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Long‐term stratospheric carbon tetrafluoride (CF 4 ) increase inferred from 1985–2004 infrared space‐based solar occultation measurements
Author(s) -
Rinsland C. P.,
Mahieu E.,
Zander R.,
Nassar R.,
Bernath P.,
Boone C.,
Chiou L. S.
Publication year - 2006
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 - 10.1029/2005gl024709
Subject(s) - stratosphere , occultation , mixing ratio , atmospheric sciences , atmospheric chemistry , environmental science , trace gas , analytical chemistry (journal) , ozone , physics , meteorology , chemistry , astrophysics , environmental chemistry
The long‐term stratospheric carbon tetrafluoride (CF 4 ) increase has been determined from infrared high spectral resolution solar occultation Fourier transform spectrometer measurements between 3 and 50 hPa (∼20 to 40 km altitude) and latitudes from 50°N to 50°S during 1985, 1992, 1993, 1994, and 2004. The 1985 to 1994 measurements were recorded from the ATMOS (Atmospheric Trace MOlecule Spectroscopy) instrument at 0.01 cm −1 resolution and in 2004 by the Atmospheric Chemistry Experiment (ACE) instrument at 0.02 cm −1 resolution. Stratospheric volume mixing ratios, inferred from a polynomial fit to averages from the time periods considered here, increased from 49.37 ± 2.60 pptv (10 −12 per unit volume) in 1985 to 58.38 ± 4.14 pptv in 1992, 60.46 ± 2.97 pptv in 1993, 60.11 ± 3.60 pptv in 1994 and to 70.45 ± 3.40 pptv in 2004. The stratospheric CF 4 mixing ratio has continued to increase but at a slower rate than in previous years, for example, (1.14 ± 0.68)% yr −1 in 2004 as compared to (2.77 ± 0.47)% yr −1 in 1985, 1 sigma. Correlations of CF 4 with N 2 O taking into account the increase of N 2 O with time also show the increase in the stratospheric CF 4 burden over the two decade measurement time span. Our space‐based measurements show that the slowdown in the rate of CF 4 accumulation previously reported from surface measurements through 1997 has propagated to the stratosphere and is continuing.