Yufan Xu -

Dec. 2, 2020, noon - 1 p.m.

Presented By:
Yufan Xu,

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Laboratory Heat Transfer Measurements of Magnetoconvective (MC) in Liquid Gallium - & - Radial Anisotropy in the Indian Ocean from Higher Mode Surface Waves and a Hierarchical Transdismensional Approach

Yufan Xu: Laboratory Heat Transfer Measurements of Magnetoconvection in Liquid Gallium. The Earth's molten outer core and its magnetic dynamo are prevalent geophysical characteristics that exist among many planets in the solar system and other planetary systems. Turbulent flows in the Earth's molten outer core, driven by convection, generate a planetary-scale, nearly axial, and dipole-dominated magnetic field. The behaviors of strongly turbulent convection in the presence of strong Lorentz forces are mostly unknown. Thus, we present results of laboratory experiments on heat transfer of non-rotating Rayleigh-Bénard convection of liquid gallium in the presence of a vertical magnetic field. The experiment is carried out in two cylindrical containers with diameter-to-height aspect ratio Gamma = 1 and 2 for 10^ 6 <~ Ra <~ 10^8 and 0 <~ Ch <~ 10^5. Combined with the results from the previous studies, our experiment shows a more complete picture of near-onset to supercritical behaviors of heat transfer in liquid metal magnetoconvection (MC) over a large range of parameter space (10^ 3 <~ Ra <~ 10^9). ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// Erik Weidner: Radial Anisotropy in the Indian Ocean from Higher Mode Surface Waves and a Hierarchical Transdismensional Approach. A fully non-linear transdimensional hierarchical Markov Chain Monte Carlo approach was developed and applied to fundamental and higher mode Love and Rayleigh wave dispersion data to constrain radial anisotropy in the Indian Ocean. We obtained three-dimensional tomographic models of shear-wave velocity and anisotropy with quantitative uncertainties down to the mantle transition zone. We compared these models to results from regularized linear inversions of the same data set obtained with and without prior constraints on 410- and 660-discontinuities topography. We found that the undulations of these discontinuities had little effect on the resulting models. We also compared results from non-linear joint and separate inversions of Love and Rayleigh waves and tested the effect of depth parametrization on the models.