Vertical profiles of aerosol properties in the summer troposphere of central Europe, scandinavia and the svalbard region

Abstract

Abstract During the Marginal Ice Zone Experiment in the Fram Strait between Greenland and Spitsbergen (MIZEX-84), the German research aircraft Falcon performed boundary-layer cloud physical and meteorological measurements. During the ferry flight from Germany to Spitsbergen and in the course of the MIZEX-experiment in June and July 1984 an aerosol payload was used to obtain vertical profiles of particle concentration and light scattering. The measurements in the Arctic summer aerosol revealed a rather uniform distribution of total particle concentration, (N), and light scattering coefficient, (σsp), over the first 6000 m of altitude. In general, the measured values of N and σsp were of the same magnitude as above 3000 m over central and northern Europe. Higher number concentrations and light scattering around 1500 and 4500 m a.s.l. indicated preferred levels of long range transport. An air mass analysis by means of three-dimensional back trajectories from different arrival altitudes showed that most of the time the air at all levels had spent at least 4 days in the nearest 500 km about the arrival point. In general, our findings confirm the picture of the summer Arctic troposphere being an aerosol sink region with wet scavenging processes in the boundary layer eliminating the particulate matter which is imported at preferred altitudes. In contrast to the frequent transport from mid-latitude source regions in winter, summer pollution enters the Arctic infrequently allowing for long aging, horizontal and vertical mixing, and wet scavenging in the boundary layer. An analysis of an individual incursion of polluted air showed concentrations up to levels found during Arctic haze in winter and considerable horizontal inhomogeneity even several days after the air mass entered the Arctic. The ferry flight from Munich to Spitsbergen yielded the first upper tropospheric data on aerosol number and light scattering connecting the European source region with the Arctic. At the same time these data provided input to feasibility studies concerning future spaceborne aerosol sensing systems.