Data for 2020 Dongsha Internal Solitary Waves Paper

During an oceanographic cruise aboard the R/V Tan Kah Kee from April 15 to May 21, 2020, in the South China Sea, a 46-hour mooring experiment was conducted to the northwest of Dongsha Atoll at 21.24◦N, 116.07◦E. The site features a gentle topographic slope angle of 0.61◦ based on the SRTM15 PLUS topography dataset (Smith & Sandwell, 1997). A full-depth mooring with a bottom tripod lander frame was deployed starting at 17:44 local time (LT) on May 15. Key measurements obtained in this experiment included the following:(1) Full-depth temperature measurement : The Instruments incorporated 1 CTD (RBR), 2 TDs (RBR), 3 CTs (JFE Advantech), 25 SBE56 temperature loggers (Sea-Bird Electronics), and 76 ONT18S temperature loggers (Ocean Net Tech. Co., Ltd.). Within 119 m distance above the bottom (Dab), 51 ONT18S loggers were deployed with avertical spacing of 9 cm−20 m, with a denser spacing near the seafloor. ONT18S loggers have a 0.3 s time constant and 1×10−4 ◦C noise level. A RBR CTD with turbidity sensor was mounted at Dab = 1.1 m. Sampling rates for ONT18S loggers and CTD were 16 Hz to resolve fine-scale structures. (2) Near-bottom velocity measurements: A current meter (SeaGuard) deployed at Dab = 1.9 m, and an ADCP (300 kHz, Teledyne RDI) deployed at Dab = 130 m provided velocity data in the depth range of Dab = [20 126] m with a 4 m bin size.(3) CTD and microstructure profiling: CTD rosette casts (911Plus, Sea-Bird Electronics) reached Dab ∼ 20 m every 3 hours. A Vertical Micro-structure Profiler (VMP- 250, Rockland Scientific), was deployed hourly from 19:00 LT on May 15 to 00:30 LT on May 18 at a sampling rate of 512 Hz, and measured the turbulent kinetic energy dissipation rate ε down to Dab = [5 − 50] m.In this research, we reveal that internal solitary wave induces intense thermal jets with vertical velocities up to 2 m/s in the near-bottom ocean. These thermal jets trigger bottom instabilities by injecting lighter water through the bottom pycnocline. Turbulent mixing is enhanced by 800 times and micro-burst of sediment resuspension on the order of minutes are induced by the thermal jets.