The TIC-MOC cruise onboard the R/V Hespérides, March 2015, Brazil-Malvinas Confluence

The TIC-MOC oceanographic cruise was designed to characterize the dynamics of the Brazil-Malvinas Confluence (BMC) region. The cruise was carried in March 2015 on board the R/V Hespérides, departing from Ushuaia and arriving to Salvador de Bahía. There were a total of 66 hydrographic stations, carried out between 8 and 22 March 2015. All stations were offshore from the continental platform and within 45ºS-35ºS and 61ºW-50ºW, with 14 stations reaching down to the seafloor, 24 stations down to 2000 m and 28 stations down to 400-500 m. Conductivity-temperature-depth (CTD) data were obtained with a SeaBird 911 Plus multi-parametric probe, with redundant salinity and temperature sensors, and dissolved oxygen was sampled with a SBE-43 sensor. Water velocity data was obtained at the stations with a lowered acoustic Doppler current profiler (LADCP) and along the ship’s track with the vessel-mounted ADCP (VADCP). Due to the flooding of the upper-looking LADCP, for most stations the velocity was recorded using only the 300 kHz downward looking LADCP, at 4-m vertical bins. During the entire ship’s track inside the study region, the VADCP gathered velocity data in low-range mode (one velocity profile every 5 min between about 20 and 700 m at 8-m depth bins) and a thermosalinograph gathered salinity and temperature data (every 5 s at a depth of 5 m). The LADCP was attached, together with the CTD, to a 12-liters 24-Niskin-bottle rosette. Water samples from the Niskin bottles at standard depths were used to calibrate the salinity and DO sensors, as well as to determine the concentration of four inorganic nutrients (nitrate, nitrite, phosphate and silicate). Finally, eight subsurface drifters (dragged at either 100 or 200 m) were released early in the cruise and two profiling floats were launched and carried out a total of 42 profiles (down to about 800 m) during about one week. The cruise’s chief scientist was Josep Pelegrí, the chief technician was Ramon Ametller and the vessel’s captain was Julio Albaladejo. The cruise was supported by the Spanish Government through project “Tipping Corners of the Meridional Overturning Circulation” (TIC-MOC, reference number CTM2011-28867).

TIC-MOC海洋科考航次旨在刻画巴西-马尔维纳斯汇合区（Brazil-Malvinas Confluence, BMC）的动力学特征。本次航次于2015年3月在"埃斯佩里德斯号"（R/V Hespérides）科考船上开展，从乌斯怀亚（Ushuaia）启航，终抵萨尔瓦多·德·巴伊亚（Salvador de Bahía）。航次共设置66个水文测站，作业时段为2015年3月8日至22日。所有测站均位于大陆架以外海域，地理范围介于南纬45°至35°、西经61°至50°之间，其中14个测站的观测深度直达海底，24个测站观测深度达2000米，28个测站观测深度为400~500米。采用SeaBird 911 Plus多参数探头获取导电率-温度-深度（Conductivity-Temperature-Depth, CTD）数据，该探头配备冗余盐度与温度传感器；使用SBE-43传感器采集溶解氧数据。测站处的海流流速数据通过下放式声学多普勒海流剖面仪（lowered acoustic Doppler current profiler, LADCP）获取，而船舶航线上的流速数据则通过船载ADCP（vessel-mounted ADCP, VADCP）采集。由于朝上的LADCP发生进水，绝大多数测站仅采用300 kHz朝下观测的LADCP进行流速记录，垂直分层分辨率为4米。在研究区域内的全部航行航段中，VADCP以低量程模式采集流速数据（每5分钟获取1条流速剖面，观测深度范围约20~700米，垂直分层8米）；船载温盐计（thermosalinograph）以每5秒1次的频率采集5米深度处的盐度与温度数据。LADCP与CTD一同搭载于12升24瓶式尼斯金采水器阵列上。取自标准深度尼斯金采水瓶的水样，被用于校准盐度与溶解氧传感器，同时用于测定4种无机营养盐（硝酸盐、亚硝酸盐、磷酸盐、硅酸盐）的浓度。本航次初期共投放8台水下漂流浮标（布放深度分别为100米或200米），同时投放2台剖面浮标，在约一周时间内完成总计42条剖面观测（最大观测深度约800米）。本次航次的首席科学家为Josep Pelegrí，首席技师为Ramon Ametller，船长为Julio Albaladejo。本航次由西班牙政府通过项目"经向翻转环流临界拐点"（Tipping Corners of the Meridional Overturning Circulation, TIC-MOC，编号CTM2011-28867）资助。