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| Titel |
Predictability limit of convection models of the Earth's mantle |
| VerfasserIn |
Léa Bello, Nicolas Coltice, Tobias Rolf, Paul J. Tackley |
| 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 |
250091813
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| Publikation (Nr.) |
 EGU/EGU2014-6126.pdf |
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| Zusammenfassung |
| The reconstruction of the convective flow in the Earth’s mantle is a crucial issue for a
diversity of disciplines, from seismology to sedimentology. In the past 15 years, several types
of reconstructions have been proposed using convection models forward and backward in
time. However, so far there are no studies of the limit of predictability these models are
facing. Indeed, given the chaotic nature of convection in the Earth’s mantle, uncertainties on
initial conditions grow exponentially with time and limit forecasting and hindcasting
abilities.
We use here an approach similar to those used in dynamic meteorology, and more
recently for the geodynamo, to evaluate the predictability limit of mantle dynamics forecasts.
Following the pioneering works in weather forecast [1], we study the time evolution of twin
experiments, started from two very close initial temperature fields and monitor the error
growth. We extract a characteristic time of the system, called Lyapunov time, which is used to
estimate the predictability limit. The range of predictability depends on the initial error and
the error tolerance in our model. We compute 3D spherical convection solutions using
StagYY [2] and first evaluate the influence of the Rayleigh number on the limit
of predictability. Then, we investigate the effects of various rheologies, from the
simplest (isoviscous mantle) to more complex ones (plate-like behavior and floating
continents).
We show that the Lyapunov time increases with the wavelength of the flow and reaches
130My in the fully chaotic regime of mantle convection with plate-like behavior and floating
contients. Such a Lyapunov time, together with the uncertainties in mantle temperature
distribution, suggests prediction of the Earth’s mantle structure from an initial given state is
limited to |
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