Session2: Ports, Coastal Engineering and Management
Title: THE RELATION BETWEEN PROPAGATION PATHS OF BAROMETRIC WAVES OVER THE EAST CHINA SEA AND SEA-LEVEL FLUCTUATIONS OFF THE WEST COAST OF KYUSHU, JAPAN
Tomonori Saita, Toru Yamashiro
Secondary undulations caused by meteorological disturbances over the East China Sea are frequently observed in the sea areas off the west coast of Kyushu Island, Japan. In this study, numerical analyses were carried out to determine the relationship between the propagation paths of barometric waves over the East China Sea and characteristics of sea-level fluctuations in these sea areas. The results indicate that a drastic increase in the propagation velocity causes a strong reflection of water surface waves at the Okinawa Trough (a back-arc basin with a section more than 1000 m deep and approximately 200 km wide) and that this is an important factor affecting the behavior of the waves at the edge of the trough. Therefore, the magnitude of sea-level fluctuations off Kyushu Island strongly depends on the relationship between the propagation path of the barometric wave and the Okinawa Trough, specifically the incident angle and position of the wave relative to the trough. The results also suggest that the propagation paths of barometric waves have a significant influence on the timing of peaks in sea-level fluctuations in the sea areas off Meshima Island, Uji Island, Nagasaki, Kami-Koshiki Island, and Makurazaki. In some cases, the peak in sea-level fluctuations may occur around 4 h earlier off Kyushu Island than that off Meshima Island, which is located on the west side of the Okinawa Trough.