Modelling Currents Along The Western Coast OfEstonia As Superposition Of HelmholtzOscillators

Abstract

Both extensive field work and modelling efforts have been focused on the marine area along the western coast of Estonia in order to investigate the water exchange and environmental processes. The system of two basins connected with the open Baltic Sea by four channels has been described as superposition of five individual Helmholtz oscillators. The oscillations of currents were modelled using HIRLAM winds and open sea level data as an input. The model was verified against a 3 month-period of field measurements and continuous 2 year-long flow simulation records were obtained in all the channels. The model behaviour has been analysed in stationary and nonstationary conditions. The main forcing function for the system appeared to be the wind, sea level differences and density differences having a secondary role. It appeared that all the straits function together and the situation in the area under discussion is mostly determined by the water exchange processes forced by the two major nearby basins, i.e. the Baltic Proper and the Gulf of Riga. Some ecological consequences (such as frontal pulsations, etc.) of the water exchange processes are discussed as well.