Importance of station-to-station line orientation in performing coastal acoustic tomography to obtain sea current speed

To perform the coastal acoustic tomography measurement, the locations of stations should be first selected at some appropriate sites on or near the coast. When selecting the locations, it is important to consider vehicle accessibility, the presence of structures such as barges, and the absence of obstructions to sound transmission and reception. Based on these conditions, the five stations were selected for the coastal acoustic tomography observation in Yeosu Bay of South Korea in 2023. In this observation, total six sound propagation lines were used for the inversion of the sea current speed. The sea current speed estimated for each sound propagation line was compared to that from ADCP installed in Yeosu Bay. As a result, when the angle between a line along which the Yeosu Bay's dominant sea current flows and the sound propagation line was small, the estimated current speed was similar to that from ADCP data. This can be considered to be because the smaller the time difference obtained from tomography measurement, the greater the impact of arrival time measurement error on the current speed. This result shows that the orientation of the lines between stations should also be considered important for selecting the locations of stations.