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Reconciliation of Halogen-Induced Ozone Loss with the Total-Column Ozone RecordThe observed depletion of the ozone layer from the 1980s onwards is attributed to halogen source gases emitted by human activities. However, the precision of this attribution is complicated by year-to-year variations in meteorology, that is, dynamical variability, and by changes in tropospheric ozone concentrations. As such, key aspects of the total-column ozone record, which combines changes in both tropospheric and stratospheric ozone, remain unexplained, such as the apparent absence of a decline in total-column ozone levels before 1980, and of any long-term decline in total-column ozone levels in the tropics. Here we use a chemistry-climate model to estimate changes in halogen-induced ozone loss between 1960 and 2010; the model is constrained by observed meteorology to remove the eects of dynamical variability, and driven by emissions of tropospheric ozone precursors to separate out changes in tropospheric ozone. We show that halogen-induced ozone loss closely followed stratospheric halogen loading over the studied period. Pronounced enhancements in ozone loss were apparent in both hemispheres following the volcanic eruptions of El Chichon and, in particular, Mount Pinatubo, which significantly enhanced stratospheric aerosol loads. We further show that approximately 40% of the long-term non-volcanic ozone loss occurred before 1980, and that long-term ozone loss also occurred in the tropical stratosphere. Finally, we show that halogeninduced ozone loss has declined by over 10% since stratospheric halogen loading peaked in the late 1990s, indicating that the recovery of the ozone layer is well underway.
Document ID
20150002805
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Shepherd, T. G. (Reading Univ. United Kingdom)
Plummer, D. A. (Environment Canada Victoria, British Columbia, Canada)
Scinocca, J. F. (Environment Canada Victoria, British Columbia, Canada)
Hegglin, M. I. (Reading Univ. United Kingdom)
Fioletov, V. E. (Environment Canada Toronto, Ontario, Canada)
Reader, M. C. (Victoria Univ. Victoria, British Columbia, Canada)
Remsberg, E. (NASA Langley Research Center Hampton, VA, United States)
von Clarmann, T. (Karlsruhe Inst. of Technology Germany)
Wang, H. J. (Georgia Inst. of Tech. Atlanta, GA, United States)
Date Acquired
March 11, 2015
Publication Date
May 11, 2014
Publication Information
Publication: Nature Geoscience
Volume: 7
Issue: 6
Subject Category
Geophysics
Report/Patent Number
NF1676L-18918
Funding Number(s)
WBS: WBS 479717.02.01.01.38
Distribution Limits
Public
Copyright
Other