PRESSURE-FORCED SEICHES OF LARGE-AMPLITUDE IN INLETS OF THE BALEARIC-ISLANDS .2. OBSERVATIONAL STUDY

In part 1 of this study, Gomis et al. [1993] proposed a possible mecha nism for the generation of large-amplitude seiches observed in inlets of the Balearic Islands. In part 2 we revise the proposed mechanism in light of recent observations. These consist of simultaneous records o f sea level/bottom pressure measured at three locations inside and out side Ciutadella inlet and atmospheric pressure measured at four sites inland nearby. First, results that support the existence of offshore s urface waves of atmospheric origin are shown. Next, a detailed analysi s of atmospheric data reveals the passage of non dispersive waves with a predominant direction and phase speed that seem to be about the sam e during seiche events. Finally, coherence, phase difference, and admi ttance functions estimated for different pairs of instruments are comp ared with the theoretical results. All observations indicate that larg e-amplitude seiches observed in Ciutadella are likely the result of a resonant coupling between offshore surface waves generated by atmosphe ric disturbances and the fundamental mode of that inlet, as suggested in part 1. However, the analytical model used in part 1 is clearly too simple to explain the observed characteristics of the offshore surfac e waves.