1987 Vol. 6, No. 4
Display Method:
1987, (4): 493-502.
Abstract:
The vertical characters of temperature, salinity and density fluctuations in shallow region of the East China Sea are analysed by using 12 CTD short records with 1-hour intervals. The average S,t and p profiles can be divided into three distinctive layers:the thermocline, and the layers above and below it. The fluctuations of t, S and p are basically caused by internal waves, but there are somewhat intrusions or entrainments at the thermocline boundaries. The vertical displacement of the thermocline centre is up to more than 6.35m and the thermocline thickness changes from 3.5 to 8.0 m. Their varature with time are intermittent and rather irregular. The vertical wavenumber spectra of temperature fluctuations have been estimated by using the maximum entropy method, indicating that energy is mainly contained in the low-wavenumber range (<0.13cpm) with two sharp peaks probably corresponding to the first and second modes of internal waves, whose dependence is estimated to be less than β-2. There exist dependences of β-3 and β-5, respectively in the midium range (0.13-0.64 cpm), representing finestructure or its mixture with internal waves, and the high range (>0.64 cpm) indicating weak finestructure.
The vertical characters of temperature, salinity and density fluctuations in shallow region of the East China Sea are analysed by using 12 CTD short records with 1-hour intervals. The average S,t and p profiles can be divided into three distinctive layers:the thermocline, and the layers above and below it. The fluctuations of t, S and p are basically caused by internal waves, but there are somewhat intrusions or entrainments at the thermocline boundaries. The vertical displacement of the thermocline centre is up to more than 6.35m and the thermocline thickness changes from 3.5 to 8.0 m. Their varature with time are intermittent and rather irregular. The vertical wavenumber spectra of temperature fluctuations have been estimated by using the maximum entropy method, indicating that energy is mainly contained in the low-wavenumber range (<0.13cpm) with two sharp peaks probably corresponding to the first and second modes of internal waves, whose dependence is estimated to be less than β-2. There exist dependences of β-3 and β-5, respectively in the midium range (0.13-0.64 cpm), representing finestructure or its mixture with internal waves, and the high range (>0.64 cpm) indicating weak finestructure.
1987, (4): 503-509.
Abstract:
Based on the ray theory of waves and the linear model of sea waves, a joint distribution of periods and heights is derived. The theoretical expression has the same merits as those of Lon-guet-Higgins', but the wave height distribution is still Rayleigh's.
Based on the ray theory of waves and the linear model of sea waves, a joint distribution of periods and heights is derived. The theoretical expression has the same merits as those of Lon-guet-Higgins', but the wave height distribution is still Rayleigh's.
1987, (4): 510-518.
Abstract:
The mathematical background of the rotary spectral estimation of the ocean current vector and the related rotary variates are described briefly in this paper, some achievements in the confidence intervals of the rotary spectral estimator of the vector are summerized. On this basis, the expectation and variance expressions for the autospectral estimator of the rotary spectrum of vector are derived by resorting to some hypotheses and results of the scalar spectral estimator. And then its confidence interval is given. Finally, some computation examples for the rotary spectral estimator of vector are furnished.
The mathematical background of the rotary spectral estimation of the ocean current vector and the related rotary variates are described briefly in this paper, some achievements in the confidence intervals of the rotary spectral estimator of the vector are summerized. On this basis, the expectation and variance expressions for the autospectral estimator of the rotary spectrum of vector are derived by resorting to some hypotheses and results of the scalar spectral estimator. And then its confidence interval is given. Finally, some computation examples for the rotary spectral estimator of vector are furnished.
1987, (4): 519-530.
Abstract:
The systems of diurnal tidal wave (K1) and semi-diurnal tidal wave (M2) in the Beibu Gulf are studied with numerical method. Also discussed in this paper are the influences of the Qiongzhou Strait, the bottom friction term, the horizontal turbulent friction term and the inertial (acceleration) term in dynamic equations on the tidal system. The calculated results show that there is an independent left-handed tidal system in the diurnal tidal wave of the gulf, the amphidromic point being roughly located at Taigeli Island; that the semi-diurnal wave constitutes no tidal system, generating a small tidal range in the region near Feizhulong Islands; and that the influence of the tidal wave from the strait on the tidal system of the K1 is not evident, but its effect on the system of the M2 component tide is quite obvious. The bottom friction term, the horizontal turbulent friction term, and the inertial term have effects upon the tidal system in the gulf.
The systems of diurnal tidal wave (K1) and semi-diurnal tidal wave (M2) in the Beibu Gulf are studied with numerical method. Also discussed in this paper are the influences of the Qiongzhou Strait, the bottom friction term, the horizontal turbulent friction term and the inertial (acceleration) term in dynamic equations on the tidal system. The calculated results show that there is an independent left-handed tidal system in the diurnal tidal wave of the gulf, the amphidromic point being roughly located at Taigeli Island; that the semi-diurnal wave constitutes no tidal system, generating a small tidal range in the region near Feizhulong Islands; and that the influence of the tidal wave from the strait on the tidal system of the K1 is not evident, but its effect on the system of the M2 component tide is quite obvious. The bottom friction term, the horizontal turbulent friction term, and the inertial term have effects upon the tidal system in the gulf.
1987, (4): 531-536.
Abstract:
The daily weather maps of the 850 hPa level and the monthly mean wind maps of tropical regions published by ECMWF are utilized to study the cross-eguatorial currents. It is found out that there are 3 branches of the cross-equatorial current in the area between the east coast of Africa and the West Pacific. The effect of the cross-equatorial current originnated from the north coast of Australia on the typhoon genesis in the Northwest Pacific region is very important.
The daily weather maps of the 850 hPa level and the monthly mean wind maps of tropical regions published by ECMWF are utilized to study the cross-eguatorial currents. It is found out that there are 3 branches of the cross-equatorial current in the area between the east coast of Africa and the West Pacific. The effect of the cross-equatorial current originnated from the north coast of Australia on the typhoon genesis in the Northwest Pacific region is very important.
1987, (4): 537-546.
Abstract:
A computational method for the ocean ship routing based on optimization theory is presented in this paper. In the computational programme "breaking circle method" is used, by which a principal contradictory line can be obtained in the operations research. The automatic selection of calculating network and the initial values have been realized. The quantitative estimation for the change of navigating speed under the different conditions of ocean wave and current has been done. The objectivly quantitative computational method is provided for ocean ship routing and forecast service following ship tracks. The calculating examples and practical experiments of ships have proved that this computational method is highly effective.
A computational method for the ocean ship routing based on optimization theory is presented in this paper. In the computational programme "breaking circle method" is used, by which a principal contradictory line can be obtained in the operations research. The automatic selection of calculating network and the initial values have been realized. The quantitative estimation for the change of navigating speed under the different conditions of ocean wave and current has been done. The objectivly quantitative computational method is provided for ocean ship routing and forecast service following ship tracks. The calculating examples and practical experiments of ships have proved that this computational method is highly effective.
1987, (4): 547-557.
Abstract:
Having answered the question why the empirical frequency curve of annual extreme wind speeds at Tanggu, Tianjin of China does not fit the Pearson-Ⅲ type, the authors obtained a better fitting for the Weibull distribution through extremum analysis, and found out a better numerical solution for estimating the Weibull distribution parameters by a new iterative technique. The fitting results of annual extreme wind speed have been proved to be quite satisfactory by using the x2 criterion and Kolmogorov criterion.
Having answered the question why the empirical frequency curve of annual extreme wind speeds at Tanggu, Tianjin of China does not fit the Pearson-Ⅲ type, the authors obtained a better fitting for the Weibull distribution through extremum analysis, and found out a better numerical solution for estimating the Weibull distribution parameters by a new iterative technique. The fitting results of annual extreme wind speed have been proved to be quite satisfactory by using the x2 criterion and Kolmogorov criterion.
1987, (4): 558-567.
Abstract:
The distribution of some chemical elements in the Huanghai Sea sediment is statistically revealed on the basis of the new geochemical fundamental law presented respectively by Ahrens and Vistelius. The distribution characteristics of 8 elements (i.e. Cu, Hg, Zn, Cd, Pb, Cr, As and Corg) are described and the significant level of their average concentration difference between the surface and bottom sediments is examined by t test method. Finally the background value is worked out.
The distribution of some chemical elements in the Huanghai Sea sediment is statistically revealed on the basis of the new geochemical fundamental law presented respectively by Ahrens and Vistelius. The distribution characteristics of 8 elements (i.e. Cu, Hg, Zn, Cd, Pb, Cr, As and Corg) are described and the significant level of their average concentration difference between the surface and bottom sediments is examined by t test method. Finally the background value is worked out.
1987, (4): 568-576.
Abstract:
This is the first study of the flocculation of dissolved Fe, Al, Mn, Si, Cu, Pb and Zn during mixing in Zhujiang Estuary, based on the experiment on a series of solutions of salinities ranging from 0 to 24 by mixing the Zhujiang water near Zhongshan University and the seawater in Wan-shan Archipelago area. The mechanism of flocculation of the 7 elements is explored, and the effects of time, acidity and temperature on flocculation are discussed. The results show that the flocculation rates of Fe and Pb in the Zhujiang water are almost a hundred per cent, while that for Cu reaches 76%; for Mn, 51%; for Al, 48%; for Zn, 28%; and for Si, 1.2%, indicating that Si is conservative.
This is the first study of the flocculation of dissolved Fe, Al, Mn, Si, Cu, Pb and Zn during mixing in Zhujiang Estuary, based on the experiment on a series of solutions of salinities ranging from 0 to 24 by mixing the Zhujiang water near Zhongshan University and the seawater in Wan-shan Archipelago area. The mechanism of flocculation of the 7 elements is explored, and the effects of time, acidity and temperature on flocculation are discussed. The results show that the flocculation rates of Fe and Pb in the Zhujiang water are almost a hundred per cent, while that for Cu reaches 76%; for Mn, 51%; for Al, 48%; for Zn, 28%; and for Si, 1.2%, indicating that Si is conservative.
1987, (4): 577-588.
Abstract:
Based on the analysis of new data of a total of 60 000 km, the authors propose a new spreading model of the tectonic evolution of the South China Sea Basin and suggest that magnetic anomalies in the Basin are the magnetic anomalies of a new type in marginal basins, that the tectonic development of the Basin can be divided into three seafloor spreading phases and that the southward migration of spreading ridge is related to the asymmetric spreading.
Based on the analysis of new data of a total of 60 000 km, the authors propose a new spreading model of the tectonic evolution of the South China Sea Basin and suggest that magnetic anomalies in the Basin are the magnetic anomalies of a new type in marginal basins, that the tectonic development of the Basin can be divided into three seafloor spreading phases and that the southward migration of spreading ridge is related to the asymmetric spreading.
1987, (4): 589-598.
Abstract:
The sediments on the inner shelf of the northern South China Sea, mainly composed of terrigenous fragments, are continually transported herein by streams and floods. The coastal and strait-bottom erosion by waves and currents also contribute to the sedimentation. Under the dynamic conditions of the sea, the terrigenous sediments are differentiated with the coarse debris deposited mainly within the 20 m isobath off Guangdong, Guangxi and the Hainan Island. Organisms thrive in some areas, forming coral-reef platforms, foraminifera sand and shell sand. Chemically-formed clay minerals and various authigenic ones are developed in gulf and outlet areas. The modern sediments, thin in depth, are attributed to the short period of ingression of the sea, and their distribution is controlled by a variety of factors with the sea-level changes dominating.
The sediments on the inner shelf of the northern South China Sea, mainly composed of terrigenous fragments, are continually transported herein by streams and floods. The coastal and strait-bottom erosion by waves and currents also contribute to the sedimentation. Under the dynamic conditions of the sea, the terrigenous sediments are differentiated with the coarse debris deposited mainly within the 20 m isobath off Guangdong, Guangxi and the Hainan Island. Organisms thrive in some areas, forming coral-reef platforms, foraminifera sand and shell sand. Chemically-formed clay minerals and various authigenic ones are developed in gulf and outlet areas. The modern sediments, thin in depth, are attributed to the short period of ingression of the sea, and their distribution is controlled by a variety of factors with the sea-level changes dominating.
1987, (4): 599-612.
Abstract:
Phytoplankton samples were collected bi-weekly by towing a 20 μm mesh net in the Indian River Lagoon from January to August, 1985. Two-way ANOVA and T-method was used in analyzing data. Identified were 145 species of phytoplankton including 89 species of diatoms and 54 species of dinoflagellates which led to the discovery of some subtle succession patterns of phytoplankton.
Phytoplankton samples were collected bi-weekly by towing a 20 μm mesh net in the Indian River Lagoon from January to August, 1985. Two-way ANOVA and T-method was used in analyzing data. Identified were 145 species of phytoplankton including 89 species of diatoms and 54 species of dinoflagellates which led to the discovery of some subtle succession patterns of phytoplankton.
1987, (4): 613-621.
Abstract:
Three experimental ecosystem enclosures were employed to test the effects of Bohai crude oil on the structure of phytoplankton community. The results indicate that, while the species composition were changed (from larger diatoms to microflagellates or smaller diatoms), the species diversity and the total cell number of phytoplankton community were practically unchanged. All of the effects of oil disappeared in 12 days.
Three experimental ecosystem enclosures were employed to test the effects of Bohai crude oil on the structure of phytoplankton community. The results indicate that, while the species composition were changed (from larger diatoms to microflagellates or smaller diatoms), the species diversity and the total cell number of phytoplankton community were practically unchanged. All of the effects of oil disappeared in 12 days.
1987, (4): 643-647.
Abstract:
1987, (4): 622-629.
Abstract:
A method combining boundary and finite element approaches as well as modal analysis to solve the acoustical scattering from elastic obstacle in infinite fluid is described. An elastic cylinder with finite length immersed in water is chosen as an example for numerical demonstration. The computed frequency response and direction pattern of the backscattering target strength of the cylinder are conformable to those measured.
A method combining boundary and finite element approaches as well as modal analysis to solve the acoustical scattering from elastic obstacle in infinite fluid is described. An elastic cylinder with finite length immersed in water is chosen as an example for numerical demonstration. The computed frequency response and direction pattern of the backscattering target strength of the cylinder are conformable to those measured.
1987, (4): 642-642.
Abstract:
1987, (4): 630-641.
Abstract:
By using a process of successive approximations, the Boundary-Layer equations are solved to determine the separation points of a circular cylinder in oscillatory flow under the conditions of vortex existing. Combining with the discrete vortex model, the separation points and the fluid force coefficients are calculated at different KC numbers and Re numbers, A modified Morison equation is used in calculating the inline forces, and good agreements are obtained between the calculated results and those from other's experiments.
By using a process of successive approximations, the Boundary-Layer equations are solved to determine the separation points of a circular cylinder in oscillatory flow under the conditions of vortex existing. Combining with the discrete vortex model, the separation points and the fluid force coefficients are calculated at different KC numbers and Re numbers, A modified Morison equation is used in calculating the inline forces, and good agreements are obtained between the calculated results and those from other's experiments.
