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| Titel |
A new formulation of equivalent effective stratospheric chlorine (EESC) |
| VerfasserIn |
P. A. Newman, J. S. Daniel, D. W. Waugh, E. R. Nash |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 7, no. 17 ; Nr. 7, no. 17 (2007-09-03), S.4537-4552 |
| Datensatznummer |
250005182
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| Publikation (Nr.) |
 copernicus.org/acp-7-4537-2007.pdf |
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| Zusammenfassung |
| Equivalent effective stratospheric chlorine (EESC) is a convenient
parameter to quantify the effects of halogens (chlorine and bromine) on
ozone depletion in the stratosphere. We show, discuss, and analyze a
new formulation of EESC that now includes the effects of age-of-air
dependent fractional release values and an age-of-air spectrum. This
EESC can be more appropriately applied to various parts of the
stratosphere because of this dependence on mean age-of-air. This new
formulation provides quantitative estimates of EESC that can be directly
related to inorganic chlorine and bromine throughout the stratosphere.
In this paper, we first provide a detailed description of the EESC
calculation. We then use this EESC formulation to estimate that
human-produced ozone depleting substances will recover to 1980 levels in
2041 in the midlatitudes, and 2067 over Antarctica. These recovery
dates are based upon the assumption that the international agreements
for regulating ozone-depleting substances are adhered to. In addition
to recovery dates, we also estimate the uncertainties and possible
problems in the estimated times of recovery. The midlatitude recovery
of 2041 has a 95% confidence uncertainty from 2028 to 2049, while the
2067 Antarctic recovery has a 95% confidence uncertainty from 2056 to
2078. The principal uncertainties are from the estimated mean
age-of-air and fractional release values, and the assumption that these
quantities are time independent. Using other model estimates of age
decrease due to climate change, we estimate that midlatitude recovery
may be significantly accelerated. |
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