Global ALE/GAGE/AGAGE Monitoring Network

In the ALE/GAGE/AGAGE global network program, continuous high frequency gas chromatographic measurements of two biogenic/anthropogenic gases (methane, CH4; nitrous oxide, N2O; and six anthropogenic gases (chlorofluorocarbons CFCl3, CF2Cl2, and CF2ClCFCl2; methyl chloroform, CH3CCl3; chloroform, CHCl3; and carbon tetrachloride, CCl4) are carried out at five globally distributed sites. Additional important species (H2, CO, HFC-134a, HCFC-141b, and HCFC-142b) have been added at select sites in recent years.

The program, which began in 1978, is divided into three parts associated with three changes in instrumentation: the Atmospheric Lifetime Experiment (ALE), which used Hewlett Packard HP5840 gas chromatographs; the Global Atmospheric Gases Experiment (GAGE), which used HP5880 gas chromatographs; and the present Advanced GAGE (AGAGE). AGAGE uses two types of instruments: a gas chromatograph with multiple detectors (GC-MD), and a gas chromatograph with mass spectrometric analysis (GC-MS). The GC-MD is a new fully automated system produced at the Scripps Institution of Oceanography containing a custom-designed sample module and HP5890 and Carle Instruments gas chromatographic components. The GC-MS is a fully automated system produced at the University of Bristol and comprised of an adsorption-desorption preconcentration module and HP5973 gas chromatographic and mass spectrometric module.

The current station locations are Cape Grim, Tasmania (41° S, 145° E), Cape Matatula, American Samoa (14° S, 171° E), Ragged Point, Barbados (13° N, 59° W), Mace Head, Ireland (53° N, 10° W), and Trinidad Head, California (41° N, 124° W). Stations also previously existed at Cape Meares, Oregon (45° N, 124° W), and Adrigole, Ireland (52° N, 10° W). The current Mace Head station replaced the Adrigole station and the station at Trinidad Head replaced the Cape Meares station.

Presently, data from all three experiments are available. Data through September 2004 are now available for all five existing sites. Individual measurements (generally made 4 times daily at each site for ALE, 12 times daily at each site for GAGE, and more than 30 times daily at each site for AGAGE) and monthly summary averages are provided for each site. All ALE and GAGE data have been recalculated according to the current AGAGE calibration standards, thus creating a unified ALE/GAGE/AGAGE data set based upon the same standards. All ALE/GAGE/AGAGE data presented here are reported in the SIO-1998 calibration scale (Prinn et al., 2000).

The ALE/GAGE/AGAGE data are contributed by R. Prinn, Massachusetts Institute of Technology; D. Cunnold, Georgia Institute of Technology; P. Fraser, Commonwealth Scientific and Industrial Research Organisation; R. Weiss, Scripps Institution of Oceanography; P. Simmonds, Bristol University; S. O'Doherty, Bristol University; L.P. Steele, Commonwealth Scientific and Industrial Research Organisation; P. Salameh, Scripps Institution of Oceanography; and R.H.J. Wang, Georgia Institute of Technology.

Reference:

Prinn, R.G., R.F. Weiss, P.J. Fraser, P.G. Simmonds, D.M. Cunnold, F.N. Alyea, S. O'Doherty, P. Salameh, B.R. Miller, J. Huang, R.H.J. Wang, D.E. Hartley, C. Harth, L.P. Steele, G. Sturrock, P.M. Midgely, and A. McCulloch. 2000. A history of chemically and radiatively important gases in air deduced from ALE/GAGE/AGAGE. Journal of Geophysical Research 115: 17751-92.

在ALE/GAGE/AGAGE全球观测网络计划中，研究团队在全球5个分布站点开展高频连续气相色谱检测，检测对象涵盖2种生源/人为源气体（甲烷（CH4）、一氧化二氮（N2O））以及6种人为源气体：三氯氟甲烷（CFCl3）、二氯二氟甲烷（CF2Cl2）、二氯氟氯氟甲烷（CF2ClCFCl2）、甲基氯仿（CH3CCl3）、氯仿（CHCl3）及四氯化碳（CCl4）。近年来，部分站点新增了对H2、CO、HFC-134a、HCFC-141b和HCFC-142b等重要痕量气体物种的检测。

本计划始于1978年，根据仪器设备的三次迭代升级分为三个阶段：大气寿命实验（Atmospheric Lifetime Experiment, ALE），采用惠普（Hewlett Packard）HP5840型气相色谱仪；全球大气气体实验（Global Atmospheric Gases Experiment, GAGE），采用HP5880型气相色谱仪；以及当前的进阶GAGE（Advanced GAGE, AGAGE）。AGAGE系统包含两类仪器：多检测器气相色谱仪（GC-MD）与质谱分析型气相色谱仪（GC-MS）。其中GC-MD为斯克里普斯海洋研究所（Scripps Institution of Oceanography）定制研发的全自动化系统，集成了定制化样品模块及HP5890与Carle Instruments的气相色谱组件。GC-MS则由布里斯托大学（University of Bristol）制造，为全自动化系统，由吸附-脱附预浓缩模块与HP5973型气相色谱-质谱组件构成。

当前观测站点包括：塔斯马尼亚州格里姆角（41°S，145°E）、美属萨摩亚马塔乌拉角（14°S，171°E）、巴巴多斯拉格德角（13°N，59°W）、爱尔兰梅斯黑德（53°N，10°W）以及加利福尼亚州特立尼达角（41°N，124°W）。此前还设有俄勒冈州迈尔斯角（45°N，124°W）与爱尔兰阿德里戈尔（52°N，10°W）两个站点：现任梅斯黑德站点替代了阿德里戈尔站点，特立尼达角站点则替代了迈尔斯角站点。

目前，三个实验阶段的全部数据均已公开。截至2004年9月的数据集已面向全部5个现有站点开放。各站点均提供原始观测数据（ALE阶段通常为每日4次观测，GAGE阶段为每日12次，AGAGE阶段则超过每日30次）与月度汇总平均值。所有ALE与GAGE阶段的数据均已按照当前AGAGE的校准标准重新计算，从而形成了基于统一标准的ALE/GAGE/AGAGE整合数据集。本文呈现的全部ALE/GAGE/AGAGE数据均采用SIO-1998校准标尺（Prinn等，2000）进行报告。

本ALE/GAGE/AGAGE数据集由以下人员贡献：麻省理工学院（Massachusetts Institute of Technology）R. Prinn、佐治亚理工学院（Georgia Institute of Technology）D. Cunnold与R.H.J. Wang、联邦科学与工业研究组织（Commonwealth Scientific and Industrial Research Organisation, CSIRO）P. Fraser与L.P. Steele、斯克里普斯海洋研究所R. Weiss与P. Salameh、布里斯托大学（University of Bristol）P. Simmonds与S. O'Doherty。

参考文献：
Prinn, R.G., Weiss, R.F., Fraser, P.J., Simmonds, P.G., Cunnold, D.M., Alyea, F.N., O'Doherty, S., Salameh, P., Miller, B.R., Huang, J., Wang, R.H.J., Hartley, D.E., Harth, C., Steele, L.P., Sturrock, G., Midgely, P.M. 及 McCulloch, A.，2000年：基于ALE/GAGE/AGAGE数据推导的大气中化学与辐射活性气体历史记录，《Journal of Geophysical Research》（地球物理研究杂志），115卷：17751-17792。