Overview of the atmospheric research program during the International Arctic Ocean Expedition of 1991 (IAOE-91) and its scientific results

• Main Authors: Leck, C., Bigg, E.K., Covert, D.S., Heintzenberg, J., Maenhaut, W., Nilsson, E.D., Wiedensohler, A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Milton Park : Taylor & Francis 2017
• Subjects: aerosols; atmospheric particulates; atmospheric research programme; cloud albedo; cloud condensation nuclei; condensation nuclei; dimethyl/sulphide; dimethylsulphide; global sulphur cycle; IAOE-91; International Arctic Ocean Expedition; research programmes; 550; Arctic; Arctic Ocean; albedo
• Online Access: https://doi.org/10.34657/1150; https://oa.tib.eu/renate/handle/123456789/432

The broad aim of the Atmospheric program of the International Arctic Ocean Expedition (IAOE-91) was to test the hypothesis that marine biogenically produced dimethyl sulfide (DMS) gas can exert a significant global climatic control. The hypothesis states that DMS is transferred to the atmosphere and is oxidised to form airborne particles. Some of these grow large enough to act as cloud condensation nuclei (CCN) which help determine cloud droplet concentration. The latter has a strong influence on cloud albedo and hence on the radiation balance of the area affected. In summer, the central Arctic is a specially favourable region for studying the natural sulfur cycle in that the open waters surrounding the pack ice are the only significant sources of DMS and there are almost no anthropogenic particle sources. Concentrations of seawater and atmospheric DMS decreased at about the same rate during the period of measurements, (1 August to 6 October, latitudes 75°N to 90°N) spanning about three orders of magnitude. Methane sulfonate and nonsea salt sulfate in the submicrometer particles, which may be derived from atmospheric DMS, also decreased similarly, suggesting that the first part of the hypothesis under test was true. Influences on cloud droplet concentration and radiation balance could not be measured. Size-resolved aerosol chemistry showed a much lower proportion of methane sulfonate to be associated with supermicrometer particles than has been found elsewhere. Its molar ratio to nonsea salt sulfate suggested that the processes controlling the particulate chemistry do not exhibit a net temperature dependence. Elemental analysis of the aerosol also revealed the interesting possibility that debris from Siberian rivers transported on the moving ice represent a fairly widespread source of supermicrometer crustal material within the pack ice. Highly resolved measurements of aerosol number size distributions were made in the diameter range 3 nm to 500 nm. 3 distinct modal sizes were usually present, the “ultrafine”, ...