1989 Vol. 8, No. 4
Display Method:
1989, (4): 467-483.
Abstract:
The lower frequency part of the theoretical wind wave spectrum proposed by the authors (Wen et al., 1988a, b, c) has been improved and the form of spectrum is appreciably simplified.In addition to the field data collected in the Bohai Sea region and used in the previous papers, those obtained in the Huanghai Sea, the East China Sea and the South China Sea have been employed so that the improved spectra can be verified on a more extensive observational basis.Computed results agree with the observations well.Further comparisons have been made between the proposed spectra and the JONSWAP spectrum.Though the two types of spectrum are close to each other in form, the former shows, as a whole, better agreement with the observation than the latter.By introducing an improved relation between the peakness factor and significant wave steepness, the spectrum contains only significant wave height and period as parameters.For spectra given in this form, the computed peak frequencies coincide approximately with observed values and the compuled peak magnitudes of spectra agree basically with observations, but, because of the statistic variability inherent in the measurements of significant wave heights and periods, there ate certain discrepancies between computed and measured spectrum peak magnitudes.
The lower frequency part of the theoretical wind wave spectrum proposed by the authors (Wen et al., 1988a, b, c) has been improved and the form of spectrum is appreciably simplified.In addition to the field data collected in the Bohai Sea region and used in the previous papers, those obtained in the Huanghai Sea, the East China Sea and the South China Sea have been employed so that the improved spectra can be verified on a more extensive observational basis.Computed results agree with the observations well.Further comparisons have been made between the proposed spectra and the JONSWAP spectrum.Though the two types of spectrum are close to each other in form, the former shows, as a whole, better agreement with the observation than the latter.By introducing an improved relation between the peakness factor and significant wave steepness, the spectrum contains only significant wave height and period as parameters.For spectra given in this form, the computed peak frequencies coincide approximately with observed values and the compuled peak magnitudes of spectra agree basically with observations, but, because of the statistic variability inherent in the measurements of significant wave heights and periods, there ate certain discrepancies between computed and measured spectrum peak magnitudes.
1989, (4): 485-496.
Abstract:
In order to avoid prescribing open boundary condition on the upstream side of the Hangzhou Bay, in numerical simulation of the tides and residual currents of the Bay, a 1-D model for the Qiantang River is connected to the 2-D model for the Hangzhou Bay.The harmonic constants of diurnal constituent[(K1+O1)/2], semidiurnal constituent (M2) and shallow water constituent (M4) are obtained.The results produced by the combined model are in better agreement with the observed ones than those produced solely by the original 2-D model.The combined model gives much more reliable results for tide-induced residual water level and current.
In order to avoid prescribing open boundary condition on the upstream side of the Hangzhou Bay, in numerical simulation of the tides and residual currents of the Bay, a 1-D model for the Qiantang River is connected to the 2-D model for the Hangzhou Bay.The harmonic constants of diurnal constituent[(K1+O1)/2], semidiurnal constituent (M2) and shallow water constituent (M4) are obtained.The results produced by the combined model are in better agreement with the observed ones than those produced solely by the original 2-D model.The combined model gives much more reliable results for tide-induced residual water level and current.
1989, (4): 497-510.
Abstract:
On the basis of the fact that the sharp thermocHne in the Bohai Sea and the northern Huanghai Sea is often distributed in the deep valley areas, it has been long thought that the reason of the formation of the sharp thermocHne is that the cold water can be easily kept in valleys.But recent investigations carried out in the southern Huanghai Sea in summer show that all of the sharp thermocHne areas were distributed in the shallow sloping-bottom areas but not in the deep valley areas.Only in autumn would the sharp thermoclines translate to the deep valley areas.In summer, they are characterized by shallow upper mixing layer and thin thickness in the southern Huanghai Sea.In addition to entrainment coming from lower boundary of upper mixing layer the entrainment from upper border of bottom homogeneous layer induced by tidal mixing also plays an important role in the growth and decay of thermoclines in these seas.
On the basis of the fact that the sharp thermocHne in the Bohai Sea and the northern Huanghai Sea is often distributed in the deep valley areas, it has been long thought that the reason of the formation of the sharp thermocHne is that the cold water can be easily kept in valleys.But recent investigations carried out in the southern Huanghai Sea in summer show that all of the sharp thermocHne areas were distributed in the shallow sloping-bottom areas but not in the deep valley areas.Only in autumn would the sharp thermoclines translate to the deep valley areas.In summer, they are characterized by shallow upper mixing layer and thin thickness in the southern Huanghai Sea.In addition to entrainment coming from lower boundary of upper mixing layer the entrainment from upper border of bottom homogeneous layer induced by tidal mixing also plays an important role in the growth and decay of thermoclines in these seas.
1989, (4): 511-520.
Abstract:
In this paper, the numerical modelling of the tidal level and current in the Bohai Sea was carried out with ADI method, by taking the sum of four main tidal components M2, S2K2, O1 as the open boundary condition.The calculated values were consistent with the predicted ones (the observed values in the case of calm) in the Tidal Table.On the basis of the modelling of the tide, the sea level and current fields under the effects of strong wind were simulated.The calculated results were also quite satisfactory.
In this paper, the numerical modelling of the tidal level and current in the Bohai Sea was carried out with ADI method, by taking the sum of four main tidal components M2, S2K2, O1 as the open boundary condition.The calculated values were consistent with the predicted ones (the observed values in the case of calm) in the Tidal Table.On the basis of the modelling of the tide, the sea level and current fields under the effects of strong wind were simulated.The calculated results were also quite satisfactory.
1989, (4): 521-533.
Abstract:
In this paper the variations of the sea surface temperature anomalies (SSTA) in the Equatorial Eastern Pacific are analysed.The results show that there are two peaks in the spectrum.One is the low frequency oscillation with a period of 3-5 years, and the other is the quasi-biennial oscillation.The former shows a westward migration in the warm episode of SSTA and the latter has the opposite trend.The El Nino events will be formed while the two frquency bands are in phase in the warming stage of SSTA in the Equatorial Eastern Pacific.
In this paper the variations of the sea surface temperature anomalies (SSTA) in the Equatorial Eastern Pacific are analysed.The results show that there are two peaks in the spectrum.One is the low frequency oscillation with a period of 3-5 years, and the other is the quasi-biennial oscillation.The former shows a westward migration in the warm episode of SSTA and the latter has the opposite trend.The El Nino events will be formed while the two frquency bands are in phase in the warming stage of SSTA in the Equatorial Eastern Pacific.
1989, (4): 535-547.
Abstract:
In this paper, analysed are the effects of synoptic wind, earth-rotation inertia and land surface roughness on sea (lake) breeze process, on the basis of the calculated results of a 2-D primitive equation model with turbulent energy closure.The results show that a moderate background wind field acts as a trigger for sea (lake) breeze onset, and presents prominent effect on the breeze intensity, inland advance rate and structure feature.The effects of Coriolis force not only make the breeze veering round, but also damp the development of the breeze component normal to shore.
The paper also discussed the dynamic method of wind field initialization based on one-site radiosonde.Three approaches of initialization have been tested.In comparison, it was found that the approach of one-dimensional dynamic initialization with nudging term was preferable to the others.
In this paper, analysed are the effects of synoptic wind, earth-rotation inertia and land surface roughness on sea (lake) breeze process, on the basis of the calculated results of a 2-D primitive equation model with turbulent energy closure.The results show that a moderate background wind field acts as a trigger for sea (lake) breeze onset, and presents prominent effect on the breeze intensity, inland advance rate and structure feature.The effects of Coriolis force not only make the breeze veering round, but also damp the development of the breeze component normal to shore.
The paper also discussed the dynamic method of wind field initialization based on one-site radiosonde.Three approaches of initialization have been tested.In comparison, it was found that the approach of one-dimensional dynamic initialization with nudging term was preferable to the others.
1989, (4): 549-558.
Abstract:
During the multi-disciplinary investigations on the waters of Nansa Islands for three cruises respectively in 1985.1986.1987.it is found that the dissolved oxygen maximum (DOmax) in its vertical distribution usually exists between 20m and 75m deep.The deep position of O2 maximum is near the thermocline below and above the deep chlorophyll maximum, as well as above the light-beam attenuation coefficient maximum.In the parts of O2 maximum occurring, the minimum of CO2 partial pressure and the maximum of pH value are also found at the same depth.It is still difficult to explain the features exactly by using the published research results about the oxygen maximum in its vertical distribution on the waters of middle and high latitude.
In the present paper, the dissolved oxygen maximum in its vertical distribution on the waters of low latitude is described.It is made by an internal wave which holds eddy mixture.The feature appears to arise from the biological photosynthesis with stratification, from the action of the thermocline preventing oxygen from escaping to the atmosphere.when the environment is suitable for organisms to grow.
During the multi-disciplinary investigations on the waters of Nansa Islands for three cruises respectively in 1985.1986.1987.it is found that the dissolved oxygen maximum (DOmax) in its vertical distribution usually exists between 20m and 75m deep.The deep position of O2 maximum is near the thermocline below and above the deep chlorophyll maximum, as well as above the light-beam attenuation coefficient maximum.In the parts of O2 maximum occurring, the minimum of CO2 partial pressure and the maximum of pH value are also found at the same depth.It is still difficult to explain the features exactly by using the published research results about the oxygen maximum in its vertical distribution on the waters of middle and high latitude.
In the present paper, the dissolved oxygen maximum in its vertical distribution on the waters of low latitude is described.It is made by an internal wave which holds eddy mixture.The feature appears to arise from the biological photosynthesis with stratification, from the action of the thermocline preventing oxygen from escaping to the atmosphere.when the environment is suitable for organisms to grow.
1989, (4): 559-564.
Abstract:
The tectonic types of the Zhujiang (Pearl) River Mouth Basin in the South China Sea are epicontinental rift-depression basins.Prior to Early Cretaceous time, the Dongsha Uplift arid its surrounding depressions had been combined with the Eurasia Plate in a single unit.Many ENE-trending narrow rifted basins were formed in the third episode of Yanshan orogeny (Late Laramide).The rifted basins in the Paleocene and Eocene were stretched and extended, forming Zhu 1, Zhu 2 and Zhu 3 depressions.The Dongsha Uplift is located between Zhu 1 and Zhu 2 depressions.covering an area of 28 000 Km2.Its geologic evolution can be divided into four stages:
(1) Late Cretaceous-Paleocene block-faulting stage.
(2) Eocene-Oligocene uplifting and eroding stage.
(3) Late Oligocene-Early Miocene sustained subsiding stage.
(4) Middle Miocene-Recent noncompensated subsiding stage.
The Dongsha Uplift is a structural zone favourable for oil-gas accumulation.
The tectonic types of the Zhujiang (Pearl) River Mouth Basin in the South China Sea are epicontinental rift-depression basins.Prior to Early Cretaceous time, the Dongsha Uplift arid its surrounding depressions had been combined with the Eurasia Plate in a single unit.Many ENE-trending narrow rifted basins were formed in the third episode of Yanshan orogeny (Late Laramide).The rifted basins in the Paleocene and Eocene were stretched and extended, forming Zhu 1, Zhu 2 and Zhu 3 depressions.The Dongsha Uplift is located between Zhu 1 and Zhu 2 depressions.covering an area of 28 000 Km2.Its geologic evolution can be divided into four stages:
(1) Late Cretaceous-Paleocene block-faulting stage.
(2) Eocene-Oligocene uplifting and eroding stage.
(3) Late Oligocene-Early Miocene sustained subsiding stage.
(4) Middle Miocene-Recent noncompensated subsiding stage.
The Dongsha Uplift is a structural zone favourable for oil-gas accumulation.
1989, (4): 565-576.
Abstract:
The total inline wave forces, the irregular wave forces in particular, on an isolated pile are investigated by experiment.The relationships between force coefficients Cd and CM including in Morison's Eq., and KC number or Reynolds number Re, and the variation of Cd and Cm in frequency domain are analysed with the method of least-squares in time domain and that of cross-spectral analysis.The plots of C4 and Cm versus KC are given for both regular and irregular waves and those for irregular waves are used for numerical simulation of the irregular wave forces on the vertical pile and the results are in fairly good agreement with the test data.Based on the experimental results, the applicability of the spectral analysis method for calculating irregular wave forces on an isolated pile is investigated with the coherency γ between wave and wave forces and with KC number.
The total inline wave forces, the irregular wave forces in particular, on an isolated pile are investigated by experiment.The relationships between force coefficients Cd and CM including in Morison's Eq., and KC number or Reynolds number Re, and the variation of Cd and Cm in frequency domain are analysed with the method of least-squares in time domain and that of cross-spectral analysis.The plots of C4 and Cm versus KC are given for both regular and irregular waves and those for irregular waves are used for numerical simulation of the irregular wave forces on the vertical pile and the results are in fairly good agreement with the test data.Based on the experimental results, the applicability of the spectral analysis method for calculating irregular wave forces on an isolated pile is investigated with the coherency γ between wave and wave forces and with KC number.
1989, (4): 577-586.
Abstract:
For the calculation of wave-current force on horizontal cylinder a modified Morison's equation is used.A redefined Keulegan-Carpenter number KC2 is determined for the horizontal cylinder in wave-current co-existing field.The force coefficients are well related to the redefined KC2 number.As to the comparison with the force on vertical cylinder, the characteristics of force on horizontal cylinder are quite similar to those on vertical cylinder, but the force coefficients for horizontal cylinder are larger than those for vertical cylinder.It is proved by the authors' calculation that the results of monochromatic wave can be used directly for the determination of irregular wave-current force on horizontal cylinder in time domain.
For the calculation of wave-current force on horizontal cylinder a modified Morison's equation is used.A redefined Keulegan-Carpenter number KC2 is determined for the horizontal cylinder in wave-current co-existing field.The force coefficients are well related to the redefined KC2 number.As to the comparison with the force on vertical cylinder, the characteristics of force on horizontal cylinder are quite similar to those on vertical cylinder, but the force coefficients for horizontal cylinder are larger than those for vertical cylinder.It is proved by the authors' calculation that the results of monochromatic wave can be used directly for the determination of irregular wave-current force on horizontal cylinder in time domain.
1989, (4): 587-600.
Abstract:
Based on a two-dimensional numerical M2 tidal model of the Huanghai and Bohai Seas, sediment transport of particles with different sizes in the computational area is given.It is concluded that tidal currents play an important role in sediment transport and deposition in the Huanghai and Bohai Seas.
Based on a two-dimensional numerical M2 tidal model of the Huanghai and Bohai Seas, sediment transport of particles with different sizes in the computational area is given.It is concluded that tidal currents play an important role in sediment transport and deposition in the Huanghai and Bohai Seas.
1989, (4): 601-601.
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1989, (4): 601-603.
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1989, (4): 603-604.
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1989, (4): 605-606.
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1989, (4): 606-609.
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