Possible relationship between Pacific interdecadal climate variability and the periodic 18.6-year tidal oscillation in the ocean

Abstract

We have reviewed previous observational and modeling studies on Pacific interdecadal climate variability and discussed a roadmap for investigating possible relationships between the climate variability and the periodic 18.6-year tidal oscillation in the ocean. Instrumental data in the 20^th century show significant bidecadal climate variability over the mid-latitude North Pacific. Meanwhile, it is recognized that the real climate variability over the North Pacific is under tropical influences via atmospheric teleconnections, which can be occurred intrinsically even without the tidal oscillations. Although proxy data for several hundred years show significant periodic 18.6-yr variations in the Pacific, whether the signal is relevant to basin-scale climate variability or results from local oceanic tidal variations is debatable. For the hypothesis of the tidal control or regulation of the basin-scale climate variability to be accepted by the international communities of climate research, influences of the tidal oscillation on the Pacific climate variability need to be evaluated and mechanisms that link the two phenomena need to be proposed. It is also important that uncertainties in the tidal influences based on modeling approach be estimated.