Dynamics of thermal convection with Newtonian temperature-dependent viscosity at high Rayleigh number

Tine B. Larsen, David A. Yuen, Andrei V. Malevsky, Jamie L. Smedsmo

Publikation: Bidrag til tidsskriftArtikelForskningpeer review

10 Citationer (Scopus)

Abstrakt

Two-dimensional, time-dependent convection with a Newtonian temperature-dependent viscosity has been investigated in wide aspect-ratio boxes. Large-scale circulations have been found in the regime with volumetrically averaged Rayleigh numbers, Rav ranging between O(105) and O(108). Viscosity contrasts up to 1000 have been examined. The horizontally averaged temperature in the interior, 〈T〉 1 2, does not vary much within the above range of Rav for large-aspect-ratio boxes. The horizontal Fourier spectra of the viscosity field show a decrease of magnitude in the viscosity with shorter wavelength. The viscosity spectra decay differently with decreasing wavelength than the corresponding thermal spectra. Lithospheric processes, such as lubrication of subduction and lithospheric thinning, are facilitated by high Rav. The vertical correlation function for the temperature anomalies used recently for comparing convection calculations with tomographic models is found to be strongly time-dependent for Rav ≤ O(106). The temporal fluctuations of the vertical correlation function decrease for higher Rayleigh numbers. Correlation functions for low Ra are broad and smooth, while those for high Ra, greater than 107, are narrow and fragmented.

OriginalsprogEngelsk
Sider (fra-til)9-33
Antal sider25
TidsskriftPhysics of the Earth and Planetary Interiors
Vol/bind89
Udgave nummer1-2
DOI
StatusUdgivet - maj 1995

Programområde

  • Programområde 5: Natur og klima

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