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| Titel |
Maximum Entropy Production Temperature Profiles with a realistic radiative scheme |
| VerfasserIn |
Corentin Herbert, Didier Paillard, Bérengère Dubrulle |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072384
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| Zusammenfassung |
| The atmosphere of the Earth, like any fluid heated from below, is subject to vertical instability
which triggers convection. Convection in the atmosphere occurs on small time and space
scales. Even though the resolution of numerical climate models has refined over the years,
the scales involved in convection cannot be represented explicitly in most global
models, and sub-grid parameterizations are usually required. Here, we develop an
alternative view based on a global thermodynamic variational principle. We compute
convective flux profiles and temperature profiles at steady-state in an implicit way, by
maximizing the entropy production rate associated with the vertical transport of
energy.
Two different frameworks are examined, corresponding respectively to the idealized case
of a gray atmosphere, and a more realistic radiative model. We use a narrow band model
based on a Net Exchange Formulation radiative scheme: in the Net Exchange Formulation,
the basic objects describing radiative transfer are not fluxes but rather the net rate of energy
exchanged between two given layers of the atmosphere. This formulation is well suited for
use in simple climate models, and it also allows for a finer description of the radiative
exchanges.
In the second case, we are also able to discuss the effect of variations of the
atmospheric composition, like a doubling of the carbon dioxide concentration. The first
estimates of climate sensitivity obtained in this manner are consistent with — although
slightly lower than — the results of traditional models of equivalent complexity. |
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