IMOS - SOOP Ocean Carbon Dioxide Data from MV L'Astrolabe voyage AL1213R2 (Dumont d'Urville station - Hobart)

This data was collected in January 2013 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on MV L'Astrolabe (IMOS platform code: FHZI) voyage AL1213R2.\n\nDeparted: Dumont d'Urville station, Antarctica, January 26, 2012\nArrived: Hobart Australia, January 31, 2012\n\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 (Table 1) that cover the range of CO2 values expected in the ocean are analysed about every three hours to calibrate the gas analyser. Atmospheric XCO2 (dry) is measured after the standards by pumping clean outside air from an intake on the forward mast of the ship. \n\nThe seawater intake is at about 3m depth in the bow of the ship. A remote temperature sensor (Seabird Electronics SBE38) located at the intake is used to measure sea surface temperature (SST). Sea surface salinity is measured using a thermosalinograph (Seabird Electronics SBE21) mounted in the bow thruster space near the intake. The travel time between the intake and CO2 system is typically about 50 seconds with warming usually less than 0.4ºC. The thermosalinograph water is from the same intake and supply line. Meteorological data, salinity, SST, and ships position and time are taken from the ship’s logging system. The salinity values measured by the SBE21 were checked against discrete bottle samples collected on the voyage.\n\nMeteorological data, salinity, SST, and ships position and time are taken from the ships logging system.

本数据集由国际海洋观测系统（Integrated Marine Observing System, IMOS）机遇船舶走航CO₂测量研究小组，于2013年1月在MV L'Astrolabe（IMOS平台代码：FHZI）的AL1213R2航次中采集。
本航次于2012年1月26日从南极洲德蒙迪乌尔维尔站起航，2012年1月31日抵达澳大利亚霍巴特。

## CO₂系统概述
表层海水二氧化碳逸度（fCO₂）采用General Oceanics Inc.生产的自动化系统（型号8050；Pierrot等，2009）进行测量。将海水喷入平衡腔室，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除湿后，再通过纳菲隆干燥管进一步干燥，随后流经Licor 7000型非分散红外气体分析仪，以测量干燥空气的CO₂摩尔分数（XCO₂）。CO₂测量过程会暂时停止气体流动，所有测量均在大气压下完成。约每3小时分析一组覆盖海洋预期CO₂浓度范围的4种CO₂标准气体（见表1），以完成气体分析仪的校准。完成标准气体校准后，通过船舶前桅的进气口抽取清洁室外空气，用于测量干燥大气的XCO₂。

海水取水口位于船舶船首约3米水深处。取水口处安装有远程温度传感器（SeaBird Electronics SBE38），用于测量海表温度（Sea Surface Temperature, SST）。船首侧推舱内取水口附近安装有热敏盐度计（SeaBird Electronics SBE21），用于测量海表盐度。取水口至CO₂系统的输水时长通常约为50秒，输水过程中水温升高通常低于0.4℃。热敏盐度计的取水水源与CO₂系统取自同一取水口及供水管路。

气象数据、盐度、海表温度以及船舶位置与时间信息均取自船舶日志系统。研究人员通过本次航次采集的离散瓶采样本，对SBE21测得的盐度值进行了校准验证。