Weijia Kuang$^{a,b}$, Benjamin F. Chao$^{b}$
$^{a}$ JCET, UMBC, Maryland, USA $^{b}$ Space Geodesy Branch, Code 926, NASA GSFC, Maryland, USA
wkuang@umbc.edu, kuang@bowie.gsfc.nasa.gov
The Earth?s liquid outer core is in convection, as suggested by the existence of the geomagnetic field in much of the Earth?s history. One consequence of the convection is the redistribution of mass resulting from relative motion among fluid parcels with slightly different densities. This time dependent mass redistribution inside the core produces a small perturbation on the gravity field of the Earth. With our numerical dynamo solutions, we find that the mass redistribution (and the resultant gravity field) symmetric about the equator is much stronger than that anti-symmetric about the equator. Furthermore, the resultant gravity field variation increases with the Rayleigh number. With reasonable scaling from the current dynamo solutions, we could expect that at the surface of the Earth, such gravity field variation is on the order of $10^{-10}$ relative to the mean (i.e. spherically symmetric) gravity field of the Earth. This numerical result suggests that time-varying gravity field perturbation due to core mass redistribution may be measured with modern space geodetic observations, which will result a new means of detecting dynamical processes in the Earth?s deep interior.