Oxygen Isotopic Composition of Snow Formed under an Antarctic Anticyclone (Special Issue of the Proceedings of the First Symposium on Antarctic Meteorology and Glaciology)

Abstract

In order to investigate the formation process of snow under an Antarctic anticyclone and the transportation process of water vapor into the anticyclone, the oxygen isotopic composition of fallen snow at Syowa Station and drifting snow and firn in Mlzuho Plateau was determined. Fallen snow at Syowa Station is formed by the isobaric cooling process from a cloud layer under the upper inversion. Water vapor is transported to the Antarctic anticyclone and subsides in it. Snow is formed by the isobaric cooling process under the subsidence inversion. The surface air temperature is much lower than the temperature of formation of snow. Therefore, on ice sheet, water vapor moves from fallen snow to surface snow. The systematic decrease of oxygen isotopic compostion of snow with depth is formed in the snow cover with well developed depth-hoar of upward crystal growth under the influence of an Antarctic anticyclone, whereas the systematic increase is formed in that with depth-hoar of downward crystal growth under the influence of a circumpolar cyclone.