PRESSURE-FORCED SEICHES OF LARGE-AMPLITUDE IN INLETS OF THE BALEARIC-ISLANDS

Large-amplitude harbor seiches usually occur in summer in the Balearic Islands. A significant correlation between sea level oscillations and atmospheric pressure disturbances has been found, though a proved phy sical mechanism to account for this atmosphere-ocean interaction is st ill missing. Using a flat bottom, shallow water model, we show that a direct coupling between atmospheric pressure and the free mode of an i nlet is unlikely but that an oceanic wave of atmospheric origin can ac t as an intermediate mechanism and adequately force the inlet by reson ance. The phase relationship derived from this mechanism is in good ag reement with observations, provided the whole spectrum of oceanic wave s is in opposite phase to the generating atmospheric disturbance. We a lso show that the very large oscillations observed at Ciutadella (an e longated, shallow inlet in the west coast of Menorca, Balearic Islands ) can be explained in terms of the particular shape of this inlet.