Influence of the Atmospheric Wave Velocity in the Coastal Amplification of Meteotsunamis

Abstract

Extremely large seiche oscillations are regularly observed in some specific areas around the world even in the absence of any seismic forcing. These seiches have been successfully associated with strong atmospheric pressure perturbations inducing sea level oscillations at the open ocean, before entering the inlet, which are in turn resonantly amplified by the geometric characteristics of the inlet. The coastal behaviour of such waves, although of different origin, is similar to tsunami waves behaviour, and is sometimes referred to as meteotsunamis. In some specific places, such as Ciutadella inlet, Balearic Islands, western Mediterranean, these seiche oscillations are stronger than expected, even taking into account the large amplification factor by resonance of the inlet. For these cases, some external amplification, before entering the inlet, is necessary to explain the phenomenon. In this paper, it is numerically shown how the phase speed of the atmospheric pressure disturbance generating the surface waves is a critical factor in the energy transfer between the atmosphere, and the ocean.