Characteristics of the concentration and composition of aerosols during Foehn in West Greenland

Abstract

Measurements of the number of aerosol particles in 5 size ranges (0.3–0.5, 0.5–1, 1–2, 2–5, and > 5 μm in diameter) were carried out continuously at Godhavn (69°15’N, 53°34’W), West Greenland from the middle of December 1989 to the end of January 1990. The concentrations of particles larger than 0.3 μm were less than 10 cm^-3 near the surface. This concentration is 1/2 to 1/5 of that measured at Inuvik, Arctic Canada and at Alta, Northern Norway at a similar latitude. The fluctuation of the number concentrations was very small when Greenland was covered by high pressure, and a weak downslope wind was blowing from the island ice cap. Sudden change to strong northeasterly wind was accompanied by an abrupt increase of air temperature. Concurrent with these changes, the number concentration of smaller particles decreased, and particles larger than 2 μm in diameter increased. These variations are considered to be caused by a strong Foehn, accompanying a well-developed low pressure cell passing north-east along the southern coast of Greenland. After the Foehn had ceased, weak southerly winds were accompanied by greater number of particles of 1–2 μm. Many sea salt particles were brought from the sea south of the station which was not completely covered by sea ice, even in the midwinter seasons. The number concentration and composition of aerosols were closely related to the wind system at Godhavn, West Greenland.