Ventilation or water exchange between the subtropical and tropic Pacific is studied with a simple none thermodynamic two and half layer model. The shallow upper layer is assumed to communicate with its lower counterpa...Ventilation or water exchange between the subtropical and tropic Pacific is studied with a simple none thermodynamic two and half layer model. The shallow upper layer is assumed to communicate with its lower counterpart by entrainment and detrainment at rates W e and W d . Trenberth wind stress data (Trenberth Data Center, 1995) are chosen to drive the upper moving ocean to obtain a stable state. The results show that the subtropical and tropic Pacific exchange water in two ways. One is the direct exchanging by which the surface water in the mid latitude goes down and moves to the tropical region in the subsurface layer and upwells back to the Ekman layer and finally moves northward to complete its journey; and the other is the way of detour, by which water in the subtropical Pacific moves first to the western boundary region along geostrophic flow contours and goes down to the tropic region as southward boundary currents. These two ways contribute almost the same amount to the water exchange between the subtropical and tropic Pacific gyres although the spatial scale in the latter is ten times greater than that of the former. LPSs (Luyten et al., 1983) ventilation theory is reviewed to give a clear picture of how the water exchange in large scale has been studied and the numerical results in this paper are compared with both the conclusions of such analysis theory and some previous observation (tritium survey) reports.展开更多
Typical wind fields in winter and summer were applied in a three-dimensional model for simulating the wind-driven current fields in the study region 27.0 °N to 34.5°N, 120.0°E to 126.0°E. Deta from...Typical wind fields in winter and summer were applied in a three-dimensional model for simulating the wind-driven current fields in the study region 27.0 °N to 34.5°N, 120.0°E to 126.0°E. Deta from three cruises in 1993 and 1994 were analyzed to obtain the horizontal and vertical structures of total suspended matter (TSM) there. Based on this study, a numerical method was derived to show that it is in winter, not summer, that the suspended matter (SM) is catrried out from the mouth of the Changjiang River to the deep ocean, and yield some other important conclusions.展开更多
How to determine the future open boundary conditions of the diffusive equation for certain bays or estuaries is still a question, although the present conditions can be easily obtained by observation.In this paper, a ...How to determine the future open boundary conditions of the diffusive equation for certain bays or estuaries is still a question, although the present conditions can be easily obtained by observation.In this paper, a new concept "the effective reach" led to the conclusion on theopen boundary for the case n- 1 was confirmed by some numerical experiments. This rational boundary condition for simulating the pollutants diffusive fields can be effectively applied to environmental problems.展开更多
A time-dependent, three-dimensional finite difference model is presented for simulating the stratifiedYellow Sea and northem East China Sea. The mode is forced by time-dependent observed wind, surfaceflux of heat, and...A time-dependent, three-dimensional finite difference model is presented for simulating the stratifiedYellow Sea and northem East China Sea. The mode is forced by time-dependent observed wind, surfaceflux of heat, and tidal turbulence. With this model, momentum and temperature distribution can be computed,and an approximation for the sub-grid scale effects is introduced by the use of mass and momentumexchange coefficients. The vertical exchanges are quite dependent on these assumed coefficents, whichare complicated functions of the turbulence energy of tide and wind, of the stratified strength and otherfactors. This model was applied to describe the mechanics of the variations in strength and thickness ofthe thermocline covering almost the whole Yellow Sea and northern East Chna Sea in summer. Comparisonsof the computed output with obtained survey data led to some important conclusions.展开更多
文摘Ventilation or water exchange between the subtropical and tropic Pacific is studied with a simple none thermodynamic two and half layer model. The shallow upper layer is assumed to communicate with its lower counterpart by entrainment and detrainment at rates W e and W d . Trenberth wind stress data (Trenberth Data Center, 1995) are chosen to drive the upper moving ocean to obtain a stable state. The results show that the subtropical and tropic Pacific exchange water in two ways. One is the direct exchanging by which the surface water in the mid latitude goes down and moves to the tropical region in the subsurface layer and upwells back to the Ekman layer and finally moves northward to complete its journey; and the other is the way of detour, by which water in the subtropical Pacific moves first to the western boundary region along geostrophic flow contours and goes down to the tropic region as southward boundary currents. These two ways contribute almost the same amount to the water exchange between the subtropical and tropic Pacific gyres although the spatial scale in the latter is ten times greater than that of the former. LPSs (Luyten et al., 1983) ventilation theory is reviewed to give a clear picture of how the water exchange in large scale has been studied and the numerical results in this paper are compared with both the conclusions of such analysis theory and some previous observation (tritium survey) reports.
文摘Typical wind fields in winter and summer were applied in a three-dimensional model for simulating the wind-driven current fields in the study region 27.0 °N to 34.5°N, 120.0°E to 126.0°E. Deta from three cruises in 1993 and 1994 were analyzed to obtain the horizontal and vertical structures of total suspended matter (TSM) there. Based on this study, a numerical method was derived to show that it is in winter, not summer, that the suspended matter (SM) is catrried out from the mouth of the Changjiang River to the deep ocean, and yield some other important conclusions.
文摘How to determine the future open boundary conditions of the diffusive equation for certain bays or estuaries is still a question, although the present conditions can be easily obtained by observation.In this paper, a new concept "the effective reach" led to the conclusion on theopen boundary for the case n- 1 was confirmed by some numerical experiments. This rational boundary condition for simulating the pollutants diffusive fields can be effectively applied to environmental problems.
文摘A time-dependent, three-dimensional finite difference model is presented for simulating the stratifiedYellow Sea and northem East China Sea. The mode is forced by time-dependent observed wind, surfaceflux of heat, and tidal turbulence. With this model, momentum and temperature distribution can be computed,and an approximation for the sub-grid scale effects is introduced by the use of mass and momentumexchange coefficients. The vertical exchanges are quite dependent on these assumed coefficents, whichare complicated functions of the turbulence energy of tide and wind, of the stratified strength and otherfactors. This model was applied to describe the mechanics of the variations in strength and thickness ofthe thermocline covering almost the whole Yellow Sea and northern East Chna Sea in summer. Comparisonsof the computed output with obtained survey data led to some important conclusions.
