Impact of the horizontal gradient of sound speed on seafloor geodetic positioning
The complex and dynamic marine environment results in a sound speed structure characterized by distinct vertical stratification.Additionally,influenced by oceanographic processes such as warm currents and internal waves,the sound speed field exhibits significant horizontal gradients,which are critical factors affecting high-precision underwater positioning.In this paper,the impact of horizontal gradients in the sound speed field on underwater positioning is investigated based on a three-dimensional ray-tracing positioning model,and the definition of the average gradient of the sound speed field and its inversion model are presented.Then the main factors influencing the accuracy of horizontal gradient inversion are further analyzed.The results indicate that positioning errors are closely related to the direction of the horizontal gradient,the location of seafloor transponders,and the size of the surface trajectory network.When the magnitude of the horizontal gradient reaches 10-5(m/s/m),it can lead to positioning errors exceeding decimeter level in deep sea environments at depths of 3000 m.The seafloor positioning model considering the horizontal gradient parameters of the sound speed field can significantly enhance positioning accuracy.Moreover,the estimation of the horizontal gradient parameter in the average sense can achieve centimeter-level precision posi-tioning.
horizontal gradientunderwater positioning3D acoustic ray tracingaverage gradientpositioning errorparame-ter inversion
万方数据
维普
