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| Titel |
Estimation of ECHAM5 climate model closure parameters with adaptive MCMC |
| VerfasserIn |
H. Järvinen, P. Räisänen, M. Laine, J. Tamminen, A. Ilin, E. Oja, A. Solonen, H. Haario |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 20 ; Nr. 10, no. 20 (2010-10-25), S.9993-10002 |
| Datensatznummer |
250008848
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| Publikation (Nr.) |
 copernicus.org/acp-10-9993-2010.pdf |
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| Zusammenfassung |
| Climate models contain closure parameters to which the model climate
is sensitive. These parameters appear in physical parameterization
schemes where some unresolved variables are expressed by predefined
parameters rather than being explicitly modeled. Currently, best
expert knowledge is used to define the optimal closure parameter
values, based on observations, process studies, large eddy
simulations, etc. Here, parameter estimation, based on the adaptive
Markov chain Monte Carlo (MCMC) method, is applied for estimation of
joint posterior probability density of a small number (n=4) of
closure parameters appearing in the ECHAM5 climate model. The
parameters considered are related to clouds and precipitation and
they are sampled by an adaptive random walk process of the MCMC. The
parameter probability densities are estimated simultaneously for all
parameters, subject to an objective function. Five alternative
formulations of the objective function are tested, all related to
the net radiative flux at the top of the atmosphere. Conclusions of
the closure parameter estimation tests with a low-resolution ECHAM5
climate model indicate that (i) adaptive MCMC is a viable option for
parameter estimation in large-scale computational models, and (ii)
choice of the objective function is crucial for the identifiability
of the parameter distributions. |
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