ADCP current measurements (38 kHz) during RV MARIA S. MERIAN cruise MSM107

Upper-ocean velocities along the cruise track of Maria S. Merian cruise MSM107 were continuously collected by a vessel-mounted Teledyne RD Instruments 38 kHz Ocean Surveyor ADCP.
The transducer was located at 6.0 m below the water line. The instrument was operated in narrowband mode with 32 m bins and a blanking distance of 16.0 m, while 50 bins were recorded using a pulse of 2.85 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 (0.34° +/- 0.9292°) and scale factor (0.9996 +/- 0.0145) of the Ocean Surveyor signal. The average interval was set to 60 s.
Velocity quality flagging is based on following threshold criteria: abs(UC) or abs(VC) > 1.5 m/s, rms(UC_z) or rms(VC_z) > 0.3.

本数据集通过搭载于船艇的Teledyne RD Instruments 38 kHz Ocean Surveyor型声学多普勒流速剖面仪（ADCP），沿玛丽亚·S·梅里安号（Maria S. Merian）科考航次MSM107的航行轨迹，持续采集上层海洋流速数据。
该换能器安装于吃水线以下6.0米处。本仪器工作于窄带模式，采用32米的距离单元配置，盲区距离为16.0米，以2.85秒的脉冲时长记录了50个距离单元的数据。
船舶自身的航行速度通过全球定位系统（GPS）获取的定位数据解算得到。数据采集软件VmDas内部集成了船舶陀螺平台输出的航向、俯仰、横摇数据与导航数据，用于将ADCP测得的相对流速转换为地球坐标系下的绝对流速。
ADCP流速数据的精度主要取决于GPS定位解的质量与船舶航向数据的精度，额外的误差来源包括换能器与船舶中心线的安装偏差。
数据后处理环节包含基于航迹水迹的校准工作：对Ocean Surveyor信号的安装偏差角（0.34° ± 0.9292°）与尺度因子（0.9996 ± 0.0145）进行校准，并将平均处理间隔设为60秒。
流速数据的质量标记基于以下阈值判定标准：|UC|或|VC| > 1.5 m/s，或UC_z、VC_z的均方根值（rms）> 0.3。