Propagation and amplification of meteotsunamis in multiple harbors along the eastern Yellow Sea coast

Abstract

This study investigates the propagation and principal resonance characteristics of meteorological tsunamis (i.e., meteotsunamis) along the eastern Yellow Sea coast, which were anomalously strong in multiple harbors on April 25–26, 2008. Meteorological and sea level data were used to examine the link between atmospheric disturbances and meteotsunamis, and meteorological images were collected to estimate the propagation of atmospheric disturbances. Significant tsunami-like sea level oscillations were sequentially detected at the harbor tide gauges with increased spectral energy within broad period bands of less than 30 min, containing the fundamental period of each harbor. Meteorological parameters indicating the passage of a squall line, such as air pressure disturbances, wind disturbances, high rain rates, and lightning strikes, were also observed. The long ocean waves forced by the propagating squall line generated internal resonances, causing local amplification in multiple harbors. It appears that meteotsunami-induced harbor seiches were generated. Our results demonstrated that the pressure-forced meteotsunamis propagated toward the entrance of the harbors located on the propagation path, resulting in additional amplification by harbor resonance after the Proudman resonance amplifying the long waves in the open sea. The resonance characteristics favorable to additional amplification are the propagation of intense air pressure disturbances, harbors with large quality factors, and dominant period bands of the incoming long waves. The proposed resonance characteristics of specific sites can help in improving the accuracy of the current meteotsunami monitoring system in the Yellow Sea.