| Hourly sea level records taken at Quebec-Lauzon in the St. Lawrence estuary, Canada, are analysed both in frequency domain from 1970 to 1979 and time domain during 1973. Periodic variations, identified by spectral analysis and adjusted by harmonic regression, explain 90 to 95% of the total sea level variability. The residual (non tidal) variations of sea level, stochastic in nature, are responsible of great amplitudes of seiches and storm surges. Such series, representing less than 10%, is tested for its stationnarity and randomness and fitted by AutoRegressive-MovingAverage (ARMA) model. The long-period variations (2 to 28 days) correspond to atmospheric pressure and winds. The short-period variations (2 hours to 1 day) call be attributed to seich-like... |
