IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS2011_T03 (Hobart-Fremantle)

This data was collected in August 2011 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS2011_T03.Departed:     Hobart, TAS, Aug 12, 2011Arrived:     Fremantle, WA, Aug 22, 2011CO2 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 that cover the range of CO2 values expected in the ocean are analysed about every four hours to calibrate the gas analyser. The standard gas concentrations are on the WMO-X2007 mole fraction scale for CO2-in-air. Atmospheric XCO2 (dry) is measured after the standards by pumping clean outside air from an intake on the forward mast of the ship. Seawater intake and ancillary data:The seawater intake is located at about 5.5m depth in the bow of the ship. Sea surface salinity is measured using a thermosalinograph (Seabird Electronics SBE21) located next to the CO2 system. A remote temperature sensor (Seabird Electronics SBE 38) located at the intake is used to measure sea surface temperature (SST). The travel time between the intake and CO2 system is typically about 4 minutes with warming usually less than 0.6ºC. The thermosalinograph water is from the same intake, but the supply lines separate after the intake. A comparison of thermosalinograph and equilibrator temperature records shows the temperature difference in the two lines is generally less than 0.1ºC. The thermosalinograph water line travels outside the ship and is typically warmer than the equilibrator. The travel time in water line to the thermosalinograph is 2.5 minutes faster than to the equilibrator. Meteorological data, salinity, SST, and ships position and time are taken from the ships logging system. These parameters and the data quality are maintained by the Australian Marine National Facility.

本数据集由澳大利亚海洋观测系统（IMOS，Integrated Marine Observing System）的“机遇船走航CO₂测量”研究小组，于2011年8月搭载南调查者号（RV Southern Surveyor）科考船（IMOS平台代码：VLHJ）执行航次SS2011_T03期间采集。起航地：塔斯马尼亚州霍巴特，2011年8月12日；抵达地：西澳大利亚州弗里曼特尔，2011年8月22日。CO₂系统概况：采用通用海洋有限公司（General Oceanics Inc.）自动化系统（型号8050；Pierrot等，2009）测量表层海水二氧化碳逸度（fCO₂，fugacity of carbon dioxide）。具体测量流程为：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；随后将顶空气体依次经热电冷凝器、纳菲恩干燥管（nafion drying tube）输送，通过利科（LI-COR）7000型非色散红外气体分析仪（non-dispersive infrared gas analyser）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，且所有测量均在大气压条件下开展。每约4小时分析一组覆盖海洋水体预期CO₂浓度范围的4种CO₂标准气，以完成气体分析仪的校准。标准气浓度采用WMO-X2007空气中CO₂摩尔分数基准。完成标准气校准后，通过船舶前桅杆上的进气口抽取洁净外界空气，用于测量大气干燥XCO₂。海水取水与辅助数据：海水取水口位于船首约5.5米水深处。CO₂系统旁配备了西贝尔电子公司（Seabird Electronics）生产的SBE21型热盐计（thermosalinograph），用于测量海表盐度；取水口处安装有西贝尔电子公司SBE 38型远程温度传感器，用于测量海表温度（SST，Sea Surface Temperature）。从取水口到CO₂系统的输水耗时通常约4分钟，其间水温升高幅度通常不超过0.6℃。热盐计的供水同样取自该取水口，但输水线路在取水口后即与CO₂系统的输水线路分离。对比热盐计与平衡舱的温度记录可知，两条输水线路的温差通常小于0.1℃；热盐计输水线路沿船体外铺设，通常比平衡舱输水线路温度更高。热盐计输水线路的输水耗时比平衡舱输水线路短2.5分钟。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。上述参数及对应数据质量由澳大利亚海洋国家设施（Australian Marine National Facility）负责维护与管理。