Using the tunderwater corner reflector (CR) to simulate the acoustic scattering characteristics of the military target is a new technology to counter active sonar detection. Existing underwater CRs only have the ability to interfere with the acoustic field, but have limitations in acoustic wave modulation. Therefore, acoustic metasurfaces applied on CRs to enhance the ability of acoustic wave modulation has a great application prospect. A fast prediction method based on the Kirchhoff approximation (KA) and the ray tracing theory is proposed to calculate the acoustic scattering characteristics of CR with acoustic metasurfaces in grooves array type. The accuracy of the method is verified by the finite element method (FEM) simulation. The modulation effect of CR with grooves array in different gradient combinations on the structural scattering acoustic field is analyzed. The research shows that the CR with different combinations of the acoustic metasurface has an obvious modulation effect on the amplitude of the acoustic waves and the deflection of acoustic field. In particular, the grooves array in combination with positive and negative gradients has an obvious deflection impact on the scattering acoustic field.

During a month from 28 June till 27 July 1987 measurements were made of variations in the chemical composition of shallow water basins occurring on the north side of the Ebbaelva gap section at the southwestern foot of Lovehovden. The waters have variable mineral contents and ion composition. The resulting data indicate a marked effect of various kinds of water feeding the basin, including water derived from the melting of snow and that released due to permafrost degradation, depending on bedrock and the intensity of biogenic processes which operate in areas of basin occurrence.