Surface flow velocity on Qaanaaq ice cap, Greenland in July 2014

The surface motion of the glacier was measured by surveying 5 stakes (1.5-2.0 m long aluminium poles) installed in the ice at Qaanaaq ice cap. We used dual-frequency GPS receivers and antennas (GNSS GEM-1) to measure the three-dimensional positions of the stakes. One antenna was fixed on the roof of Qaanaaq Club House as a reference station. At Q1403, the antennae were mounted on the stakes and operated every seconds. The stakes at Q1401-Q1405 except for Q1403 were surveyed with the same devices for 30 minutes. These data were processed in static mode by the GPS software (RTKLIB) to compute the position of the stakes every 30 minutes. Measurement errors were estimated below 10 mm.本研究针对卡纳克冰盖（Qaanaaq ice cap）冰层中布设的5根测桩（长1.5~2.0米的铝制标杆）开展野外测量，以获取冰川表面运动数据。本次测量采用双频GPS接收机与天线（GNSS GEM-1），采集各测桩的三维位置坐标。其中一根天线固定于卡纳克俱乐部（Qaanaaq Club House）屋顶，作为基准站。针对编号Q1403的测桩，天线搭载于桩体之上，按每秒频次开展作业。除Q1403外，Q1401至Q1405其余测桩均采用同款设备开展了时长30分钟的测量作业。上述测量数据通过GPS软件（RTKLIB）以静态模式进行解算，每30分钟输出一次测桩的位置坐标。经估算，本次测量的误差低于10毫米。