One year of particle size distribution and aerosol chemical composition measurements at the Zeppelin Station, Svalbard, March 2000-March 2001

One year of aerosol size distribution and chemical composition measurements conducted at the Zeppelin station on Svalbard (78degrees 58' N and 11degrees 53'E) is presented. The data, which cover the period March 2000-April 2001, show a very strong seasonal dependence of the number mode particle size. The transition from one seasonal characteristic regime to the other occurs rapidly and takes place over only a few days. As expected, the largest integrated aerosol surface and particle volumes are observed during the Arctic haze period in spring. On a seasonal scale the total number density covariate with the incoming solar radiation, which points to photochemistry as an important component during new particle formation in the Arctic summer. However, maximum number densities are observed during the second part of the summer concurrent with a relative reduction in the incoming radiation. The onset of this period of enhanced particle number densities coincides in time with the surface temperature remaining steadily above the freezing point and the melting of the snow cover. A similar transition occurring over the Siberian tundra is proposed as a potential source of aerosol precursor gases, which could explain the enhanced particle number densities during the second half of the summer. A second maximum of ammonium in particles during late summer and fall, concurrent with a reduction in sea salt and nss-sulfate present in particles would be consistent with continental source without a significant anthropogenic component. The data presented in the study also illustrate the usefulness of measurements that extend over several seasons where phenomenon that occur with in one season, the summer in this case, can be put into context. (C) 2003 Elsevier Ltd. All rights reserved.