Whole Mantle Electrical Conductivity & the Velocity Field ofUpper Core-Constraints from Applied Mantle Filter Theory, GDS, and improvements in the Global Geomagnetic Database

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Initial results of deep mantle electrical conductivity studies underway suggest that a localized jump in electrical conductivity is present at midmantle depths, with a peak in the conductivity gradient roughly coincident with the 670 km seismic discontinuity. The PI will obtain higher resolution models of the electrical conductivity of the whole mantle. This involves calculating equivalent scalar magnetotelluric impedance functions from ratios of magnetic field Fourier coefficients. The transformation of spectral ratios into impedances is made possible by knowledge of the magnetic field source structure. He will apply concepts of robust statistical parameter estimation to the problem of spherical harmonic analysis.