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

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.

Departed: Hobart, Australia, January 10, 2013
Arrived: Dumont d'Urville station, Antarctica, January 15, 2013

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机会船走航CO₂测量研究小组于2013年1月采集自“L'Astrolabe”号科考船（IMOS平台代码：FHZI）的AL1213R2航次。

起航与抵达：
本航次于2013年1月10日从澳大利亚霍巴特起航，2013年1月15日抵达南极洲迪蒙·迪维尔站（Dumont d'Urville station）。

CO₂系统概述：
表层海水二氧化碳分压（fugacity of carbon dioxide, fCO₂）采用通用海洋学公司（General Oceanics Inc.）的自动化系统（型号8050；Pierrot等，2009）进行测定。具体流程为：将海水喷入平衡腔，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、纳菲恩干燥管（nafion drying tube）后，流入Licor 7000型非分散红外气体分析仪（non-dispersive infrared gas analyser），以测定干燥空气的CO₂摩尔分数（XCO₂）。CO₂测量过程中会暂时暂停气流，测量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外部洁净空气，以此测定大气干燥XCO₂。

海水取水与参数测量：
海水取水口位于船舶船首约3米水深处。取水口处安装了远程温度传感器（Seabird Electronics SBE38），用于测量海表温度（sea surface temperature, SST）。在取水口附近的首侧推舱内安装了热盐仪（Seabird Electronics SBE21），用于测量海表盐度。从取水口到CO₂分析系统的输送时长通常约为50秒，期间海水升温通常不超过0.4℃。热盐仪的供水同样取自该取水口及供水管路。气象数据、盐度、SST以及船舶位置与时间均取自船舶日志系统。SBE21测量得到的盐度值，与本航次采集的离散瓶采样本进行了比对校准。

气象数据及船舶信息来源：
气象数据、盐度、SST以及船舶位置与时间均取自船舶日志系统。