engleski

The appearance of Proudman resonance and surface seiches in the area of Split (Adriatic Sea)

The paper examines the occurrence of Proudman resonance in front of Split harbour (Adriatic Sea) and harbour seiches, including the possibility of their coupling. The dataset comprises air and sea pressure (sea level) data collected in August-December 2000, characterized by rather strong synoptic disturbances that took place over the harbour. The analyses encompass empirical tools such as time-series analysis, high- and band-pass filtering, spectral and wavelet analyses, whereas the theoretical approach includes the conceptual model of the resonance and barotropic 2D numerical model of the harbour seiches. The resonance seems to be generated in front of the harbour and then propagates inside, covering the periods between 7.7 and 28.5 min as a result of a complex atmospheric gravity wave structure and having a gain between air pressure and sea level equaling 5-40 cm/hPa. The seiches were documented to occur at the periods of 6.5, 3.0, 1.6 and 1.15 min, and were verified by the barotropic 2D numerical model. In addition, two model runs were executed: the first one with present topography and the second one with the nautical marina removed (built in 1972). The comparison quantify the influence of the marina on the seiche characteristics. Namely, the leading seiche modes of 7.1-min and 5.0-min periods, calculated for the present topography, were probably joined in the 6.2-min mode before 1972. On the other hand, the numerical model showed that the 3.0-min seiche mode keeps its period, having the maximum amplitude at the north end of the harbour calculated for both runs. Finally, the seiches and resonance may endanger the navigation near the entrance and within the marina during the enhanced seiche episodes.

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