Earth magnetic pole

The geographic position of the Earth magnetic pole and the dipole moment $M_E$ can be calculated from the first three coefficients of the International Geomagnetic Reference Field (IGRF) published 5-yearly by IAGA Working Group 8¹³. For full precision interpolate the values $g_{10},g_{11},$ and $h_{11}$ for the date requested and determine the geographic longitude $\lambda_D$, latitude $\Phi_D$ and moment $M_E$ by (Hapgood, 1997; Hapgood, 1992; Kertz, 1969):

$$\lambda_D = \arctan( h_{11} / g_{11} ) \hspace{1cm} \Phi_D = ... ...hspace{1cm} M_E = \sqrt{g_{10}^2 + g_{11}^2 + h_{11}^2}*R_E^3,$$ (21)

where $R_E$= 6378.14 km is the Earth equatorial radius and $\lambda_D$ lies in the fourth quadrant.

For the period 1975-2000 we derive following linear approximations with a precision of $0^\circ.05$:

$$\lambda_D = 288^\circ.44 - 0^\circ.04236y_0 \hspace{1cm} \Ph... ...1cm} M_E = 3.01117 - 0.00226y_0 [10^{-6} \mbox{T}\cdot R_E^3],$$ (22)

where $y_0$ are Julian years from J2000.0.