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| Titel |
Constraining parameters in state-of-the-art marine pelagic biogeochemical models. Is it sufficient to use typical observations of standing-stocks? |
| VerfasserIn |
Ulrike Loeptien, Heiner Dietze |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094022
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| Publikation (Nr.) |
 EGU/EGU2014-9310.pdf |
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| Zusammenfassung |
| In order to constrain potential feedbacks in the climate system, simple pelagic biogeochemical
models (BGCMs) are coupled to 3-dimensional ocean-atmosphere models. These so-called earth
system models are frequently applied to calculate climate projections. All BGCs rely on a set of
rather uncertain parameters. Among them are generally the Michaelis Menten (MM) constants,
utilized in the hyperbolic MM- formulation (which specifies the limiting effect of light and
nutrients on carbon assimilation by autotrophic phytoplankton). All model parameters are typically
tuned in rather subjective trial-and-error exercises where the parameters are changed manually
until a "reasonable" similarity with observed standing stocks is achieved.
In the present study, we explore with twin experiments (or synthetic ``observations") the demands
on observations that would allow for a more objective estimation of model parameters. These parameter
retrieval experiments are based on ``perfect" (synthetic) observations which we, step by step, distort to
approach realistic conditions. Finally, we confirm our findings with real-world observations. In summary,
we find that even modest noise (10%) inherent to observations may hinder the parameter retrieval already.
Particularly, the MM constants are hard to constrain. This is of concern since the MM parameters are
key to the model`s sensitivity to anticipated changes of the external conditions. |
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