IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS2011_V04 (Fremantle -Geraldton)

This data was collected in August/September 2011 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS2011_V04.Departed:     Fremantle, WA, Aug 25, 2011Arrived:     Geraldton, WA, Sep 13, 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.

本数据集由海洋综合观测系统（Integrated Marine Observing System，IMOS）机遇船舶走航CO₂测量研究组，于“南考察号”（RV Southern Surveyor，IMOS平台代码：VLHJ）航次SS2011_V04执行期间，在2011年8月至9月间采集。
起航：西澳大利亚州弗里曼特尔，2011年8月25日
抵达：西澳大利亚州杰拉尔顿，2011年9月13日

CO₂系统概况：本研究采用通用海洋设备公司（General Oceanics Inc.）8050型自动化系统（Pierrot等，2009）测定海水表层二氧化碳逸度（fCO₂）。具体流程为将海水喷入平衡舱，使顶空气体中的CO₂与海水达成气液平衡；随后将顶空气体依次泵经热电冷凝器与纳菲隆干燥管进行除湿，再通入Licor 7000型非色散红外气体分析仪，以测定干燥空气中的CO₂摩尔分数（XCO₂）。测量过程会暂时中断气流，且所有测量均在大气压下进行。每约4小时便会分析一组覆盖海洋环境预期CO₂浓度范围的4种标准CO₂气体，以校准气体分析仪；标准气体的浓度采用世界气象组织WMO-X2007空气中CO₂摩尔分数标度。标准气体校准完成后，通过船舶前桅的进气口抽取洁净外界空气，以测定干燥大气中的XCO₂。

海水取水及辅助数据：海水取水口位于船舶船艏约5.5米水深处。海水表层盐度由安装于CO₂系统旁的热盐深仪（Seabird Electronics SBE21）测定；取水口处安装的远程温度传感器（Seabird Electronics SBE 38）用于获取海水表层温度（SST）。取水口至CO₂系统的输水行程通常耗时约4分钟，输水过程中水温升高一般低于0.6℃。热盐深仪的取水水源与CO₂系统相同，但输水管道在取水口处分流。对热盐深仪与平衡舱的温度记录进行对比后发现，两条输水管道内的水温差通常小于0.1℃；热盐深仪的输水管道沿船舶外部敷设，其水温通常高于平衡舱侧管道，且输水至热盐深仪的行程比至平衡舱快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。上述参数及数据质量由澳大利亚国家海洋设施（Australian Marine National Facility）负责维护。