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| Titel |
A closer look at Arctic ozone loss and polar stratospheric clouds |
| VerfasserIn |
N. R. P. Harris, R. Lehmann, M. Rex, P. Gathen |
| 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 ; 10, no. 17 ; Nr. 10, no. 17 (2010-09-08), S.8499-8510 |
| Datensatznummer |
250008762
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| Publikation (Nr.) |
 copernicus.org/acp-10-8499-2010.pdf |
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| Zusammenfassung |
| The empirical relationship found between column-integrated Arctic ozone loss
and the potential volume of polar stratospheric clouds inferred from
meteorological analyses is recalculated in a self-consistent manner using
the ERA Interim reanalyses. The relationship is found to hold at different
altitudes as well as in the column. The use of a PSC formation threshold
based on temperature dependent cold aerosol formation makes little
difference to the original, empirical relationship. Analysis of the
photochemistry leading to the ozone loss shows that activation is limited by
the photolysis of nitric acid. This step produces nitrogen dioxide which is
converted to chlorine nitrate which in turn reacts with hydrogen chloride on
any polar stratospheric clouds to form active chlorine. The rate-limiting
step is the photolysis of nitric acid: this occurs at the same rate every
year and so the interannual variation in the ozone loss is caused by the
extent and persistence of the polar stratospheric clouds. In early spring
the ozone loss rate increases as the solar insolation increases the
photolysis of the chlorine monoxide dimer in the near ultraviolet. However
the length of the ozone loss period is determined by the photolysis of
nitric acid which also occurs in the near ultraviolet. As a result of these
compensating effects, the amount of the ozone loss is principally limited by
the extent of original activation rather than its timing. In addition a
number of factors, including the vertical changes in pressure and total
inorganic chlorine as well as denitrification and renitrification, offset
each other. As a result the extent of original activation is the most
important factor influencing ozone loss. These results indicate that
relatively simple parameterisations of Arctic ozone loss could be developed
for use in coupled chemistry climate models. |
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