Measurements of the chemical composition of cloudwater at a clean air site in central Scandinavia¹

1 Accepted for publication by lvar S. A. Isaksen, Member of Advisory Board.

Abstract

A total of 179 samples of cloudwater were obtained during the summers of 1983 and 1984 at a clean-air site in the mountains of central Scandinavia. Impaction of droplets on teflon-coated wires provided samples with a time resolution of 5-30 min. Supporting data include cloud liquid water content, rainwater composition, aerosol number concentration, wind speed and direction, and 48-h isobaric trajectories.

Collected samples were analyzed for pH. Na⁺, K⁺, Mg²⁺, Ca⁺², NH⁺⁴, CI^-, NO^-₃, and SO²₄. A wide range of concentrations were encountered, with, for example. sulfate concentrations ranging from 1 to 1600 μeq 1-1. Transport of air from remote regions (north Atlantic Ocean, Arctic) is shown to be associated with the very low concentrations. while the high concentrations occurred in conjunction with transport from industrial regions in Europe. Median clean-air concentrations in Arctic air. calculated from cloudwater composition and liquid water content, were 3 pptv ammonia (gas and aerosol combined). 6 pptv nitrate (gas and aerosol), and 30 ng m^-3 sulfate.

Notes

1 Accepted for publication by lvar S. A. Isaksen, Member of Advisory Board.