Variational methods and core modes - Earth Dynamics: Deformations and Oscillations of the Rotating Earth - page 466

90

0

Radius

Figure 8.9 The generalised displacement potential for the prograde equatorial
translational mode. For Earth model Cal8 it has a period of

−

4.1118 hours.

Azimuthal component

Meridional projection

Rotation
axis

Equator

Figure 8.10 Displacement vector field for the prograde equatorial translational
mode. The motion parallel to the equatorial plane and projected on the meridional
plane is shown on the right, while the azimuthal motion is shown on the left in
perspective.

The angular frequency is positive for the retrograde equatorial mode, which
travels eastward at the rate Ω σ. The generalised displacement potential for the

retrograde equatorial mode is shown in Figure 8.11. The displacement vector field
for this mode is plotted in Figure 8.12. As well as the dominant motion parallel to
the equatorial plane as shown on the right, there is a large azimuthal component
shown on the left in perspective.

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