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| Titel |
Accelerating the spin-up of the coupled carbon and nitrogen cycle model in CLM4 |
| VerfasserIn |
Y. Fang, C. Liu, L. R. Leung |
| 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 ; 8, no. 3 ; Nr. 8, no. 3 (2015-03-24), S.781-789 |
| Datensatznummer |
250116186
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| Publikation (Nr.) |
 copernicus.org/gmd-8-781-2015.pdf |
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| Zusammenfassung |
| The commonly adopted biogeochemistry spin-up process in an Earth system model
(ESM) is to run the model for hundreds to thousands of years subject to
periodic atmospheric forcing to reach dynamic steady state of the
carbon–nitrogen (CN) models. A variety of approaches have been proposed to
reduce the computation time of the spin-up process. Significant improvement
in computational efficiency has been made recently. However, a long
simulation time is still required to reach the common convergence criteria of
the coupled carbon–nitrogen model. A gradient projection method was proposed
and used to further reduce the computation time after examining the trend of
the dominant carbon pools. The Community Land Model version 4 (CLM4) with a
carbon and nitrogen component was used in this study. From point-scale
simulations, we found that the method can reduce the computation time by
20–69% compared to one of the fastest approaches in the literature. We
also found that the cyclic stability of total carbon for some cases differs
from that of the periodic atmospheric forcing, and some cases even showed
instability. Close examination showed that one case has a carbon periodicity
much longer than that of the atmospheric forcing due to the annual fire
disturbance that is longer than half a year. The rest was caused by the
instability of water table calculation in the hydrology model of CLM4. The
instability issue is resolved after we replaced the hydrology scheme in CLM4
with a flow model for variably saturated porous media. |
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