2003 Vol. 25, No. 4
Display Method:
2003, 25(4): 1-9.
Abstract:
A full-spectral third-generation ocean wind-wave model WAVEWATCH Ⅲ (henceforth denoted as WWATCH),which has been developed at the Ocean Modeling Branch(OMB) of the Environmental Modeling Center (EMC) of the National Centers for Environmental Prediction (NCEP),is used to simulate the wind wave during the year 1996 with wind input of NCEP re-analysis data 4 times daily in the South China Sea (SCS).The significant wave heights(SWH) from WWATCH model and TOPEX/Poseidon (T/P) altimetric data are compared over the crossover points in the SCS for the year 1996,and the wind speeds from NCEP re-analysis data and T/P data are also compared to help analyze the results from the WWATCH model.The temporal variation of SWHs from WWATCH is generally consistent with that from T/P,and the maximum differences between SWHs from WWATCH and T/P occur in low wind speed during summer monsoon especially.The spatial consistency of SWHs from WWATCH and T/P in center areas is better than that close to the model boundary.
A full-spectral third-generation ocean wind-wave model WAVEWATCH Ⅲ (henceforth denoted as WWATCH),which has been developed at the Ocean Modeling Branch(OMB) of the Environmental Modeling Center (EMC) of the National Centers for Environmental Prediction (NCEP),is used to simulate the wind wave during the year 1996 with wind input of NCEP re-analysis data 4 times daily in the South China Sea (SCS).The significant wave heights(SWH) from WWATCH model and TOPEX/Poseidon (T/P) altimetric data are compared over the crossover points in the SCS for the year 1996,and the wind speeds from NCEP re-analysis data and T/P data are also compared to help analyze the results from the WWATCH model.The temporal variation of SWHs from WWATCH is generally consistent with that from T/P,and the maximum differences between SWHs from WWATCH and T/P occur in low wind speed during summer monsoon especially.The spatial consistency of SWHs from WWATCH and T/P in center areas is better than that close to the model boundary.
2003, 25(4): 10-17.
Abstract:
The astronomy-storm tide in the Bohai Sea was modeled by using three-dimensional model and data from 82 selected strong weather processes.The model was tested with real observation data,and satisfactory results were obtained.Form the astronomical highest (lowest) tide levels,the extreme high(low) water levels of multiyear return periods and the extrerne-storm set-up (set-down) of multiyear return periods,which were obtained by the yearly extreme high(low) water levels and the yearly extreme storm set-up(set-down) observed at the coastal hydrographic stations,A linear combination formula for calculating the extreme water levels of multiyear return periods at 5 typical areas in the Bohai Sea is established.The formula can be used in the design of marine engmeeenng projects.
The astronomy-storm tide in the Bohai Sea was modeled by using three-dimensional model and data from 82 selected strong weather processes.The model was tested with real observation data,and satisfactory results were obtained.Form the astronomical highest (lowest) tide levels,the extreme high(low) water levels of multiyear return periods and the extrerne-storm set-up (set-down) of multiyear return periods,which were obtained by the yearly extreme high(low) water levels and the yearly extreme storm set-up(set-down) observed at the coastal hydrographic stations,A linear combination formula for calculating the extreme water levels of multiyear return periods at 5 typical areas in the Bohai Sea is established.The formula can be used in the design of marine engmeeenng projects.
2003, 25(4): 18-28.
Abstract:
Using the observational data of the Second SCS Air-Sea Flux Experiment on the Xisha air-sea flux research tower during May 7 to June 17,2000,the radiation budget,latent and sensible heat fluxes and net oceanic heat budgets before and after summer monsoon onset were calculated.It is found that there are considerable changes on air-sea fluxes,especially on latent heat fluxes and net oceanic heat budget after summer monsoon onset.Furthermore,the analyzed results of five synoptic stages are compared and the special characteristics of flux transfer during the different stages around onset of SCS monsoon are discussed.The fluxes change shows that there is an oceanic heat accumulating process in pre-onset and break period and an oceanic heat loss process in the onset period.Also the latent fluxes and water vapor transported to continent can be influenced by the duration and intension of the southwester especially,further influence on the rainfall appearance in China continent.Finally,through comparison of the Xisha fluxes with those obtained from Indian Ocean and western Pacific Ocean,their differences may be seen.It can explain why after monsoon onset,the SST can keep stable values over the SCS while over the Arabian Sea and the Bay of Bengal they decrease quickly.
Using the observational data of the Second SCS Air-Sea Flux Experiment on the Xisha air-sea flux research tower during May 7 to June 17,2000,the radiation budget,latent and sensible heat fluxes and net oceanic heat budgets before and after summer monsoon onset were calculated.It is found that there are considerable changes on air-sea fluxes,especially on latent heat fluxes and net oceanic heat budget after summer monsoon onset.Furthermore,the analyzed results of five synoptic stages are compared and the special characteristics of flux transfer during the different stages around onset of SCS monsoon are discussed.The fluxes change shows that there is an oceanic heat accumulating process in pre-onset and break period and an oceanic heat loss process in the onset period.Also the latent fluxes and water vapor transported to continent can be influenced by the duration and intension of the southwester especially,further influence on the rainfall appearance in China continent.Finally,through comparison of the Xisha fluxes with those obtained from Indian Ocean and western Pacific Ocean,their differences may be seen.It can explain why after monsoon onset,the SST can keep stable values over the SCS while over the Arabian Sea and the Bay of Bengal they decrease quickly.
2003, 25(4): 29-35.
Abstract:
The movement of Typhoon Maggie(9903) in June 1999 is one of the rare cases ever seen in the history.At 00U on June 6 Maggie was located at about 70 km to the southwest of Taiwan.When it arrived at the coastal region of Shanwei City(22.8°N,116.5°E),it turned suddenly to move southwestward along the southern China coastal line.On June 7 Maggie finally turned to move northward,making landfall to the north of Shangchuan Island.The experimental numerical prediction system on typhoon movement that was designed based on MM5 is proved quite successful for the 48 h prediction of Maggie's movement and rainfall.The mean prediction error of typhoon track is 81 km for 0-24 h and 74 km for 24-48 h.The location of typhoon center in the initial field of the model is approximately 100 km away from the actual observations.In order to modify the location of typhoon center,a bogus typhoon was introduced into the model and the prediction of typhoon track was improved in 0-24 h time interval.But the prediction error was enlarged in 24-36 h.We also performed a sensitivity experiment of changing the land of southern China into the ocean.It is found that the orientation of South China coastal line and the topography have no obvious effect on the movement of Typhoon Maggie.
The movement of Typhoon Maggie(9903) in June 1999 is one of the rare cases ever seen in the history.At 00U on June 6 Maggie was located at about 70 km to the southwest of Taiwan.When it arrived at the coastal region of Shanwei City(22.8°N,116.5°E),it turned suddenly to move southwestward along the southern China coastal line.On June 7 Maggie finally turned to move northward,making landfall to the north of Shangchuan Island.The experimental numerical prediction system on typhoon movement that was designed based on MM5 is proved quite successful for the 48 h prediction of Maggie's movement and rainfall.The mean prediction error of typhoon track is 81 km for 0-24 h and 74 km for 24-48 h.The location of typhoon center in the initial field of the model is approximately 100 km away from the actual observations.In order to modify the location of typhoon center,a bogus typhoon was introduced into the model and the prediction of typhoon track was improved in 0-24 h time interval.But the prediction error was enlarged in 24-36 h.We also performed a sensitivity experiment of changing the land of southern China into the ocean.It is found that the orientation of South China coastal line and the topography have no obvious effect on the movement of Typhoon Maggie.
2003, 25(4): 36-42.
Abstract:
Helium,neon and argon isotope compositions of fluid inclusions have been measured in massive sulfide samples from the Jade hydrothermal field at the central Okinawa Trough.Fluid-inclusion 3He/4He ratios are between 6.2 and 10.1 times the air value (Ra),and with a mean of 7.8 Ra,which are consistent with the midocean ridge basalt values[3He/4He≈(6-11) Ra].Values for 20Ne/22Ne are from 10.7 to 11.3,which are significantly higher than the atmospheric ratio (9.8).And fluid-inclusion 40Ar/36Ar ratios range from 287 to 334,which are close to the atmosperic values(295.5).These results indicate that the noble gases of trapped hydrothermal fluids in massive sulfides are a mixture of mantle-and seawater-derived components,and the helium of fluid inclusions is major from mantle,the Ne and Ar isotope compositions are major from seawater.
Helium,neon and argon isotope compositions of fluid inclusions have been measured in massive sulfide samples from the Jade hydrothermal field at the central Okinawa Trough.Fluid-inclusion 3He/4He ratios are between 6.2 and 10.1 times the air value (Ra),and with a mean of 7.8 Ra,which are consistent with the midocean ridge basalt values[3He/4He≈(6-11) Ra].Values for 20Ne/22Ne are from 10.7 to 11.3,which are significantly higher than the atmospheric ratio (9.8).And fluid-inclusion 40Ar/36Ar ratios range from 287 to 334,which are close to the atmosperic values(295.5).These results indicate that the noble gases of trapped hydrothermal fluids in massive sulfides are a mixture of mantle-and seawater-derived components,and the helium of fluid inclusions is major from mantle,the Ne and Ar isotope compositions are major from seawater.
2003, 25(4): 43-49.
Abstract:
Isotopic studies have provided significant information about the geological provenance in the eastern South China Sea.Noncarbonate fraction in sediments is composed of weathering products of silica rocks and of young volcanic rock of basaltic composition.There is negative correlation between both components.The volcanic activities are the main source of basaltic composition in the basin.The weathering products of silica rocks of continent are supplied by the Changjiang River,part of them are transported into the study area through the Taiwan Strait.The 87Sr/86Sr ratios vary systematically in the investigation area:(1) High values were found in sediments collected around continental shelf and continental slope(0.718 994).Lower values(0.713 545) occur in the area lyingon east of the continental slope to the edge of the deep basin and beyond.(2) Somewhat lower values occur around the Dongsha Islands and the Zhongsha Islands(0.709 232),the lowest value(0.704 111) was obtained in sample collected around the Huangyan Island,this value is consistent with that of basaltic component.(3) 87Sr/86Sr ratios in sediments obtained from the southern Taiwan Strait were high(0.717 940),close to that of average value of the earth crust.The 87Sr/86Sr ratios decrease markedly in southwest direction toward the deep basin.The weight percentages of the basaltic component and silica component were calculated for each sample in terms of two-component mixing model.This treatment of the data provides estimates of the concentrations of the two components that are at least qualitatively useful.The concentration of volcanogenic detritus in the southern Taiwan Strait is less than 10%.However,this parameter increases to about 50% in the vicinity of the Huangyan Island.Weathering products of silica rock transported throagh the Taiwan Strait gradually deposit in the NNW-NE deep basin.Such a theoretical distribution is quite consistent with the actual occurrance of volcanic detritus and silica detritus.
Isotopic studies have provided significant information about the geological provenance in the eastern South China Sea.Noncarbonate fraction in sediments is composed of weathering products of silica rocks and of young volcanic rock of basaltic composition.There is negative correlation between both components.The volcanic activities are the main source of basaltic composition in the basin.The weathering products of silica rocks of continent are supplied by the Changjiang River,part of them are transported into the study area through the Taiwan Strait.The 87Sr/86Sr ratios vary systematically in the investigation area:(1) High values were found in sediments collected around continental shelf and continental slope(0.718 994).Lower values(0.713 545) occur in the area lyingon east of the continental slope to the edge of the deep basin and beyond.(2) Somewhat lower values occur around the Dongsha Islands and the Zhongsha Islands(0.709 232),the lowest value(0.704 111) was obtained in sample collected around the Huangyan Island,this value is consistent with that of basaltic component.(3) 87Sr/86Sr ratios in sediments obtained from the southern Taiwan Strait were high(0.717 940),close to that of average value of the earth crust.The 87Sr/86Sr ratios decrease markedly in southwest direction toward the deep basin.The weight percentages of the basaltic component and silica component were calculated for each sample in terms of two-component mixing model.This treatment of the data provides estimates of the concentrations of the two components that are at least qualitatively useful.The concentration of volcanogenic detritus in the southern Taiwan Strait is less than 10%.However,this parameter increases to about 50% in the vicinity of the Huangyan Island.Weathering products of silica rock transported throagh the Taiwan Strait gradually deposit in the NNW-NE deep basin.Such a theoretical distribution is quite consistent with the actual occurrance of volcanic detritus and silica detritus.
2003, 25(4): 50-58.
Abstract:
A gravity Core 180 was collected from the middle Okinawa Trough.The 305 cm long core was sampled at the interval of 5 cm.Twenty-three geochemical indexes of these samples were obtained on the basis of different analytical methods.According to the explanations for vertical changing regularity of the ratio of elements to A12O3,δ18O records,clay mineral composition,grain size,combined with AMS14Cdetermination and factor analysis,Core 180 can be divided into five sections.The similar elementary combination characteristics exist in Sections 1,3 and 5,and different characteristics exist in Sections 2 and 4.Compared with detrital mineral and paleobiological analysis data,the distribution of the sedimentary compositions originated from continent,volcanic and biogenetic material has been discussed by means of correlation analysis of elementary geochemical behavior,elementary combination and sedimentary sources.The results show that the main sedimentary sources of the middle Okinawa Trough are terrigenous materials.But some essential changes maybe occur in the special layers due to the intensive influence of volcanic and biogenetic sediments.
A gravity Core 180 was collected from the middle Okinawa Trough.The 305 cm long core was sampled at the interval of 5 cm.Twenty-three geochemical indexes of these samples were obtained on the basis of different analytical methods.According to the explanations for vertical changing regularity of the ratio of elements to A12O3,δ18O records,clay mineral composition,grain size,combined with AMS14Cdetermination and factor analysis,Core 180 can be divided into five sections.The similar elementary combination characteristics exist in Sections 1,3 and 5,and different characteristics exist in Sections 2 and 4.Compared with detrital mineral and paleobiological analysis data,the distribution of the sedimentary compositions originated from continent,volcanic and biogenetic material has been discussed by means of correlation analysis of elementary geochemical behavior,elementary combination and sedimentary sources.The results show that the main sedimentary sources of the middle Okinawa Trough are terrigenous materials.But some essential changes maybe occur in the special layers due to the intensive influence of volcanic and biogenetic sediments.
2003, 25(4): 59-66.
Abstract:
According to the analysis of multichannel seismic reflection data,the BSRs are found in the southern and central areas of Okinawa Trough.The analyses of seismic attributions of amplitude,velocity and AVO explain that the BSRs are generated by the gas hydrate.And it is found that gas hydrate is closely related to fault in the Okinawa Trough.
According to the analysis of multichannel seismic reflection data,the BSRs are found in the southern and central areas of Okinawa Trough.The analyses of seismic attributions of amplitude,velocity and AVO explain that the BSRs are generated by the gas hydrate.And it is found that gas hydrate is closely related to fault in the Okinawa Trough.
2003, 25(4): 67-71.
Abstract:
Three stocks (K,H and S) of Penaeus chinensis were analysed using 41 random oligonucleotide primers with 10 bases by RAPD method.K was from the spawning stock in the western coastal waters of Korea Peninsula;H was from the Huanghai (Yellow) Sea-Bohai Sea stock;S was from the health cultured stock in Jimo,Shandong Province.Three genetic markers which can identify the three stocks were got in this study.The study may provide the basic materials for marker assisted selection (MAS) of Penaeus chinensis.
Three stocks (K,H and S) of Penaeus chinensis were analysed using 41 random oligonucleotide primers with 10 bases by RAPD method.K was from the spawning stock in the western coastal waters of Korea Peninsula;H was from the Huanghai (Yellow) Sea-Bohai Sea stock;S was from the health cultured stock in Jimo,Shandong Province.Three genetic markers which can identify the three stocks were got in this study.The study may provide the basic materials for marker assisted selection (MAS) of Penaeus chinensis.
2003, 25(4): 72-82.
Abstract:
The studies on the temporal,spatial,diel,seasonal variations and controlling mechanism were carried out during three cruises in the Taiwan Strait (August 1997,February-March 1998 and August 1998).The results show that horizontal distribution of picophytoplankton abundance was heterogeneous,specific dense areas were found for each group of picophytoplankton.There were six patterns of vertical profiles of picophytoplankton in the Taiwan Strait,of which,standard monopeak and weak monopeak dominated,the diversity of vertical profile may be due to complex topography and strong hydrodynamics (such as thermocline) in the study area.Regression analysis between picophytoplankton abundance and environmental factors shows that temperature was a key factor in horizontal distributions,while the irradiance,thermocline and halocline were important factors affecting the vertical profile in the Taiwan Strait.There were different "niches" for the different picophytoplankton groups in the study areas,this may be due to the differences among the groups in the sensitivity to tolerate temperature and ability to use light.
The studies on the temporal,spatial,diel,seasonal variations and controlling mechanism were carried out during three cruises in the Taiwan Strait (August 1997,February-March 1998 and August 1998).The results show that horizontal distribution of picophytoplankton abundance was heterogeneous,specific dense areas were found for each group of picophytoplankton.There were six patterns of vertical profiles of picophytoplankton in the Taiwan Strait,of which,standard monopeak and weak monopeak dominated,the diversity of vertical profile may be due to complex topography and strong hydrodynamics (such as thermocline) in the study area.Regression analysis between picophytoplankton abundance and environmental factors shows that temperature was a key factor in horizontal distributions,while the irradiance,thermocline and halocline were important factors affecting the vertical profile in the Taiwan Strait.There were different "niches" for the different picophytoplankton groups in the study areas,this may be due to the differences among the groups in the sensitivity to tolerate temperature and ability to use light.
2003, 25(4): 83-90.
Abstract:
The way using 3H-thymidine nucleoside as a tracer to determine bacterial production in the Daya Bay was used.The calculated results show that the bacterial production is in the range of 0.50×10-3-30.2×10-3 mg/(dm3·h).Comparing with bacterial productions in other sea areas,higher bacterial production in the Daya Bay waters was considered.The distribution features of bacterial production and relative factors affecting the bacterial production are.
The way using 3H-thymidine nucleoside as a tracer to determine bacterial production in the Daya Bay was used.The calculated results show that the bacterial production is in the range of 0.50×10-3-30.2×10-3 mg/(dm3·h).Comparing with bacterial productions in other sea areas,higher bacterial production in the Daya Bay waters was considered.The distribution features of bacterial production and relative factors affecting the bacterial production are.
2003, 25(4): 91-103.
Abstract:
Acoustic Doppler current profile and acoustics concentration profiler are applied respectively via fixed-point serial and sailing observations to measure temporal and spatial variations of current and suspended sediment concentration at the North Passage in the Changjiang (Yangtze) Estuary.Field observations show that(1) near-bed high concentration events occur in various tides,with different frequencies and formation mechanisms.They take place frequently in a moderate tide,especially at the slack or maximum tides.(2) At least three types of vertical profiles of suspended sediment concentration are found out,that is,L-type with the upper concentration smaller and the lower larger,exponential type,and floating type with the upper concentration larger and the lower smaller.(3) low-velocity zones occur owing to the effect of dredged sediment disposal on the flow,which are located at the surface column or through the whole column,for the latter case,forming flow fronts.The intensity of the zones tends to decrease with the diffusion and settling of the disposal sediment.(4) The behavior of ebb currents differs at various tidal phases.The ebb currents are directed mainly to the north in the spring and neap tides,while they are directed mainly to the south in the moderate tide.(5) Both sediment transport diffusion and settling coexist during dredged sediment disposal,under the combined action of ebb current and gravity.Disposal sediment deposit is immediate in the neap tides,and it disperses far away in the moderate and spring tides.
Acoustic Doppler current profile and acoustics concentration profiler are applied respectively via fixed-point serial and sailing observations to measure temporal and spatial variations of current and suspended sediment concentration at the North Passage in the Changjiang (Yangtze) Estuary.Field observations show that(1) near-bed high concentration events occur in various tides,with different frequencies and formation mechanisms.They take place frequently in a moderate tide,especially at the slack or maximum tides.(2) At least three types of vertical profiles of suspended sediment concentration are found out,that is,L-type with the upper concentration smaller and the lower larger,exponential type,and floating type with the upper concentration larger and the lower smaller.(3) low-velocity zones occur owing to the effect of dredged sediment disposal on the flow,which are located at the surface column or through the whole column,for the latter case,forming flow fronts.The intensity of the zones tends to decrease with the diffusion and settling of the disposal sediment.(4) The behavior of ebb currents differs at various tidal phases.The ebb currents are directed mainly to the north in the spring and neap tides,while they are directed mainly to the south in the moderate tide.(5) Both sediment transport diffusion and settling coexist during dredged sediment disposal,under the combined action of ebb current and gravity.Disposal sediment deposit is immediate in the neap tides,and it disperses far away in the moderate and spring tides.
2003, 25(4): 104-110.
Abstract:
The study results of artificial neural network algorithm applied to Ku-band microwave ocean wave-height and tide-level detecting system are specified.The way to detect the microwave returned intermediate frequency (fif) and the neural network(NN) design method of the 9/256 insertion and also training model are introduced.The precision of the measured wave-height and tide-level is risen to one order of magnitude as before but still kept low time delay while using NN.Some steps are also taken to reduce the training time of NN.
The study results of artificial neural network algorithm applied to Ku-band microwave ocean wave-height and tide-level detecting system are specified.The way to detect the microwave returned intermediate frequency (fif) and the neural network(NN) design method of the 9/256 insertion and also training model are introduced.The precision of the measured wave-height and tide-level is risen to one order of magnitude as before but still kept low time delay while using NN.Some steps are also taken to reduce the training time of NN.
2003, 25(4): 111-118.
Abstract:
The advances in the research of thermohaline ocean circulation (THC) are reviewed.Attentions are paid to the stability,multiple equilibrium states and decadal variability of the THC.
The advances in the research of thermohaline ocean circulation (THC) are reviewed.Attentions are paid to the stability,multiple equilibrium states and decadal variability of the THC.
2003, 25(4): 119-124.
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2003, 25(4): 125-134.
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2003, 25(4): 135-141.
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2003, 25(4): 142-146.
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2003, 25(4): 147-150.
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