Shipboard ADCP current measurements (75 kHz) during RV SONNE cruise SO311

Current velocities of the upper water column along the cruise track of R/V Sonne cruise SO311 were collected by a vessel-mounted 75 kHz RDI Ocean Surveyor ADCP. The ADCP transducer was located at 6.0 m below the water line. The instrument was operated in narrowband mode (WM10) with a bin size of 8.00 m, a blanking distance of 8.00 m, and a total of 100 bins, covering the depth range between 22.0 m and 814.0 m. Attitude data from the ship's motion reference unit were used by the data acquisition software VmDAS internally to convert ADCP beam velocities to geographic coordinates. The Python toolbox OSADCP (version 2.2.0) was used for data post-processing. Acoustic Interferences were identified based on outliers in the ADCP echo intensity data. Echo intensity data were cleaned accordingly and affected velocity cells were flagged to be removed prior ensemble-averaging. The ship's velocity was calculated from position fixes obtained by the Global Navigation Satellite System (GNSS), taking into account lever arms of ADCP transducer and GNSS antenna. Accuracy of the derived water velocities mainly depends on the quality of the position fixes and the ship's heading data. Further errors stem from a misalignment of the transducer with the ship's centerline. Data processing included water track calibration of the misalignment angle (-45.2061° +/- 0.7743°) and scale factor (0.9975 +/- 0.0131) of the measured velocities. The velocity data were averaged in time using an average interval of 120 s. Depth cells with ensemble-averaged percent-good values below 25% are marked as 'bad data'.

本数据集采集了桑尼号（R/V Sonne）科考航次SO311沿航迹的上层水体流速数据，数据由船载75 kHz RDI海洋勘探型声学多普勒流速剖面仪（Acoustic Doppler Current Profiler，ADCP）获取。该ADCP换能器安装于吃水线以下6.0米处。仪器工作于窄带模式（WM10），采样单元尺寸为8.00米，盲区距离为8.00米，共计100个采样单元，覆盖22.0米至814.0米的水深范围。数据采集软件VmDAS内置船舶运动参考单元的姿态数据，用于将ADCP波束流速转换为地理坐标系下的流速值。采用Python工具箱OSADCP（版本2.2.0）完成数据后处理工作。基于ADCP回波强度数据中的异常值识别声学干扰，随后对回波强度数据进行清洗，并标记出受干扰影响的流速单元，以便在集合平均前予以剔除。船舶自身航行流速由全球导航卫星系统（GNSS）获取的定位解算结果计算得到，计算过程中考虑了ADCP换能器与GNSS天线的安装杠杆臂偏差。推算得到的水体流速精度主要取决于定位解算结果与船舶艏向数据的质量，其余误差来源包括换能器与船舶中心线的安装偏差。数据处理环节针对安装偏差角（-45.2061° ± 0.7743°）与测量流速的比例因子（0.9975 ± 0.0131）开展了水流轨迹校准。流速数据以120秒为平均间隔进行时间平均。集合平均有效百分比低于25%的深度单元被标记为“坏数据”。