowpack loadings (L-snow(EC), L-snow(WIOC)) on glaciers surveyed in spring 2016 were 0.1 to 2.6 mg m(-2) and 2 to 173 mg m(-2), respectively. The median C-snow(EC) and the L-snow(EC) on those glaciers were close to or lower than those found in earlier (2007- 2009), comparable surveys. Both L-snow(EC) and L(snow)(WIOC )increased with elevation and snow accumulation, with dry deposition likely playing a minor role. Estimated area-averaged snowpack loads across Svalbard were 1.1 mg EC m(-2) and 38.3 mg WIOC m(-2) for the 2015-2016 winter. An similar to 11-year long dataset of spring surface snow measurements from the central BrOgger Peninsula was used to quantify the interannual variability of EC and WIOC deposition in snow. In most years, C-snow(EC) and C-snow(WIOC) at Ny-Alesund (50 m a.s.l.) were 2-5 times higher than on the nearby Austre Brogger-breen glacier (456 m a.s.l.), and the median EC/WIOC in Ny-Alesund was 6 times higher, suggesting a possible influence of local EC emission from Ny-Alesund. While no long-term trends between 2011 and 2018 were found, C-snow(EC) and C-snow(WIOC) showed synchronous variations at Ny-Alesund and Austre Broggerbreen. When compared with data from other circum-Arctic sites obtained by comparable methods, the median C(snow)(EC)on Svalbard falls between that found in central Greenland (lowest) and those in continental sectors of European Arctic (northern Scandinavia, Russia and Siberia; highest), which is consistent with large-scale patterns of BC in snow reported by surveys based on other methods.