Ocean Observations Using Distributed Acoustic Sensing with a 29 km long Submarine Cable in the Northern South China Sea

Abstract Distributed acoustic sensing (DAS) technology can convert seafloor telecommunication optical fibers into spatially dense arrays of strain sensors for ocean observation. DAS has the advantages of high spatial–temporal resolution, real-time data telemetry, and adaptation to severe environmental conditions. Thus, it has a large potential to fill the data gap for ocean observation over conventional equipment. In this study, we installed a DAS interrogator at the onshore controlling center of the Datang offshore wind farm in the northern South China Sea. The seafloor optical cables, about 29 km long, were converted into a dense array composed of 7091 strain sensors with a spatial sampling interval of 4 m. This study reports the preliminary results from one month’s continuous DAS data acquisition. During the acquisition period, the DAS array recorded a series of local and regional earthquakes and observed various ocean signals, including ocean waves, ships, primary and secondary microseisms, and Scholte waves generated by interactions of the ocean and the solid Earth. The spectrograms of DAS data show high consistency with the in situ observation of significant wave height and wind speed obtained by acoustic wave and current meter, and anemometers. The successful recordings of abundant marine environmental signals prove the significant potential of DAS technology to be the next generation of ocean observation equipment.