2000 Vol. 22, No. 6
Display Method:
2000, 22(6): 1-12.
Abstract:
First some obsenational charactcristics of residual currcnt and mass transport in the Hangzhou Bay and the Changjiang Estuary in winter are analyzed.Then,the residual current and its effect on mass transport are simulated with the 3-D joint model of the Hangzhou Bay and the Changjiang Estuary,in which the impacts of river flow,wind,baroclinic pressure induced by temperature and salinity,current of the East China Sea and tide (including M2,S2,K1 and O1) are taken into account.Based on these studies there are also some simulations to analyze the dynamical mechanisms of the observational characteristics.
First some obsenational charactcristics of residual currcnt and mass transport in the Hangzhou Bay and the Changjiang Estuary in winter are analyzed.Then,the residual current and its effect on mass transport are simulated with the 3-D joint model of the Hangzhou Bay and the Changjiang Estuary,in which the impacts of river flow,wind,baroclinic pressure induced by temperature and salinity,current of the East China Sea and tide (including M2,S2,K1 and O1) are taken into account.Based on these studies there are also some simulations to analyze the dynamical mechanisms of the observational characteristics.
2000, 22(6): 13-26.
Abstract:
The mean seasonal circulation in upper layer of the South China Sea (SCS) is studied using TOPEX/PnSE1DON altimetrv remnte sensing products from 1992 to 1996.The research results reveal that upper layer circulation in the SCS is predominated by seasonal alternating monsoons and its pattern varies seasonally.The winter general circulation appears to be cyclone consisted of two sub-basin cyclonic gyres.The summer circulation is generally anticyclonic,but no systematic current structure is found in the eastern SCS south of 18°N.The results also indicate that circulation in the SCS is notably westen intensified.A jet is observed,in both winter and summer,off the coast of Vietnam and the outer edge of Sunda shelf.It appears to be the strongest current in the SCS,which flows southword in winter,but northward in summer.Since the dynamic feature of this jet is mainly geostrophic rather than wind drifting,it is suggested that name it as a jet (the SCS Monsoon Jet) instead of a drift.In winter,the Sunda shelf blocks the southward flowing jet and a northeastward return current is developed along coasts of Kalimantan and Palawan Ialands.In summer,the northward flowing jet splits off the southeast coast of Hainan Island.The northern branch flows along the China shelf,consisting with the traditional path of the SCS Warm Current.The southern branch flows to the east along 18°N across the basin,turns to northeast,and joints the northern branch again off Shantou.The SCS Warm Current is strengthened there by reunification and a zone of weak flow is observed near the shelf break between these branches.In the sense of multiyear mean,the Kuroshio intrudes into the northeastern SCS only in winter and induces a sub-basin cyclonic gyre in the northern SCS.At this period,the SCS Warm Current only exists in the area east of Shantou.In summer,the predominated current in the northern SCS is northeastward.There is no indication of Kuroshio invasion there.Validation using observations from satellite tracking surface drifting buoy shows that these remote sensing results are in good agreement with surface observation.
The mean seasonal circulation in upper layer of the South China Sea (SCS) is studied using TOPEX/PnSE1DON altimetrv remnte sensing products from 1992 to 1996.The research results reveal that upper layer circulation in the SCS is predominated by seasonal alternating monsoons and its pattern varies seasonally.The winter general circulation appears to be cyclone consisted of two sub-basin cyclonic gyres.The summer circulation is generally anticyclonic,but no systematic current structure is found in the eastern SCS south of 18°N.The results also indicate that circulation in the SCS is notably westen intensified.A jet is observed,in both winter and summer,off the coast of Vietnam and the outer edge of Sunda shelf.It appears to be the strongest current in the SCS,which flows southword in winter,but northward in summer.Since the dynamic feature of this jet is mainly geostrophic rather than wind drifting,it is suggested that name it as a jet (the SCS Monsoon Jet) instead of a drift.In winter,the Sunda shelf blocks the southward flowing jet and a northeastward return current is developed along coasts of Kalimantan and Palawan Ialands.In summer,the northward flowing jet splits off the southeast coast of Hainan Island.The northern branch flows along the China shelf,consisting with the traditional path of the SCS Warm Current.The southern branch flows to the east along 18°N across the basin,turns to northeast,and joints the northern branch again off Shantou.The SCS Warm Current is strengthened there by reunification and a zone of weak flow is observed near the shelf break between these branches.In the sense of multiyear mean,the Kuroshio intrudes into the northeastern SCS only in winter and induces a sub-basin cyclonic gyre in the northern SCS.At this period,the SCS Warm Current only exists in the area east of Shantou.In summer,the predominated current in the northern SCS is northeastward.There is no indication of Kuroshio invasion there.Validation using observations from satellite tracking surface drifting buoy shows that these remote sensing results are in good agreement with surface observation.
2000, 22(6): 27-33.
Abstract:
In order to improve the prediction of numerical tidal model in continental shelf,the open boundary conditions are optimized by assimilating the observed data into the model in which the adjoint method,based on optimal control theory,is used.The nonlinear shallow water equations are considered in which horizontal kinematicnonlinearities,nonlinear bottom friction and horizontal eddy diffusion are included.The adjoint model is obtained byusing Lagrange multipliers.This study contains two parts: Part Ⅰ (this paper)─the establishment of the adjointmodel and twin-experiment,and part Ⅱ (another paper)─the numerical results which are incorporated the datafrom tide stations with/without TOPEX/POSEIDON altimeter data for optimizing the open boundary conditions ofthe model.
In order to improve the prediction of numerical tidal model in continental shelf,the open boundary conditions are optimized by assimilating the observed data into the model in which the adjoint method,based on optimal control theory,is used.The nonlinear shallow water equations are considered in which horizontal kinematicnonlinearities,nonlinear bottom friction and horizontal eddy diffusion are included.The adjoint model is obtained byusing Lagrange multipliers.This study contains two parts: Part Ⅰ (this paper)─the establishment of the adjointmodel and twin-experiment,and part Ⅱ (another paper)─the numerical results which are incorporated the datafrom tide stations with/without TOPEX/POSEIDON altimeter data for optimizing the open boundary conditions ofthe model.
Influence of initializing on the sea surface wind field numerical forecasting model in limited areas
2000, 22(6): 34-39.
Abstract:
On the base of the sea surface field numerical forecasting model which has been used in forecasting themarine elements,on the Bohai Sea,“initializing" and “non-initializing" are compared through a contrast experiment.The results show that the influence of initializing is very important to sea surface field numerical model in limited areas,especially the wind field or the sea at the beginning periods that can be seen from the different ability of forecasting between sea wind and land wind.
On the base of the sea surface field numerical forecasting model which has been used in forecasting themarine elements,on the Bohai Sea,“initializing" and “non-initializing" are compared through a contrast experiment.The results show that the influence of initializing is very important to sea surface field numerical model in limited areas,especially the wind field or the sea at the beginning periods that can be seen from the different ability of forecasting between sea wind and land wind.
2000, 22(6): 40-46.
Abstract:
Interaction between current and underwater bottom topography modulates roughness of the sea surface,which in turn yields variation of the radar scattering echo.By using the continuity equation and weak hydrodynamic interaction theory in the relaxation time approximation,the spatial variation of the radar scattering cross-section has been proved as proportional to the gradient of current velocity.The current direction is first determined byusing two-dimensional (2-D)correlation of spatial variation of backscattering measured by the SAR imagery,as thepriori knowledge of the current direction is not available.The inverse algorithm to successively derive 2-D underwater bottom topography from the SAR imagery is developed.As an application,the SAR SIR-C image over the sea areaof Hong Kong,China is studied.
Interaction between current and underwater bottom topography modulates roughness of the sea surface,which in turn yields variation of the radar scattering echo.By using the continuity equation and weak hydrodynamic interaction theory in the relaxation time approximation,the spatial variation of the radar scattering cross-section has been proved as proportional to the gradient of current velocity.The current direction is first determined byusing two-dimensional (2-D)correlation of spatial variation of backscattering measured by the SAR imagery,as thepriori knowledge of the current direction is not available.The inverse algorithm to successively derive 2-D underwater bottom topography from the SAR imagery is developed.As an application,the SAR SIR-C image over the sea areaof Hong Kong,China is studied.
2000, 22(6): 47-54.
Abstract:
The characteristics of vertical profiles and seasonal variations of biogenic elements in the Huanghai Sea Cold Water Mass (HSCWM) are discussed based on the field data of the project China-Korea Joint Research on the Seawater Circulation and Mass Flux in the Huanghai Sea.The results show that nutrients are generally depleted by phytoplankton in the upper layer,but enriched in the depth below pycnocline rather than the euphotic zone throughorganism decomposition during the stratified period in the HSCWM.The stratification is also very obvious in vertical profiles of dissolved oxygen,pH and chlorophyll,with high content in the upper layer and low content in the lowerlayer.The maximum values occur in the middle layer (20～30 m) for DO in the period from May to October andpH in May and July,which are resulted from the coaction of thermocline and intensive photosynthesis due to subsurface chlorophyll maximum in the same layer.The factors influencing the content and distributions of biogenic elements and their interrelationships are also discussed and analyzed.
The characteristics of vertical profiles and seasonal variations of biogenic elements in the Huanghai Sea Cold Water Mass (HSCWM) are discussed based on the field data of the project China-Korea Joint Research on the Seawater Circulation and Mass Flux in the Huanghai Sea.The results show that nutrients are generally depleted by phytoplankton in the upper layer,but enriched in the depth below pycnocline rather than the euphotic zone throughorganism decomposition during the stratified period in the HSCWM.The stratification is also very obvious in vertical profiles of dissolved oxygen,pH and chlorophyll,with high content in the upper layer and low content in the lowerlayer.The maximum values occur in the middle layer (20～30 m) for DO in the period from May to October andpH in May and July,which are resulted from the coaction of thermocline and intensive photosynthesis due to subsurface chlorophyll maximum in the same layer.The factors influencing the content and distributions of biogenic elements and their interrelationships are also discussed and analyzed.
2000, 22(6): 55-62.
Abstract:
By approaching variations of physical and chemical properties (i.e.,rates of vapour and dissolution,surface tension,coefficient of viscosity and density) of spilled oils during weathering from application of grey system theory,GM(1,1) and GM(0,m) of forecasting models of the physical and chemical properties of spilled oils during weathering are established.The results show that: (1) the precision and accuracy of the forecasting of GM(1,1) and GM(0,m) with statistical test are satisfactory,(2) the grey relativities of the physical and chemical properties of spilled oils during weathering can be expressed as the parameters of grey recognition of GM(0,m) and (3) The surface tension,the coefficient of viscosity and the density can be taken as the factors of forecasting of the rates of vapour and dissolution of spilled oils during weathering.
By approaching variations of physical and chemical properties (i.e.,rates of vapour and dissolution,surface tension,coefficient of viscosity and density) of spilled oils during weathering from application of grey system theory,GM(1,1) and GM(0,m) of forecasting models of the physical and chemical properties of spilled oils during weathering are established.The results show that: (1) the precision and accuracy of the forecasting of GM(1,1) and GM(0,m) with statistical test are satisfactory,(2) the grey relativities of the physical and chemical properties of spilled oils during weathering can be expressed as the parameters of grey recognition of GM(0,m) and (3) The surface tension,the coefficient of viscosity and the density can be taken as the factors of forecasting of the rates of vapour and dissolution of spilled oils during weathering.
2000, 22(6): 63-72.
Abstract:
The contents of major clement composition of the phenocrysts and matrix glass as well as spinel inclusions and melt inclusions in the phenocrysts of the basalt dredged from 133 site of the Okinawa Trough are determined by electron microprobe.The results show that the basalt is a dorgalite consisting of phenocrysts of bytownite,chrysolite,clinopyroxene and magnetite as well as labradorite microcrystal and matrix glass as well as a few bits of broken vein quartz.Glassy melt inclusions and chromohercynite or chrompleonaste exist in bytownite and chrysolite.The formation of spinels is related to fraction melting of the mantle.The melt inclusions stand for a primary alkali olivine basaltic magma,whose composition corresponds to olivine gabbro.The basaltic magma generated in fraction melting of spinel-lherzoliteof the upper mantle and evolved in a process of "alkali olivine basaltic magma→trachy-basahitic magma→basaltic trachyte magma→trachytic magma".Assimilation and contamination of crustal material may present during magma upwelling in every evolutionary stage.
The contents of major clement composition of the phenocrysts and matrix glass as well as spinel inclusions and melt inclusions in the phenocrysts of the basalt dredged from 133 site of the Okinawa Trough are determined by electron microprobe.The results show that the basalt is a dorgalite consisting of phenocrysts of bytownite,chrysolite,clinopyroxene and magnetite as well as labradorite microcrystal and matrix glass as well as a few bits of broken vein quartz.Glassy melt inclusions and chromohercynite or chrompleonaste exist in bytownite and chrysolite.The formation of spinels is related to fraction melting of the mantle.The melt inclusions stand for a primary alkali olivine basaltic magma,whose composition corresponds to olivine gabbro.The basaltic magma generated in fraction melting of spinel-lherzoliteof the upper mantle and evolved in a process of "alkali olivine basaltic magma→trachy-basahitic magma→basaltic trachyte magma→trachytic magma".Assimilation and contamination of crustal material may present during magma upwelling in every evolutionary stage.
2000, 22(6): 73-80.
Abstract:
The middle part of the South China Sea consists of continental slopes,island slopes and a deep-sea basin.Since the 1970s,many seismic surveys have been carried out there.More than 4 000 km 48-channel seismic reflection data from this area have been interpreted.Five seismic interfaces have been distinguished,named T1,T2,T4,T6 and Tg respectively.Meanwhile,five seismic reflection sequences,named Ⅰ-Ⅴ,have been divided into the ages of Quatemary and Pliocene,Later Miocene,Earlier and Middle Miocene,Oligocene and Pre-Oligocene separately.Sequences Ⅰ-Ⅱ overlie all parts of the area.In the continental slopes and island slopes,the sequences Ⅲ～Ⅴ are mainly found in the grabens.Sequence Ⅲ is found at most profiles of the deep-sea basin (DSB),and the sequence Ⅳ is seen not only at the margins of east subbasin(ESB) but also at the margins of southwest subbabin(SWSB).Strong reflection from Moho is found at most profiles of the DSB.The depth of Moho varies between 10 and 12 km,with a thickness of 6～8 km for the crust.Calculated by age-basement depth correlation formula,the age of basaltic basement in the SWSB is 51～39 Ma.It is indicated that the evolution of the SWSB is simultaneous with or earlier than the ESB rather than later than it.
The middle part of the South China Sea consists of continental slopes,island slopes and a deep-sea basin.Since the 1970s,many seismic surveys have been carried out there.More than 4 000 km 48-channel seismic reflection data from this area have been interpreted.Five seismic interfaces have been distinguished,named T1,T2,T4,T6 and Tg respectively.Meanwhile,five seismic reflection sequences,named Ⅰ-Ⅴ,have been divided into the ages of Quatemary and Pliocene,Later Miocene,Earlier and Middle Miocene,Oligocene and Pre-Oligocene separately.Sequences Ⅰ-Ⅱ overlie all parts of the area.In the continental slopes and island slopes,the sequences Ⅲ～Ⅴ are mainly found in the grabens.Sequence Ⅲ is found at most profiles of the deep-sea basin (DSB),and the sequence Ⅳ is seen not only at the margins of east subbasin(ESB) but also at the margins of southwest subbabin(SWSB).Strong reflection from Moho is found at most profiles of the DSB.The depth of Moho varies between 10 and 12 km,with a thickness of 6～8 km for the crust.Calculated by age-basement depth correlation formula,the age of basaltic basement in the SWSB is 51～39 Ma.It is indicated that the evolution of the SWSB is simultaneous with or earlier than the ESB rather than later than it.
2000, 22(6): 81-87.
Abstract:
The results of enclosure experiment and other in situ ecological experiments,which were carried out between 20 August and 16 September 1996,show that food selection of hybrid tilapia,Oreochromis mossambicus×O.niloticus,and its ecological effects are dependent on food resources available in enclosures.Biomass and production of phytoplankton in the enclosures that stocked tilapia are usually higher than the control enclosure.However,flagellate algae such as Prorocentrum micans,is difficult to be dominant species when more than 8 000 tilapia per hm2 is stocked.Tilapia do not exhibit significant impacts on copepods when their preferable food is abundant,but selectively capture copepods of large body size when other food resources are scarce.Concentrations of nitrite,nitrate,ammonia and total nitrogen,and chemical oxygen demand are not significant different between the enclosures stocked tilapia and the control enclosure.Concentration of reactive phosphate in the enclosures that stocked tilapia with densities of more than 8 000 fish per hm2,is relatively high because of improved phosphorus cycle.
The results of enclosure experiment and other in situ ecological experiments,which were carried out between 20 August and 16 September 1996,show that food selection of hybrid tilapia,Oreochromis mossambicus×O.niloticus,and its ecological effects are dependent on food resources available in enclosures.Biomass and production of phytoplankton in the enclosures that stocked tilapia are usually higher than the control enclosure.However,flagellate algae such as Prorocentrum micans,is difficult to be dominant species when more than 8 000 tilapia per hm2 is stocked.Tilapia do not exhibit significant impacts on copepods when their preferable food is abundant,but selectively capture copepods of large body size when other food resources are scarce.Concentrations of nitrite,nitrate,ammonia and total nitrogen,and chemical oxygen demand are not significant different between the enclosures stocked tilapia and the control enclosure.Concentration of reactive phosphate in the enclosures that stocked tilapia with densities of more than 8 000 fish per hm2,is relatively high because of improved phosphorus cycle.
2000, 22(6): 88-94.
Abstract:
Using Platyrnonas halgolankeca and Nitzschia closterium (Ehrenb) as food,the batch culture feeding experiments and fecal pellets production rate experiments are carried out to study the effect of food particle concentration on the feeding behavior of Calanus sinicus.The ingestion rate (expressed as fecal production rate) of every C.sinicus increased from 0 to 100 pellets/d with the increase of food concentration,even when the food concentration was very high (200 000 and 380 000 cells/cm3 for P.halgolankeca and N.closterium repectively).
Using Platyrnonas halgolankeca and Nitzschia closterium (Ehrenb) as food,the batch culture feeding experiments and fecal pellets production rate experiments are carried out to study the effect of food particle concentration on the feeding behavior of Calanus sinicus.The ingestion rate (expressed as fecal production rate) of every C.sinicus increased from 0 to 100 pellets/d with the increase of food concentration,even when the food concentration was very high (200 000 and 380 000 cells/cm3 for P.halgolankeca and N.closterium repectively).
2000, 22(6): 95-101.
Abstract:
During 1994～1999,84 vessel surveys were conducted with having a photos taken,and 392 individuals were recorded.At the same time,totally 20 observation sites were established,and the record for 239 months amounted to 12 624 individuals.Chinese white dolphins occur all around Xiamen waters of 700 km2,and they may swim upstream to the Jiulong River but never swim out of Jinmen Island and Wuyu Isle.Generaly,the dolphina are sighted very close to the shore and most frequently occur in areas included west harbour of Xiamen and the mouth of Tong'an Bay.The frequency when the dolphins jumped out of the water varies with season,which is the highest in April to May.According to surveys and supplementary surveys,nearly 60 individuals are estimated in Xiamen waters,and only 40 individuals are distinctively recorded through having a photos taken.Now the population has the tendency to decrease,so in-situ and off-situ measures should be both employed to emphasize the conservation of Chinese white dolphins,the first-class protected species in China.
During 1994～1999,84 vessel surveys were conducted with having a photos taken,and 392 individuals were recorded.At the same time,totally 20 observation sites were established,and the record for 239 months amounted to 12 624 individuals.Chinese white dolphins occur all around Xiamen waters of 700 km2,and they may swim upstream to the Jiulong River but never swim out of Jinmen Island and Wuyu Isle.Generaly,the dolphina are sighted very close to the shore and most frequently occur in areas included west harbour of Xiamen and the mouth of Tong'an Bay.The frequency when the dolphins jumped out of the water varies with season,which is the highest in April to May.According to surveys and supplementary surveys,nearly 60 individuals are estimated in Xiamen waters,and only 40 individuals are distinctively recorded through having a photos taken.Now the population has the tendency to decrease,so in-situ and off-situ measures should be both employed to emphasize the conservation of Chinese white dolphins,the first-class protected species in China.
2000, 22(6): 102-109.
Abstract:
The coupled model,which is the combination of Boussinesq equations and the general description for three-dimensional (3-D) flows with the volume of fluid (VOF) method,has been developed for the numerical simulations of nonlinear waves in a large domain.That is,the whole computational domain Ω is divided into two sub-regions.In the near-field around a structure,Ω1,the flow is governed by 3-D Navier-Stokes equations and numerically solved by the VOF method.Whereas in the sub-region Ω2(Ω2=Ω-Ω1),the flow is governed by two-dimensional Boussinesq equations and numerically solved with the predictor-corrector algorithm.The velocity and the wave surface elevation are matched to the common boundaries of the two subregions.Numerical verifications have been conducted for the case of wave propagation and interaction with a square caisson.It is shown that the coupledmodel is effective on computing nonlinear waves in a large domain with taking into account the complicated flow field near a structure.
The coupled model,which is the combination of Boussinesq equations and the general description for three-dimensional (3-D) flows with the volume of fluid (VOF) method,has been developed for the numerical simulations of nonlinear waves in a large domain.That is,the whole computational domain Ω is divided into two sub-regions.In the near-field around a structure,Ω1,the flow is governed by 3-D Navier-Stokes equations and numerically solved by the VOF method.Whereas in the sub-region Ω2(Ω2=Ω-Ω1),the flow is governed by two-dimensional Boussinesq equations and numerically solved with the predictor-corrector algorithm.The velocity and the wave surface elevation are matched to the common boundaries of the two subregions.Numerical verifications have been conducted for the case of wave propagation and interaction with a square caisson.It is shown that the coupledmodel is effective on computing nonlinear waves in a large domain with taking into account the complicated flow field near a structure.
2000, 22(6): 110-116.
Abstract:
A new method for the solution of wave radiation stresses is proposed by linking wave radiation stresses with the variables in the parabolic mild-slope equation.The governing equations are solved numerically by the finite difference method.Numerical results show that the new model with high accuracy can be efficiently solved with little programming effort,and can be applied to the solution of wave radiation stresses in large coastal areas.
A new method for the solution of wave radiation stresses is proposed by linking wave radiation stresses with the variables in the parabolic mild-slope equation.The governing equations are solved numerically by the finite difference method.Numerical results show that the new model with high accuracy can be efficiently solved with little programming effort,and can be applied to the solution of wave radiation stresses in large coastal areas.
2000, 22(6): 117-123.
Abstract:
In the sea ice numerical simulation of the Bohai Sea,under the same meteorological and oceanographic conditions,the ice thickness always trends to a certain value,which can be called diagnostic thickness,although the initial thickness is different.Through the analysis of ice growth mechanism,the existence of diagnostic thickness is discussed.The ice temperature and the heat flux at ice-cover surface,the transmitted solar radiation and the heat flux at ice-cover bottom under different ice thicknesses are contrasted.The dynamic process and the approach time when the sea ice approaches the diagnostic thickness are discussed.Under different air temperatures,wind speeds,relative humidities and oceanic heat fluxes,the diagnostic thicknesses are calculated respectively.The relationship between the actual ice thickness and the diagnostic thickness in the winter of 1997/1998 of the Liaodong Gulf are analyzed.The study of the sea ice diagnostic thickness will be useful to the sea ice numerical simulation and the de-termination of the sea ice design parameters in the Bohiai Sea.
In the sea ice numerical simulation of the Bohai Sea,under the same meteorological and oceanographic conditions,the ice thickness always trends to a certain value,which can be called diagnostic thickness,although the initial thickness is different.Through the analysis of ice growth mechanism,the existence of diagnostic thickness is discussed.The ice temperature and the heat flux at ice-cover surface,the transmitted solar radiation and the heat flux at ice-cover bottom under different ice thicknesses are contrasted.The dynamic process and the approach time when the sea ice approaches the diagnostic thickness are discussed.Under different air temperatures,wind speeds,relative humidities and oceanic heat fluxes,the diagnostic thicknesses are calculated respectively.The relationship between the actual ice thickness and the diagnostic thickness in the winter of 1997/1998 of the Liaodong Gulf are analyzed.The study of the sea ice diagnostic thickness will be useful to the sea ice numerical simulation and the de-termination of the sea ice design parameters in the Bohiai Sea.
2000, 22(6): 124-130.
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2000, 22(6): 131-135.
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2000, 22(6): 136-140.
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