“…The results show the amplitudes of depression wave and elevation wave were around 25 m and 10 m, respectively. This deformation of shoaling NIW was also found at nearshore of Dongsha Atoll by previous studies 10 , 52 – 54 . Figure 5 The shoaling processes of the NIWs observed in the northern South China Sea.…”
Fundamentally, river plume dynamics are controlled by the buoyancy due to river effluent and mixing induced by local forcing such as winds and tides. Rarely the influence of far-field internal waves on the river plume dynamics is documented. Our 5-day fix-point measurements and underway acoustic profiling identified hydrodynamic processes on the dispersal pathway of the Pearl River plume. The river plume dispersal was driven by the SW monsoon winds that induced the intrusion of cold water near the bottom. The river effluent occupied the surface water, creating strong stratification and showing on-offshore variability due to tidal fluctuations. However, intermittent disruptions weakened stratification due to wind mixing and perturbations by nonlinear internal waves (NIWs) from the northern South China Sea (NSCS). During events of NIW encounter, significant drawdowns of the river plume up to 20 m occurred. The EOF deciphers and ranks the contributions of abovementioned processes: (1) the stratification/mixing coupled by wind-driven plume water and NIWs disruptions (81.7%); (2) the variation caused by tidal modulation (6.9%); and (3) the cold water intrusion induced by summer monsoon winds (5.1%). Our findings further improve the understanding of the Pearl River plume dynamics influenced by the NIWs from the NSCS.
“…The results show the amplitudes of depression wave and elevation wave were around 25 m and 10 m, respectively. This deformation of shoaling NIW was also found at nearshore of Dongsha Atoll by previous studies 10 , 52 – 54 . Figure 5 The shoaling processes of the NIWs observed in the northern South China Sea.…”
Fundamentally, river plume dynamics are controlled by the buoyancy due to river effluent and mixing induced by local forcing such as winds and tides. Rarely the influence of far-field internal waves on the river plume dynamics is documented. Our 5-day fix-point measurements and underway acoustic profiling identified hydrodynamic processes on the dispersal pathway of the Pearl River plume. The river plume dispersal was driven by the SW monsoon winds that induced the intrusion of cold water near the bottom. The river effluent occupied the surface water, creating strong stratification and showing on-offshore variability due to tidal fluctuations. However, intermittent disruptions weakened stratification due to wind mixing and perturbations by nonlinear internal waves (NIWs) from the northern South China Sea (NSCS). During events of NIW encounter, significant drawdowns of the river plume up to 20 m occurred. The EOF deciphers and ranks the contributions of abovementioned processes: (1) the stratification/mixing coupled by wind-driven plume water and NIWs disruptions (81.7%); (2) the variation caused by tidal modulation (6.9%); and (3) the cold water intrusion induced by summer monsoon winds (5.1%). Our findings further improve the understanding of the Pearl River plume dynamics influenced by the NIWs from the NSCS.
“…In (Terletska (2020)) was shown that results of field observations (Moum (2003), Osborn (1980), Orr (2003), Nam (2010), Fu (2016), laboratory experiments (Helfrich (1986), Cheng (2011)) and numerical experiments that simulate ISW transformation in laboratory scales (Talipova (2013), Terletska (2020)) are in good agreement with proposed classification. All data were identified as belonged to corresponding diagram domain.…”
Section: Regimes Of Isw Transformation Over Slope-shelf Topographymentioning
Abstract. Internal solitary waves (ISW) emerge in the ocean and seas in different forms and break on the shelf zones in a variety of ways. Their breaking on slopes can produce intensive mixing that produces such process as biological productivity and sediment transport. Mechanisms of ISW of depression interaction with the slopes related to breaking and changing polarity as they shoal. We assume that parameters that described the process of interaction of ISW in a two-layer fluid with the idealised shelf-slope are: the non-dimensional wave amplitude α (wave amplitude normalized on the upper layer thickness), the ratio of the height of the bottom layer on the shelf to the incident wave amplitude β and angle γ. Based on three-dimensional αβγ classification diagram with four types of interaction with the slopes it was discussed: (1) ISW propagates over slope without changing polarity and wave breaking; (2) ISW changes polarity over slope without breaking; (3) ISW breaks over slope without changing polarity; (4) ISW both breaks and change polarity over the slope. Relations between the parameters α,β,γ for each regime were obtained using the empirical condition for wave breaking and weakly nonlinear theory for the criterion of changing the polarity of the wave. In the present paper the α,β,γ diagram was validated for idealised real scale topography configurations. Results of the numerical experiments that were carried out in the present paper and results of field and laboratory experiments from other papers are in good agreement with proposed classification and estimations. Based on 85 numerical experiments ISWs energy loss during interaction with slope topography with 0.5° < γ < 90° was estimated. Hot spots zones of high levels of energy loss were shown for idealized configuration that mimics continental shelf at Lufeng Region SCS.
“…These effects is believed can led significant impacts on the propagation of the solitary wave. However, the internal waves usually have a negative polarity which has been proved by the observation of internal wave packets in the deep ocean [20]. This is due to changes in the sign of the coefficient in the quadratic nonlinear term, ν, which is well explained by the KdV theory, [2,4].…”
Internal solitary waves have been documentedin several parts of the world. This paper intends to look at the effects of the variable topography and rotation on the evolution of the internal waves of depression. Here, the wave is considered to be propagating in a two-layer fluid system with the background topography is assumed to be rapidly and slowly varying. Therefore, the appropriate mathematical model to describe this situation is the variable-coefficient Ostrovsky equation. In particular, the study is interested in the transition of the internal solitary wave of depression when there is a polarity change under the influence of background rotation. The numerical results using the Pseudospectral method show that, over time, the internal solitary wave of elevation transforms into the internal solitary wave of depression as it propagates down a decreasing slope and changes its polarity. However, if the background rotation is considered, the internal solitary waves decompose and form a wave packet and its envelope amplitude decreases slowly due to the decreasing bottom surface. The numerical solutions show that the combination effect of variable topography and rotation when passing through the critical point affected the features and speed of the travelling solitary waves.
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