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

This data was collected in December 2011 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on MV L'Astrolabe (IMOS platform code: FHZI) voyage AL1112R0.

Departed: Dumont d'Urville station, Antarctica, December, 2011
Arrived: Hobart Australia, December 12, 2011

Data was collected from 6th-10th of December.

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.

本数据集由隶属于海洋综合观测系统（Integrated Marine Observing System，IMOS）的机遇船舶航次CO₂在线测量研究小组，于2011年12月搭乘MV L'Astrolabe号（IMOS平台代码：FHZI）执行航次AL1112R0期间采集。

启航地：南极洲迪蒙·迪尔维尔站，启航时间：2011年12月
抵达地：澳大利亚霍巴特，抵达时间：2011年12月12日

数据采集时段为2011年12月6日至10日。

## 二氧化碳系统概述
表层海水二氧化碳逸度（fCO₂，fugacity of carbon dioxide）采用通用海洋科学公司（General Oceanics Inc.）自动化测量系统（型号8050；Pierrot等，2009）进行测定。具体流程为：将海水喷入平衡腔室，使顶空气体中的二氧化碳与海水达成气液平衡；顶空气体经热电冷凝器、纳菲昂干燥管后，通入Licor 7000型非分散红外气体分析仪，以测定干燥空气中的二氧化碳摩尔分数（XCO₂）。测量过程需临时暂停气体流量，且全程处于常压环境。每约3小时便会对覆盖海洋环境典型CO₂浓度范围的4种CO₂标准气体（见表1）进行分析，以完成气体分析仪的校准。标准气体分析完成后，通过抽取船舶前桅进气口处的清洁室外空气，测定干燥大气中的XCO₂。

海水采样口位于船舶船首约3米水深处。采样口处安装的赛默百德电子（Seabird Electronics）SBE38型远程温度传感器，用于测定海表温度（SST）；海表盐度则通过安装在采样口附近船首推力器舱内的赛默百德电子SBE21型流动式温盐分析仪进行测定。从采样口至CO₂分析系统的输水延时通常约为50秒，水温升高幅度一般不超过0.4℃，且温盐分析仪的采样水源与CO₂测量系统取自同一采样口及输水管道。SBE21型温盐分析仪测得的盐度值，将与本航次采集的离散采水器样本进行比对校正。

气象数据、盐度、海表温度、船舶位置及时间信息均来自船舶日志系统。
气象数据、盐度、海表温度、船舶位置及时间信息均取自船舶日志系统。