IMOS - SOOP Ocean Carbon Dioxide Data from MV L'Astrolabe voyage AL1112R4 (Dumont d'Urville station - Hobart)

This data was collected in March 2012 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on MV L'Astrolabe (IMOS platform code: FHZI) voyage AL1112R4.\n\nDeparted: Dumont d'Urville station, Antarctica, March 02, 2012\nArrived: Hobart Australia, March 07, 2012\n\n\nCO2 System Overview:\nThe 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. \n\nThe 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.\n\nMeteorological data, salinity, SST, and ships position and time are taken from the ships logging system.

本数据集由澳大利亚海洋学研究所（IMOS）的"机遇船舶走航CO₂测量"研究小组，于2012年3月在MV L'Astrolabe（IMOS平台代码：FHZI）的AL1112R4航次中采集。

起航地点：南极迪蒙·迪维尔站，2012年3月2日
抵达地点：澳大利亚霍巴特，2012年3月7日

CO₂系统概述：
表层海水二氧化碳逸度（fCO₂）采用General Oceanics Inc.公司的自动化测量系统（型号8050；Pierrot等，2009）完成测定。将海水喷入平衡舱，使顶空气体中的CO₂与海水达到平衡。顶空气体经热电冷凝器、纳菲昂干燥管处理后，流经Licor 7000型非色散红外气体分析仪，以测量干燥空气中的CO₂摩尔分数（XCO₂）。CO₂测量过程中会暂时中断气流，且所有测定均在大气压下进行。每约3小时分析一组覆盖海洋预期CO₂浓度范围的4种CO₂标准气体（见表1），用于校准气体分析仪。标准气体测量完成后，通过船舶前桅的进气口抽取外部洁净空气，以测定大气干燥态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），用于测量海表温度（Sea Surface Temperature, SST）。船首侧推舱内靠近取水口的位置安装了热盐仪（SeaBird Electronics SBE21），用于测定海表盐度。取水口至CO₂分析系统的输水时长通常约为50秒，期间水温升高幅度一般小于0.4℃。热盐仪的水样取自同一取水口及输水管道。气象数据、盐度、海表温度、船舶位置与时间信息均取自船舶日志系统。本次航次中，研究人员通过离散采水样品对SBE21测得的盐度值进行了校准校核。

气象数据、盐度、海表温度、船舶位置与时间信息均取自船舶日志系统。