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| Titel |
Improvement and evaluation of simulated global biogenic soil NO emissions in an AC-GCM |
| VerfasserIn |
J. Steinkamp, M. G. Lawrence |
| 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 ; 11, no. 12 ; Nr. 11, no. 12 (2011-06-28), S.6063-6082 |
| Datensatznummer |
250009874
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| Publikation (Nr.) |
 copernicus.org/acp-11-6063-2011.pdf |
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| Zusammenfassung |
| Biogenic NO emissions from soils (SNOx) play important direct and indirect
roles in tropospheric chemistry. The most widely applied algorithm to
calculate SNOx in global models was published 15 years ago by Yienger and Levy
(1995), and was based on very few measurements. Since then, numerous new measurements
have been published, which we used to build up a compilation of world wide
field measurements covering the period from 1978 to 2010. Recently, several
satellite-based top-down approaches, which recalculated the different sources
of NOx (fossil fuel, biomass burning, soil and lightning), have shown an
underestimation of SNOx by the algorithm of Yienger and Levy
(1995). Nevertheless, to our knowledge no general improvements of this
algorithm, besides suggested scalings of the total source magnitude, have yet
been published. Here we present major improvements to the algorithm, which
should help to optimize the representation of SNOx in atmospheric-chemistry
global climate models, without modifying the underlying principals or
mathematical equations. The changes include: (1) using a new landcover map,
with twice the number of landcover classes, and using annually varying
fertilizer application rates; (2) adopting a fraction of 1.0 % for the applied
fertilizer lost as NO, based on our compilation of measurements; (3) using the
volumetric soil moisture to distinguish between the wet and dry states; and
(4) adjusting the emission factors to reproduce the measured emissions in our
compilation (based on either their geometric or arithmetic mean
values). These steps lead to increased global annual SNOx, and our total
above canopy SNOx source of 8.6 Tg yr−1 (using the geometric mean)
ends up being close to one of the satellite-based top-down approaches (8.9 Tg yr−1).
The above canopy SNOx source using the arithmetic mean
is 27.6 Tg yr−1, which is higher than all previous estimates, but
compares better with a regional top-down study in eastern China. This
suggests that both top-down and bottom-up approaches will be needed in future
attempts to provide a better calculation of SNOx. |
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