title: Comparison of halocarbon measurements in an atmospheric dry whole air sample.
abstract: The growing awareness of climate change/global warming, and continuing concerns regarding stratospheric ozone depletion, will require continued measurements and standards for many compounds, in particular halocarbons that are linked to these issues. In order to track atmospheric mole fractions and assess the impact of policy on emission rates, it is necessary to demonstrate measurement equivalence at the highest levels of accuracy for assigned values of standards. Precise measurements of these species aid in determining small changes in their atmospheric abundance. A common source of standards/scales and/or well-documented agreement of different scales used to calibrate the measurement instrumentation are key to understanding many sets of data reported by researchers. This report describes the results of a comparison study among National Metrology Institutes and atmospheric research laboratories for the chlorofluorocarbons (CFCs) dichlorodifluoromethane (CFC-12), trichlorofluoromethane (CFC-11), and 1,1,2-trichlorotrifluoroethane (CFC-113); the hydrochlorofluorocarbons (HCFCs) chlorodifluoromethane (HCFC-22) and 1-chloro-1,1-difluoroethane (HCFC-142b); and the hydrofluorocarbon (HFC) 1,1,1,2-tetrafluoroethane (HFC-134a), all in a dried whole air sample. The objective of this study is to compare calibration standards/scales and the measurement capabilities of the participants for these halocarbons at trace atmospheric levels. The results of this study show agreement among four independent calibration scales to better than 2.5% in almost all cases, with many of the reported agreements being better than 1.0%.
authors.affiliation: National Institute of Standards and Technology (NIST), Chemical Sciences Division, Materials Measurement Laboratory, Gaithersburg, Maryland, United States.
authors.forename: George C
authors.initials: GC
authors.lastname: Rhoderick
authors.affiliation: National Oceanic and Atmospheric Administration (NOAA), Global Monitoring Division, Earth Systems Research Laboratory, Boulder, Colorado, United States.
authors.forename: Bradley D
authors.initials: BD
authors.lastname: Hall
authors.affiliation: Scripps Institution of Oceanography, La Jolla (SIO), University of California, San Diego, La Jolla, California, United States.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Harth
authors.affiliation: Korea Research Institute of Standards and Science (KRISS), Division of Metrology for Quality Life, Yusong, Daejeon, Republic of Korea.
authors.forename: Jin Seog
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Korea Research Institute of Standards and Science (KRISS), Division of Metrology for Quality Life, Yusong, Daejeon, Republic of Korea.
authors.forename: Jeongsoon
authors.initials: J
authors.lastname: Lee
authors.affiliation: National Oceanic and Atmospheric Administration (NOAA), Global Monitoring Division, Earth Systems Research Laboratory, Boulder, Colorado, United States.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Montzka
authors.affiliation: Scripps Institution of Oceanography, La Jolla (SIO), University of California, San Diego, La Jolla, California, United States.
authors.forename: Jens
authors.initials: J
authors.lastname: Mühle
authors.affiliation: Swiss Federal Laboratories for Materials Science and Technology (Empa), Laboratory for Air Pollution/Environmental Technology, Dubendorf, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Reimann
authors.affiliation: Swiss Federal Laboratories for Materials Science and Technology (Empa), Laboratory for Air Pollution/Environmental Technology, Dubendorf, Switzerland.
authors.forename: Martin K
authors.initials: MK
authors.lastname: Vollmer
authors.affiliation: Scripps Institution of Oceanography, La Jolla (SIO), University of California, San Diego, La Jolla, California, United States.
authors.forename: Ray F
authors.initials: RF
authors.lastname: Weiss