IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS2011_V03 (Hobart-Hobart)

This data was collected in August 2011 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS2011_V03.Departed:     Hobart, TAS, Aug 01, 2011Arrived:     Hobart, TAS, Aug 10, 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.

本数据集由澳大利亚海洋观测系统（Integrated Marine Observing System, IMOS）的机遇船走航CO₂测量研究小组，于2011年8月在RV Southern Surveyor科考船（IMOS平台代码：VLHJ）的航次SS2011_V03中采集。本次航次于2011年8月1日从塔斯马尼亚州霍巴特港启航，同年8月10日返回该港。

CO₂系统概述：表层海水二氧化碳分压（fCO₂）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Pierrot等，2009）测定。具体流程如下：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、纳菲隆（Nafion）干燥管干燥，再通入Licor 7000型非分散红外气体分析仪（non-dispersive infrared gas analyser），以测定干燥空气的CO₂摩尔分数（XCO₂）。CO₂测量过程中会暂时中断气流，所有测量均在大气压条件下开展。每间隔约4小时，使用覆盖海洋环境预期CO₂浓度范围的4套标准气体对气体分析仪进行校准，标准气体的浓度采用WMO-X2007空气CO₂摩尔分数标度。通过船舶前桅杆上进气口抽取清洁外界空气，在完成标准气体校准后测定大气干燥态XCO₂。

海水采集与辅助数据：海水采样口位于船首约5.5米水深处。CO₂系统旁搭载了海鸟电子（Seabird Electronics）SBE21型船用温盐计（thermosalinograph），用于测量海表盐度；采样口处安装有海鸟电子（Seabird Electronics）SBE38型远程温度传感器，用于测定海表温度（sea surface temperature, SST）。采样口到CO₂系统的输水行程通常约4分钟，输水过程中水温升高幅度一般小于0.6℃。船用温盐计的取水水源与CO₂系统同源，但两条输水管道在采样口后即分流。对船用温盐计与平衡舱的温度记录对比显示，两条管道的水温差通常小于0.1℃；由于船用温盐计的输水管道沿船外布置，其水温通常高于平衡舱输水管道。船用温盐计的输水行程比平衡舱输水行程短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。本数据集的参数与数据质量控制工作由澳大利亚国家海洋研究设施（Australian Marine National Facility）负责维护。