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| Titel |
Global sea-to-air flux climatology for bromoform, dibromomethane and methyl iodide |
| VerfasserIn |
F. Ziska, B. Quack, K. Abrahamsson, S. D. Archer, E. Atlas, T. Bell, J. H. Butler, L. J. Carpenter, C. E. Jones, N. R. P. Harris, H. Hepach, K. G. Heumann, C. Hughes, J. Kuss, K. Krüger, P. Liss, R. M. Moore, A. Orlikowska, S. Raimund, C. E. Reeves, W. Reifenhäuser, A. D. Robinson, C. Schall, T. Tanhua, S. Tegtmeier, S. Turner, L. Wang, D. Wallace, J. Williams, H. Yamamoto, S. Yvon-Lewis, Y. Yokouchi |
| 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 ; 13, no. 17 ; Nr. 13, no. 17 (2013-09-06), S.8915-8934 |
| Datensatznummer |
250085678
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| Publikation (Nr.) |
 copernicus.org/acp-13-8915-2013.pdf |
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| Zusammenfassung |
| Volatile halogenated organic compounds containing bromine and iodine, which
are naturally produced in the ocean, are involved in ozone depletion in both
the troposphere and stratosphere. Three prominent compounds transporting
large amounts of marine halogens into the atmosphere are bromoform (CHBr3),
dibromomethane (CH2Br2) and methyl iodide (CH3I). The input of marine
halogens to the stratosphere has been estimated from observations and
modelling studies using low-resolution oceanic emission scenarios derived from
top-down approaches. In order to improve emission inventory estimates, we
calculate data-based high resolution global sea-to-air flux estimates of
these compounds from surface observations within the HalOcAt (Halocarbons in the Ocean
and Atmosphere) database
(https://halocat.geomar.de/). Global maps of marine and atmospheric surface
concentrations are derived from the data which are divided into coastal,
shelf and open ocean regions. Considering physical and biogeochemical
characteristics of ocean and atmosphere, the open ocean water and atmosphere
data are classified into 21 regions. The available data are interpolated onto
a 1°×1° grid while missing grid values are interpolated with latitudinal and
longitudinal dependent regression techniques reflecting the compounds'
distributions. With the generated surface concentration climatologies for the
ocean and atmosphere, global sea-to-air concentration gradients and
sea-to-air fluxes are calculated. Based on these calculations we estimate a
total global flux of 1.5/2.5 Gmol Br yr−1 for CHBr3, 0.78/0.98 Gmol Br yr−1
for CH2Br2 and 1.24/1.45 Gmol Br yr−1 for CH3I (robust fit/ordinary least
squares regression techniques). Contrary to recent studies, negative fluxes
occur in each sea-to-air flux climatology, mainly in the Arctic and Antarctic
regions. "Hot spots" for global polybromomethane emissions are located in the
equatorial region, whereas methyl iodide emissions are enhanced in the
subtropical gyre regions. Inter-annual and seasonal variation is contained
within our flux calculations for all three compounds. Compared to earlier
studies, our global fluxes are at the lower end of estimates, especially for
bromoform. An under-representation of coastal emissions and of extreme events
in our estimate might explain the mismatch between our bottom-up emission
estimate and top-down approaches. |
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