IMOS - SOOP Ocean Carbon Dioxide Data from RV Southern Surveyor voyage ST032008

This data was collected in August 2008 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage ST032008.

Departed: Gladstone, Queensland, August 12, 2008
Arrived: Sydney, New South Wales, August 16, 2008

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.

本数据集由综合海洋观测系统（Integrated Marine Observing System, IMOS）的机会船舶走航CO₂测量研究小组，于2008年8月在“南方勘探者号”（RV Southern Surveyor，IMOS平台代码：VLHJ）的ST032008航次中采集。

起航地点：澳大利亚昆士兰州格拉德斯通，2008年8月12日
抵达地点：澳大利亚新南威尔士州悉尼，2008年8月16日

CO₂系统概况：
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；Pierrot等，2009），对表层海水二氧化碳分压（fCO₂）进行测定。具体流程为：将海水喷入平衡腔，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、纳菲恩干燥管输送，再通过Licor 7000型非色散红外气体分析仪，测定干燥空气的CO₂摩尔分数（XCO₂）。CO₂测量在常压下进行，测量过程中会暂时中断气流。约每4小时便会使用一组覆盖海洋典型CO₂浓度范围的4种CO₂标准气体，对气体分析仪进行校准。标准气体的浓度基于WMO-X2007空气中CO₂摩尔分数标度。完成标准气体校准后，通过船舶前桅杆上的进气口抽取洁净外部空气，以测定大气干燥XCO₂。

海水取样口与配套辅助数据：
海水取样口位于船舶船首约5.5米水深处。CO₂系统旁搭载了热盐计（thermosalinograph，Seabird Electronics SBE21），用于测定海表盐度。取样口处安装了远程温度传感器（Seabird Electronics SBE 38），用以测量海表温度（SST）。海水从取样口输送至CO₂系统的耗时通常约为4分钟，期间水温升高通常不超过0.6℃。热盐计的供水同样取自该取样口，但供水管线在取样口处分流。对比热盐计与平衡腔的温度记录可知，两条管线的温差通常小于0.1℃。热盐计的供水管线沿船舶外部铺设，其水温通常高于平衡腔管线。热盐计供水管线的输水耗时比平衡腔管线快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。