Statistical properties of coastal long waves analysed through sea-level time-gradient functions: exemplary analysis of the Siracusa, Italy, tide-gauge data

Abstract

Abstract. This study presents a new method to analyse the properties of the sea-level signal recorded by coastal tide gauges in the long wave range that is in a window between wind/storm waves and tides and is typical of several phenomena like local seiches, coastal shelf resonances and tsunamis. The method consists of computing four specific functions based on the time gradient (slope) of the recorded sea level oscillations, namely the instantaneous slope (IS) as well as three more functions based on IS, namely the reconstructed sea level (RSL), the background slope (BS) and the control function (CF). These functions are examined through a traditional spectral fast Fourier transform (FFT) analysis and also through a statistical analysis, showing that they can be characterised by probability distribution functions PDFs such as the Student's t distribution (IS and RSL) and the beta distribution (CF). As an example, the method has been applied to data from the tide-gauge station of Siracusa, Italy.

Detection and Characterization of Meteotsunamis in the Gulf of Genoa

“…Meteotsunami are also observed in several other places on the Mediterranean coasts, even along the narrow and deep shelf areas in the Tyrrhenian and Ionian Seas [28][29][30]. The barotropic response of the Gulf of Naples to atmospheric disturbances was investigated and modeled by Gravili et al [31], whereas Bressan and Tinti [32] evidenced the presence of 20 min period oscillations at Siracusa by the analysis of a long term time series of sea-level measurements. Šepic et al [33] analyzed more than 30 meteotsunamis which affected the Mediterranean Sea in the period 2010-2014, identifying the synoptic situations most frequently associated.…”