Atmospheric CO2 Record from In Situ Measurements at Amsterdam Island (1980-1995)

Until 1993 air samples were collected continuously through an air intake located at the top of a tower, 9 m above ground and 65 m above mean sea level. Since 1994, the intake has been situated 20 m above ground and 76 m above mean sea level. The tower is located at the north-northwest end of the island on the edge of a 55 m cliff. The air is dried by means of a cryogenic water trap at -60°C. Until 1990, determinations of CO2 were made by using successively two Hartmann-Braun URAS 2T nondispersive infrared (NDIR) analyzers. Since 1991, CO2 determinations have been made using a Siemens ULTRAMAT 5F NDIR. Standard gases in use from October 1980 to December of 1984 were CO2-in-N2 mixtures certified by Scripps Institution of Oceanography (SIO). The N2 scale was corrected for the carrier gas effect to obtain the air scale (WMO mole fraction scale). In 1985, CO2-in-air mixtures expressed in the 1985 WMO mole fraction in air scale were introduced. In 1990, a new series of 12 primary standard gases were gravimetrically prepared, then linearly adjusted at the laboratory and checked several times (i.e., 1990, 1992, and 1993) through intercalibrations with DSIR in New Zealand and NOAA/CMDL, which both used the 1985 mole fraction scale. The agreement was always better than 0.1 ppm (Monfray et al. 1992). Since 1993, the 1993 mole fraction scale has been used thanks to a new series of 10 cylinders provided by SIO. For access to the data files, click this link to the CDIAC data transition website: http://cdiac.ess-dive.lbl.gov/trends/co2/amster.html1993年之前，研究人员通过位于地面以上9米、平均海平面以上65米的塔顶进气口持续采集空气样本。自1994年起，该进气口的安装高度调整为地面以上20米、平均海平面以上76米。该塔坐落于岛屿北西北端的一处55米高悬崖边缘。空气样本先通过-60℃的低温水汽阱进行干燥处理。 1990年之前，二氧化碳（CO₂）浓度测定先后采用两台Hartmann-Braun URAS 2T型非色散红外（NDIR）分析仪。自1991年起，改用Siemens ULTRAMAT 5F型非色散红外分析仪开展二氧化碳浓度测定。 1980年10月至1984年12月期间使用的标准气体为斯克里普斯海洋研究所（Scripps Institution of Oceanography, SIO）标定的氮中二氧化碳混合气体。为获得空气标尺（世界气象组织（World Meteorological Organization, WMO）摩尔分数标尺），需针对载气效应校正氮基标尺。1985年，采用1985年世界气象组织（WMO）空气摩尔分数标尺的空气基二氧化碳混合气体正式投入使用。 1990年，研究人员通过重量法制备了一套共12瓶一级标准气体，并在实验室内完成线性校准；随后分别于1990年、1992年及1993年，通过与新西兰科学与工业研究部（Department of Scientific and Industrial Research, DSIR）及美国国家海洋和大气管理局/气候监测与诊断实验室（National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory, NOAA/CMDL）开展互校工作对其进行多次核验，上述两家机构均采用1985年摩尔分数标尺。三方测量结果的一致性始终优于0.1 ppm（Monfray等，1992）。 自1993年起，得益于斯克里普斯海洋研究所（SIO）提供的一套共10瓶新气瓶，研究人员开始采用1993年世界气象组织（WMO）摩尔分数标尺。 如需获取数据文件，请点击以下链接跳转至CDIAC数据过渡网站：http://cdiac.ess-dive.lbl.gov/trends/co2/amster.html