Measurements of NOx and aerosol particles at the Ny-Alesund Zeppelin mountain station on Svalbard: Influence of regional and local pollution sources

The accumulation of anthropogenic pollution in the Arctic during winter and spring can be studied from only relatively few sites. In 1989 a new research station was put into operation on Zeppelin mountain, Svalbard (78 degrees 55'N, 11 degrees 53'E, 474 m above sea level). The location near the top of the mountain was chosen to minimize impacts from the nearby village of Ny-Alesund. Meteorological data, mixing ratios of NOx, and concentrations of aerosol particles measured from February to May 1994 are used to identify different types of influences on the station. During periods of low atmospheric stability and wind speeds, relatively high NOx mixing ratios and variability together with a high number concentration of nucleation mode particles can be used to identify local pollution. During 6.4% of the time of our campaign the air was contaminated by local pollution sources, with the majority of events occurring later in the campaign. Based on isentropic back-trajectories four major source regions for air arriving at the station are identified. These are Western Europe, Russia, the Arctic and North Atlantic regions. Elevated levels of pollution were seen when air arrived from either Western Europe or Russia. Western European flow showed, on average, the highest NOx mixing ratios, while Russian flow showed the highest mass loading of aerosols. Background air during flow from the Arctic or North Atlantic regions showed a median scattering coefficient of 3.8 x 10(-6) and 1.3 x 10(-6) m(-1),respectively, and CN concentrations of 180 and 270 cm(-3), respectively. Median ozone and NOx mixing ratios during these periods were 37 ppbv and about 20 pptv, respectively.