An improvement for calculating the correlation between the geomagnetic and the Earth's gravitational fields

There is a correlation between the geomagnetic and the Earth's gravitational fields to a certain degree. We should consider the zeral harmonic terms to calculate the correlation function. Correlation between the geomagnetic non-dipole field of epoch 1980, which was moved eastwards 165; and the departure part of the Earth's gravitational field from the hydrostatic equilibrium, yields a value of 0.6278. It is significant at the 0.01 level. Calculating the correlations of different epochs, we find that the westward drifting velocity of the geomagnetic non-dipole field is 0.3° year⁻¹. It is not necessary to calculate the correlations between any individual harmonic term from either field.