Acoustic Pulses Reflection at Frequencies of 43 kHz and 200 kHz When Probing the Ice Cover from Under Water in Arctic Conditions

The research is aimed at developing new methods for measuring parameters of the sea surface and the ice thickness to obtain reliable information about wind-wave and ice conditions, as well as the interaction of sea waves with the ice cover. The use of hydroacoustic methods makes it possible to obtain information about waves and ice cover, regardless of the time of day (illumination), cloudiness, precipitation intensity, and will allow measurements to be taken in stormy conditions. The work is devoted to study the characteristics of the reflection of acoustic signals at frequencies of 43 kHz and 200 kHz when probing the ice cover from under water. This paper presents the results of the work of the underwater dual-frequency sonar “Trident-2” at the “Cape Baranova” polar station of the Arctic and Antarctic Research Institute in the Laptev Sea area adjacent to the Shokalsky Strait in the winter of 2020–2021. The presented results confirm the possibility of observing daily fluctuations in the ice cover caused by tidal changes in water levels. However, when using a frequency of 43 kHz, an increased sensitivity to suspended ice descending from the lower edge of the ice sheet was found, which may complicate the use of this frequency to determine the thickness of the ice sheet.