nc file: ADCP current measurements (75 kHz) during RV SONNE cruise SO287@en

Upper-ocean velocities along the cruise track of RV SONNE cruise SO287 were continuously collected by a vessel-mounted Teledyne RD Instruments 75 kHz Ocean Surveyor ADCP. The transducer was located at 6.0 m below the water line. The instrument was operated in narrowband mode with 8 m bins and a blanking distance of 8 m, while 100 bins were recorded using a pulse of 1.45 s. The ship's velocity was calculated from position fixes obtained by the Global Positioning System (GPS). Heading, pitch and roll data from the ship's gyro platforms and the navigation data were used by the data acquisition software VmDas internally to convert ADCP velocities into earth coordinates. Accuracy of the ADCP 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 post-processing included water track calibration of the misalignment angle (-0.13° +/- 0.5240°) and scale factor (0.9994 +/- 0.0077) of the Ocean Surveyor signal. The average interval was set to 60 s.

本数据集采集了SONNE号科考船（RV SONNE）SO287航次沿航迹的上层海洋流速数据，采集设备为船载Teledyne RD Instruments 75 kHz海洋勘探型声学多普勒流速剖面仪（ADCP，Acoustic Doppler Current Profiler）。该换能器安装于吃水线以下6.0米处。仪器工作于窄带模式，配置8米的采样分层与8米的盲区距离，以1.45秒的脉冲时长完成100个采样分层的记录。船舶自身的航行速度通过全球定位系统（GPS，Global Positioning System）获取的定位解算结果计算得到。数据采集软件VmDas会利用船舶陀螺平台采集的航向、纵倾与横摇数据，以及导航数据，在内部将ADCP测得的相对流速转换为大地坐标系下的绝对流速。ADCP流速数据的精度主要取决于定位解算结果与船舶航向数据的质量，额外的误差来源还包括换能器与船舶中心线的安装偏差。本次数据后处理流程包含对海洋勘探型ADCP信号的航迹校准：其中安装偏角的校准值为-0.13° ± 0.5240°，尺度因子的校准值为0.9994 ± 0.0077。数据平均采样间隔设置为60秒。