Mantle Conductivity from the Geomagnetic Sq Field

Abstract

The amplitude ratio and phase difference of the spherical harmonics of the magnetic potential between the internal and external parts of the geomagnetic Sq field are obtained at every hour of universal time from March 1-20, 1980. It is found that the phase difference in the P₂¹ mode is small when the external current vortex is above the Pacific Ocean. This suggests a significant effect of the currents induced in the ocean. The phase difference in the P₃² mode shows an irregular UT variation pattern. This is perhaps caused by the effect of the internal P₃², or higher mode magnetic field, induced in the inhomogeneously distributed oceans by the external P₂¹ mode, which has the largest amplitude.