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| Titel |
Emission and transport of bromocarbons: from the West Pacific ocean into the stratosphere |
| VerfasserIn |
S. Tegtmeier, K. Krüger, B. Quack, E. L. Atlas, I. Pisso, A. Stohl, X. Yang |
| 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 ; 12, no. 22 ; Nr. 12, no. 22 (2012-11-16), S.10633-10648 |
| Datensatznummer |
250011588
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| Publikation (Nr.) |
 copernicus.org/acp-12-10633-2012.pdf |
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| Zusammenfassung |
| Oceanic emissions of halogenated very short-lived substances (VSLS) are
expected to contribute significantly to the stratospheric halogen loading
and therefore to ozone depletion. The amount of VSLS transported into the
stratosphere is estimated based on in-situ observations around the tropical
tropopause layer (TTL) and on modeling studies which mostly use prescribed
global emission scenarios to reproduce observed atmospheric concentrations.
In addition to upper-air VSLS measurements, direct observations of oceanic
VSLS emissions are available along ship cruise tracks. Here we use such
in-situ observations of VSLS emissions from the West Pacific and tropical
Atlantic together with an atmospheric Lagrangian transport model to estimate
the direct contribution of bromoform (CHBr3), and dibromomethane
(CH2Br2) to the stratospheric bromine loading as well as their
ozone depletion potential. Our emission-based estimates of VSLS profiles are
compared to upper-air observations and thus link observed oceanic emissions
and in situ TTL measurements. This comparison determines how VSLS emissions
and transport in the cruise track regions contribute to global upper-air
VSLS estimates. The West Pacific emission-based profiles and the global
upper-air observations of CHBr3 show a relatively good agreement
indicating that emissions from the West Pacific provide an average
contribution to the global CHBr3 budget. The tropical Atlantic,
although also being a CHBr3 source region, is of less importance for
global upper-air CHBr3 estimates as revealed by the small
emission-based abundances in the TTL. Western Pacific CH2Br2
emission-based estimates are considerably smaller than upper-air
observations as a result of the relatively low sea-to-air flux found in the
West Pacific. Together, CHBr3 and CH2Br2 emissions from the
West Pacific are projected to contribute to the stratospheric bromine budget
with 0.4 pptv Br on average and 2.3 pptv Br for cases of maximum emissions
through product and source gas injection. These relatively low estimates
reveal that the tropical West Pacific, although characterized by strong
convective transport, might overall contribute less VSLS to the
stratospheric bromine budget than other regions as a result of only low
CH2Br2 and moderate CHBr3 oceanic emissions. |
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