Deep-sea internal waves observed by differential pressure gauges and a temperature sensor offshore eastern Taiwan

To examine the temperature impact on the DPG signals related to internal motions, four Cox-Webb differential pressure gauges (DPGs) fixed on the ocean bottom and a high-resolution temperature sensor (T-sensor) 13 m above the seafloor as a square-kilometer array deployed offshore eastern Taiwan facing the open Pacific Ocean. The DPGs and T-sensor were built by the Institute of Earth Sciences of Academia Sinica and Royal Netherlands Institute for Sea Research (NIOZ), respectively. In addition, a Nortek AquaDopp acoustic current meter with pressure sensor was attached on the same vertical string with the T-sensor at 2936 m. The multiple instruments in the array were located at depths between 3000 and 3200 m with inter-station horizontal distances ranging from about 300 m to 1 km. The time series data with 2 mHz sampling rate in ASCII format were used to study propagation of the deep-sea internal waves between September 2017 and April 2018. Fifteen events of the internal motions were selected by T-sensor-DPG correlation coefficient > 0.7 at every DPG in a 3-day time window that is shifted in time by 1 day. The propagating direction and apparent horizontal phase speed of the internal waves can be estimated by the DPG data using array analysis methods.