IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS2011_V02 (Brisbane-Auckland)

This data was collected in May/June 2011 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS2011_V02.Departed:     Brisbane, QLD, May 13, 2011Arrived:     Auckland, NZ, Jun 04, 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.

本数据集由国际海洋观测系统（IMOS, Integrated Marine Observing System）自愿走航船舶CO₂测量研究小组，于2011年5至6月期间在研究船"RV Southern Surveyor"（IMOS平台代码：VLHJ）的SS2011_V02航次中采集。本航次于2011年5月13日从澳大利亚昆士兰州布里斯班起航，于2011年6月4日抵达新西兰奥克兰。

### CO₂系统概述
本研究采用General Oceanics公司自动化测量系统（型号8050；参考文献Pierrot et al 2009）测定表层海水二氧化碳逸度（fCO₂, fugacity of carbon dioxide）。具体流程为：将海水喷入气液平衡舱，使顶空气体中的CO₂与海水达到平衡；随后将顶空气体依次经热电冷凝器、纳菲昂（nafion）干燥管处理，再通入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测量环节会临时暂停气流，且所有测量均在大气压条件下完成。每间隔约4小时，将使用一套覆盖海洋预期CO₂浓度范围的4种标准CO₂气体，对气体分析仪进行校准。标准气的浓度基于WMO-X2007空气中CO₂摩尔分数标尺。完成标准气校准后，通过船舶前桅的进气口抽取清洁外界空气，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。CO₂系统旁配备Seabird Electronics SBE21型热盐计，用于测量海表盐度；采样口处安装有Seabird Electronics SBE 38型远程温度传感器，用于测定海表温度（SST, sea surface temperature）。采样口至CO₂系统的输水时长通常约为4分钟，期间水温升高幅度一般不超过0.6℃。热盐计的取水同样来自该采样口，但输水管道在采样口后即与CO₂系统的输水管道分离。对比热盐计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℃；热盐计输水管道沿船舶外部铺设，其水温通常高于平衡舱输水管道。热盐计输水管道的输水时长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。上述参数及对应数据质量由澳大利亚海洋国家设施（Australian Marine National Facility）负责维护。