Visual Demonstration of Tidal Movement with Clear Cycles by Time Frequency Analysis

Sumitoshi Ogata, Takahiro Kawakami, Kenta Kirimoto

Abstract

The present study deals with tidal movement in a Japanese coastal area where the half day and one day tidal periods are generally observed. We aim to make the dynamics of this tidal movement much clearer from a point of view of time frequency analysis using a short time Fourier transform(STFT) and a wavelet transform(WT) in addition to a conventional fast Fourier transform(FFT). These three approaches are complementary each other and available for the comprehensive understandings of complicated, oceanic phenomena. The STFT analysis reveals that the four tidal periods are observed only when the tidal power becomes relatively weak around every low tide. On the other hand, two of four periods become indiscriminating around every high tide due to a masking effect of the major, strong tidal powers. We also demonstrate that the WT analysis is exclusively available for visualizing the phase shift process of these two major tidal periods.

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DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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