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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
D17309,
doi:10.1029/2005JD006371,
2006
Attribution of recovery in lower-stratospheric ozone
Eun-Su Yang
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
Derek M. Cunnold
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
Ross J. Salawitch
Jet Propulsion Laboratory/California Institute of Technology, Pasadena, California, USA
M. Patrick McCormick
Center for Atmospheric Sciences, Hampton University, Hampton, Virginia, USA
James Russell III
Center for Atmospheric Sciences, Hampton University, Hampton, Virginia, USA
Joseph M. Zawodny
NASA Langley Research Center, Hampton, Virginia, USA
Samuel Oltmans
Global Monitoring Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA
Michael J. Newchurch
Atmospheric Science Department, University of Alabama, Huntsville, Alabama, USA
Abstract
Multiple satellite and ground-based observations provide consistent evidence that the thickness of Earth's protective ozone
layer has stopped declining since 1997, close to the time of peak stratospheric halogen loading. Regression analyses with
Effective Equivalent Stratospheric Chlorine (EESC) in conjunction with further analyses using more sophisticated photochemical
model calculations constrained by satellite data demonstrate that the cessation of ozone depletion between 18 and 25 km altitude
is consistent with a leveling off of stratospheric abundances of chlorine and bromine, due to the Montreal Protocol and its
amendments. However, ozone increases in the lowest part of the stratosphere, from the tropopause to 18 km, account for about
half of the improvement in total column ozone during the past 9 years at Northern Hemisphere midlatitudes. The increase in
ozone for altitudes below 18 km is most likely driven by changes in transport, rather than driven by declining chlorine and
bromine. Even with this evidence that the Montreal Protocol and its amendments are having the desired, positive effect on
ozone above 18 km, total column ozone is recovering faster than expected because of the apparent transport driven changes
at lower altitudes. Accurate prediction of future levels of stratospheric ozone will require comprehensive understanding of
the factors that drive temporal changes at various altitudes and partitioning of the recent transport-driven increases between
natural variability and changes in atmospheric structure perhaps related to anthropogenic climate change.
Received 15
June
2005;
accepted 21
April
2006;
published 9
September
2006.
Keywords: stratospheric ozone layer;
ozone recovery;
ozone trends.
Index Terms: 0340 Atmospheric Composition and Structure: Middle atmosphere: composition and chemistry; 0341 Atmospheric Composition and Structure: Middle atmosphere: constituent transport and chemistry (3334); 1610 Global Change: Atmosphere (0315, 0325); 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513).
Read Full Article (file size: 3596821 bytes) Cited by
Citation: Yang, E.-S., D. M. Cunnold, R. J. Salawitch, M. P. McCormick, J. Russell III, J. M. Zawodny, S. Oltmans, and M. J. Newchurch
(2006),
Attribution of recovery in lower-stratospheric ozone,
J. Geophys. Res.,
111,
D17309,
doi:10.1029/2005JD006371.
Copyright 2006 by the American Geophysical Union.
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