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| Titel |
The Modular Arbitrary-Order Ocean-Atmosphere Model of the RMIB: MAOOAM |
| VerfasserIn |
Lesley De Cruz, Jonathan Demaeyer, Stéphane Vannitsem |
| 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 |
250127413
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| Publikation (Nr.) |
 EGU/EGU2016-7288.pdf |
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| Zusammenfassung |
| The coupled ocean-atmosphere system exhibits a decadal variability at midlatitudes, which
gives rise to the North-Atlantic Oscillation (NOA). The driving mechanism behind this
variability has been the subject of much interest and debate in recent years. This conundrum
was addressed using several low-order coupled ocean-atmosphere models for midlatitudes,
with an increasing level of physical realism: OA-QG-WS v1 [1], v2 [2], and most
recently, VDDG [3]. The VDDG-model was designed to capture the key dynamics of
the coupled ocean-atmosphere system, featuring a two-layer atmosphere over a
shallow-water ocean layer with passively advected temperature. It incorporates both
frictional coupling and an energy balance scheme which accounts for radiative and heat
fluxes between ocean and atmosphere. The spectral expansion was truncated at 10
atmospheric and 8 oceanic modes, and a coupled low-frequency variability was
found.
We present an extended version of the VDDG model, in which an arbitrary number of
atmospheric and oceanic modes can be retained. The modularity of the new model version
allows one to easily modify the model physics. Using this new model, named the “Modular
Arbitrary-Order Ocean-Atmosphere Model” (MAOOAM), we analyse the dependence of the
model dynamics on the truncation level of the spectral expansion. Indeed, previous studies
have shown that spurious behaviour may exist in low-resolution models, which can be
unveiled by a comparison with their high-resolution counterparts [4]. In particular, we assess
the robustness of the coupled low-frequency variability when the number of modes is
increased.
References
[1] Vannitsem, S.: Dynamics and predictability of a low-order wind-driven
ocean–atmosphere coupled model, Climate dynamics, 42, 1981–1998, 2014.
[2] Vannitsem, S. and De Cruz, L.: A 24-variable low-order coupled
ocean–atmosphere model: OA-QG-WS v2, Geoscientific Model Development, 7,
649–662, 2014.
[3] Vannitsem, S., Demaeyer, J., De Cruz, L., and Ghil, M.: Low-frequency
variability and heat transport in a low-order nonlinear coupled ocean–atmosphere
model, Physica D: Nonlinear Phenomena, 309, 71–85, 2015. |
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