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Results from the International Halocarbons in Air Comparison Experiment (IHALACE)



Bradley Hall, George C. Rhoderick, A Engel, J. Muhle, J. W. Elkins, F. Artuso, E. Atlas, M. Aydin, D. Blake, E. G. Brunke, S. Chiavarini, P. J. Fraser, J. Happell, Paul B. Krummel, I. Levin, M. Loewenstein, M. Malone, S. A. Montzka, S. O'Doherty, S. Reimann, E. S. Saltzman, H. E. Scheel, L. P. Steele, M. K. Vollmer, R. F. Weiss, D. Worthy, Y. Yokouchi


The International Halocarbons in Air Comparison Experiment (IHALACE) was conducted to document relationships between calibrations scales among various laboratories that measure atmospheric greenhouse and ozone depleting gases. Six stainless steel cylinders containing natural and modified natural air samples were circulated among 19 laboratories. Results from this experiment reveal relatively good agreement among commonly used calibration scales for a number of trace gases, such as chlorofluorocarbons (CFCs), hydrofluorochlorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Some scale relationships were found to be consistent with those derived from bi-lateral experiments or from analysis of atmospheric data, while others revealed discrepancies. However, the transfer of calibration scales among laboratories is problematic in many cases, meaning that measurements tied to a common scale may not, in fact, be compatible. These findings illustrate the need for improved communication and coordination of calibration activities in the measurement of halogenated and related trace gases.
Atmospheric Measurement Techniques


international comparison, climate change, halocarbons, atmospheric measurements


Hall, B. , Rhoderick, G. , Engel, A. , Muhle, J. , Elkins, J. , Artuso, F. , Atlas, E. , Aydin, M. , Blake, D. , Brunke, E. , Chiavarini, S. , Fraser, P. , Happell, J. , Krummel, P. , Levin, I. , Loewenstein, M. , Malone, M. , Montzka, S. , O'Doherty, S. , Reimann, S. , Saltzman, E. , Scheel, H. , Steele, L. , Vollmer, M. , Weiss, R. , Worthy, D. and Yokouchi, Y. (2013), Results from the International Halocarbons in Air Comparison Experiment (IHALACE), Atmospheric Measurement Techniques, [online],, (Accessed April 12, 2024)
Created May 31, 2013, Updated October 12, 2021