(Table 2) Horizontal ice flow velocities, azimuths (relative to true north), and vertical ice-particle velocities in the vicinity of Vostok Station, Antarctica

In the austral summer seasons 2001/02 and 2002/03, Global Positioning System (GPS) data were collected in the vicinity of Vostok Station to determine ice flow velocities over Lake Vostok. Ten GPS sites are located within a radius of 30 km around Vostok Station on floating ice as well as on grounded ice to the east and to the west of the lake. Additionally, a local deformation network around the ice core drilling site 5G-1 was installed.
The derived ice flow velocity for Vostok Station is 2.00 m/a ± 0.01 m/a. Along the flowline of Vostok Station an extension rate of about 10**-5/a (equivalent to 1 cm/km/a) was determined. This significant velocity gradient results in a new estimate of 28700 years for the transit time of an ice particle along the Vostok flowline from the bedrock ridge in the southwest of the lake to the eastern shoreline. With these lower velocities compared to earlier studies and, hence, larger transit times the basal accretion rate is estimated to be 4 mm/a along a portion of the Vostok flowline. An assessment of the local accretion rate at Vostok Station using the observed geodetic quantities yields an accretion rate in the same order of magnitude. Furthermore, the comparison of our geodetic observations with results inferred from ice-penetrating radar data indicates that the ice flow may not have changed significantly for several thousand years.

在2001/02和2002/03年的南半球夏季，研究人员于沃斯托克站（Vostok Station）周边区域采集了全球定位系统（Global Positioning System, GPS）数据，以测定沃斯托克湖（Lake Vostok）上方的冰流速度。共计10个GPS测站布设于沃斯托克站周边30千米半径范围内，覆盖浮冰区域，以及湖泊东西两侧的基岩附着冰体。此外，研究人员还在冰芯钻探场地5G-1周边搭建了局部形变监测网。经测算，沃斯托克站的冰流速度为2.00米/年 ± 0.01米/年。沿沃斯托克站的冰流流线，研究人员测得约10^-5/年的拉伸速率（等效于1厘米/千米/年）。这一显著的速度梯度使得冰粒沿沃斯托克湖冰流流线从湖西南侧基岩脊迁移至东岸的迁移时间被重新估算为28700年。相较于此前的研究，本次测算得到的冰流速度更低，因此迁移时间更长；沿沃斯托克湖部分冰流流线的基底增生速率被估算为4毫米/年。通过观测得到的大地测量数据对沃斯托克站的局部增生速率进行评估，所得结果的数量级与前述估算一致。此外，将本次大地测量观测结果与冰穿透雷达数据反演得到的结果进行对比后可知，数千年来冰流并未发生显著变化。