In coastal waters, the energy flux of shoreward waves is
modulated by tides. Significantmodulations of the wave heights
at major tidal periods were observed by using buoy data in
intermediate depth water [10], [11]. The periodic modulations
of significant wave height (SWH) at the M2 tidal frequency
were detected by high-frequency (HF) radars due to the forcing
of tidal current variations [12], [13]. However, the blind zone of
the HF radar ranges from several to tens of kilometers, so it is
not applicable to use the HF radar in the coastal waters close to
the shoreline.