Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 16, 223-237, 2016
https://doi.org/10.5194/nhess-16-223-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
21 Jan 2016
Statistical properties of coastal long waves analysed through sea-level time-gradient functions: exemplary analysis of the Siracusa, Italy, tide-gauge data
L. Bressan and S. Tinti Department of Physics and Astronomy (DIFA), University of Bologna, Bologna, Italy
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.

Citation: Bressan, L. and Tinti, S.: Statistical properties of coastal long waves analysed through sea-level time-gradient functions: exemplary analysis of the Siracusa, Italy, tide-gauge data, Nat. Hazards Earth Syst. Sci., 16, 223-237, https://doi.org/10.5194/nhess-16-223-2016, 2016.
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Short summary
A new method is presented to analyse coastal tide-gauge recordings in the period range typical of local seiches, coastal shelf resonances and tsunamis. The method computes the instantaneous slope IS, the reconstructed sea level (RSL), and the control function (CF), that are shown to follow the Student's t distribution (IS and RSL) and the Beta distribution (CF) functions. As an example, the method is applied to data from the tide-gauge station of Syracuse, Italy.
A new method is presented to analyse coastal tide-gauge recordings in the period range typical...
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