IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS032009

This data was collected in July 2009 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS032009.Departed:     Lautoka Fiji, July 3, 2009Arrived:     Noumea, New Caledonia, July 27, 2009CO2 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综合观测系统（Integrated Marine Observing System, IMOS）的“机会船舶走航CO₂测量”研究小组，于2009年7月搭乘“南方考察者号”（RV Southern Surveyor）科考船（IMOS平台编号：VLHJ）执行SS032009航次期间采集。
起航港：斐济劳托卡，2009年7月3日
抵达港：新喀里多尼亚努美阿，2009年7月27日

### CO₂系统概况
本次测量采用通用海洋科学仪器公司（General Oceanics Inc.）自动化系统（型号8050；Pierrot等，2009）测定表层海水二氧化碳分压（fCO₂）。具体流程为：将海水喷入平衡舱，使顶空气体中的CO₂与海水达到气液平衡；随后将顶空气体依次经热电冷凝器、纳菲恩（nafion）干燥管输送，再通过Licor 7000型非色散红外气体分析仪（non-dispersive infrared gas analyser），测量干燥空气的CO₂摩尔分数（XCO₂）。CO₂测量环节会暂时中断气流，且所有测量均在大气压条件下开展。每间隔约4小时，便会分析一组覆盖海洋典型CO₂浓度范围的4种CO₂标准气体，以完成气体分析仪的校准。标准气体的浓度采用世界气象组织（World Meteorological Organization, WMO）-X2007空气CO₂摩尔分数尺度。完成标准气体校准后，通过船首桅杆的进气口抽取洁净外界空气，以此测量大气干燥态XCO₂。

### 海水取水与辅助数据
海水取水口位于船艏约5.5米水深处。CO₂系统旁安装有希比尔电子（Seabird Electronics）SBE21型热盐仪（thermosalinograph），用于测量海表盐度。取水口处搭载希比尔电子（Seabird Electronics）SBE38型远程温度传感器，用于测定海表温度（SST）。取水口至CO₂系统的输水路径耗时通常约4分钟，输水过程中水温升高幅度一般小于0.6℃。热盐仪的取水水源与CO₂系统同源，但两条输水管道在取水口后即分支独立。对比热盐仪与平衡舱的温度记录可知，两条输水管道的温差通常小于0.1℃；热盐仪输水管道沿船体外壁铺设，整体温度通常高于平衡舱输水管道，且其输水耗时比平衡舱输水管道短2.5分钟。

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。上述观测参数及对应数据质量均由澳大利亚海洋国家设施（Australian Marine National Facility）负责维护。