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| Titel |
Trends and inter-annual variability of methane emissions derived from 1979-1993 global CTM simulations |
| VerfasserIn |
F. Dentener, M. Weele, M. Krol, S. Houweling, P. Velthoven |
| 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 ; 3, no. 1 ; Nr. 3, no. 1 (2003-02-03), S.73-88 |
| Datensatznummer |
250000711
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| Publikation (Nr.) |
 copernicus.org/acp-3-73-2003.pdf |
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| Zusammenfassung |
| The trend and interannual variability of methane sources are derived from
multi-annual simulations of tropospheric photochemistry using a 3-D global
chemistry-transport model. Our semi-inverse analysis uses the fifteen years
(1979--1993) re-analysis of ECMWF meteorological data and annually varying
emissions including photo-chemistry, in conjunction with observed CH4
concentration distributions and trends derived from the NOAA-CMDL surface stations. Dividing the world in four zonal regions
(45--90 N, 0--45 N, 0--45 S, 45--90 S) we find good agreement in each region between (top-down) calculated
emission trends from model simulations and (bottom-up) estimated anthropogenic emission trends based on the EDGAR global anthropogenic
emission database, which amounts for the period 1979--1993 2.7 Tg CH4
yr-1. Also the top-down determined total global methane emission compares well with the total of the bottom-up estimates. We use the
difference between the bottom-up and top-down determined emission trends to
calculate residual emissions. These residual emissions represent the inter-annual variability of the methane emissions. Simulations have been
performed in which the year-to-year meteorology, the emissions of ozone precursor gases, and the stratospheric ozone column distribution are either
varied, or kept constant. In studies of methane trends it is most important
to include the trends and variability of the oxidant fields. The analyses reveals that the variability of the emissions is of the order of
8Tg CH4 yr-1, and likely related to wetland emissions and/or
biomass burning. |
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