IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS2011_V05 (Geraldton-Fremantle)

This data was collected in September/October 2011 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS2011_V05.Departed:     Geraldton, WA, Sept 21, 2011Arrived:     Fremantle, WA, Oct 17, 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IMOS船舶走航CO₂测量研究小组于2011年9-10月搭载“南方探索者号”调查船（RV Southern Surveyor，IMOS平台代码：VLHJ）执行航次SS2011_V05期间采集。
起航地点：西澳大利亚州杰拉尔顿，2011年9月21日；抵达地点：西澳大利亚州弗里曼特尔，2011年10月17日。

CO₂系统概况：本研究采用通用海洋学公司（General Oceanics Inc.）型号8050自动化测量系统（Pierrot等，2009），测定表层海水二氧化碳逸度分压（fCO₂）。具体流程为：将海水喷入气液平衡舱，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通入热电冷凝器、纳菲恩干燥管（nafion drying tube），随后流经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）。CO₂测量过程中会临时暂停气流，且测定在常压环境下进行。每约4小时会分析一组覆盖海洋典型CO₂浓度范围的4种标准CO₂气体，用于校准气体分析仪。标准气体浓度采用WMO-X2007空气CO₂摩尔分数标度。完成标准气体校准后，通过船舶前桅杆上的进气口抽取清洁外部空气，以测定大气干燥态XCO₂。

海水采样及辅助数据：海水采样口位于船舶船首约5.5米水深处。紧邻CO₂系统安装的热盐深仪（thermosalinograph，Seabird Electronics SBE21）用于测量海表盐度；采样口处安装的远程温度传感器（Seabird Electronics SBE 38）用于测定海表温度（SST）。从采样口到CO₂系统的输水时长通常约4分钟，输水过程中水温升高幅度一般小于0.6℃。热盐深仪的供水同样取自该采样口，但输水管道在采样口后即与CO₂系统的输水管道分离。对比热盐深仪与气液平衡舱的温度记录可知，两条输水管道的水温差通常小于0.1℃。热盐深仪的输水管道沿船舶外壁铺设，其水温通常高于气液平衡舱的输水管道。热盐深仪输水管道的输水时长较气液平衡舱管道快2.5分钟。

气象数据、盐度、海表温度、船舶位置及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海洋国家设施（Australian Marine National Facility）负责维护。