Breakthrough in research on turbulent heat flux in the ocean and contribution to new ocean detection technologies

The energy of the Earth's climate system almost entirely comes from solar radiation, which affects climate change in the form of heat. Seawater covers approximately 70% of the area and has a high specific heat capacity, which can store a large amount of heat and engage in complex heat exchange with the atmosphere, thus having a critical impact on the Earth's climate.

The channel for heat exchange between the ocean and the atmosphere is the sea air interface. At present, the technology for observing the atmospheric boundary layer in the sea air interface is very mature. However, due to limitations in observation techniques and methods, researchers are still unclear about the mode of heat transfer in the upper boundary layer of the ocean. The heat transfer in the ocean is mainly achieved through seawater turbulence, and previous studies have shown that small-scale seawater turbulence has a crucial impact on temperature and sea air heat exchange due to its strong ability to transfer heat vertically. Therefore, the observation of heat flux in the turbulent microstructure of seawater has become the key to the study of heat transfer in the upper boundary layer of the ocean.

In order to solve the limitations of sensor accuracy and sensitivity in direct observation of ocean heat flux, the research team of the South China Sea Institute of Oceanography, Chinese Academy of Sciences, based on the previously developed fast temperature sensor for ocean exploration, combined with the acoustic Doppler three-dimensional point current meter (ADV), independently developed the ocean heat flux meter, which can observe the turbulent heat flux, momentum flux, end motion energy dissipation rate and heat dissipation rate at the same point, And it can work underwater at 1-5000 meters.

Among them, ADV is used to measure the three-dimensional flow velocity of turbulent flow in the ocean, and the ocean detection rapid temperature sensor is used to measure the temperature of turbulent flow in the ocean. The combination of the two can simultaneously and simultaneously measure the velocity and temperature fields in turbulent flow in the ocean. Then, flow velocity data was corrected using ADV attitude data, and a method for measuring turbulent heat flux in the vertical direction of the ocean based on the covariance of vertical velocity and temperature fluctuations was used to achieve the measurement of turbulent heat flux below the sea surface.

The research team used an ocean heat flux meter to observe the turbulence of seawater near the coast of Sanya and in the northern South China Sea. For the first time, the underwater heat flux was measured, and based on the observed data, the role of ocean turbulence eddies in heat flux transport in wind and wave areas was analyzed. In addition, it was determined that turbulent heat flux and momentum flux are closely related to semi diurnal and diurnal tides, with the former reaching during low tide and the latter reaching during low tide, indicating the relationship between tides and vertical turbulent flux.

In addition to observing the heat flux of turbulent seawater, researchers also suggest that ocean heat flux meters can be used for observing heat flux in deep-sea hydrothermal regions. The deep-sea hydrothermal region has abundant marine biological and mineral resources, all of which rely on the eruption of deep-sea hydrothermal fluids. At present, there is no mature technical solution to achieve heat flux measurement in deep-sea hydrothermal zones, but with improvements and improvements to the ocean heat flux meter, there is hope that it can become a solution to this problem.

The development of an ocean heat flux meter enables the monitoring of seawater heat flux. Researchers can use this to quantitatively study the heat absorbed by the ocean from the atmosphere and solar radiation, as well as the heat feedback from the ocean to the atmosphere, in order to gain a deeper understanding of climate change patterns, establish more realistic climate models, improve ocean forecasting capabilities, and promote the development of climate research.

In recent years, the observation of marine turbulent microstructures has received increasing attention, and European and American countries and Japan have made a series of progress in the research of turbulent microstructure profilers and formed a series of products. The research on marine turbulence microstructure profilers in China has just begun, and the successful development of marine heat flux meters is also a major progress in China's marine turbulence research instruments. Not only have we completed fixed-point mixed observations of marine turbulence, but we have also taken the lead in measuring underwater heat flux, making significant progress in China's research on marine turbulence. With the improvement of ocean heat flux meters, China will achieve greater results in the field of ocean heat flux research.

Source: Today's Science

Editor's comment: Thanks to advanced science and technology, researchers have developed many high-precision and cutting-edge instruments and equipment, which have played a positive role in solving various puzzles. Faced with the observation of turbulent microstructures in the ocean, researchers have developed an ocean heat flux meter, which is a great progress in ocean flux research. In the future, we believe that with the help of science, our research on the ocean will be more in-depth.

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