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| Titel |
CLM4-BeTR, a generic biogeochemical transport and reaction module for CLM4: model development, evaluation, and application |
| VerfasserIn |
J. Y. Tang, W. J. Riley, C. D. Koven, Z. M. Subin |
| 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 ; 6, no. 1 ; Nr. 6, no. 1 (2013-01-29), S.127-140 |
| Datensatznummer |
250017363
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| Publikation (Nr.) |
 copernicus.org/gmd-6-127-2013.pdf |
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| Zusammenfassung |
| To improve regional and global biogeochemistry modeling and climate
predictability, we have developed a generic reactive transport module for
the land model CLM4 (called CLM4-BeTR (Biogeochemical Transport and
Reactions)). CLM4-BeTR represents the transport, interactions, and biotic
and abiotic transformations of an arbitrary number of tracers (aka chemical
species) in an arbitrary number of phases (e.g., dissolved, gaseous, sorbed,
aggregate). An operator splitting approach was employed and consistent
boundary conditions were derived for each modeled sub-process. Aqueous
tracer fluxes, associated with hydrological processes such as surface run-on
and run-off, belowground drainage, and ice to liquid conversion were also
computed consistently with the bulk water fluxes calculated by the soil
physics module in CLM4. The transport code was evaluated and found in good
agreement with several analytical test cases using a time step of 30 min. The model was then applied at the Harvard Forest site with a
representation of depth-dependent belowground biogeochemistry. The results
indicated that, at this site, (1) CLM4-BeTR was able to simulate
soil–surface CO2 effluxes and soil CO2 profiles accurately; (2) the
transient surface CO2 effluxes calculated based on the tracer
transport mechanism were in general not equal to the belowground CO2
production rates with the magnitude of the difference being a function of
averaging timescale and site conditions: differences were large
(−20 ~ 20%) on hourly, smaller (−5 ~ 5%)
at daily timescales, and persisted to the monthly timescales with a
smaller magnitude (<4%); (3) losses of CO2 through
processes other than surface gas efflux were less than 1% of the overall
soil respiration; and (4) the contributions of root respiration and
heterotrophic respiration have distinct temporal signals in surface CO2
effluxes and soil CO2 concentrations. The development of CLM4-BeTR will
allow detailed comparisons between ecosystem observations and predictions
and insights to the modeling of terrestrial biogeochemistry. |
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