Investigation of tidal evolution in the Bohai Sea using the combination of satellite altimeter records and numerical models

Abstract

Understanding secular tidal variability is fundamental for many practical purposes such as navigation, coastal engineering and flood warning. Observational tidal evolution is primarily based on coastal tide gauge records whose location and number are extremely limited. Tides undergo significant changes in the Bohai Sea mainly due to coastline changes induced by human activities while there are no publicly accessible long-term hourly tide gauges in the Bohai Sea. In this paper, we investigate secular tidal evolution of four major constituents (M2, S2, O1, and K1) in the Bohai Sea based on multi-satellite altimeter records and the numerical model. Both satellite results and model results indicate consistent feature of tidal changes for M2 tide in the Bohai Sea: M2 amplitudes remarkably increase in the Bohai Bay and Liaodong Bay while noticeably decrease in the Laizhou Bay; M2 phases significantly decrease in the Bohai Bay and Laizhou Bay while substantially increase in the south of the Liaodong Bay. The tidal changes of S2, K1, and O1 constituents revealed by multi-satellite altimeters and the numerical model are contradictory in many parts in the Bohai Sea. Such inconsistency may be related to residual mesoscale ocean variability in satellite results and the ignored contribution of water depth changes to tidal evolution in model results.