Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10121257 | Physics of the Earth and Planetary Interiors | 2005 | 14 Pages |
Abstract
Convective motions in Earth's outer core are responsible for the generation of the geomagnetic field. We present liquid sodium convection experiments in a spherical vessel, designed to model the convective state of planetary cores such as the Earth's. Heat transfer, azimuthal fluid velocities, and properties of temperature fluctuations were measured for different rotation rates and temperature drops across the convecting sodium. We observed small-scale convective motions with strong, large-scale azimuthal winds and developed turbulence despite the fact that convective heat transport was weak and the temperature profile was close to diffusive. In the context of Earth's outer core, our observations suggest models which imply a thermal Rayleigh number Raâ6Ã1023 and a convective velocity near 2Ã10â4 âm/s. Also, the energy spectrum of outer core may exhibit important structure down to length and time scales of 1âkm and 30 days. Furthermore, we calculate an estimate of Ohmic dissipation, 0.1âTW, in the core based on the shape of experimentally observed power spectra.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geophysics
Authors
Woodrow L. Shew, Daniel P. Lathrop,