Observing Internal Solitary Waves in the Lombok Strait by Coastal Acoustic Tomography

Abstract

The subsurface structures of internal solitary waves were observed over two days from 27 to 29 February 2019, by two bottom-moored coastal acoustic tomography systems over a path length of 18.286 km in the Lombok Strait, Indonesia. One-way travel times along the transmission path between the acoustic stations were determined for the first three arrival peaks. The resulting three travel times were used to execute a four-layer (0–50, 150–300, 300–450, and 400–603 m) temperature inversion, constructing an underdetermined problem. The inverted four-layer temperatures show three positive peaks and two negative peaks during the observation period, implying the sequential passage of internal solitary waves with depressed and elevated interfaces. The generation of these temperature peaks is synchronized with the diurnal tides, and the peak heights decrease with depth. The inverted four-layer temperatures are in excellent agreement with conductivity-temperature-depth data obtained near the acoustic stations.