IAOS has made significant progress in the research of marine mixing driven by multiscale dynamic processes
Release date: 2019-04-10

On October 5, 2018, the famous international journal Nature Communications published online a paper titled Latitude-dependent finescale turbulent shear generations in the Pacific tropical-extratropical upper ocean, which shows the latest research findings. This paper was jointly completed by the scientific research team whose members include the first author Dr. Zhang Zhiwei, a young scholar from OUC’s Key Laboratory of Physics and Oceanography, Ministry of Education, the co-communication authors professor Tian Jiwei from the Institute for Advanced Ocean Study (IAOS) and professor Qiu Bo from University of Hawaii, USA, and the joint authors professor Zhao Wei from the Institute for Advanced Ocean Study and associated professor Huang Xiaodong from Key Laboratory of Physics and Oceanography, Ministry of Education.

(Paper link: https://www.nature.com/articles/s41467-018-06260-8)

Ocean turbulence mixing is a key factor in maintaining the energy balance of the global ocean circulation and plays a fundamental role in modulating the vertical distribution of heat and matter in the upper layers of the ocean, the biogeochemical processes and even global climate change. However, due to the current lack of understanding of the turbulent mixing drive mechanism and the inability of ocean models to distinguish turbulent mixing processes directly, oceanographers have to parameterize the “mixing effect”, which has become the main bottleneck to improve the simulation and prediction capabilities of the ocean models.

The research team used the year-long simultaneous observational data from submersible buoy observation network (consisting a total of 17 submersible buoys) constructed by Ocean University of China (OUC) along the Pacific 143°E meridian and for the first time revealed the mixed meridional distribution characteristics and driving mechanism in the tropical-extratropical Pacific upper ocean. The study finds that the mixing rate of Pacific upper ocean between 0–22°N have a W-shaped latitudinal distribution with three peaks at 0–2°N, 12–14°N, and 20–22°N, respectively. The study further finds that mechanisms of the three mixing peaks are associated with strong sub-inertial shear of the equatorial currents, parametric subharmonic instability of diurnal internal tides, and anticyclonic eddy’s chimney effect on wind-driven near-inertial waves, respectively. Since the multiscale dynamic processes mentioned above have similar latitudinal distributions in other oceans, the findings are valid for the world’s tropical-extratropical oceans. The findings not only greatly enrich the theoretical framework of marine multiscale process interactions and energy series, but also lay a foundation for improving the vertical mixed parameterization schemes of ocean models.

The scientific research team led by professor Tian Jiwei from the Institute for Advanced Ocean Study has been adhering to the research concept of combining ocean observation and ocean dynamics for many years. It has successfully constructed the Pacific and South China Sea submersible buoy observation networks internationally, has carried out many large-scale scientific observation experiments such as the South China Sea Internal Wave Experiment and the South China Sea Mesoscale Vortex Experiment and has made many breakthroughs in the field of ocean multiscale process interaction and energy series.

The mixing mechanism of turbulent changes with latitude