Quantifying the probability of meteotsunami occurrence from synoptic atmospheric patterns

A synoptic atmospheric index is constructed for the region of the Balearic Islands, Spain. The index links the occurrence of meteotsunamis, i.e., atmospherically induced high-frequency sea level oscillations (2min<120min), to contemporaneous meteorological synoptic conditions above the region. The correlation between the synoptic index and wave heights is found to be significant and high (up to 0.75). The vertical wind profile is recognized as the most important variable governing the sea level response to atmospheric conditions. The probability of the occurrence of a meteotsunami can be then evaluated from synoptic atmospheric variables. The results show that there exists an index threshold, below which the probability for an intense meteotsunami occurrence is extremely low. However, meteotsunami-favorable synoptic conditions (the index exceeding the threshold value) are crucial but insufficient; some mesoscale features, not reflected in the synoptic pattern, are found to play an important role in meteotsunami generation. The constructed index is potentially applicable to other world locations where a set of tsunamigenic synoptic conditions may be defined in a similar way as at the Balearic Islands. The index can be used to estimate the rate of meteotsunami occurrence under the conditions of past, present, and future climates. It can also be effectively used in meteotsunami warning systems, especially to switch between a silent mode (index below the threshold value) to an event mode.