On the upper limit of undertone periods

Received 1979 November 20; in original form 1979 April 2 Summary. The severity of the effect of the Earth‘s rotation on the transverse motions within the fluid core of the Earth is examined. It is shown that, for any model of the fluid core, tfie formalism adapted from free oscillation theory is applicable only for periods less than 12 hr. In the limiting case, as the frequency is decreased to 2 cycle day-’, all modes of response in the fluid are excited to the same order.