Surface flow velocity on Qaanaaq ice cap, Greenland in July 2013

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 Q1203, the antennae were mounted on the stakes and operated every seconds. The stakes at Q1201-Q1205 except for Q1203 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.本数据集聚焦卡纳克冰盖（Qaanaaq ice cap）的冰川表面运动监测：于冰体内部布设5根长度为1.5~2.0米的铝制标杆，通过测定各标杆的空间位置获取冰川位移数据。我们采用双频全球定位系统（Global Positioning System，GPS）接收机与全球导航卫星系统（Global Navigation Satellite System，GNSS）GEM-1型天线，完成各标杆的三维空间坐标测定。其中一根天线被固定于卡纳克俱乐部会所屋顶，作为基准观测站。在Q1203测点处，天线直接安装于标杆之上，以秒级采样间隔开展连续观测。除Q1203外，Q1201至Q1205的其余标杆均采用同款设备开展了时长30分钟的测量作业。所有观测数据均通过GPS解算软件（RTKLIB）以静态模式进行后处理，每30分钟解算一次各标杆的位置坐标。经误差评估，本次测量的精度误差低于10毫米。