Resonant Amplification of Diurnal Tides in the Gulf of Finland

Based on the analysis of sea level data from seven coastal tide gauges, the resonance mechanism of diurnal tide formation in the Gulf of Finland was investigated. The main role in the formation of the tidal regime in the Baltic Sea is played by the independent tide, the response of the water column of the basin to the direct impact of the tide-generating forces. An important feature of the tide in the Baltic Sea is the predominance of diurnal tides over semidiurnal ones. It was found that the closer the frequency of the tidal harmonic to the natural frequency of the basin, the stronger the equilibrium response of this tidal harmonic. Such resonance increase in the tidal diurnal components is caused by tidal resonance, the influence of natural oscillations of the Gulf of Finland and the entire Baltic Sea with a period of about 27 hours. It is the presence of resonant amplification of diurnal tidal oscillations in the Gulf of Finland that leads to the fact that the maximum tidal range in this part of the sea reaches 19 cm.