The variations in the free surface of Lake Baikal at three stations (Bol’shie Koty, Listvyanka, and Baikal’sk) are measured. A modern recording method and an advanced technique of record processing are used. Based on 1-year-long observation data, the amplitudes of seiche oscillations and their seasonal changes are analyzed. It is found, in particular, that 67-min seiches are manifested in different seasons. Numerical calculations of seiches in Lake Baikal are made with the use of up-to-date bathymetric data on one-dimensional, plan, and spherical models. Spatial structures of oscillations with periods of 277, 152, 84, 67, and 59 min, corresponding to the well-expressed peaks of power spectral density, are studied. It is shown that the first four periods correspond to uninodal, binodal, trinodal, and quadrinodal longitudinal seiche modes of Lake Baikal. The periods of three solutions can correspond to the value of 59 min. The first of them is the seiche of the lake’s South Basin, and two others are characterized by significant amplitude growth in the Small Sea and Chivyrkui Bay.

An instrumental package for monitoring hydrophysical processes (internal and surface gravity waves, including tides, seiches, and wind waves) in the shallow part of the ocean shelf is described as well as methods and approaches.

To study the specific features of free surface oscillations in the northwestern part of Posyet Bay (the Sea of Japan), a series of experimental works using an installation with a laser meter for measuring hydrosphere pressure variations were carried out in 2012 and 2014. In the course of the joint analysis, measurement results for oscillations with periods of 10–30 min and the results of calculations using a numerical model of shallow water with a difference approximation on an irregular triangular space grid, datasets of the space–time parameters for the resonance oscillations of the studied water area were obtained. The results of the numerical simulations confirm the manifestation of the resonance properties of Novgorodskaya, Expedicii, and Reyd Pallada Bays water areas on the oscillations singled out during the experimental studies. The positions of the peaks on the model resonance curves are consistent with the positions of the clearly pronounced peaks of the energy spectrum in the field data.

Characteristics of barotropic seiche oscillations of the middle part of the Peter the Great gulf are considered with the use of a spectral-finite difference model. The model is based on a linearized system of shallow water equations. Difference approximation is carried out on an irregular triangular spatial grid. The numerical method involves solving the eigenvalue problem and is able to directly obtain a set of frequencies and the corresponding shapes of seiche oscillations. The grid computational domain covers the Amurskiy bay and the Ussuriyskiy bay. The Zolotoy Rog bay and the Alekseeva bay are described in more detail on the grid. The spatial-temporal characteristics of a number of seiche oscillations corresponding to well-defined peaks of the energy spectrum of the sea level data from the “Vladivostok” station of the Russian tsunami warning service are calculated and presented. The results of calculations for the Alekseeva bay are compared to the data of natural measurements and to the solution to the Cauchy problem.

The field experiment with the installation of autonomous pressure gages in the Troitsa and Vityaz’ bays was held for studying the specific features of free surface oscillations in the Posyet Bay (the...