求助一到地球物理的题

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知道地球磁场的single dipole moment Mx, Mz,My如何求 相交的位置
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1 s/ ]' ^+ F+ U1 p: }; i1 ^: P(2) The Earth’s main magnetic field at the surface (radius = 6371 km) can be approximated by a single dipole moment at the Earth's centre with the following (x,y,z) components:

# b; o7 L, D  o  u# smz = -7.7 x 1022 A m2, mx = -0.479 x 1022 A m2, my = 1.399 x 1022 A m2.
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Calculate the location (latitude, longitude) where the axis of this dipole field intersects the Earth's surface (i.e. where the magnetic field is locally purely vertical and upward).