Shipboard Acoustic Doppler Current Profiler measurements during R/V Littorina cruise L10-22@en

Vessel-mounted Acoustic Doppler Current Profiler (ADCP) measurements were carried out to acquire velocity profiles at two sites north (start: latitude & longitude: 54.229515,7.8437233) and northwest (start: latitude & longitude: 54.20431,7.862079) of Helgoland (Germany) during neap tide in June 2022 (29.06.2022 and 30.06.2022). The parallel transect method was adopted to acquire data over a semidiurnal tidal cycle that spanned 13 hours. On both days, surveys were conducted in a way where all the transects were traversed multiple times only from one direction. Each transect was ~1500 m and had a spacing of ~150 m. With a vessel speed of ~4 to 5 knots, each circuit formed by the 4 transect lines was traversed about ~13 times during the survey period of 13 hours. The measurements were conducted in bottom tracking mode with a 614.4-kHz Teledyne RD Instruments WorkHorse broadband ADCP. The ADCP was installed in convex and Janus configuration with a beam angle of 20 degrees to the supporting pole from the starboard side of the ship FK Littorina. The transducer face of the ADCP was 1.16 m below the water level, with a blank after transmitting (WF) set to 0.44 m. The ADCP was operated in a dynamic sea state (WM1) profiling mode with a depth cell length (WS) of 0.5 m and a total of 80 depth cells (WN). The bottom track pings per ensemble (BP) and pings per ensemble (WP) were set to 1; thus, 1 ensemble has 2 pings. The depth range covered by the ADCP is 2.10 m to 41.60 m. The data acquisition software ViSea DAS from Aqua Vision (https://aquavision.nl/services/visea-users/) used pitch and roll data from the ADCP's internal built-in motion reference unit and navigation and heading data from an auxiliary unit onboard the research vessel on a serial RS-232 interface to convert ADCP velocities into earth coordinates. The navigational data received correction signals to receive RTK \"fix\" status during the survey period, and the ADCP offsets were determined before the surveys to ensure the thoroughness and reliability of the data collection process.2022年6月（2022年6月29日与30日）的小潮期间，研究团队于德国黑尔戈兰岛北侧（起始经纬度：54.229515, 7.8437233）及西北侧（起始经纬度：54.20431, 7.862079）的两个测点，利用船载声学多普勒流速剖面仪（Vessel-mounted Acoustic Doppler Current Profiler，ADCP）开展流速剖面数据采集工作。本次研究采用平行断面法，在持续13小时的半日潮周期内完成数据采集。两日的调查均采用单向多次遍历所有断面的作业模式：单条断面长度约1500米，断面间距约150米。作业船航速约4至5节，在13小时的调查周期内，由4条断面组成的单次循环航次被遍历约13次。本次测量采用614.4kHz的泰莱达·RD仪器公司（Teledyne RD Instruments）WorkHorse宽带ADCP，并设置为底跟踪模式。该ADCP安装于作业船FK Littorina的右舷支撑杆上，采用凸面雅努斯构型，波束与支撑杆夹角为20度。ADCP的换能器阵面距水面深度为1.16米，发射后盲区（WF，blank after transmitting）设置为0.44米。该ADCP工作于动态海况（WM1）剖面模式，深度单元长度（WS，depth cell length）为0.5米，总深度单元数（WN，total depth cells）为80个。每个底跟踪数据组的声脉冲数（BP，bottom track pings per ensemble）与每个数据组的声脉冲数（WP，pings per ensemble）均设置为1，因此1个数据组包含2个声脉冲。该ADCP的测量深度范围为2.10米至41.60米。本次实验采用Aqua Vision公司开发的数据采集软件ViSea DAS（https://aquavision.nl/services/visea-users/），通过RS-232串行接口，调取ADCP内置运动参考单元采集的纵摇、横摇数据，以及调查船辅助单元提供的导航与航向数据，将ADCP测得的流速数据转换为大地坐标系下的结果。调查期间，导航数据接收修正信号以维持RTK（Real-Time Kinematic，实时动态差分）"fix"固定解状态；同时，调查开展前已完成ADCP安装偏移量的标定工作，以保障数据采集流程的完整性与可靠性。