Amplification factors of Abiki oscillations along the western coast of Kyushu Island

Abstract

In order to examine the local effects for Abiki amplification in bay and ports, data analysis is performed using tide and atmospheric pressure time-series measured at 10 locations along the western coast of Kyushu Island during February 21 to 25, 2009. Abiki oscillations were defined by subtracting the predicted tide from measured tide levels. Using the threshold value of Abiki wave weight, zero-up and zero-down crossing methods, the durations of Abiki amplification are evaluated. Positive relationships (R²=0.44) between the wave height and duration of Abiki amplification are confirmed. Tidal motions of spring tide play an important role as for the local amplification factor after comparison with the time series between synoptic atmospheric pressure, predicted tide, slight atmospheric pressure change, and Abiki wave height.