Geodetic observation and interpretation of ice flow velocities in the southern part of subglacial Lake Vostok

Статья принята к печати 3 сентября 2012 г. Accumulation, Antarctica, flow velocity, flux gate, GPS, mass balance. Аккумуляция, Антарктида, баланс массы, скорость течения, створ ледяного потока, GPS. Results of geodetic in-situ observations of ice-fl ow velocities in the southern part of subglacial Lake Vostok are combined with data sets of the ice surface topography, ice thickness, surface accumulation, basal accretion and fi rn/ice density for interpretations regarding the glaciological setting of the Lake Vostok system. Based on the icefl ow velocities and the ice thickness, mean surface accumulation rates are derived applying the fl ux gate method. These are representative for surface segments extending from the southern part of Lake Vostok to the Ridge B ice divide. They are consistent with the present-day accumulation rate at Vostok station and its variation upstream and thus suggest that the area has been close to steady state. In addition, ice-fl ow dynamics are investigated along a fl ow line segment extending from 26 km upstream to 12 km downstream from Vostok station. The analysis suggests defi ciencies in current modelling approaches within the transition zone from flto grounded ice.