IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS062008

This data was collected in April 2009 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS062008.Departed:     Sydney, New South Wales, April 16, 2008Arrived:     Noumea, New Caledonia, April 29, 2008CO2 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测量研究小组于2009年4月采集，数据源自“南调查者号（RV Southern Surveyor）”科考船航次SS062008（IMOS平台代码：VLHJ）。
起航信息：新南威尔士州悉尼港，2008年4月16日；抵达信息：新喀里多尼亚努美阿港，2008年4月29日。

## CO₂系统概况
表层海水二氧化碳逸度（fCO₂）采用通用海洋学公司（General Oceanics Inc.）的自动化测量系统（型号8050；Pierrot等，2009）进行测定。具体流程为：将海水喷入平衡腔，使顶空气体中的二氧化碳与海水达成气液平衡；顶空气体经热电冷凝器、纳菲恩干燥管除湿后，送入LICOR 7000型非色散红外气体分析仪，以测定干燥空气的二氧化碳摩尔分数（XCO₂）。测量二氧化碳浓度时会暂时中断气流，所有测定均在常压下完成。
每约4小时分析一组覆盖海洋典型CO₂浓度范围的4种标准气体，用于校准气体分析仪。标准气体的浓度采用世界气象组织（World Meteorological Organization, WMO）-X2007空气中CO₂摩尔分数标度。完成标准气体校准后，通过船舶前桅杆的进气口抽取洁净外界空气，测定干燥大气的XCO₂值。

## 海水采样与辅助数据
海水采样口位于船舶船艏约5.5米水深处。表层海水盐度采用安装在CO₂系统旁的赛默毕德电子（Seabird Electronics）SBE21型热盐计测定；安装于采样口处的赛默毕德电子SBE38型远程温度传感器用于测定表层海水温度（SST）。
采样口至CO₂分析系统的输水行程通常约为4分钟，输水过程中的水温升幅一般不超过0.6℃。热盐计的进水同样取自该采样口，但输水管道在采样口处分流。对比热盐计与平衡腔的温度记录可知，两条输水管道间的水温差通常小于0.1℃；由于热盐计输水管道沿船舶外壁布设，其水温通常高于平衡腔侧管道。热盐计输水管道的行程比平衡腔侧管道短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。上述参数及数据质量由澳大利亚国家海洋设施（Australian Marine National Facility）负责维护。