In situ Carbon 13 and Oxygen 18 Ratios of Atmospheric CO2 from Cape Grim, Tasmania, Australia,1982-1993 (DB1014)

Since 1982, a continuous program of sampling atmospheric CO2 to determine stable isotope ratios has been maintained at the Australian Baseline Air Pollution Station, Cape Grim, Tasmania (40°, 40'56"S, 144°, 41'18"E). The process of in situ extraction of CO2 from air, the preponderance of samples collected in conditions of strong wind from the marine boundary layer of the Southern Ocean, and the determination of all isotope ratios relative to a common high purity CO2 reference gas with isotopic δ13C close to atmospheric values, are a unique combination of factors with respect to obtaining a globally representative signal from a surface site. Air samples are collected during baseline condition episodes at a frequency of around one sample per week. Baseline conditions are characterized by wind direction in the sector 190°-280°, condensation nucleus concentration below 600 per cm-3, and steady continuous CO2 concentrations (variation ± 0.2 ppmv per hour). A vacuum pump draws air from either the 10 m or 70 m intakes and sampling alternates between the two intakes. The air from the intake is dried with a trap immersed in an alcohol bath at about -80°C. Mass spectrometer analyses for δ13C and δ18O are carried out by CSIRO's Division of Atmospheric Research in Aspendale, usually one to three weeks following collection. This record is possibly the most accurate representation of global atmospheric 13C behavior over the last decade and may be used to partition the uptake of fossil-fuel carbon emissions between ocean and terrestrial plant reservoirs. Using these data, Francey et al. (1995) observed a gradual decrease in δ13C from 1982 to 1993, but with a pronounced flattening from 1988 to 1990; a trend that appears to involve the terrestrial carbon cycle. For access to the data files, click this link to the CDIAC data transition website: http://cdiac.ess-dive.lbl.gov/ndps/db1014.html This dataset was transferred from the CDIAC Archive and published on ESS-DIVE in 2018 under the project title "Carbon Dioxide Information Analysis Center (CDIAC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); CSIRO Division of Atmospheric Research, Australia". In 2023, the project title was updated to "Carbon Dioxide Information Analysis Center (CDIAC); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)" to enable consistent management of all datasets previously hosted by the CDIAC Archive that are now published on ESS-DIVE.自1982年起，澳大利亚塔斯马尼亚州格雷姆角（Cape Grim）澳大利亚基准空气污染站（坐标：南纬40°56′，东经144°41′18″）便持续开展大气二氧化碳（CO₂）采样项目，以测定其稳定同位素比值。该项目结合了多项独特的关键要素：从空气中原位提取二氧化碳样品、绝大多数样本采集自南大洋海洋边界层的强风环境，以及以同位素δ¹³C值接近大气水平的高纯度二氧化碳参考气为基准测定所有同位素比值。这些要素的组合使得该地面观测站能够获取具有全球代表性的大气信号。研究人员在基准条件时段采集空气样本，采样频率约为每周1次。基准条件的判定标准为：风向处于190°至280°区间、凝结核浓度低于600个/立方厘米，以及二氧化碳浓度稳定连续（每小时波动幅度不超过±0.2ppmv）。真空泵从10米或70米高度的采样进气口抽取空气，两个进气口交替使用。采集到的空气通过置于约-80℃酒精浴中的低温捕集阱进行干燥处理。针对δ¹³C与δ¹⁸O的质谱分析工作由位于阿斯彭代尔的澳大利亚联邦科学与工业研究组织（CSIRO）大气研究分部完成，通常在样本采集后的1至3周内开展。该记录可能是近十年来全球大气¹³C变化特征最精准的表征数据，可用于划分海洋与陆地植物储库对化石燃料碳排放的吸收份额。依托这些数据，Francey等人（1995年）观测到1982年至1993年间δ¹³C值呈逐步下降趋势，但在1988年至1990年间出现明显的趋平态势；这一趋势似乎与陆地碳循环相关。若需获取数据文件，请点击此链接跳转至二氧化碳信息分析中心（CDIAC）数据迁移网站：http://cdiac.ess-dive.lbl.gov/ndps/db1014.html。本数据集由CDIAC档案库迁移而来，并于2018年以如下项目标题发布于ESS-DIVE平台："美国田纳西州橡树岭市橡树岭国家实验室（ORNL）二氧化碳信息分析中心（CDIAC）；澳大利亚联邦科学与工业研究组织大气研究分部"。2023年，该项目标题更新为"美国田纳西州橡树岭市橡树岭国家实验室（ORNL）二氧化碳信息分析中心（CDIAC）"，以实现对此前由CDIAC档案库托管、现发布于ESS-DIVE平台的所有数据集的统一管理。