IMOS - SOOP Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS042008

This data was collected in March 2008 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS042008.

Departed: Hobart, Tasmania, March 20, 2008
Arrived: Hobart, Tasmania, March 26, 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.

本数据集由澳大利亚海洋综合观测系统（Integrated Marine Observing System，IMOS）机遇船舶走航CO₂测量研究小组，于2008年3月搭乘'南方调查者号'（RV Southern Surveyor，IMOS平台代码：VLHJ）执行航次SS042008期间采集。

起航地：塔斯马尼亚州霍巴特，2008年3月20日
抵达地：塔斯马尼亚州霍巴特，2008年3月26日

## CO₂系统概述
表层海水二氧化碳逸度（fCO₂）采用通用海洋学公司（General Oceanics Inc.）的自动化测量系统（型号8050；Pierrot等，2009）进行测定。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；顶空气体经热电冷凝器后，再通过纳菲昂（Nafion）干燥管，随后流入Li-Cor 7000型非色散红外气体分析仪，用于测定干燥空气的CO₂摩尔分数（XCO₂）。测量CO₂时需临时暂停气流，测量过程处于常压环境下。每隔约4小时分析一组覆盖海洋典型CO₂浓度范围的4种CO₂标准气体，以校准气体分析仪。标准气体的浓度采用WMO-X2007空气中CO₂摩尔分数基准。完成标准气体分析后，通过安装在船舶前桅的进气口抽取清洁外界空气，测定干燥大气中的XCO₂。

## 海水取样口及辅助数据
海水取样口位于船舶船首约5.5米水深处。海水表层盐度采用安装于CO₂系统旁的热盐仪（Seabird Electronics SBE21）测定；安装于取样口的远程温度传感器（Seabird Electronics SBE 38）用于测定海水表层温度（SST，Sea Surface Temperature）。从取样口到CO₂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低于0.6℃。热盐仪的取水水源与CO₂系统相同，但输水管道在取样口后分流。对热盐仪与平衡舱的温度记录进行对比后发现，两条输水管道的水温差通常低于0.1℃。热盐仪的输水管道沿船舶外部布设，水温通常高于平衡舱的输水管道。热盐仪输水管道的输水时长比平衡舱的输水管道短2.5分钟。

气象数据、盐度、SST、船舶位置及时间信息均取自船舶日志系统。上述参数与数据质量均由澳大利亚国家海洋科研设施（Australian Marine National Facility）维护。