The Chandlerian Period of minimum excitation

Abstract

Up to the present, the Chandlerian Period has been defined as the mean period of the revolution of the pole around its mean position. However, as the motion of the excitation pole does not contain the Chandlerian component, we can determine the length of the Chandlerian Period under the condition that the motion of the excitation pole attains a minimum after elimination of the Chandlerian component. It is calculated as 416 (mean solar) days. It means the period deduced from the angular velocity of the pole around the instantaneous excitation pole, and is able to match better those deduced from the theory of the internal constitution of the Earth. The calculated results using the recent data of ERP with a high precision show that the Chandlerian Period in this sense seems to have a reality.The main results are shown in the Figure on the next pape.This paper was published in full form in the Journal of the Geodetic Society of Japan, 33 (1987) pp.97–100.