FastFind »   Lastname: doi:10.1029/ Year: | Advanced Search  

AGU: Geophysical Research Letters

 

Keywords

  • atmospheric chlorine
  • ozone

Index Terms

  • Atmospheric Composition and Structure: Evolution of the atmosphere
  • Atmospheric Composition and Structure: Middle atmosphere: composition and chemistry
  • Atmospheric Composition and Structure: Middle atmosphere: constituent transport and chemistry

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L23812, 5 PP., 2006
doi:10.1029/2006GL027600

Temporal decrease in upper atmospheric chlorine

L. Froidevaux

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

N. J. Livesey

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

W. G. Read

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

R. J. Salawitch

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

J. W. Waters

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

B. Drouin

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

I. A. MacKenzie

School of GeoSciences, University of Edinburgh, Edinburgh, UK

H. C. Pumphrey

School of GeoSciences, University of Edinburgh, Edinburgh, UK

P. Bernath

Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada

C. Boone

Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada

R. Nassar

Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada

S. Montzka

Office of Oceanic and Atmospheric Research, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA

J. Elkins

Office of Oceanic and Atmospheric Research, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA

D. Cunnold

School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA

D. Waugh

Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland, USA

We report a steady decrease in the upper stratospheric and lower mesospheric abundances of hydrogen chloride (HCl) from August 2004 through January 2006, as measured by the Microwave Limb Sounder (MLS) aboard the Aura satellite. For 60°S to 60°N zonal means, the average yearly change in the 0.7 to 0.1 hPa (∼50 to 65 km) region is −27 ± 3 pptv/year, or −0.78 ± 0.08 percent/year. This is consistent with surface abundance decrease rates (about 6 to 7 years earlier) in chlorine source gases. The MLS data confirm that international agreements to reduce global emissions of ozone-depleting industrial gases are leading to global decreases in the total gaseous chlorine burden. Tracking stratospheric HCl variations on a seasonal basis is now possible with MLS data. Inferred stratospheric total chlorine (ClTOT) has a value of 3.60 ppbv at the beginning of 2006, with a (2-sigma) accuracy estimate of 7%; the stratospheric chlorine loading has decreased by about 43 pptv in the 18-month period studied here. We discuss the MLS HCl measurements in the context of other satellite-based HCl data, as well as expectations from surface chlorine data. A mean age of air of ∼ 5.5 years and an age spectrum width of 2 years or less provide a fairly good fit to the ensemble of measurements.

Received 17 July 2006; accepted 20 October 2006; published 14 December 2006.

Citation: Froidevaux, L., et al. (2006), Temporal decrease in upper atmospheric chlorine, Geophys. Res. Lett., 33, L23812, doi:10.1029/2006GL027600.

Cited By

Please wait one moment ...