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Geodynamo Modeling of Core-Mantle InteractionsAngular momentum exchange between the Earth's mantle and core influences the Earth's rotation on time scales of decades and longer, in particular in the length of day (LOD) which have been measured with progressively increasing accuracy for the last two centuries. There are four possible coupling mechanisms for transferring the axial angular momentum across the core-mantle boundary (CMB): viscous, magnetic, topography, and gravitational torques. Here we use our scalable, modularized, fully dynamic geodynamo model for the core to assess the importance of these torques. This numerical model, as an extension of the Kuang-Bloxham model that has successfully simulated the generation of the Earth's magnetic field, is used to obtain numerical results in various physical conditions in terms of specific parameterization consistent with the dynamical processes in the fluid outer core. The results show that depending on the electrical conductivity of the lower mantle and the amplitude of the boundary topography at CMB, both magnetic and topographic couplings can contribute significantly to the angular momentum exchange. This implies that the core-mantle interactions are far more complex than has been assumed and that there is unlikely a single dominant coupling mechanism for the observed decadal LOD variation.
Document ID
20010090463
Document Type
Conference Paper
Authors
Kuang, Wei-Jia (Maryland Univ. Greenbelt, MD United States)
Chao, Benjamin F. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Smith, David E.
Date Acquired
August 20, 2013
Publication Date
January 31, 2001
Subject Category
Geophysics
Meeting Information
IAGA/IASPEI Scientific Assembly(Hanoi)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.