2006 Vol. 28, No. 2
Display Method:
2006, 28(2): 1-13.
Abstract:
On the basis of hydrographic data obtained in 5 cruises of 2000 onboad the R/V Chofu Maru and the QuikSCAT wind data during 5 cruises of 2000,the velo city and volume transport (VT) of the Kuroshio in the East China Sea (ECS) are computed by using the modified inverse method.The following main results have been obtained.(1) The wind speeds and wind-driver currents both are strongest in January February among 5 cruises of 2000,and the directions of wind-driver current are northward only in July of 2000,which streng then the Kuroshio current in the ECS.(2) The lowest value of salinity at the surface is minimalin summer,and the lowest value of salinity at the surface is maximal in January-February.This means that the Changjiang River discharge diffuses northeastw ard at the surface layer in summer,but it diffuses southward at the surface layer in winter.(3) The current structure and its variations at Section PN in 5 cruises of 2000 are as follows.The Kuroshio at Section PN has two current cores in January February,October and November,and only one current core in April and July,respectively.The main axis of Kuroshio is located at the computational point 9 of Section PN in January February,and at the computational point 8 of Section PN,which moves toward the shelf,in other months,respectively.(4) The Kuroshio through Section T K has multi-current cores during 5 cruises of 2000.The main current core of Kuro-shio occurs only at the computational point 8,whose water depth is greater than 1 200 m,in November,and occurs at the computational point 2 or 4,whose water depth is less than the 400 m levels,in other months,respectively.(5) The net northeastward volume transport through Section PN is maximal,28.1×106 m3/s,in November among 5 cruises of 2000,and is next in July,and is minimal,24.6×106 m3/s,in October among 5 cruises of 2000.The annual average of its net northeast ward VT is 26.4×106 m3/s in 2000.(6) The week cyclonic eddy occurs only in November and in area east of the Kuroshio at Section PN.But an anticy clonic and warm eddy occurs in area east of the Kuroshio at Section PN in other months,especially,is strongest in October.When an anticyclonic and warm eddy east of the Kuroshio strengthens,the VT of Kuroshio seems to decrease,such as in October.Inversely,when an anticy clonic and warm eddy east of the Kuroshioi is week,such as in July,or when the cyclonic eddy occurs east of the Kuroshioi,the VT of Kuroshio seems to increase,such as in November.In comparison of the current patterns of the circulation in October and November in the ECS,their variations of the circulation are greater in the ECS.This shows also that the interaction between the Kuroshioi and meso-scale eddies near the Kuroshio is important.(7) The net eastward VT through Section TK is maximal also in November among 5 cruises of 2000,and is next in July,and is minimal in October and January February among 5 cruises of 2000.Its annual average net eastward VT through Section TK is 21.9×106 m3/s in 2000.(8) The net northward VT through Section A is maximal,3.5 and 3.1×106 m3/s,in January-February and April,respectively,and is minimalin July among 5 cruises of 2000.Its annual aver age net northward VT through Section A is 2.7×106 m3/s in 2000.This means that the VT of the Tsushima Current is maximal in January February and April,and is minimal in July among 5 cruises of 2000.
On the basis of hydrographic data obtained in 5 cruises of 2000 onboad the R/V Chofu Maru and the QuikSCAT wind data during 5 cruises of 2000,the velo city and volume transport (VT) of the Kuroshio in the East China Sea (ECS) are computed by using the modified inverse method.The following main results have been obtained.(1) The wind speeds and wind-driver currents both are strongest in January February among 5 cruises of 2000,and the directions of wind-driver current are northward only in July of 2000,which streng then the Kuroshio current in the ECS.(2) The lowest value of salinity at the surface is minimalin summer,and the lowest value of salinity at the surface is maximal in January-February.This means that the Changjiang River discharge diffuses northeastw ard at the surface layer in summer,but it diffuses southward at the surface layer in winter.(3) The current structure and its variations at Section PN in 5 cruises of 2000 are as follows.The Kuroshio at Section PN has two current cores in January February,October and November,and only one current core in April and July,respectively.The main axis of Kuroshio is located at the computational point 9 of Section PN in January February,and at the computational point 8 of Section PN,which moves toward the shelf,in other months,respectively.(4) The Kuroshio through Section T K has multi-current cores during 5 cruises of 2000.The main current core of Kuro-shio occurs only at the computational point 8,whose water depth is greater than 1 200 m,in November,and occurs at the computational point 2 or 4,whose water depth is less than the 400 m levels,in other months,respectively.(5) The net northeastward volume transport through Section PN is maximal,28.1×106 m3/s,in November among 5 cruises of 2000,and is next in July,and is minimal,24.6×106 m3/s,in October among 5 cruises of 2000.The annual average of its net northeast ward VT is 26.4×106 m3/s in 2000.(6) The week cyclonic eddy occurs only in November and in area east of the Kuroshio at Section PN.But an anticy clonic and warm eddy occurs in area east of the Kuroshio at Section PN in other months,especially,is strongest in October.When an anticyclonic and warm eddy east of the Kuroshio strengthens,the VT of Kuroshio seems to decrease,such as in October.Inversely,when an anticy clonic and warm eddy east of the Kuroshioi is week,such as in July,or when the cyclonic eddy occurs east of the Kuroshioi,the VT of Kuroshio seems to increase,such as in November.In comparison of the current patterns of the circulation in October and November in the ECS,their variations of the circulation are greater in the ECS.This shows also that the interaction between the Kuroshioi and meso-scale eddies near the Kuroshio is important.(7) The net eastward VT through Section TK is maximal also in November among 5 cruises of 2000,and is next in July,and is minimal in October and January February among 5 cruises of 2000.Its annual average net eastward VT through Section TK is 21.9×106 m3/s in 2000.(8) The net northward VT through Section A is maximal,3.5 and 3.1×106 m3/s,in January-February and April,respectively,and is minimalin July among 5 cruises of 2000.Its annual aver age net northward VT through Section A is 2.7×106 m3/s in 2000.This means that the VT of the Tsushima Current is maximal in January February and April,and is minimal in July among 5 cruises of 2000.
2006, 28(2): 14-21.
Abstract:
Based on dynamic and thermodynamic research of sea ice and the ice conditions in the Bohai Sea,a particle-in-cell (PIC) sea ice model has been applied to the Bohai Sea,China.The PIC method is introduced into the sea ice model to efficiently reduce the numeric diffusion inherent in conventional models.The ice thickness distribution function is introduced in the model,as well,and the multi-category ice thickness distribution is used,instead of the three-level ice thickness distribution of level ice,rubble ice and open water in the Bohai Sea ice model Numeric experiments of the ideal ice fields are carried out for simulating the dynamic process of ice thickness variation.And comparison experiments of forecasts for different cases of the real ice conditions in the Bohai Sea are made by using the PIC model with the operational ice model.It is found that the PIC model has some advant age in improving ice edge forecast accuracy.
Based on dynamic and thermodynamic research of sea ice and the ice conditions in the Bohai Sea,a particle-in-cell (PIC) sea ice model has been applied to the Bohai Sea,China.The PIC method is introduced into the sea ice model to efficiently reduce the numeric diffusion inherent in conventional models.The ice thickness distribution function is introduced in the model,as well,and the multi-category ice thickness distribution is used,instead of the three-level ice thickness distribution of level ice,rubble ice and open water in the Bohai Sea ice model Numeric experiments of the ideal ice fields are carried out for simulating the dynamic process of ice thickness variation.And comparison experiments of forecasts for different cases of the real ice conditions in the Bohai Sea are made by using the PIC model with the operational ice model.It is found that the PIC model has some advant age in improving ice edge forecast accuracy.
2006, 28(2): 22-28.
Abstract:
Annual subduction rate in the subtropical mode water (STMW) formation regions in the Nort hPacific has been calculated from the assimilated ocean model data and the observation of the flux between the ocean and atmosphere by using Huang's equation of subduction rate (1995),and the mechanism in its interannual variation is further studied.It has been found that the significant periods of the subduction rate are respectively 6 a in the western STMW formation region,2~5 a in the central STMW formation region and 2 a in eastern STMW formation region Besides,decadal variations exist in all regions:interannual variations of the subduction rate in the western STMW formation region were stronger before 1985 and then trail off with weaker amplitudes.In the central STMW formation region,the amplitudes for interannual variations were greater between 1975 and 1992,corresponding to a mean value of the subduction rate of 33.99 m/a,much bigger than two other spans (1970~1975 and 1993~1998) There was an abrupt change of the subduction rate in the eastern STMW formation region between 1992 and 1993,the mean value of the subduction rate changed from 46.31 m/a to 22.02 m/a around 1992,in the western STMW formation region.In the analysis,the correlation is good between variations of the subduction rate and the netheat flux in the western STMW formation region,and variations of the subduction rate in the central STMW formation region are deter mined by variations of local Ekman mass transports and the geostrophic currents.While in the eastern STMW formation region,the subduction rate is directly determ ined by the cure of the wind.
Annual subduction rate in the subtropical mode water (STMW) formation regions in the Nort hPacific has been calculated from the assimilated ocean model data and the observation of the flux between the ocean and atmosphere by using Huang's equation of subduction rate (1995),and the mechanism in its interannual variation is further studied.It has been found that the significant periods of the subduction rate are respectively 6 a in the western STMW formation region,2~5 a in the central STMW formation region and 2 a in eastern STMW formation region Besides,decadal variations exist in all regions:interannual variations of the subduction rate in the western STMW formation region were stronger before 1985 and then trail off with weaker amplitudes.In the central STMW formation region,the amplitudes for interannual variations were greater between 1975 and 1992,corresponding to a mean value of the subduction rate of 33.99 m/a,much bigger than two other spans (1970~1975 and 1993~1998) There was an abrupt change of the subduction rate in the eastern STMW formation region between 1992 and 1993,the mean value of the subduction rate changed from 46.31 m/a to 22.02 m/a around 1992,in the western STMW formation region.In the analysis,the correlation is good between variations of the subduction rate and the netheat flux in the western STMW formation region,and variations of the subduction rate in the central STMW formation region are deter mined by variations of local Ekman mass transports and the geostrophic currents.While in the eastern STMW formation region,the subduction rate is directly determ ined by the cure of the wind.
2006, 28(2): 29-38.
Abstract:
The commonly used turbulent heat flux es in the National Centers for Environment Prediction-National Center for Atmospheric Research reanaly sis 2 (NCEP 2) are evaluated using three air-sea flux research tower observations and two cruises in the South China Sea Monsoon experiment (SCSMEX) as the references.The mean latent heat fluxes from NCEP2 are overestimated 6(11%),2(2%),7(7%) and 13 W/m2 (16%) during experiment Xisha2000,Xisha1998,Kexue 1 and Shiyan 3 respectively and underestimated 10 W/m2 (11%) in Xisha2002.The overestimations in sensible heat flux change from 7 (130%),3(64%),7(170%),5(53%) to 5 W/m2 (72%) in Xisha2002,Xisha2000,Xisha1998,Kexue 1 and Shiyan 3 experiments.The correlations between the time series of NCEP2 and the observations are relatively weak.The errors from the oceanic turbulent heat losses in NCEP2 are mainly due to bulk variables and algorithm.In all variables,the errors coming from sea surface temperature and wind speed are especially important.The results suggest that the recalculated NCEP2 surface turbulent heat fluxes using COARE algorithm are more physically reasonable,especially for latent heat flux.
The commonly used turbulent heat flux es in the National Centers for Environment Prediction-National Center for Atmospheric Research reanaly sis 2 (NCEP 2) are evaluated using three air-sea flux research tower observations and two cruises in the South China Sea Monsoon experiment (SCSMEX) as the references.The mean latent heat fluxes from NCEP2 are overestimated 6(11%),2(2%),7(7%) and 13 W/m2 (16%) during experiment Xisha2000,Xisha1998,Kexue 1 and Shiyan 3 respectively and underestimated 10 W/m2 (11%) in Xisha2002.The overestimations in sensible heat flux change from 7 (130%),3(64%),7(170%),5(53%) to 5 W/m2 (72%) in Xisha2002,Xisha2000,Xisha1998,Kexue 1 and Shiyan 3 experiments.The correlations between the time series of NCEP2 and the observations are relatively weak.The errors from the oceanic turbulent heat losses in NCEP2 are mainly due to bulk variables and algorithm.In all variables,the errors coming from sea surface temperature and wind speed are especially important.The results suggest that the recalculated NCEP2 surface turbulent heat fluxes using COARE algorithm are more physically reasonable,especially for latent heat flux.
2006, 28(2): 39-45.
Abstract:
The information of influence of solar activities in the data series is picked-up by using step-by step filtering and analyzed.It is revealed that the interdecadal variability of the monsoon climate over the East China Sea is very clear and represented in the following aspects.(1) The abrupt change.The atmospheric temperature at the sea level pressure layer and in the troposphere in July (summer) over the East China Sea has under gone a sharp change in the past half century which occurred in July 1978.Since July 1978,a period of persistent high temperature has began after a period of more than 30 a with comparatively low temperature.It lasted until the end of the 20th century.The temperature rising was more than 0.4℃.The data analysis indicates that the atmosphere temperature at all levels in the troposphere over the East China Sea in summer has this interdecadal variability.(2) Persistent increasing of the air temperature at the upper levels of the atmosphere.The atmosphere temperature at the middle part of the stratosphere (10 hPa) over the East China Sea in July (summer) is a persistent process of temperaturer ising with a wave form.The temperature has increased over 4 in the recent more than 50 years.The yearly ratio of the temperature rising is more than 0.075℃/a.The temperature at the bottom of the strato sphere (100 hPa) over the East China Sea also has the characteristic of the persistent rising of the temperature,which has shown a tendency of slowly rising since 1948 and has increased by 1.9℃ in the recent 53 a.The yearly ratio of the temperature rising is 0.036℃/a.(3) The periodicity.The air temperatures at different atmosphere levels over the East China Sea have the interdecadal variability with a 22 a period in various degrees.The amplitudes of the 22 a components rapidly decrease from upper to lower atmosphere levels.This indicates that the 22 a period is clear at the upper air,but not clear at the lower levels.There are also obvious decadal variations with an 11 a period at the middle part of the troposphere and the bottom of the stratosphere over the East China Sea.Based on the analysis,it is known that the 22 a period is caused by the period magnetic variation of the magnetic field of the sunspots.The 11 a period corresponds to the 11 a period of the relative number of the sunspots,and both are the reflection of the solar activity in the atmospheric climate.
The information of influence of solar activities in the data series is picked-up by using step-by step filtering and analyzed.It is revealed that the interdecadal variability of the monsoon climate over the East China Sea is very clear and represented in the following aspects.(1) The abrupt change.The atmospheric temperature at the sea level pressure layer and in the troposphere in July (summer) over the East China Sea has under gone a sharp change in the past half century which occurred in July 1978.Since July 1978,a period of persistent high temperature has began after a period of more than 30 a with comparatively low temperature.It lasted until the end of the 20th century.The temperature rising was more than 0.4℃.The data analysis indicates that the atmosphere temperature at all levels in the troposphere over the East China Sea in summer has this interdecadal variability.(2) Persistent increasing of the air temperature at the upper levels of the atmosphere.The atmosphere temperature at the middle part of the stratosphere (10 hPa) over the East China Sea in July (summer) is a persistent process of temperaturer ising with a wave form.The temperature has increased over 4 in the recent more than 50 years.The yearly ratio of the temperature rising is more than 0.075℃/a.The temperature at the bottom of the strato sphere (100 hPa) over the East China Sea also has the characteristic of the persistent rising of the temperature,which has shown a tendency of slowly rising since 1948 and has increased by 1.9℃ in the recent 53 a.The yearly ratio of the temperature rising is 0.036℃/a.(3) The periodicity.The air temperatures at different atmosphere levels over the East China Sea have the interdecadal variability with a 22 a period in various degrees.The amplitudes of the 22 a components rapidly decrease from upper to lower atmosphere levels.This indicates that the 22 a period is clear at the upper air,but not clear at the lower levels.There are also obvious decadal variations with an 11 a period at the middle part of the troposphere and the bottom of the stratosphere over the East China Sea.Based on the analysis,it is known that the 22 a period is caused by the period magnetic variation of the magnetic field of the sunspots.The 11 a period corresponds to the 11 a period of the relative number of the sunspots,and both are the reflection of the solar activity in the atmospheric climate.
2006, 28(2): 46-50.
Abstract:
The marine sediment acoustic characteristics (such as so und speed and attenuation) as well as their relationship with physical characteristics (including soil mechanics) are two important research topics in marine sediment acoustics.A new developed real-time monitoring multi-frequency in situ sediment geoacoustic measuring sysem was introduced.The geoacoustic measuring system is designed for sound speed measurements of the seabed measuring.The measuring frequencies are 8,10,12 and 15 kHz.A transmitting waveforms,receiving gain and sampling length could be changed according to sediments.A sampling rate is designed from 500 kHz to 2 MHz,and an operating depth is 300 m.The geoacoustic measuring system has a tilt sensor and eight channels expansion.A set of in situ sound speeds of four different frequencies is observed in the Hangzhou Bay.
The marine sediment acoustic characteristics (such as so und speed and attenuation) as well as their relationship with physical characteristics (including soil mechanics) are two important research topics in marine sediment acoustics.A new developed real-time monitoring multi-frequency in situ sediment geoacoustic measuring sysem was introduced.The geoacoustic measuring system is designed for sound speed measurements of the seabed measuring.The measuring frequencies are 8,10,12 and 15 kHz.A transmitting waveforms,receiving gain and sampling length could be changed according to sediments.A sampling rate is designed from 500 kHz to 2 MHz,and an operating depth is 300 m.The geoacoustic measuring system has a tilt sensor and eight channels expansion.A set of in situ sound speeds of four different frequencies is observed in the Hangzhou Bay.
2006, 28(2): 51-55.
Abstract:
A new high precise source of data has recently become available using multibeam sonar systems in hydrography.The multibeam sonar systems can provide hydrogr aphic quality depth data as well as highresolution seafloor sonar images.The seafloor backscatter strength data of each beam are utilized from the multibeam sonar and the automatic classification technology,so that the seafloor type identification maps can be got.To analyze all kinds of error effects in backscatter strength data is based on the relationship between backscatter strength and seafloor types.Analyzing the influences of local bottom slope and near nadir reflection in backscatter strength data is emphasized on and the correction algorithms and results of these two influent factors are also given.After processing the raw backscatter strength data and correcting error effects,the processed backscatter strength data can be got which only reflect the features of seafloor types.Applying to the processed backscatter strength data and mosaicked seafloor sonar images,seafloor classification and geomorphy interpretation are engaged in.
A new high precise source of data has recently become available using multibeam sonar systems in hydrography.The multibeam sonar systems can provide hydrogr aphic quality depth data as well as highresolution seafloor sonar images.The seafloor backscatter strength data of each beam are utilized from the multibeam sonar and the automatic classification technology,so that the seafloor type identification maps can be got.To analyze all kinds of error effects in backscatter strength data is based on the relationship between backscatter strength and seafloor types.Analyzing the influences of local bottom slope and near nadir reflection in backscatter strength data is emphasized on and the correction algorithms and results of these two influent factors are also given.After processing the raw backscatter strength data and correcting error effects,the processed backscatter strength data can be got which only reflect the features of seafloor types.Applying to the processed backscatter strength data and mosaicked seafloor sonar images,seafloor classification and geomorphy interpretation are engaged in.
2006, 28(2): 56-65.
Abstract:
An operational algorithm of aerosol retrieval is described based on the FY-1C/1D data over global oceans.A sing le-channel algorithm is proposed.A look-up table(LUT) for aerosol retrieval is established using a state-of-art radiative transfer model 6S(second simulation of the satellite signal in the solar spectrum).The LUT shows that the apparent reflectance is the function of observation geometry (solar and viewing angles) and aerosol optical depth.Eventually,the LUT is used to retrieve the aerosol optical depth by the observed apparent reflectance.The data quality checking,cloud mask and sun-glint discrimination are considered during the operation processing.This algorithm has been used to test aerosol retrieval for FY-1C data since 2001 and introduced into the FY-1D operation performing including daily and monthly mean composite aerosol product since 2002.Analysis of the result reveals that all main aerosol sources are located over the global oceans and also reveals season variety in the globally averaged aerosol optical depth.They are nearly close to results of other similar foreign sensors in spatial distribution and numeral quantity.
An operational algorithm of aerosol retrieval is described based on the FY-1C/1D data over global oceans.A sing le-channel algorithm is proposed.A look-up table(LUT) for aerosol retrieval is established using a state-of-art radiative transfer model 6S(second simulation of the satellite signal in the solar spectrum).The LUT shows that the apparent reflectance is the function of observation geometry (solar and viewing angles) and aerosol optical depth.Eventually,the LUT is used to retrieve the aerosol optical depth by the observed apparent reflectance.The data quality checking,cloud mask and sun-glint discrimination are considered during the operation processing.This algorithm has been used to test aerosol retrieval for FY-1C data since 2001 and introduced into the FY-1D operation performing including daily and monthly mean composite aerosol product since 2002.Analysis of the result reveals that all main aerosol sources are located over the global oceans and also reveals season variety in the globally averaged aerosol optical depth.They are nearly close to results of other similar foreign sensors in spatial distribution and numeral quantity.
2006, 28(2): 66-84.
Abstract:
There are several kinds of Late Pleistocene facies in the Shenhu Bay of Fujian Province,China,including alluvial gravel-bearing sandy clay,lacustrine clay,vast oyster reef,estuary and tidal sand and clay and so-called red sand,a kind of eolian deposits.The sedimentary features and the inferred paleoenvironmental changes are discussed.On the bases of the data,a tectonic movement pattern is proposed.It shows that the bay underwent a historical change from land to sea,sea to land,land to sea,sea to land and land to sea again.It has included the following stages since 60 000 a B.P.:subsidence(red alluvial gravelbearing sandy clay was deposing)-lifting in the same place with the "eustatic" sea-level change(the paleooyster was growing and the oyster beach was formed)-a quick lifting related to a strong paleoearthquack(oyster beach platform and land depressions were formed)-Early Holocene relatively stable stage (the paleoforests were growing in the depressions)-sudden subsidence related to a strong paleoeart hquack (the lagoons in the depressions were formed and the paleoforests were sunk in the lagoons)-relative sta-bility) slightly lifting (the land was formed again)-sudden subsidence related to a strong paleoearthquack (the paleooyster beach came back in the sea bottom of the intertidal and undertidal zones,the paleoforests are sunk in the more deep sea bottom).
There are several kinds of Late Pleistocene facies in the Shenhu Bay of Fujian Province,China,including alluvial gravel-bearing sandy clay,lacustrine clay,vast oyster reef,estuary and tidal sand and clay and so-called red sand,a kind of eolian deposits.The sedimentary features and the inferred paleoenvironmental changes are discussed.On the bases of the data,a tectonic movement pattern is proposed.It shows that the bay underwent a historical change from land to sea,sea to land,land to sea,sea to land and land to sea again.It has included the following stages since 60 000 a B.P.:subsidence(red alluvial gravelbearing sandy clay was deposing)-lifting in the same place with the "eustatic" sea-level change(the paleooyster was growing and the oyster beach was formed)-a quick lifting related to a strong paleoearthquack(oyster beach platform and land depressions were formed)-Early Holocene relatively stable stage (the paleoforests were growing in the depressions)-sudden subsidence related to a strong paleoeart hquack (the lagoons in the depressions were formed and the paleoforests were sunk in the lagoons)-relative sta-bility) slightly lifting (the land was formed again)-sudden subsidence related to a strong paleoearthquack (the paleooyster beach came back in the sea bottom of the intertidal and undertidal zones,the paleoforests are sunk in the more deep sea bottom).
2006, 28(2): 85-92.
Abstract:
Far-field seismic waves recorded at the Shidao Seismog raphic Station,located in the South China Sea,are used to inverse earth anisotropy and shear wave velocity vertical distribution under the station respectively.(1) The approach of rotated correction function is applied to five satisfactory ScS wave recordings at distance of 25°~35° to inverse shear wave splitting parameters of lithosphere.The inversion result of the deepest earthquake shows that the polarization of fast shear wave is N94°E and the extensional stress or the moving direction of the mantle mass in the Xisha region is nearly EW.It suggests that the crust in this region is a transitional one and driving force beneath comes from the mass flow whose flowing direction is consistent with the moving of Eurasian plate in the South China Sea.The time delay between fast and slow shear waves is 1 3 s,from which the anisotropy effective thickness is estimated about 100 km.(2) The method of receiver function is used for nine high quality P wave recordings with three components at distance of 20°~60° to inverse vertical distribution of shear wave velocity beneath the station.The result indicates that the crust can be divided into three layers:above 5 km where there is a gradient zone including several small layers,in which shear wave velocity increases from 1.5 to 3.5 km/s gradually;between 5 and 16 km the velocity is about 3.8 km/s in average including several small layers;between 16.0 and 26.5 km the velocity is about 3.6 km/s which is an obvious low velocity layer.The buried depth of Moho discontinuity is 26.5 km and beneath the Moho the velocity is about 4.7 km/s in average,including several small layers,especially an obvious low velocity layer just beneath the Moho.The analysis of the arrival time of transformed waves and the velocity swinging variation around initial model suggest the smaller layers maybe are not reliable,but the velocity layer between 16.0 and 26.5 km may be is real one implying the plasticity of the lower crust.
Far-field seismic waves recorded at the Shidao Seismog raphic Station,located in the South China Sea,are used to inverse earth anisotropy and shear wave velocity vertical distribution under the station respectively.(1) The approach of rotated correction function is applied to five satisfactory ScS wave recordings at distance of 25°~35° to inverse shear wave splitting parameters of lithosphere.The inversion result of the deepest earthquake shows that the polarization of fast shear wave is N94°E and the extensional stress or the moving direction of the mantle mass in the Xisha region is nearly EW.It suggests that the crust in this region is a transitional one and driving force beneath comes from the mass flow whose flowing direction is consistent with the moving of Eurasian plate in the South China Sea.The time delay between fast and slow shear waves is 1 3 s,from which the anisotropy effective thickness is estimated about 100 km.(2) The method of receiver function is used for nine high quality P wave recordings with three components at distance of 20°~60° to inverse vertical distribution of shear wave velocity beneath the station.The result indicates that the crust can be divided into three layers:above 5 km where there is a gradient zone including several small layers,in which shear wave velocity increases from 1.5 to 3.5 km/s gradually;between 5 and 16 km the velocity is about 3.8 km/s in average including several small layers;between 16.0 and 26.5 km the velocity is about 3.6 km/s which is an obvious low velocity layer.The buried depth of Moho discontinuity is 26.5 km and beneath the Moho the velocity is about 4.7 km/s in average,including several small layers,especially an obvious low velocity layer just beneath the Moho.The analysis of the arrival time of transformed waves and the velocity swinging variation around initial model suggest the smaller layers maybe are not reliable,but the velocity layer between 16.0 and 26.5 km may be is real one implying the plasticity of the lower crust.
2006, 28(2): 93-100.
Abstract:
Data from measuring experiments on the axial stress-strain/sound velocity are reported and analyzed for the short columnar samples of seafloor surface sediments of the southern South China Sea,the result shows that there are three types on the variance of sedimental compressional wave velocity:(1) following the stress-strain curve variance the sound velocity varies from the strain beginning,the sound velocity values come out maximum when the stress value reaches maximum,at the strain ending,the sound velocity value is higher or lower than that of the strain beginning;(2) the sound velocity decreases with the strain increase and the sound velocity minimum values come out at the strain ending;(3) the sound velocity increases with the strain increase and maximnm values come out at the end of the course of the stress-strain1.These results are related to the characteristics of seafloor surface sediments such as physical-me-chanical features,grain contact state and sediment microst ructure,etc1.These research results will contribute to evaluating the basic stabilization of seafloor engineering in a bearing capacity state,and survey seafloor sediment engineering-mechanical characteristics by the acoustic remote sensing methodl.
Data from measuring experiments on the axial stress-strain/sound velocity are reported and analyzed for the short columnar samples of seafloor surface sediments of the southern South China Sea,the result shows that there are three types on the variance of sedimental compressional wave velocity:(1) following the stress-strain curve variance the sound velocity varies from the strain beginning,the sound velocity values come out maximum when the stress value reaches maximum,at the strain ending,the sound velocity value is higher or lower than that of the strain beginning;(2) the sound velocity decreases with the strain increase and the sound velocity minimum values come out at the strain ending;(3) the sound velocity increases with the strain increase and maximnm values come out at the end of the course of the stress-strain1.These results are related to the characteristics of seafloor surface sediments such as physical-me-chanical features,grain contact state and sediment microst ructure,etc1.These research results will contribute to evaluating the basic stabilization of seafloor engineering in a bearing capacity state,and survey seafloor sediment engineering-mechanical characteristics by the acoustic remote sensing methodl.
2006, 28(2): 101-108.
Abstract:
On the basis of the data of four seasonal investigations in the East China Sea (23°30'~33°00'N,118°30'~128°00'E) from 1997 to 2000,the distribution and the seasonal changes of Ostracods abundance and the relationship between its abundance dynamics and environment and fishing ground were discussed in this paper through qualitative and quantitative methods.Results showed that the average abundance (2.57 ind/m3) of Ostracods peaked in autumn,which was equal to 41.59% of total abundance in four seasons.It was the second highest value (1.72 ind/m3) in summer,equaled to 36.55% of the total abundance.0.90 ind/m3 in winter and 0.70 ind/m3 in spring,which was the lowest value in four seasons.The dominant species of Ostracods separately were Euconchoecia chierchiae Muller in spring and winter,Euconchoecia maimai.Tseng in summer and Cypridina dentata (Muller) in autumn.Moreover,it was found that the total abundance showed linear correlation with surface salinity in spring and with surface water temperature in winter,while the abundance in summer and autumn did not show significant correlation with hydrogr aphic environmental factors.Ostracods,whose abundance was equal to 3.47% in the total zooplankton,only being lower. Copepods and Decapods in pelagic Crustacean,was an important pelagic animal.High abundance area of Ostr acods was located in north offshore of the East China Sea for four seasons while low abundance area occurred in nearshore of Zhoushan fishing ground.In south of the East China Sea,high abundance area of Ostracods was located in offshore in winter and spring but nearshore in summer and autumn.These suggested that Ostracods was a kind of typical warm water zooplankt on whose abundance was related to high water temperature seasons or warm water current.The agg regated behavior of Ostracods was dependent on the influence of its dominant species.It was also found that Ostracods,whose hig habundance area of very nearly overlapped the grazing areas of Todarodes pacificus,Navodon Septentrionalis and Scomber japonicus,became a kind of important diet for fish because of their characteristics of distribution and aggregation.
On the basis of the data of four seasonal investigations in the East China Sea (23°30'~33°00'N,118°30'~128°00'E) from 1997 to 2000,the distribution and the seasonal changes of Ostracods abundance and the relationship between its abundance dynamics and environment and fishing ground were discussed in this paper through qualitative and quantitative methods.Results showed that the average abundance (2.57 ind/m3) of Ostracods peaked in autumn,which was equal to 41.59% of total abundance in four seasons.It was the second highest value (1.72 ind/m3) in summer,equaled to 36.55% of the total abundance.0.90 ind/m3 in winter and 0.70 ind/m3 in spring,which was the lowest value in four seasons.The dominant species of Ostracods separately were Euconchoecia chierchiae Muller in spring and winter,Euconchoecia maimai.Tseng in summer and Cypridina dentata (Muller) in autumn.Moreover,it was found that the total abundance showed linear correlation with surface salinity in spring and with surface water temperature in winter,while the abundance in summer and autumn did not show significant correlation with hydrogr aphic environmental factors.Ostracods,whose abundance was equal to 3.47% in the total zooplankton,only being lower. Copepods and Decapods in pelagic Crustacean,was an important pelagic animal.High abundance area of Ostr acods was located in north offshore of the East China Sea for four seasons while low abundance area occurred in nearshore of Zhoushan fishing ground.In south of the East China Sea,high abundance area of Ostracods was located in offshore in winter and spring but nearshore in summer and autumn.These suggested that Ostracods was a kind of typical warm water zooplankt on whose abundance was related to high water temperature seasons or warm water current.The agg regated behavior of Ostracods was dependent on the influence of its dominant species.It was also found that Ostracods,whose hig habundance area of very nearly overlapped the grazing areas of Todarodes pacificus,Navodon Septentrionalis and Scomber japonicus,became a kind of important diet for fish because of their characteristics of distribution and aggregation.
2006, 28(2): 109-113.
Abstract:
The regulation of three biogenic amines over the reproductive neuroendocrine activity of male Scylla serrata was investigated by invivo injection and invitro incubation.The testicular index,the ratio of the mature sections among the seminiferous tubules,and the ratio of Type Bcells among the androgenic glandular cells were taken as the quantitative indexes.In vivo injections indicated that:5-HT can significantly promote the testicular development and the secretion of the androg enic gland in S.serrata;DA can inhibit the testicular development,but no influence on the secretion of the androgenic gland is found;no significant difference was observed between the OA-injected group and the concurrent control.In vitro incubations showed that:5-HT can stimulate the secretion of the brain and the thoracic ganglia,thus accelerate that of the androgenic gland;in the OA and the DA groups,however,no significant influence on the secretion of the brain and the thoracic ganglia was observed.As to the optic ganglia,the three biogenic amines hardly have any effects on the secretion.It is the first time for invitro experiments to report the regulation of biogenic amines over the reproductive neuroendocrine of male crustaceans.Our results corrobo rate that 5-HT first activate the brain and the thoracic ganglia to secret GSH,then promote the testicular development through the androgenic gland.
The regulation of three biogenic amines over the reproductive neuroendocrine activity of male Scylla serrata was investigated by invivo injection and invitro incubation.The testicular index,the ratio of the mature sections among the seminiferous tubules,and the ratio of Type Bcells among the androgenic glandular cells were taken as the quantitative indexes.In vivo injections indicated that:5-HT can significantly promote the testicular development and the secretion of the androg enic gland in S.serrata;DA can inhibit the testicular development,but no influence on the secretion of the androgenic gland is found;no significant difference was observed between the OA-injected group and the concurrent control.In vitro incubations showed that:5-HT can stimulate the secretion of the brain and the thoracic ganglia,thus accelerate that of the androgenic gland;in the OA and the DA groups,however,no significant influence on the secretion of the brain and the thoracic ganglia was observed.As to the optic ganglia,the three biogenic amines hardly have any effects on the secretion.It is the first time for invitro experiments to report the regulation of biogenic amines over the reproductive neuroendocrine of male crustaceans.Our results corrobo rate that 5-HT first activate the brain and the thoracic ganglia to secret GSH,then promote the testicular development through the androgenic gland.
2006, 28(2): 114-120.
Abstract:
On the basis of the research of juvenile (2,3,4 months) and medium-term (6,8,10,12 months) growth and survival of three population of two different geographic areas in Chlamys farrerifrom Russia and China and their F1hybrids derived from Chinese cultural population (CC)♀×Russian wild population (RW)♂and F'1 hybrids derived from Chinese wild population (CW)♀×Russian wild population (RW)♂,the study of the later period (12,14,16,19,21,24 months) growth and development of Chlamys farreri was carried out.The four determined results indicated that there existed different extentheterosis (3.16%~37.18%) for growth in F1 hybrids and F'1 hybrids,the former had a stronger heterosis and it was a better cross combination,the uptrend among traits were wet weight being greater than shell width being greater than shell length being greater than shell height,Chinese cultural population could be recognized as excellent parent,and the growth rate (the daily increment) had reached a peak at 16 months(November),it was a good time for harvest of Chlamys farreri.
On the basis of the research of juvenile (2,3,4 months) and medium-term (6,8,10,12 months) growth and survival of three population of two different geographic areas in Chlamys farrerifrom Russia and China and their F1hybrids derived from Chinese cultural population (CC)♀×Russian wild population (RW)♂and F'1 hybrids derived from Chinese wild population (CW)♀×Russian wild population (RW)♂,the study of the later period (12,14,16,19,21,24 months) growth and development of Chlamys farreri was carried out.The four determined results indicated that there existed different extentheterosis (3.16%~37.18%) for growth in F1 hybrids and F'1 hybrids,the former had a stronger heterosis and it was a better cross combination,the uptrend among traits were wet weight being greater than shell width being greater than shell length being greater than shell height,Chinese cultural population could be recognized as excellent parent,and the growth rate (the daily increment) had reached a peak at 16 months(November),it was a good time for harvest of Chlamys farreri.
2006, 28(2): 121-127.
Abstract:
Hy pocotyls of Bruguiera gymnorrhiza were collected at various stages of development while still on the parent plant.Length,density,fresh weight,dry weight,water content,osmotic potential,ions concentrations and contents (Ca2+,Mg2+,Na+,K+,Cl-) were determined.The result showed that the hypocotyls of B.gymnorrhiza undergoed some growth before becoming detached from the parent plant.They accumulated large amounts organic nutriments and ions during the development.The growth of hypocotyls could divided into 3 stages according to the changes of each physiology characteristics:The first 45 d was the fruit stage.The following 60 d were a period of highest activity after the hypocotylemerged through the fruit wall.In the final 60 d before detachment,the seedlings came into being.The osmotic potential of mature hypocotyls B.gymnorrhiza was negative than that of the solution on whichtheir parent plant vegetated,while the ions concentrations were approaching to those of the solution on which their parent plant vegetating.Thus help the seedlings survive better in the flooding and saline conditions.The density of mature hypocotyls of B.gymnorrhiza were lower than seawater,thus the hypocotyls can float and be dispersed by tide.
Hy pocotyls of Bruguiera gymnorrhiza were collected at various stages of development while still on the parent plant.Length,density,fresh weight,dry weight,water content,osmotic potential,ions concentrations and contents (Ca2+,Mg2+,Na+,K+,Cl-) were determined.The result showed that the hypocotyls of B.gymnorrhiza undergoed some growth before becoming detached from the parent plant.They accumulated large amounts organic nutriments and ions during the development.The growth of hypocotyls could divided into 3 stages according to the changes of each physiology characteristics:The first 45 d was the fruit stage.The following 60 d were a period of highest activity after the hypocotylemerged through the fruit wall.In the final 60 d before detachment,the seedlings came into being.The osmotic potential of mature hypocotyls B.gymnorrhiza was negative than that of the solution on whichtheir parent plant vegetated,while the ions concentrations were approaching to those of the solution on which their parent plant vegetating.Thus help the seedlings survive better in the flooding and saline conditions.The density of mature hypocotyls of B.gymnorrhiza were lower than seawater,thus the hypocotyls can float and be dispersed by tide.
2006, 28(2): 128-134.
Abstract:
A fishery acoustic survey was conducted in the northern waters of South China Sea by calibrated Simrad EK500 echosounder on board R/V Beidou in spring (April to June),summer (July to September),autumn (October to December) and winter (December to February) from December 1997 to June 1999.Based on the data,this article assessed the stocks of 23 species of 5 commer cial taxonomical groups) Trichiuridae were assessed,Decapterus maruadsi,Trachurusjaponicus,Nemipterus and Priacanthidae.The results show that stocks of Trichiuridae,Decapterus maruadsi,Trachurus japonicus,Nemipterus and Priacanthidae are 5.04×105,1.63×105,1.04×105,9.8×104 and 9.2×104 t,respectively,in the north waters of South China Sea.In addition,regional distribution and seasonal variation of stock densities of the species were still analyaed.
A fishery acoustic survey was conducted in the northern waters of South China Sea by calibrated Simrad EK500 echosounder on board R/V Beidou in spring (April to June),summer (July to September),autumn (October to December) and winter (December to February) from December 1997 to June 1999.Based on the data,this article assessed the stocks of 23 species of 5 commer cial taxonomical groups) Trichiuridae were assessed,Decapterus maruadsi,Trachurusjaponicus,Nemipterus and Priacanthidae.The results show that stocks of Trichiuridae,Decapterus maruadsi,Trachurus japonicus,Nemipterus and Priacanthidae are 5.04×105,1.63×105,1.04×105,9.8×104 and 9.2×104 t,respectively,in the north waters of South China Sea.In addition,regional distribution and seasonal variation of stock densities of the species were still analyaed.
2006, 28(2): 135-139.
Abstract:
On the basis of measured mud fluid data in the Northern Channel of Changjiang Estuary in China,the periodical changes of mudfluid are discussed.It is thought that the mudfluid changes in three kind of periods in the Northern Channel of Changjiang Estuary.It is pointed out that the tidal period is influenced by the tidal velocity change,at which the flood current erodes the mud fluid and results in the mud fluid scale reducing and the slack current makes fine sediments flocculation and deposition and results in the mud fluid scale increasing.The semi-monthly changes of the mud fluid are controlled by the am ount of fine sediments supply.The annual period change of the mud fluid is controlled by the water temperature,which controls the fine sediments flocculation in the Changjiang Estuary.The annual change of sediment supply and the dynamics are also important influencing factors.
On the basis of measured mud fluid data in the Northern Channel of Changjiang Estuary in China,the periodical changes of mudfluid are discussed.It is thought that the mudfluid changes in three kind of periods in the Northern Channel of Changjiang Estuary.It is pointed out that the tidal period is influenced by the tidal velocity change,at which the flood current erodes the mud fluid and results in the mud fluid scale reducing and the slack current makes fine sediments flocculation and deposition and results in the mud fluid scale increasing.The semi-monthly changes of the mud fluid are controlled by the am ount of fine sediments supply.The annual period change of the mud fluid is controlled by the water temperature,which controls the fine sediments flocculation in the Changjiang Estuary.The annual change of sediment supply and the dynamics are also important influencing factors.
2006, 28(2): 140-145.
Abstract:
A numerical model for calculating wave-induced current is established by using the basic principles of Hardy-Cross method,and several improving methods of raising the efficiency and the precision in the calculation are also put forward.To aim at the problem that there still exists unknown place around a man-made island,a method is put forward to solve the problem.Through a calculating test,it is proved that the model can be used to calculate wave-induced current around a non-water area such as a man-made island,thus cleared away an obstacle is ceeared away in using the Hardy-Cross method.
A numerical model for calculating wave-induced current is established by using the basic principles of Hardy-Cross method,and several improving methods of raising the efficiency and the precision in the calculation are also put forward.To aim at the problem that there still exists unknown place around a man-made island,a method is put forward to solve the problem.Through a calculating test,it is proved that the model can be used to calculate wave-induced current around a non-water area such as a man-made island,thus cleared away an obstacle is ceeared away in using the Hardy-Cross method.
2006, 28(2): 146-150.
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2006, 28(2): 151-155.
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2006, 28(2): 156-164.
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2006, 28(2): 165-170.
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2006, 28(2): 171-174.
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2006, 28(2): 175-177.
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