IMF-associated cloudiness above near-pole station Vostok: Impact on wind regime in winter Antarctica

Abstract

Changes in the cloudiness above the Antarctic station Vostok during the winter season were examined in relation to strong disturbances in the interplanetary magnetic field (IMF). A reliable relationship between cloud formation and IMF has been found: cloudiness increased under the influence of a strong southward IMF and decreased under the northward IMF. The surface temperature at Vostok station, which is derivative of the constant radiation cooling of air situated at the ice sheet and adiabatic warming of the air masses, incoming into the central Antarctica from the middle and upper troposphere, is enhanced or reduced. Quite opposite regularity in the temperature changes is typical of altitudes higher than the suggested cloud layer position (5–8 km). The processes occurring on the Antarctic ridge leads to anomalous winds at the ice dome and decay of the circumpolar vortex at the periphery of the Antarctic continent. As a result, the surface easterlies at the coast stations are replaced by southerlies, and the cold air masses flow from Antarctica out over the Southern Ocean.