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，利用声学多普勒流速剖面仪（ADCP）与温盐记录仪（CT recorder）开展锚泊观测。研究共部署两套锚系系统，分别布设于近岸区域（a1：水底深度183 m）与陆架边缘（a2：水底深度270 m）。每套锚系均自上而下搭载了冰剖面声呐（Ice Profiling Sonar，IPS：ASL Environmental Sciences公司IPS4 420 kHz型号）、向上观测型声学多普勒流速剖面仪（ADCP：RD Instruments Workhorse Sentinel 300 kHz型号）以及温盐记录仪（CT-recorders：SeaBird SBE-37 MicroCAT型号）。a1与a2站位的ADCP除测量流速外，还分别以8米的层间距对9层与10层水体的体积反向散射强度（SV）进行了采集。部署前校准结果表明，其温度测量精度可达2 mK，盐度测量精度可达4×10⁻³。锚系搭载的ADCP与CT记录仪的水深数据，通过IPS压力传感器采集的压力值，结合ADCP测得的倾角，并假定锚系缆绳呈直线状态计算得到。该区域东侧的冰舌存在使锚系遭遇冰山撞击的风险。事实上，a2站位的锚系曾两次遭遇冰山撞击，压力传感器记录到了快速的深度突降。所幸两套锚系均顺利完成了为期一年的观测任务。