Nitrogen Oxides (NOx) in the Arctic Troposphere at Ny-Ålesund (Svalbard Islands): Effects of Anthropogenic Pollution Sources

Atmospheric measurements of nitrogen oxides (NOx = NO + NO2), ozone (O3) and other constituents were carried out during three field campaigns (29 March-30 April 2010, 1-26 April 2011, 18 May-8 October 2015) at Ny-Ålesund. The study focused on the variability of important O3 precursors, such as NOx, in the Arctic troposphere, and on the impact from anthropogenic sources on their measured concentrations: higher NO and NO2 levels were mostly associated with the lowest wind speeds and northern directions, indicating local pollution. Long-range transported sources from Russia and Europe were also identified with an occurrence of high NOx levels. Several ozone depletion events were observed and associated to winds blowing from the north-west direction (Arctic Ocean). Most of these events were connected to the lower NO and NO2 concentrations. Measurements of halogen and low molecular weight carbonyl compounds in 2010 and 2011, respectively, showed variable effects during the ozone depletion events. Other data, such as high time-resolved radon progeny measurements, were used in 2015 to identify source tracking and transport of air masses, local effects and atmospheric stability dynamics that could influence the NOx concentrations at Ny-Ålesund.