IMOS - SOOP Ocean Carbon Dioxide Data from RV Southern Surveyor voyage SS102008

This data was collected in October 2008 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Southern Surveyor (IMOS platform code: VLHJ) voyage SS102008.

Departed: Sydney, New South Wales, October 10, 2008
Arrived: Newcastle, New South Wales, October 20, 2008

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 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.

Seawater intake and ancillary data:
The 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 0.5ºC. The thermosalinograph water is from the same intake, but the supply lines separate after the intake. The travel time and warming in the two lines is very similar. Meteorological 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综合海洋观测系统（Integrated Marine Observing System，IMOS）的「机遇船舶走航CO₂测量」研究小组，于2008年10月搭乘「南方考察者号」（RV Southern Surveyor，IMOS平台代码：VLHJ）执行SS102008航次期间采集。

起航：新南威尔士州悉尼市，2008年10月10日
抵港：新南威尔士州纽卡斯尔市，2008年10月20日

## CO₂系统概况
本研究采用通用海洋公司（General Oceanics Inc.）型号8050的自动化系统（Pierrot等，2009），测定表层海水二氧化碳分压（fCO₂）。具体流程为：将海水喷入平衡舱，使顶空气体中的CO₂与海水达到气液平衡；随后将顶空气体经热电冷凝器、纳菲恩干燥管后，输送至Licor 7000型非分散红外气体分析仪（non-dispersive infrared gas analyser），以测定干燥空气中的CO₂摩尔分数（XCO₂）。测量过程中会暂时切断气流，测定在常压下进行。每间隔约4小时，将使用一套覆盖海洋预期CO₂浓度范围的4种CO₂标准气体校准气体分析仪。标准气体的浓度基于世界气象组织（World Meteorological Organization，WMO）X2007空气中CO₂摩尔分数标度。在完成标准气体校准后，通过船舶前桅进气口抽取清洁外界空气，以测定大气干燥态XCO₂。

## 海水取水与辅助数据
海水取水口位于船舶船首约5.5米水深处。CO₂系统旁配置了海鸟电子（Seabird Electronics）SBE21型热盐深仪，用于测定海表盐度；取水口处安装了海鸟电子（Seabird Electronics）SBE 38型远程温度传感器，用于测量海表温度（Sea Surface Temperature，SST）。从取水口到CO₂系统的输水时长通常约为4分钟，水体升温幅度一般小于0.5℃。热盐深仪的取水同样来自该取水口，但两条输水管道在取水口处分流，二者的输水时长与升温幅度基本一致。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，相关参数及数据质量由澳大利亚海洋国家设施（Australian Marine National Facility）维护。