IMOS - SOOP Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS2011_V04 (Fremantle -Geraldton)

This data was collected in August/September 2011 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS2011_V04.\n\nDeparted: \tFremantle, WA, Aug 25, 2011\nArrived: \tGeraldton, WA, Sep 13, 2011\n\nCO2 System Overview:\nThe 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. \n\nSeawater intake and ancillary data:\nThe 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. \n\nMeteorological 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（IMOS）机遇船舶走航CO₂测量研究小组，于2011年8月至9月在“南方勘探者号”（RV Southern Surveyor，IMOS平台代码：VLHJ）的SS2011_V04航次中采集完成。

起航地点：西澳大利亚州弗里曼特尔（Fremantle, WA），2011年8月25日
抵达地点：西澳大利亚州杰拉尔顿（Geraldton, WA），2011年9月13日

CO₂系统概述：
本研究采用通用海洋学公司（General Oceanics Inc.）生产的自动化检测系统（型号8050；参考Pierrot等2009年的研究成果），对表层海水二氧化碳分压（fugacity of carbon dioxide, fCO₂）进行测定。具体检测流程如下：将海水喷入平衡舱（equilibration chamber），使顶空气体（headspace gas）中的CO₂与海水充分达到气液平衡；随后将顶空气体泵送至热电冷凝器（thermoelectric condenser），经纳菲恩干燥管（nafion drying tube）去除水汽后，流经Licor 7000型非色散红外气体分析仪（non-dispersive infrared gas analyser），以测定干燥空气中的CO₂摩尔分数（XCO₂）。CO₂测定过程会暂时中断气流，且所有测定均在常压环境下完成。每约4小时便会使用一套覆盖海洋常见CO₂浓度范围的4种标准CO₂气体，对气体分析仪进行校准。标准气体的浓度基于WMO-X2007空气中CO₂摩尔分数刻度。完成标准气体校准后，通过船舶前桅的进气口抽取洁净外界空气，以测定大气干燥态XCO₂。

海水取水口与辅助观测数据：
海水取水口位于船舶船首约5.5米深度处。CO₂系统旁搭载了赛伯德电子（Seabird Electronics）SBE21型热盐仪，用于测定海表盐度。取水口处还安装了赛伯德电子SBE 38型远程温度传感器，用于测量海表温度（SST）。取水口至CO₂系统的输水行程通常约为4分钟，输水过程中的水温升温幅度一般小于0.6℃。热盐仪的供水取自同一取水口，但输水管道在取水口处分流。对比热盐仪与平衡舱的温度记录可知，两条输水管道的水温差通常小于0.1℃。热盐仪的输水管道沿船舶外部铺设，通常比平衡舱的输水管道温度更高，且其输水行程比平衡舱短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。上述观测参数及对应数据质量均由澳大利亚海洋国家设施（Australian Marine National Facility）负责维护与质量管理。