The use of underwater sonar at small angles of incidence for in-situ measurements of sea surface parameters

This paper presents the results of experimental measurements of the sea surface parameters during the ship expedition to the Gorky reservoir in the Nizhny Novgorod region in October 2016. The measurements were carried out using underwater sonar at low angles of incidence. The method is based on the analysis of spectral and energy characteristics of the reflected acoustic waves at underwater surface waves observation. A feature of this method is the simultaneous use of multiple antennas with different radiation patterns. The variance of slopes of surface waves was determined using the original algorithm based on the analysis of the Doppler spectrum shift of backscattered radiation measured using two antennas with different antenna patterns. The vertical velocity variance of the water surface was determined using the previously proposed algorithm based on the measurement of the Doppler spectrum width of the backscattered radiation. The accuracy of the retrieval algorithms in the experiment was controlled using synchronous measurements by Froude buoy. As a result, for the first time experimentally confirmed the possibilities to retrieve the variance of slopes using the measurements of the Doppler spectrum shift.