A brief review is made on the theory of the Lagrangian residual circulation and inter-tidal transports in a convectively weakly nonlinear system. In the review the emphasis is put on the systematical development of th...A brief review is made on the theory of the Lagrangian residual circulation and inter-tidal transports in a convectively weakly nonlinear system. In the review the emphasis is put on the systematical development of the theory and its weakness of convectively weakly nonlinear approximation. The fundamentals of a Lagrangian tidally-averaged theory on circulation with inter-tidal transport processes have been proposed for a general nonlinear coastal/estuarine system. The Lagrangian residual velocity is strictly de- fined, and it has been verified to be able to embody the velocity field of circulation. A new concept of the concentration for inter- tidal transport processes is presented. The concentration describing the inter-tidal transport processes should be a ＂Lagrangian inter-tidal concentration＂ defined and named, but not the Eulcrian tidally-averaged concentration used traditionally. The circulation described here contains a set of infinite temporal-spatial fields of velocity/concentration, each of which corresponds to a specific value of tidal phases varying continuously over one tidal cycle. When the convectively weakly nonlinear condition（ with a smaller order of eddy diffusion and sources） is approximately satisfied, a set of infinite temporal-spatial fields of velocity/concentration can be reduced to a single one.. the mass transport velocity/the Eulerian tidally averaged concentration as exhibited traditionally.展开更多
The results of the new concept of coastal sea circulation are demonstrated by numerical simulations for the first time.The numerical experiments in three types of rectangular model seas illustrate the dependence of ci...The results of the new concept of coastal sea circulation are demonstrated by numerical simulations for the first time.The numerical experiments in three types of rectangular model seas illustrate the dependence of circulation on tidal phases due to the convectively nonlinear effect which is estimated by a newly defined drift dispersion index.Then,the present theory is applied in the Bohai Sea of China.At the Bohai Straits and the Huanghe River mouth area the circulation direction even reverses owing to different initial tidal phases which shows that the theory copes with nonlinearity well.The calculated M2 tide-induced residual circulation shows that a clockwise gyre exists in the center of an anticlockwise gyre in the central Bohai Sea due to the topographic features.In the Bohai Gulf the tide induced circulation shows a 3D structure with outflow at the surface and the inflow at the bottom which can partly explains the spread of the Huanghe River fresh water out of the Bohai Gulf and the inflow of the sediment from the Huanghe River.展开更多
In this study, we examine the results obtained by the Finite-volume Coastal Ocean Circulation Model(FVCOM) regarding the effects of eddy viscosity and bathymetry on the three-dimensional(3 D) Lagrangian residual veloc...In this study, we examine the results obtained by the Finite-volume Coastal Ocean Circulation Model(FVCOM) regarding the effects of eddy viscosity and bathymetry on the three-dimensional(3 D) Lagrangian residual velocity(LRV) in a narrow bay. The results are cast in terms of two nondimensional numbers: the ratio of friction to local acceleration(δ) and the ratio of the minimum depth over shoals to the maximum depth in the channel(ε). The ratio δ depends on the eddy viscosity and mean depth. For a given eddy viscosity, when ε > 0.5, the along-estuary LRV tends to be vertically sheared and when ε < 0.5, the exchange is laterally sheared. When ε << 1, the structure of the 3 D, depth-integrated, and breadth-averaged LRV changes only slightly as δ increases. For ε values between 0.33 and 0.5, the structure of the 3 D LRV is mainly laterally sheared. In the same ε range, the 3 D and depth-integrated LRV exhibit reversed structures from high to low δ values. In addition, the breadth-averaged LRV weakens the typical twolayered circulation when δ decreases. When ε is 1, the two-layered vertical structure reverses direction, and a three-layered vertical structure develops in the outer bay as δ decreases.展开更多
基金The National Key Basic Research Science Foundation ("973"project) of China under contract No. 2002CB412402the National Natu-ral Science Foundation of China under contract No. 40276007the Program for New Century Excellent Talents in University of China NCET-05-0592
文摘A brief review is made on the theory of the Lagrangian residual circulation and inter-tidal transports in a convectively weakly nonlinear system. In the review the emphasis is put on the systematical development of the theory and its weakness of convectively weakly nonlinear approximation. The fundamentals of a Lagrangian tidally-averaged theory on circulation with inter-tidal transport processes have been proposed for a general nonlinear coastal/estuarine system. The Lagrangian residual velocity is strictly de- fined, and it has been verified to be able to embody the velocity field of circulation. A new concept of the concentration for inter- tidal transport processes is presented. The concentration describing the inter-tidal transport processes should be a ＂Lagrangian inter-tidal concentration＂ defined and named, but not the Eulcrian tidally-averaged concentration used traditionally. The circulation described here contains a set of infinite temporal-spatial fields of velocity/concentration, each of which corresponds to a specific value of tidal phases varying continuously over one tidal cycle. When the convectively weakly nonlinear condition（ with a smaller order of eddy diffusion and sources） is approximately satisfied, a set of infinite temporal-spatial fields of velocity/concentration can be reduced to a single one.. the mass transport velocity/the Eulerian tidally averaged concentration as exhibited traditionally.
基金The National Key Basic Research Science Foundation ("973"Project) of China under contract No. 2002CB412402the National Natu-ral Science Foundation of China under contract No. 40276007Program for New Century Excellent Talents in University of China under contract No.NCET-05-0592
文摘The results of the new concept of coastal sea circulation are demonstrated by numerical simulations for the first time.The numerical experiments in three types of rectangular model seas illustrate the dependence of circulation on tidal phases due to the convectively nonlinear effect which is estimated by a newly defined drift dispersion index.Then,the present theory is applied in the Bohai Sea of China.At the Bohai Straits and the Huanghe River mouth area the circulation direction even reverses owing to different initial tidal phases which shows that the theory copes with nonlinearity well.The calculated M2 tide-induced residual circulation shows that a clockwise gyre exists in the center of an anticlockwise gyre in the central Bohai Sea due to the topographic features.In the Bohai Gulf the tide induced circulation shows a 3D structure with outflow at the surface and the inflow at the bottom which can partly explains the spread of the Huanghe River fresh water out of the Bohai Gulf and the inflow of the sediment from the Huanghe River.
基金supported by the National Natural Science Foundation of China (No. 41676003)the National Natural Science Foundation of China–Shandong Joint Fund for Marine Science Research Centers (No.U1606402)
文摘In this study, we examine the results obtained by the Finite-volume Coastal Ocean Circulation Model(FVCOM) regarding the effects of eddy viscosity and bathymetry on the three-dimensional(3 D) Lagrangian residual velocity(LRV) in a narrow bay. The results are cast in terms of two nondimensional numbers: the ratio of friction to local acceleration(δ) and the ratio of the minimum depth over shoals to the maximum depth in the channel(ε). The ratio δ depends on the eddy viscosity and mean depth. For a given eddy viscosity, when ε > 0.5, the along-estuary LRV tends to be vertically sheared and when ε < 0.5, the exchange is laterally sheared. When ε << 1, the structure of the 3 D, depth-integrated, and breadth-averaged LRV changes only slightly as δ increases. For ε values between 0.33 and 0.5, the structure of the 3 D LRV is mainly laterally sheared. In the same ε range, the 3 D and depth-integrated LRV exhibit reversed structures from high to low δ values. In addition, the breadth-averaged LRV weakens the typical twolayered circulation when δ decreases. When ε is 1, the two-layered vertical structure reverses direction, and a three-layered vertical structure develops in the outer bay as δ decreases.
