Airborne aerosol and black carbon measurements over the East Siberian Sea, Spring 1992

In April 1992 we performed measurements of Arctic aerosol properties from an aircraft flying over the East Siberian Sea from Cherskiy (69 degrees N, 161 degrees E) to Bennett Island (76.5 degrees N, 149 degrees E). Eight round-trip flights were made over this 1000 kilometer path, with each flight incorporating several profiling descents from approximately 4.2 km altitude to the surface. On a 10-second time base were recorded measurements of aerosol black carbon (BC), condensation nuclei (CN), air temperature and absolute barometric pressure, from which altitude was deduced. Some profiles showed considerable vertical structure with numerous temperature inversions and stratified aerosol layers. Peak BC and CN concentrations exceeded 1000 ng m(-3) and 1000 cm(-3) respectively. Occasionally, extremely clean air was found in some layers. Other descents showed stable temperature profiles, with aerosol BC and CN distributed throughout the lower 4 km of the atmosphere. In most cases, the surface temperature-inversion layer contained high concentrations of aerosol species. We conclude that the atmosphere in this remote area is strongly affected by anthropogenic emissions from distant source regions, and that the meteorological and aerosol concentration profile structures were similar to those regularly observed in the western sectors of the Arctic in springtime. (C) 1997 Elsevier Science B.V.