Abstract. The Gulf of Thailand is dominated by diurnal tides, which might be taken to
indicate that the resonant frequency of the gulf is close to one cycle per
day. However, when applied to the gulf, the classic quarter-wavelength
resonance theory fails to yield a diurnal resonant frequency. In this study,
we first perform a series of numerical experiments showing that the gulf has
a strong response near one cycle per day and that the resonance of the South
China Sea main area has a critical impact on the resonance of the gulf. In
contrast, the Gulf of Thailand has little influence on the resonance of the
South China Sea main area. An idealized two-channel model that can reasonably
explain the dynamics of the resonance affecting the Gulf of Thailand is then
established in this study. We find that the resonant frequency around one
cycle per day in the main area of the South China Sea can be explained with
the quarter-wavelength resonance theory, and the large-amplitude response at
this frequency in the Gulf of Thailand is basically a passive response of the
gulf to the increased amplitude of the wave in the southern portion of the
main area of the South China Sea.
Tidal resonance in the Gulf of Thailand
