SEICHE OSCILLATIONS IN LAKE ONEGA

The results of numerical modeling of barotropic seiche oscillations in Lake Onega are presented. The model is based on a linearized system of shallow water equations on a rotating sphere without taking into account the dissipative terms. The spatial approximation of the equations is performed on an irregular triangular grid. The use of a computational grid with high spatial resolution in solving the spectral-difference eigenvalue problem made it possible to obtain a good correspondence between the calculated periods and the measured ones. Spatial distributions of the amplitude and phase of the first seven modes of natural oscillations of the model Lake Onega are constructed with periods of 13 h 20 min, 11 h 30 min, 6 h 30 min, 5 h 14 min, 4 h 38 min, 4 h 24 min and 4 h 10 min. The analysis showed the importance of taking into account the relatively shallow Svyatula bay. If this bay is excluded from the computational domain, the modes with periods of 13 h 20 min and 11 h 30 min are replaced by one mode with an intermediate period of 12 h 30 min.