Mooring observation data in the Cape Darnley polynya, Antarctica, 2010-2011 (JARE-51)

We conducted mooring observations with acoustic Doppler current profilers (ADCPs) and conductivity-temperature (CT) recorders inside the Cape Darnley polynya throughout winter for the first time. Two moorings were deployed near the shore (a1: bottom depth 183 m) and the shelf edge (a2: bottom depth 270 m). Each mooring was equipped with an Ice Profiling Sonar (IPS: ASL Environmental Sciences, IPS4 420 kHz), an upward-looking acoustic Doppler current profiler (ADCP: RD Instruments Workhorse Sentinel 300 kHz), and conductivity-temperature recorders (CT-recorders: SeaBird SBE-37 MicroCAT) from the top. The ADCPs at a1 and a2 measured the volume backscatter strength (SV) in addition to the current velocity for 9 and 10 layers of bin, respectively, with the 8 m interval. The pre-deployment calibration demonstrated a temperature accuracy of 2 mK and a salinity accuracy of 4 X 10-3. ADCP and CT-recorder depths were calculated from the pressure by the IPS pressure sensor and the tilt measured by the ADCP with an assumption that the mooring line was straight. In this region, the iceberg tongue in the east creates a risk of an iceberg attack on the moorings. In fact, the mooring at a2 was attacked by an iceberg twice, which was recorded by the pressure sensor as rapid dives. Fortunately, both moorings survived for one year.

本研究首次在整个冬季于达恩利角冰间湖（Cape Darnley polynya）内部，利用声学多普勒海流剖面仪（acoustic Doppler current profilers，缩写ADCPs）与电导-温度（CT）记录仪开展锚系观测。本次共布设两套锚系系统，分别布设于近岸区域（a1：水底水深183 m）与陆架边缘（a2：水底水深270 m）。每套锚系自顶部起依次搭载冰剖面声呐（Ice Profiling Sonar，缩写IPS：ASL环境科学公司，IPS4 420 kHz型号）、向上指向式声学多普勒海流剖面仪（ADCP：RD仪器公司Workhorse Sentinel 300 kHz型号）以及电导-温度记录仪（CT-recorders：海鸟公司SBE-37 MicroCAT型号）。a1与a2处的ADCP除测量海流流速外，还以8 m的层间距分别采集了9个与10个采样层的体积后向散射强度（volume backscatter strength，缩写SV）。部署前的校准结果表明，该系统的温度测量精度为2毫开尔文，盐度测量精度为4×10^-3。锚系ADCP与CT记录仪的水深数据，通过IPS压力传感器采集的压强，结合ADCP测得的倾斜角度，并假设锚系缆绳为直线状态计算得到。该区域东侧的冰舌会使锚系系统面临冰山撞击的风险。实际观测中，a2处的锚系曾两次遭遇冰山撞击，该事件被压力传感器记录为快速的压强跳变（对应锚系的快速下沉）。所幸两套锚系系统均顺利完成了为期一年的观测任务。