Mean pole,z-term and Kuroshio

Secular variations of the mean pole and the z-term in the latitudinal vatiations are discussed geophysically in relation to oceanic motions on the large scale, particularly, to the variations of the Kuroshio system.It is shown that the large scale meanders of the Kuroshio occurred when the direction of displacement of the mean pole turned to the European continent from the North East Pacific and when the z-term changed from decrease to increase. The libration of the mean pole has connection with the zonal circulation of the oceanic mass and the secular variation of the z-term has connection with that of the meridional circulation. The large abrupt decrease in the z-term during 1955–1959 has close connection with the wellknown abnormal variation of sea surface temperature in the North Pacific during the same period.The structures of occurrence of the Kuroshio meanders in 1934 and 1969 may be different from those in 1953 and 1959, and the Kuroshio meander perhaps occurred after 1916 and existed during 2 or 3 years. Particularly the occurrence of the Kuroshio meander in 1959 may originate in the abrupt southward flow of oceanic mass in the Pacific.Except for some cases great earthquakes with magnitude of nearly 8 occurred near the Japan Trench and the Kurile-Kamchatka Trench about one year before the occurrences of the Kuroshio meander, and in the regions from the Alaska Peninsula to the Japan Islands great earthquakes occurred during the disappearance of the Kuroshio meander with a few exceptions.Existence of dynamical interactions between the ocean and the solid-earth may be suggested.