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Advanced Taiwan Ocean Prediction System

Tseng, Tsu-Lun - ALL News | 2017-09-22 | Count:27

Sep/26/2017: Prof. Yign Noh’s Speech:

Title: Investigation of turbulent mixing process in the upper ocean by using large eddy simulation (LES)


Turbulent mixing in the upper ocean plays an important role not only in ocean dynamics and air-sea interaction, but also in various other problems, such as ocean pollution, plankton dynamics, and sediment transport. Large eddy simulation (LES), which reproduces small-scale turbulent structure realistically, provides us detailed information on turbulent mixing process under the ideal condition, which has been unavailable so far. The LES model of the ocean mixed layer, in which wave breaking and Langmuir circulation (LC) are realized, is developed, and applied to investigate the roles of wave breaking, LC, wind stress, convection and the Coriolis force in the vertical mixing of the upper ocean, and to parameterize their effects in the ocean mixed layer model (OMLM). A new OMLM including the effect of LC is developed based on LES results, and found to improve the predictability of the upper ocean from the OGCM, especially by resolving the persistent underestimation of the MLD in the Southern Ocean. Furthermore, by analyzing the motion of Lagrangian particles in the turbulent field simulated by LES, we can clarify the settling and dispersion of suspended particles in the upper ocean, which is critical to understand the biogeochemical process in the upper ocean. For example, it illustrates how particle settling is affected by turbulent flows, such as convection and LC. In addition, various other applications of the LES model are introduced briefly, such as the atmospheric boundary layer, clouds, ocean pollution, urban pollution and aviation turbulence.


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