IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Southern Surveyor voyage ST022010 (Fremantle-Hobart)

This data was collected in August 2010 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage ST022010.Departed: Fremantle, Australia, August 10, 2010Arrived:     Hobart, Australia, August 20, 2010CO2 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）的“机遇船舶走航CO₂测量”研究小组，于2010年8月搭乘“南方考察者”号科考船（RV Southern Surveyor，IMOS平台代码：VLHJ）执行航次ST022010期间采集。该航次于2010年8月10日从澳大利亚弗里曼特尔港启航，于2010年8月20日抵达澳大利亚霍巴特港。

CO₂系统概述：表面海水二氧化碳分压（fCO₂，fugacity of carbon dioxide）采用通用海洋学公司（General Oceanics Inc.）的自动化测量系统（型号8050；参考Pierrot等2009年研究）进行测定。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、纳菲翁干燥管输送，再通过Licor 7000型非色散红外气体分析仪（non-dispersive infrared gas analyser），测定干燥空气的CO₂摩尔分数（XCO₂，mole fraction）。CO₂测量过程中会暂时中断气流，且所有测定均在常压环境下完成。每约4小时即分析一组覆盖海洋预期CO₂浓度范围的4种标准CO₂气体，以对气体分析仪进行校准。标准气体的浓度基于世界气象组织（World Meteorological Organization，WMO）-X2007空气中CO₂摩尔分数标度。大气干基CO₂摩尔分数（XCO₂(dry)）的测定则在标准气体校准完成后，通过船舶前桅进气口抽取外部清洁空气完成。

海水采样及辅助数据：海水采样口位于船舶艏部约5.5米水深处。紧邻CO₂测量系统安装了热盐深仪（Seabird Electronics SBE21），用于测定海表盐度。采样口处搭载了远程温度传感器（Seabird Electronics SBE 38），用于测量海表温度（SST，Sea Surface Temperature）。采样口至CO₂测量系统的输水耗时通常约4分钟，期间水温升高一般低于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系统的管道分离。对比热盐深仪与平衡舱的温度记录可知，两条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部铺设，其水温通常高于平衡舱的输水管道。热盐深仪的输水耗时比平衡舱的输水耗时短约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。上述参数及对应数据的质量管控由澳大利亚海洋国家设施（Australian Marine National Facility）负责。