Excitation of Under-Ice Seiches of a Sea Port of the Sea of Okhotsk

Abstract

Multiannual observations (2009–2017) by means of autonomous seiche recorders have been conducted for marine seiches with one second discreteness in the boot basin for harbor fleet of the settlement of Okhotskoe (Sakhalin Island) at the depth of ~2 m beneath ice. The spectral analysis of the data showed the presence of several significant peaks at periods from 2 to 15 s for the moments of strong swell at the sea. These peaks are caused by wave processes, which are generated by nonlinear transformation of the under-ice rippling. Numerical modeling of the reaction of the dynamic system (water area described by Duffing equation) is carried out depending on the parameters of the experimental observations. It is shown (including the Poincaré map) that the amplitude of the external influence greatly affects the transition of the system to chaos.