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| Titel |
EMPOWER-1.0: an Efficient Model of Planktonic ecOsystems WrittEn in R |
| VerfasserIn |
T. R. Anderson, W. C. Gentleman, A. Yool |
| 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. 7 ; Nr. 8, no. 7 (2015-07-24), S.2231-2262 |
| Datensatznummer |
250116463
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| Publikation (Nr.) |
 copernicus.org/gmd-8-2231-2015.pdf |
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| Zusammenfassung |
| Modelling marine ecosystems requires insight and judgement when it comes to
deciding upon appropriate model structure, equations and parameterisation.
Many processes are relatively poorly understood and tough decisions must be
made as to how to mathematically simplify the real world. Here, we present
an efficient plankton modelling testbed, EMPOWER-1.0 (Efficient Model of Planktonic ecOsystems WrittEn in R), coded in the freely
available language R. The testbed uses simple two-layer "slab" physics
whereby a seasonally varying mixed layer which contains the planktonic
marine ecosystem is positioned above a deep layer that contains only
nutrient. As such, EMPOWER-1.0 provides a readily available and easy to use
tool for evaluating model structure, formulations and parameterisation. The
code is transparent and modular such that modifications and changes to model
formulation are easily implemented allowing users to investigate and
familiarise themselves with the inner workings of their models. It can be
used either for preliminary model testing to set the stage for further work,
e.g. coupling the ecosystem model to 1-D or 3-D physics, or for undertaking
front line research in its own right. EMPOWER-1.0 also serves as an ideal
teaching tool. In order to demonstrate the utility of EMPOWER-1.0, we
implemented a simple nutrient–phytoplankton–zooplankton–detritus (NPZD)
ecosystem model and carried out both a parameter tuning exercise and
structural sensitivity analysis. Parameter tuning was demonstrated for four
contrasting ocean sites, focusing on station BIOTRANS in the North Atlantic
(47° N, 20° W), highlighting both the utility
of undertaking a planned sensitivity analysis for this purpose, yet also the
subjectivity which nevertheless surrounds the choice of which parameters to
tune. Structural sensitivity tests were then performed comparing different
equations for calculating daily depth-integrated photosynthesis, as well as
mortality terms for both phytoplankton and zooplankton. Regarding the
calculation of daily photosynthesis, for example, results indicated that the
model was relatively insensitive to the choice of photosynthesis–irradiance
curve, but markedly sensitive to the method of calculating light attenuation
in the water column. The work highlights the utility of EMPOWER-1.0 as a
means of comprehending, diagnosing and formulating equations for the
dynamics of marine ecosystems. |
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