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Global tropospheric distribution and calibration scale of HCFC‐22
Author(s) -
Montzka S. A.,
Myers R. C.,
Butler J. H.,
Elkins J. W.,
Cummings S. O.
Publication year - 1993
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/93gl00753
Subject(s) - laboratory flask , troposphere , environmental science , calibration , atmospheric sciences , methane , climatology , mixing ratio , chemistry , geology , mathematics , statistics , organic chemistry
Measurements of atmospheric chlorodifluoro‐methane (HCFC‐22), based upon a new calibration scale developed in this laboratory, suggest a global tropospheric mean that is ∼28% lower than determined previously from surface‐based measurements. A global mean of 101.8 (±1.2, 1 s.d.) ppt and interhemispheric difference of 13 (±1) ppt were determined for HCFC‐22 in 1992 from air collected in flasks from seven remote sites located between 82° N and 90° S. These results are consistent with mixing ratios predicted from recent emission estimates and a lifetime for HCFC‐22 of 13.6 (+1.9, −1.5) yr. Based upon the analysis of flasks and archived air samples from mid‐1987 through 1992, a mean growth rate for HCFC‐22 of 7.3 (±0.3)% yr −1 was estimated for this period.