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| Titel |
Towards a climate dependent subgrid-scale parameterization in a three-layer quasi–geostrophic model |
| VerfasserIn |
Martin Pieroth, Matthias Zacharuk, Stamen Dolaptchiev, Ulrich Achatz |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126194
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| Publikation (Nr.) |
 EGU/EGU2016-5885.pdf |
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| Zusammenfassung |
| The atmosphere is a complex system involving many interacting scales. Therefore, subgrid-scale (SGS) parameterizations are essential for climate simulations and numerical weather prediction. Many of those parameterizations contain tuning parameters obtained by fitting model behavior to reference data statistics. Consequently, if the atmosphere is perturbed, and hence also the statistics, these parameters might become erroneous and the SGS parameterization may no longer be able to help simulating the dynamics of the perturbed atmosphere.
Therefore, we propose a climate dependence of the tuning parameters using the Fluctuation-Dissipation Theorem (FDT). The FDT is able to predict the changes in the statistics of a system, caused by small external forcings. Those changes are then used to update the empirical components of the tuning parameters.
This procedure is tested in a toy atmosphere provided by a three-layer quasi-geostrophic model (QG3LM). The corresponding climate model is given by a low-order model, based on a reduced number of QG3LM variance patterns, with an empirical stochastic closure as SGS parameterization. The external perturbation is given by some local anomalous heating in the extratropics.
It is shown that the FDT is able to predict the required change in the closure parameters for low numbers of resolved variance patterns in the low-order model. Moreover, the low-order model with the FDT-corrected closure improves in this case the agreement with the QG3LM, compared to the low-order model without a corrected closure. |
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