R. Nassar et al- A global inventory of stratospheric fluorine in 2004 based on Atmospheric Chemistry...
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A global inventory of stratospheric fluorine in 2004 based on Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) measurements R. Nassar, 1,2 P. F. Bernath, 1 C. D. Boone, 1 S. D. McLeod, 1 R. Skelton, 1 K. A. Walker, 1,3 C. P. Rinsland, 4 and P. Duchatelet5 Received 11 April 2006; revised 29 June 2006; accepted 7 August 2006; published 30 November 2006. [1] Total fluorine (F TOT ) in the stratosphere has been determined using Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) measurements of HF, COF 2 , COClF, CF 4 , CCl 3 F (CFC-11), CCl 2 F 2 (CFC-12), CHClF 2 (HCFC-22), CCl 2 FCClF 2 (CFC-113), CH 3 CClF 2 (HCFC-142b), CH 2 FCF 3 (HFC-134a), and SF 6 . The retrieval of HFC-134a (CH 2 FCF 3 ) from spaceborne measurements had not been carried out prior to this work. Measurements of these species have been supplemented by data from models to extend the altitude range of the profiles and have also been complemented by estimates of 15 minor fluorine species. Using these data, separate fluorine budgets were determined in five latitude zones (60 –82 N, 30 –60 N, 30 S–30 N, 30 –60 S, and 60 –82 S) by averaging over the period of February 2004 to January 2005 inclusive, when possible. Stratospheric F TOT profiles in each latitude zone are nearly linear, with mean stratospheric F TOT values ranging from 2.50 to 2.59 ppbv (with a 1 sprecision of0.04–0.07 ppbv and an estimated accuracy of 0.15 ppbv) for each zone. The highest mean F TOT value occurred in the tropics, which is qualitatively consistent with increasing levels of stratospheric fluorine and the mean stratospheric circulation pattern. Citation: Nassar, R., P. F. Bernath, C. D. Boone, S. D. McLeod, R. Skelton, K. A. Walker, C. P. Rinsland, and P. Duchatelet (2006), A global inventor y of strat osphe ric fluori ne in 2004 based on Atmospheric Chemist ry Experiment Fourier trans form spectrome ter (ACE-FTS) measurements, J. Geophys. Res., 1 11 , D22313, doi:10.1029/2006JD007395. 1. Introduc tion [2 ] Halogenated gases such as chlorofluorcarbons (CFCs), hydr ochl orof luor ocar bons (HCF Cs), and halo ns ar e very sta ble , wit h long lifetimes in the tro pospher e. When these gases are transported to the stratosphere, they dissoc iate releasing F, Cl, and Br radica ls. Cl-con tainin g radicals and the much less abundant Br-containing radicals participate in the destruction of ozone via catalytic cycles whi ch have the gre ates t impact in the spring time polarvor tices. In contrast, F radicals qui ckly react wit h CH 4 and H 2 O producing the stable reservoir molecule HF. The formation of HF prevents fluorine from undergoing similarcatalytic cycles [Stolarski and Rundel, 1975]. [3] Despit e the fact that fluo rine does not di rectly pa rtic- ipate in ozone depletion, monitoring of atmospheric fluorine levels is important for a number of reasons: (1) to compare with emission inventories reflecting the quantities of indi- vidual species used and emitted that often contain chlorine or bromine, (2) to check the validity of methods for the determinati on of total strato spheri c chlorine which is the main contribu tor to polar ozone decline, and (3) fluorinat ed species in the troposphere behave as greenhouse gases, some species with global warming potentials orders of magnitude larger than CO 2 [ World Meteor ological Organization (WMO) , 2003]. [4] HF is the dominant fluorine speci es in the middle and upper stratosphere. The Atmospheric Trace Molecule Spec- troscopy (ATMOS) instrument which flew four times on the NASA Space Shuttle (1985, 1992, 1993, and 1994) mea- sured HF along with six other fluorine species. The 1985 A TMOS meas urement s were used to create a fluori ne inv entory for 30 N, inc lud ing a pro fil e of tot al flu orin e (F TOT ) throughout the stratosphere [ Zander et al. , 1992]. The Halogen Occultati on Expe rime nt (HALOE) on the NASA Upper Atmosphe ric Research Sate llit e (UARS) measured HF bet wee n 1991 and 2005. HALOE HF at 55 km in altitude has been used to calculate total inorganic fluorine (F y ) [ Russell et al. , 1996; Anderson et al., 2000], which serves as a proxy for F TOT . [5] The Atmospher ic Chemi stry Experiment Fourier transfor m spectrometer (ACE FTS) is a high-re solution infra- red Fourier transform spectrometer (FTS) on the SCISAT-1 orJOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, D22313, doi:10.1029/2006JD007395, 2006 Click Here for Full Article 1 Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada. 2 Now at Department of Earth and Planetary Sciences and Division ofEngi neer ing and Appli ed Sci ence s, Harvard Unive rsit y, Cambr idge , Massachusetts, USA. 3 Now at Depa rtment of Physic s, Uni ver sit y of Toron to, Toron to, Ontario, Canada. 4 NASA Langley Research Center, Hampton, Virginia, USA. 5 Institute of Astrophysics and Geophysics, University of Lie `ge, Lie `ge, Belgium. Copyri ght 2006 by the American Geophysic al Union. 0148-0227/06/2006JD007395$09.00 D22313 1 of 10
R. Nassar et al- A global inventory of stratospheric fluorine in 2004 based on Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) measurements
