Responses of the ocean to the Chandler wobble

Abstract

This paper presents a feasible status report on the responses of the ocean to the Chandler wobble through analyses of sea‐level and sea‐surface temperature variations. The analysis of sea level employs a method to determine the simplest impulse response system of ocean to the Chandler wobble by a least‐squares fitting after operation of an optimal band‐pass filter. The observed amplitudes of pole tide in sea level are about 1.13 times as large as the equilibriums in the Pacific, while their phase differences show about 4° with respect to the equilibriums. However, Honolulu in the central Pacific shows an amplitude factor of 2.5 and a phase difference of 45°. The well‐known enhancements of the pole tide in the North Sea and the Baltic Sea are also confirmed.

The sea‐surface temperature variations with the Chandler period are analyzed by using a usual harmonics analysis through a least‐squares fitting over the western North Pacific to detect the possible cause affecting the pole tide in sea level. The results give evidence of the existence of nontidal 14‐month variations, probably forming a secular variation and nonequilibrium character of pole tide in sea level. They prevail along the major currents such as the Kuroshio and the Gulf Stream, but with phases opposite to the equilibrium pole tidews. The estimated amplitudes in sea level due to an expansion of seawater are large enough to mask the real pole tide induced from the wobble. However, their appearances seem too local to affect the pole tides in sea level near the Kuroshio.

It may be concluded through this study that the most feasible responses of the ocean to the Chandler wobble over the world for explaining theoretical considerations of the wobble dynamics presented so far should have values around the Pacific.