SADCP measurements of several eddies in the Southwest Atlantic in 2016-2022

The kinematic structure of several cyclonic and anticyclonic eddies in the Southwest Atlantic was measured over 6 transects using a Shipborne Acoustic Current Doppler Profiler (SADCP) onboard the R/V Akademik Sergey Vavilov and Akademik Mstislav Keldysh in 2016 - 2022. The measurements were performed during 5 oceanographic cruises in November 2016, March 2017, October 2017, October 2018, January and February 2022 (the data of cruise in 2022 contains two transects across the zone with intense eddies). These mesoscale eddies are formed at the Brazil - Malvinas Confluence zone as a result of the collision of two major western boundary currents in the Southwest Atlantic: the cold equatorward Malvinas Current and the warm poleward Brazil Current. Teledyne RD Instruments Ocean Surveyor (TRDI OS) SADCPs with a frequency of 76.8 kHz were used for the data collection. During all our surveys the profilers were set in the narrowband mode, which increases the profiling range up to 600-900 m depth. We set 60-100 vertical bins of 8-16 m each with 8 m blank distance immediately below the transducer. The draught of both ships is 6 m, which gives 18-22 m depth for the center of the first bin (the depth of the uppermost layer with velocity measurements). Time averaging of the raw data was performed over 120 s intervals. The data were collected using VmDas software and processed using WinADCP software.2016至2022年间，研究团队依托“谢尔盖·瓦维洛夫院士号”（R/V Akademik Sergey Vavilov）与“姆斯季斯拉夫·凯尔迪什院士号”（R/V Akademik Mstislav Keldysh）两艘科考船，搭载船载声学多普勒海流剖面仪（Shipborne Acoustic Current Doppler Profiler, SADCP），通过6条断面测量了西南大西洋多个气旋式涡旋（cyclonic eddies）与反气旋式涡旋（anticyclonic eddies）的运动学结构。本次观测依托5次海洋科考航次完成，分别为2016年11月、2017年3月、2017年10月、2018年10月，以及2022年1-2月（其中2022年航次包含2条穿过强涡旋区的断面）。这些中尺度涡旋（mesoscale eddies）形成于巴西-马尔维纳斯汇流区（Brazil-Malvinas Confluence zone），由西南大西洋两支主要西边界流（western boundary currents）——向赤道流动的寒冷马尔维纳斯海流（Malvinas Current）与向极流动的温暖巴西海流（Brazil Current）——碰撞交汇所产生。数据采集采用工作频率为76.8 kHz的Teledyne RD Instruments Ocean Surveyor（TRDI OS）型船载声学多普勒海流剖面仪。所有科考航次中，该剖面仪均设置为窄带模式，可将剖面测量深度范围提升至600~900米。系统初始设置包含60~100个垂直采样层，每层厚度为8~16米，换能器下方初始盲区距离为8米。两艘科考船的吃水深度均为6米，因此首个采样层中心对应的测量深度为18~22米，即开展流速测量的最上层水体深度。原始数据以120秒为间隔进行时间平均。数据采集采用VmDas软件完成，后处理则通过WinADCP软件实现。