IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from MV L'Astrolabe voyage AL1112R0 (Hobart-Dumont d'Urville station)

This data was collected in October 2011 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on MV L'Astrolabe (IMOS platform code: FHZI) voyage AL1112R0.Departed: Hobart Australia, October 21, 2011Arrived:      Dumont d'Urville station, Antarctica, October, 2011Data was collected from 25th-26th of October.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 (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. The 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.Meteorological data, salinity, SST, and ships position and time are taken from the ships logging system.

本数据集由IMOS船舶走航CO₂测量研究小组于2011年10月在MV L'Astrolabe（IMOS平台代码：FHZI）的AL1112R0航次中采集。本航次启航于澳大利亚霍巴特，时间为2011年10月21日；抵达南极迪蒙·迪尔维尔站，时间为2011年10月。数据采集时段为2011年10月25日至26日。CO₂系统概述：表层海水二氧化碳分压（fugacity of carbon dioxide, fCO₂）采用General Oceanics Inc.公司的自动化系统（型号8050；Pierrot等，2009）进行测量。具体流程为：将海水喷入平衡舱，顶空气体中的CO₂与海水达到平衡；随后顶空气体经热电冷凝器、纳菲翁干燥管后，通入Licor 7000型非色散红外气体分析仪，以测量干燥空气的二氧化碳摩尔分数（XCO₂）。测量过程中气流会暂时暂停，且测定在大气压条件下完成。每约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），用于校准气体分析仪。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，以测量大气干基XCO₂。海水采样口位于船舶船首约3米水深处。采样口处安装的远程温度传感器（Seabird Electronics SBE38）用于测量海表温度（Sea Surface Temperature, SST）。船首推进器舱内靠近采样口处安装了热盐仪（Seabird Electronics SBE21），用于测量海表盐度。采样口至CO₂分析系统的传输时间通常约为50秒，其间水温升高通常小于0.4℃。热盐仪的供水同样取自该采样口及供水管路。气象数据、盐度、海表温度、船舶位置及时间均取自船舶日志系统。SBE21测得的盐度值与本航次采集的离散瓶水样进行了比对校准。