A Universal Method to Eliminate the Effect of Sounding Velocity Errors on Multibeam Sounding Data

Abstract

The presence of sound velocity errors (SVEs) is common in multibeam sounding. Existing methods are good at eliminating these errors in the area with flatter seabed terrains but are not suitable for deep and complex seabed terrains. Therefore, a universal method is proposed in this paper to eliminate these errors in various depth and terrain areas with a regression model and the equivalent sound speed profile (ESSP). The vertical biases are calculated at these homonymy points of the main survey line and the inner swaths of the auxiliary survey line firstly. Then, a regression model is built by associating the vertical bias with the initial incident angle and travel time, and the regression coefficients are estimated with the help of the partial least squares (PLS) method. On the basis of the determined regression model and ESSP, the effects of sound errors for multibeam sounding data are eliminated. The proposed method was verified by the multibeam sounding data measured in the medium-shallow and deep water areas, and the standard deviations of the absolute values of depth differences (AVDDs) after correction were both about 2 times lower than those before correction.