IMOS - Ships of Opportunity - Ocean Carbon Dioxide Data from RV Aurora Australis voyage AA1112V1 (Hobart-Hobart)

This data was collected in July/August 2011 by the IMOS Ship of Opportunity Underway CO2 Measurement research group on RV Aurora Australis (IMOS platform code: VNAA) voyage AA1112V1.Departed:     Hobart, Tasmania, July 19, 2011Arrived: Hobart, Tasmania, August 05, 2011CO2 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 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. Seawater intake and ancillary data:The seawater intake is at about 6 m depth. 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 oceanographic lab next to the pCO2 system. The travel time between the intake and CO2 system is typically about 70 seconds with warming usually less than 0.7ºC in cold waters near freezing. 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.

本数据集由海洋综合观测系统（Integrated Marine Observing System，简称IMOS）机遇船舶走航CO₂测量研究小组，于2011年7月至8月间在RV南极光号（Aurora Australis，IMOS平台代码：VNAA）的航次AA1112V1期间采集。
本次航次启航于2011年7月19日，从塔斯马尼亚州霍巴特港出发；并于2011年8月5日返回霍巴特港。

CO₂系统概况：本研究采用通用海洋学公司（General Oceanics Inc.）生产的自动化系统（型号8050；Pierrot等，2009），测定表层海水二氧化碳分压（fugacity of carbon dioxide，fCO₂）。具体测量流程为：将海水喷入平衡腔，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（nafion drying tube）输送，再通过LI-COR 7000型非色散红外气体分析仪（non-dispersive infrared gas analyser），以测定干燥空气中的CO₂摩尔分数（XCO₂）。CO₂测量期间会暂时中断气流，所有测量均在大气压条件下完成。每间隔约3小时，会使用一套覆盖海洋典型CO₂浓度范围的4组分标准气对气体分析仪进行校准。完成标准气校准后，通过船舶前桅杆上进气管抽取外部洁净空气，以测定大气干燥态CO₂摩尔分数（XCO₂）。

海水采样与辅助数据：海水采样点水深约6米。采样点处安装有海鸟电子公司（Seabird Electronics）SBE38型远程温度传感器，用于测定海表温度（sea surface temperature，SST）。紧邻pCO₂系统的海洋学实验室中，搭载了海鸟电子公司SBE21型海水温盐仪（thermosalinograph），用于测定海表盐度。从采样点到CO₂系统的输水时长通常约70秒，在接近冰点的冷水域中，输水过程引起的水温升高通常不超过0.7℃。海水温盐仪的供水同样取自该采样点及输水管道。气象数据、盐度、海表温度、船舶位置及时间信息均取自船舶自带的日志系统。