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PHYS2403 Simulation Lab

Experiment 5: Earth's Magnetic Dipole Field

The Earth's magnetic field is generated by fluid flow in the outer core (the geodynamo). To a first approximation, it behaves like a giant bar magnet tilted relative to the rotation axis (axial dipole model). Explore the relationship between latitude, inclination angle, and total field strength, and compare the axial dipole to the real Earth field.

Earth & Dipole Settings

Station Latitude (λ)-11.5°S
Moves the marker star along the Earth's surface.
Magnetic Dipole Tilt0°
Tilts the magnetic dipole axis away from the rotation axis.
Magnetic Field Model
Quick Markers

Earth Globe & Magnetic LinesTilt = 0°

N (Geo)S (Geo)N_magS_magI = -158°

Inclination vs Latitude

0°+90°-90°Latitude

Total Intensity |B| vs Latitude

070k nT0°+90°-90°

Theoretical Axial Dipole Equations

The standard Geocentric Axial Dipole (GAD) model assumes a central magnetic dipole aligned along the rotation axis. At geomagnetic latitude λ\lambdaat the Earth's surface:

Radial component:Br=−2B0sin⁡λB_r = -2 B_0 \sin\lambda
Horizontal component:Bθ=−B0cos⁡λB_\theta = -B_0 \cos\lambda
Total intensity:Btotal=B01+3sin⁡2λB_{\text{total}} = B_0 \sqrt{1 + 3\sin^2\lambda}
Inclination rule:tan⁡I=2tan⁡λ\tan I = 2 \tan\lambda

Current Station Statistics

Inclination I-157.86°
Declination D0.00°
Total Intensity |B|32796 nT
Radial: 12361 nT
Horizontal: 30378 nT