Long-term Variation of the Tidal Characteristics at Jeju Island in the South Sea of Korea

Abstract:

Changing physical environment of the Pacific Ocean may influence the tidal phenomena and it will be interesting to know the change of the tidal characteristics in its marginal seas. In order to understand the change of the tidal characteristics in the South Sea of Korea located north of the East China Sea, long-term sea level data observed at two tide stations, Jeju (1964~2014) and Seogwipo (1985~2014), located north and south of Jeju Island in the South Sea of Korea by Korea Hydrographic and Oceanographic Administration are analyzed with the harmonic analysis method. Amplitudes of semidiurnal components, M2 and S2 have decreased although there are some fluctuations. Another semidiurnal component, N2 also appear to have decreased with large decadal fluctuations. Diurnal constituents, K1 and O1 first decreased and then increased with the minimum amplitudes in 1977 at Jeju station. Annual component SA shows large inter-annual fluctuation over 10 cm before 1980, but the fluctuation decreases afterwards. Annual mean sea level continues to rise with some fluctuations and so does the tide factor with the change of the tidal characteristics at Jeju Island.