IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from MV L'Astrolabe voyage AL1213R4 (Hobart-Dumont d'Urville station)

This data was collected in February 2013 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on MV L'Astrolabe (IMOS platform code: FHZI) voyage AL1213R4.Departed: Hobart, Australia, February 19, 2013Arrived:      Dumont d'Urville station, Antarctica, February 25, 2013CO2 System Overview:The fugacity of carbon dioxide (fCO2) in surface seawater was measured using a General Oceanics Inc. automated system (Model 8050; Pierrot et al 2009). Seawater is sprayed into an equilibration chamber and CO2 in the headspace gas equilibrates with the seawater. The headspace gas is pumped through a thermoelectric condenser followed by a nafion drying tube, before flowing through a Licor 7000 non-dispersive infrared gas analyser used to measure the CO2 mole fraction (XCO2) of the dried air. The gas flow is stopped temporarily for the CO2 measurements, which are made at atmospheric pressure. A set of four CO2 standards (Table 1) that cover the range of CO2 values expected in the ocean are analysed about every three hours to calibrate the gas analyser. Atmospheric XCO2 (dry) is measured after the standards by pumping clean outside air from an intake on the forward mast of the ship. The seawater intake is at about 3m depth in the bow of the ship. A remote temperature sensor (Seabird Electronics SBE38) located at the intake is used to measure sea surface temperature (SST). Sea surface salinity is measured using a thermosalinograph (Seabird Electronics SBE21) mounted in the bow thruster space near the intake. The travel time between the intake and CO2 system is typically about 50 seconds with warming usually less than 0.4ºC. The thermosalinograph water is from the same intake and supply line. Meteorological data, salinity, SST, and ships position and time are taken from the ship’s logging system. The salinity values measured by the SBE21 were checked against discrete bottle samples collected on the voyage.Meteorological data, salinity, SST, and ships position and time are taken from the ships logging system.

本数据集由海洋综合观测系统（IMOS）机遇船舶走航CO₂测量研究组，于2013年2月在“L'Astrolabe”号机动船（IMOS平台代码：FHZI）的AL1213R4航次中采集完成。
起航地点：澳大利亚霍巴特，2013年2月19日；
抵达地点：南极迪蒙·迪维尔站，2013年2月25日。

二氧化碳测量系统概况：表层海水二氧化碳分压（fCO₂）采用通用海洋学公司（General Oceanics Inc.）自动化测量系统（型号8050；参见Pierrot等，2009）进行测定。具体流程为：将海水喷入平衡舱，使顶空气体中的CO₂与海水达到气液平衡；随后将顶空气体泵送至热电冷凝器，经纳菲昂干燥管除湿后，通入Licor 7000型非色散红外气体分析仪，以测定干燥空气的CO₂摩尔分数（XCO₂）。测量过程中会暂时中断气流，所有CO₂测定均在常压下开展。每间隔约3小时分析一组覆盖海洋典型CO₂浓度范围的4种CO₂标准气体（详见表1），用于校准气体分析仪。完成标准气体校准后，通过船舶前桅杆的进气口抽取室外洁净空气，以测定大气干燥XCO₂。

海水取水口位于船舶船首约3米水深处。取水口处安装有远程温度传感器（Seabird Electronics SBE38），用于监测海水表层温度（SST）。在取水口附近的首侧推舱内，安装了热盐深仪（Seabird Electronics SBE21）以测定海水表层盐度。从取水口到CO₂分析系统的输水时长通常约为50秒，期间水温通常升高不足0.4℃。热盐深仪的取水水源与CO₂分析系统取自同一取水口及输水管道。

气象数据、盐度、SST、船舶位置与时间信息均取自船舶日志系统。本航次采集的离散瓶采水样，已用于校验SBE21测得的盐度数据。气象数据、盐度、SST、船舶位置与时间信息均取自船舶日志系统。