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| Titel |
Carbon-nitrogen feedbacks in the UVic ESCM |
| VerfasserIn |
R. Wania, K. J. Meissner, M. Eby, V. K. Arora, I. Ross, A. J. Weaver |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 5, no. 5 ; Nr. 5, no. 5 (2012-09-18), S.1137-1160 |
| Datensatznummer |
250002846
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| Publikation (Nr.) |
 copernicus.org/gmd-5-1137-2012.pdf |
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| Zusammenfassung |
| A representation of the terrestrial nitrogen cycle is introduced
into the UVic Earth System Climate Model (UVic ESCM). The UVic
ESCM now contains five terrestrial carbon pools and seven
terrestrial nitrogen pools: soil, litter, leaves, stem and roots
for both elements and ammonium and nitrate in the soil for
nitrogen. Nitrogen cycles through plant tissue, litter, soil
and the mineral pools before being taken up again by the plant.
Biological N2 fixation and nitrogen deposition represent
external inputs to the plant-soil system while losses occur via
leaching. Simulated carbon and nitrogen pools and fluxes are in
the range of other models and observations. Gross primary
production (GPP) for the 1990s in the CN-coupled version is
129.6 Pg C a−1 and net C uptake is
0.83 Pg C a−1, whereas the C-only version results in
a GPP of 133.1 Pg C a−1 and a net C uptake of
1.57 Pg C a−1. At the end of a transient experiment for
the years 1800–1999, where radiative forcing is held constant
but CO2 fertilisation for vegetation is permitted to occur,
the CN-coupled version shows an enhanced net C uptake of
1.05 Pg C a−1, whereas in the experiment where CO2 is
held constant and temperature is transient the land turns into
a C source of 0.60 Pg C a−1 by the 1990s. The
arithmetic sum of the temperature and CO2 effects is
0.45 Pg C a−1, 0.38 Pg C a−1 lower than seen in
the fully forced model, suggesting a strong nonlinearity in the
CN-coupled version. Anthropogenic N deposition has a positive
effect on Net Ecosystem Production of
0.35 Pg C a−1. Overall, the UVic CN-coupled version
shows similar characteristics to other CN-coupled Earth System
Models, as measured by net C balance and sensitivity to changes
in climate, CO2 and temperature. |
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