Seiches in the eastern Caribbean

Data from a network of tide gauges in the eastern Caribbean have been used to investigate the periods and amplitudes of seiches at each station, and the coherence in seiche activity between stations. Seiches in this area have very small amplitudes, but they can be readily identified in the sea level spectra obtained from high-quality, high-frequency tide gauges. Most of their periods are found to be determined by the quarter-wavelength response of the adjacent shelf, and their Q values are generally consistent with them being relatively undamped. At several stations, the forcing responsible for the seiches is clear. At others, the forcing is harder to pin down, seiches appearing seemingly randomly, and resulting in what has been called ‘continuous seiche’. Overall, it is demonstrated that seiches (or at least their statistics) need to be better understood and to be included effectively in studies of extreme sea levels. Also related to shelf resonance, two possible examples of ‘tidal ringing’ have been identified.