Atmospheric CO2 Records from Sites in the Atmospheric Environment Service Air Sampling Network (1975 and 1994)

From the mid-1970s through the mid-1990s, air samples were collected for the purposes of monitoring atmospheric CO2 from four sites in the AES air sampling network. Air samples were collected approximately once per week, between 12:00 and 16:00 local time, in a pair of evacuated 2-L thick-wall borosilicate glass flasks. Samples were collected under preferred conditions of wind speed and direction (i.e., upwind of the main station and when winds are strong and steady). The flasks were evacuated to pressures of ~1 — 10-4 mbar or 0.01 Pa prior to being sent to the stations. The airwas not dried during sample collection. The flask data from Alert show an increase in the annual atmospheric CO2 concentration from 341.35 parts per million by volume (ppmv) in 1981 to 357.21 ppmv in 1991. For Cape St. James, Trivett and Higuchi (1989) reported that the mean annual rate of increase, obtained from the slope of a least-squares regression line through the annual averages, was 1.43 ppmv per year. In August 1992, the weather station at Cape St. James was automated; as a result, the flask sampling program was discontinued at this site. Estevan Point, on the West Coast of Vancouver Island, was chosen as a replacement station. Sampling at Estevan Point started in 1992; thus, the monthly and annual CO2record from Estevan Point is too short to show any long-term trends. The sampling site at Sable Island, off the coast of Nova Scotia, was established in 1975. The flask data from Sable Island show an increase in the annual atmospheric CO2 concentration from 334.49 parts per million by volume (ppmv) in 1977 (the first full year of data) to 356.02 ppmv in 1990. For Sable Island, Trivett and Higuchi (1989) reported that the mean annual rate of increase, obtained from the slope of a least-squares regression line through the annual averages, was 1.48 ppmv per year. For access to the data files, click this link to the CDIAC data transition website: http://cdiac.ess-dive.lbl.gov/trends/co2/aes.html

1970年代中期至1990年代中期，研究人员依托AES空气采样网络（AES air sampling network）的4个监测站点采集大气样本，用于监测大气二氧化碳（CO₂）浓度。采样频率约为每周1次，于当地时间12:00至16:00之间开展，采用一对抽真空的2升厚壁硼硅酸盐玻璃烧瓶（borosilicate glass flasks）完成采样。采样优选满足特定风速与风向条件：即采样点位于主站点的上风区域，且风力强劲稳定。在送往各监测站点前，烧瓶会被抽至约1×10^-4毫巴（或0.01帕斯卡）的真空度。采样过程中未对采集的空气进行干燥处理。

来自Alert站点的烧瓶采样数据显示，大气二氧化碳年均体积浓度从1981年的341.35体积百万分比（parts per million by volume, ppmv）升至1991年的357.21 ppmv。针对Cape St. James站点，Trivett与Higuchi（1989）通过对年均值拟合最小二乘回归（least-squares regression）线，得到其年均增长斜率为1.43 ppmv/年。1992年8月，Cape St. James站点的气象站完成自动化改造，该站点的烧瓶采样项目随即终止。研究人员随后选择温哥华岛西海岸的Estevan Point作为替代站点，其采样工作于1992年启动，因此Estevan Point的CO₂月度及年度记录时长过短，尚未显现长期变化趋势。

位于新斯科舍省近海的Sable Island采样站点始建于1975年。该站点的烧瓶采样数据显示，大气二氧化碳年均体积浓度从首个完整数据年度1977年的334.49 ppmv升至1990年的356.02 ppmv。针对Sable Island站点，Trivett与Higuchi（1989）通过拟合年均值的最小二乘回归线，得到其年均增长率为1.48 ppmv/年。

如需获取数据文件，请点击此链接访问CDIAC数据迁移网站：http://cdiac.ess-dive.lbl.gov/trends/co2/aes.html