IMOS - SOOP 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, 2011
Arrived: Fremantle, WA, Oct 17, 2011

CO2 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机遇船走航CO₂测量研究小组于“南方考察者号（RV Southern Surveyor）”科考船（IMOS平台代码：VLHJ）的SS2011_V05航次中，于2011年9月至10月期间采集。

起航：西澳大利亚州杰拉尔顿（Geraldton, WA），2011年9月21日
抵达：西澳大利亚州弗里曼特尔（Fremantle, WA），2011年10月17日

CO₂系统概况：
表层海水二氧化碳逸度（fCO₂，fugacity of carbon dioxide）采用通用海洋学公司（General Oceanics Inc.）自动化测量系统（型号8050；参考Pierrot等2009年研究）进行测定。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；顶空气体经热电冷凝器、纳菲昂干燥管（Nafion drying tube）后，送入Licor 7000型非色散红外气体分析仪，以测定干燥气体的CO₂摩尔分数（XCO₂，CO₂ mole fraction）。测量过程中会暂时暂停气流，所有测定均在常压下完成。每约4小时便会使用一套覆盖海洋常见CO₂浓度范围的4种CO₂标准气体，对气体分析仪进行校准，标准气体的浓度值采用世界气象组织（WMO）X2007空气CO₂摩尔分数标度。标准气体校准完成后，通过安装在船舶前桅的进气口抽取洁净外界空气，以此测定干燥大气的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。海水表层盐度采用安装在CO₂系统旁的赛默百德电子（Seabird Electronics）SBE21型流动式温盐计（thermosalinograph）进行测定；取水口处安装的赛默百德电子SBE38型远程温度传感器，用于测定海水表层温度（SST，sea surface temperature）。从取水口到CO₂测量系统的输水时长通常约为4分钟，输水过程中水温升高一般不超过0.6℃。流动式温盐计的取水水源与CO₂系统一致，但两条输水管道在取水口处分流。对温盐计与平衡舱的温度记录进行比对后发现，两条管道内的水温差通常小于0.1℃；由于温盐计的输水管道沿船舶外壁铺设，其内水温通常高于平衡舱输水管道，且输水至温盐计的时长比至平衡舱的时长快2.5分钟。

气象数据、盐度、SST以及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管控工作由澳大利亚国家海洋设施（Australian Marine National Facility）负责。