IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS022008

This data was collected in February 2008 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS022008.Departed:     Hobart, Tasmania, February 04, 2008Arrived:      Port Adelaide, South Australia, February 26, 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.

本数据集由澳大利亚海洋观测系统（Integrated Marine Observing System, IMOS）的“机遇船舶走航CO₂测量”研究小组，于2008年2月在“南方勘探者号”（RV Southern Surveyor，IMOS平台代码：VLHJ）的SS022008航次中采集。
本航次于2008年2月4日从塔斯马尼亚州霍巴特港起航，于2008年2月26日抵达南澳大利亚州阿德莱德港。

CO₂系统概述：
本研究采用通用海洋科学公司（General Oceanics Inc.）的自动化测量系统（型号8050；参考文献Pierrot等，2009）测定表层海水二氧化碳分压（fugacity of carbon dioxide, fCO₂）。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；随后将顶空气体经热电冷凝器（thermoelectric condenser）、纳菲隆干燥管（nafion drying tube）泵送，再通过Licor 7000型非分散红外气体分析仪（non-dispersive infrared gas analyser）测定干燥空气的CO₂摩尔分数（XCO₂）。CO₂测量过程中会暂时暂停气流，测定在大气压下进行。每约4小时分析一组覆盖海洋预期CO₂浓度范围的4种标准CO₂气体，以校准气体分析仪。标准气体的浓度采用WMO-X2007空气CO₂摩尔分数尺度（WMO-X2007 mole fraction scale for CO₂-in-air）。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部空气，以此测定大气干燥XCO₂。

海水采集与辅助数据：
海水采集口位于船舶船首约5.5米水深处。CO₂系统旁配置热盐深仪（thermosalinograph，Seabird Electronics SBE21），用于测定海表盐度。采集口处安装远程温度传感器（Seabird Electronics SBE 38），用于测定海表温度（sea surface temperature, SST）。海水从采集口输送至CO₂系统的耗时通常约为4分钟，期间水温升高幅度通常不超过0.6℃。热盐深仪的供水同样取自该采集口，但供水管道在采集口后即分流。对比热盐深仪与平衡舱的温度记录可知，两条供水管道的水温差通常小于0.1℃；热盐深仪的供水管道沿船外布设，其水温通常高于平衡舱供水管道。热盐深仪的供水输送时间比平衡舱管道快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。上述参数及数据质量由澳大利亚海洋国家设施（Australian Marine National Facility）负责维护。