2003 Vol. 25, No. 1
Display Method:
2003, 25(1): 1-11.
Abstract:
Hilbert-Huang Transform (HHT)is a newly developed powerful method for nonlinear and non-stationary time series analysis.The empirical mode decomposition is the key part of HHT, while its algorithm was protected by NASA as a US patent, which limits the widely application among the scientific cotrununity.Two approaches, mirror periodic and extrema extending methods, have been developed for handling the end effects of empirical mode decomposition.The implementation of the HHT is realized in detail to widen the application.The detail comparison of results from two methods with that from Huang et al.(1998, 1999), as well as the comparison between two methods is presented.Generally, both methods reproduce faithful results as that of Huang et al.For mirror periodic method (MPM), the data is extended once forever.Ideally, it is a way for handling the end effects of the HHT, especially for the signal that has symmetric wavefortn.The extrema extending method (EEM) behaves as good as MPM, and it is better than MPM for the signal that has strong asymmetric waveform.However, it has to perform extrema envelope extending in every shifting process.
Hilbert-Huang Transform (HHT)is a newly developed powerful method for nonlinear and non-stationary time series analysis.The empirical mode decomposition is the key part of HHT, while its algorithm was protected by NASA as a US patent, which limits the widely application among the scientific cotrununity.Two approaches, mirror periodic and extrema extending methods, have been developed for handling the end effects of empirical mode decomposition.The implementation of the HHT is realized in detail to widen the application.The detail comparison of results from two methods with that from Huang et al.(1998, 1999), as well as the comparison between two methods is presented.Generally, both methods reproduce faithful results as that of Huang et al.For mirror periodic method (MPM), the data is extended once forever.Ideally, it is a way for handling the end effects of the HHT, especially for the signal that has symmetric wavefortn.The extrema extending method (EEM) behaves as good as MPM, and it is better than MPM for the signal that has strong asymmetric waveform.However, it has to perform extrema envelope extending in every shifting process.
2003, 25(1): 12-18.
Abstract:
The data of temperature and tonal flow anomaly in the equatorial Pacific Ocean which are meaned in 5°N~5°S with 5~430 m from 1980 to 2001 are analyzed with EOF method.The relation between the EOF main components of the temperature and tonal flow anomaly and El Niño is discussed.It is found that EOF first and second components of the temperature take about 80% among total amount.There are two processes in the second component.One is slow process and the other is quick process.The process fn}m warm to cold is quick and the process from cold to warm is slow.The quick process results in El Niño.The first mode means the variation of Nino3 temperature and the second mode means the variation of warm pool in the equatorial western Pacific Ocean.The EOF second component of the tonal flow means the variation of the undercurrent in the western Pacific Ocean and the sea surface current in the eastern Pacific Ocean.There are two processes in the EOF second component of the tonal flow.One which takes an half year is slow and the other which is simarlar to El Niño is quick.It is necessary for the undercurrent to stronger in the western Pacific Ocean and for the sea surface current to weaken in the eastern Pacific Ocean.El Niño can been forecasted using EOF semnd components of the temperature and tonal flow anomaly in advence 8 to 12 months to some extent.
The data of temperature and tonal flow anomaly in the equatorial Pacific Ocean which are meaned in 5°N~5°S with 5~430 m from 1980 to 2001 are analyzed with EOF method.The relation between the EOF main components of the temperature and tonal flow anomaly and El Niño is discussed.It is found that EOF first and second components of the temperature take about 80% among total amount.There are two processes in the second component.One is slow process and the other is quick process.The process fn}m warm to cold is quick and the process from cold to warm is slow.The quick process results in El Niño.The first mode means the variation of Nino3 temperature and the second mode means the variation of warm pool in the equatorial western Pacific Ocean.The EOF second component of the tonal flow means the variation of the undercurrent in the western Pacific Ocean and the sea surface current in the eastern Pacific Ocean.There are two processes in the EOF second component of the tonal flow.One which takes an half year is slow and the other which is simarlar to El Niño is quick.It is necessary for the undercurrent to stronger in the western Pacific Ocean and for the sea surface current to weaken in the eastern Pacific Ocean.El Niño can been forecasted using EOF semnd components of the temperature and tonal flow anomaly in advence 8 to 12 months to some extent.
2003, 25(1): 19-27.
Abstract:
Atmosphere and ocean data in tropical Pacific Ocean from 1980 to 2002 and a numerical model are used to analyze the relationship among the evolution of El Niño, westerly anomaly in equatorial Pacific Ocean and subsurface temperature anomaly in equatorial Pacific Ocean.The results show both the westerly anomaly in western equatorial Pacific Ocean(5°S~5°N,120°~160°E)and in central equatorial Pacific Ocean(5°S~5°N, 160°E~160°W)have the same annual variation as El Niño period, but the former has obvious intraseasonal oscillation of 2~3 months.The subsurface temperature anomaly in the western equatorial Pacific Ocean also has the oscillation period of annual scale and interannual scale.Before El Niño events onset, the subsurface water in western equatorial Pacific Ocean continues to be warmer, and strength of westerly anomaly are enhanced and its frequency increases.When the continual(≥3 months)strong westerly anomaly(zonalwind stress anomaly≥0.1×10-5N/cm2)appear in the central Pacific Ocean (5°S~5°N, 160°E~160°W) and then propagate eastwardly, and at the same time the positive subsurface temperature anomaly propagate to the eastern equatorial Pacific Ocean by Kelvin wave along the thermocline, the massive surface become anomaly warmer than normal SST, then an El Niño event is formed.Finally, the response of subsurface temperature anomaly in the equatorial Pacific Ocean to the westerly anomaly in 1982/1983 El Niño event is well simulated by a Pacific Ocean model.
Atmosphere and ocean data in tropical Pacific Ocean from 1980 to 2002 and a numerical model are used to analyze the relationship among the evolution of El Niño, westerly anomaly in equatorial Pacific Ocean and subsurface temperature anomaly in equatorial Pacific Ocean.The results show both the westerly anomaly in western equatorial Pacific Ocean(5°S~5°N,120°~160°E)and in central equatorial Pacific Ocean(5°S~5°N, 160°E~160°W)have the same annual variation as El Niño period, but the former has obvious intraseasonal oscillation of 2~3 months.The subsurface temperature anomaly in the western equatorial Pacific Ocean also has the oscillation period of annual scale and interannual scale.Before El Niño events onset, the subsurface water in western equatorial Pacific Ocean continues to be warmer, and strength of westerly anomaly are enhanced and its frequency increases.When the continual(≥3 months)strong westerly anomaly(zonalwind stress anomaly≥0.1×10-5N/cm2)appear in the central Pacific Ocean (5°S~5°N, 160°E~160°W) and then propagate eastwardly, and at the same time the positive subsurface temperature anomaly propagate to the eastern equatorial Pacific Ocean by Kelvin wave along the thermocline, the massive surface become anomaly warmer than normal SST, then an El Niño event is formed.Finally, the response of subsurface temperature anomaly in the equatorial Pacific Ocean to the westerly anomaly in 1982/1983 El Niño event is well simulated by a Pacific Ocean model.
2003, 25(1): 28-41.
Abstract:
A 9-layer 15-wave global spectral model of general circulation is used to study the effects of SSTA in various parts of the tropical Pacific Ckean so as to reveal the role of the former in the timing of onset of the South China Sea summer monsoon.It is shown in the numerical experiment that positive (negative) anomalies of the westem Pacific SST can weaken (strengthen) the subtropical high in the western Pacific; positive (negative) anomalies of the central Pacific SST can weaken (deepen) the TUTT over that part of the ocean; positive (negative) anomalies of the eastern Pacific SST can result in anti-cyclonic (cyclonic) changes in the upper-level circulation off either side of the equator in the eastern Pacific and the subtropical high strengthens (weakens) in the western Pacific.Either of the SSTA in the western and the eastern Pacific can have significant effect on the variation of the subtropical high intensity and thus on the onset timing of the southwesterly monsoon in the South China Sea, with the effect of the latter being more pronounced.The positive (negative) SSTA in the western Pacific usually occurs with the negative(positive) SSTA in the central Pacific, making suitable for general circulation conditions for early (late) onset of SCS summer moonsoon.The above pattern of SSTA is an important impacting factor on onset of SCS summer monsoon.
A 9-layer 15-wave global spectral model of general circulation is used to study the effects of SSTA in various parts of the tropical Pacific Ckean so as to reveal the role of the former in the timing of onset of the South China Sea summer monsoon.It is shown in the numerical experiment that positive (negative) anomalies of the westem Pacific SST can weaken (strengthen) the subtropical high in the western Pacific; positive (negative) anomalies of the central Pacific SST can weaken (deepen) the TUTT over that part of the ocean; positive (negative) anomalies of the eastern Pacific SST can result in anti-cyclonic (cyclonic) changes in the upper-level circulation off either side of the equator in the eastern Pacific and the subtropical high strengthens (weakens) in the western Pacific.Either of the SSTA in the western and the eastern Pacific can have significant effect on the variation of the subtropical high intensity and thus on the onset timing of the southwesterly monsoon in the South China Sea, with the effect of the latter being more pronounced.The positive (negative) SSTA in the western Pacific usually occurs with the negative(positive) SSTA in the central Pacific, making suitable for general circulation conditions for early (late) onset of SCS summer moonsoon.The above pattern of SSTA is an important impacting factor on onset of SCS summer monsoon.
2003, 25(1): 42-51.
Abstract:
The self-shading measurement error of the upwelling radiance and irradiance in different depths of infinite deep-sea water due to a optical system consisting of eight separated instruments and a rectangular frame is calculated with backward Monte Carlo technique.The relationship between the error and the sunlight azimuth relative to the system is showed.The error for different sun zeniths due to the coexisting of the system and ship is calculated as well.A multispectral iterated method for correcting the self-shading errors of remote sensing reflectance due to the Lu radiance instrument is given.Modeling computation shows that the corrected errors are less than 5% for Case 1 sea waters with chlorophyll concentration lower than 120.00 mg/m3.
The self-shading measurement error of the upwelling radiance and irradiance in different depths of infinite deep-sea water due to a optical system consisting of eight separated instruments and a rectangular frame is calculated with backward Monte Carlo technique.The relationship between the error and the sunlight azimuth relative to the system is showed.The error for different sun zeniths due to the coexisting of the system and ship is calculated as well.A multispectral iterated method for correcting the self-shading errors of remote sensing reflectance due to the Lu radiance instrument is given.Modeling computation shows that the corrected errors are less than 5% for Case 1 sea waters with chlorophyll concentration lower than 120.00 mg/m3.
2003, 25(1): 52-60.
Abstract:
An ecosystem based water quality model was designed to estimate the biochemical reaction of nutrient and dissolved oxygen in conjunction with a three-dimensional hydrodynamics and sediment model.As both phosphorus and nitrogen successively limit phytoplankton growth in many estuaries, the model simulates both these nutrient cycles using five variables, namely, dissolved inorganic nutrient, detritic organic matter, benthic matter, phytoplankton and zooplankton.
An ecosystem based water quality model was designed to estimate the biochemical reaction of nutrient and dissolved oxygen in conjunction with a three-dimensional hydrodynamics and sediment model.As both phosphorus and nitrogen successively limit phytoplankton growth in many estuaries, the model simulates both these nutrient cycles using five variables, namely, dissolved inorganic nutrient, detritic organic matter, benthic matter, phytoplankton and zooplankton.
2003, 25(1): 61-68.
Abstract:
The ecosystem based water quality model is applied to the Zhujiang River Estuary.The model results successfully represent the distribution trend of nutrients and dissolved oxygen both in the horiwntal and vertical planes during the flood season, and it shows that the model has taken into consideration the key part of the dynamical, chemical and biological processes existing in the Zhujiang River Estuary.The further studies illustrate that nitrogen is in plenty while phosphorus and light limit the phytoplankton biomass in the Zhujiang Estuary during the flood season.
The ecosystem based water quality model is applied to the Zhujiang River Estuary.The model results successfully represent the distribution trend of nutrients and dissolved oxygen both in the horiwntal and vertical planes during the flood season, and it shows that the model has taken into consideration the key part of the dynamical, chemical and biological processes existing in the Zhujiang River Estuary.The further studies illustrate that nitrogen is in plenty while phosphorus and light limit the phytoplankton biomass in the Zhujiang Estuary during the flood season.
2003, 25(1): 69-77.
Abstract:
Variations in elemental concentrations and ratios in Core B10 taken from the southern Huanghai Sea indicate climatic oscillations, sea level fluctuations and sediment supply changes in Late Quaternary in the region.During the low sea-level period of subinterglaciation of Last Glaciation (Wurm subinterglaciation), the Huanghe River was possibly discharged directly into the southern Huanghai Sea, and the submarine delta related sediments was found in the center of the sea.During the last glacial maximum, terrestrial facies peat appeared in the center of the southern Huanghai Sea.The postglacial transgression arrived at the modem isobaths of 80 m possibly in 13 ka B.P.and then a short standstill of sea level related to the Younger Dryas event appeared.During the middle and late stages of Holocene, sea level continued to rise, and relatively fine sediments with increasing chemical weathering deposited.Decrease of concentrations of CaCO3, CaO, Sr and MgO, Sr/Ba ratios but increase of concentrations of minor elements such as Cu in the section of 50~0 cm are probably due to the decrease in sediment supply from the Huanghe River in the southern Huanghai Sea because the Huanghe River has transferred north and discharged into the Bohai Sea since 1855 D.C.
Variations in elemental concentrations and ratios in Core B10 taken from the southern Huanghai Sea indicate climatic oscillations, sea level fluctuations and sediment supply changes in Late Quaternary in the region.During the low sea-level period of subinterglaciation of Last Glaciation (Wurm subinterglaciation), the Huanghe River was possibly discharged directly into the southern Huanghai Sea, and the submarine delta related sediments was found in the center of the sea.During the last glacial maximum, terrestrial facies peat appeared in the center of the southern Huanghai Sea.The postglacial transgression arrived at the modem isobaths of 80 m possibly in 13 ka B.P.and then a short standstill of sea level related to the Younger Dryas event appeared.During the middle and late stages of Holocene, sea level continued to rise, and relatively fine sediments with increasing chemical weathering deposited.Decrease of concentrations of CaCO3, CaO, Sr and MgO, Sr/Ba ratios but increase of concentrations of minor elements such as Cu in the section of 50~0 cm are probably due to the decrease in sediment supply from the Huanghe River in the southern Huanghai Sea because the Huanghe River has transferred north and discharged into the Bohai Sea since 1855 D.C.
2003, 25(1): 78-85.
Abstract:
The types, characteristics and distributions of the coastal wetlands of China are analyzed.Land reclamation, city and port development, pollution, coastal erosion, oil and gas exploitation, excessive use of biologic resource and sea-level rise are thought as the main environmental pressure factors to the degradation of coastal wetlands.According to matrix factor analysis, it is shown that environmental pressures and the degrees of the environmental degradation are different to different wetland types enduring, and coastal delta, lagoon, sand beach, coral reef, tidal flat, marine marsh and mangrove wetland are exposed to serious degradation.And human factors are the main causes attributing to this degradation.
The types, characteristics and distributions of the coastal wetlands of China are analyzed.Land reclamation, city and port development, pollution, coastal erosion, oil and gas exploitation, excessive use of biologic resource and sea-level rise are thought as the main environmental pressure factors to the degradation of coastal wetlands.According to matrix factor analysis, it is shown that environmental pressures and the degrees of the environmental degradation are different to different wetland types enduring, and coastal delta, lagoon, sand beach, coral reef, tidal flat, marine marsh and mangrove wetland are exposed to serious degradation.And human factors are the main causes attributing to this degradation.
2003, 25(1): 86-92.
Abstract:
The filtration rates of four kinds of bivalves that cultivated dominantly around Xiamen waters were measured by using a laboratory flowing system.The experimental results are shown below:(1) Filtration rates 54~74.8 are measured between among the four bivalves, sequencing decently Saccostrea cucullata > Sinonoracula construta > Mytilus vlrulis > Ruditapes philippznarum;(2)The relationship between filtration rate and individual size shows a negative exponential function(FR=aWb, FR'=aWb-1),with b-1=-0.435 6 and -0.392; (3)Filtration rates on Skeletonema costatum are much higher than on Alzzandrium tamarensis and Scrippsilla trochoidea) in Soccostrea cucullata and Ruditapes philippinarum;(4)FR' on algal densities is also showed a negative function(FR'=aDb-1),with b-1=-0.143 and -0.215 2 in Saccostrea cucullata and Ruditapes philippinarum,respectively.
The filtration rates of four kinds of bivalves that cultivated dominantly around Xiamen waters were measured by using a laboratory flowing system.The experimental results are shown below:(1) Filtration rates 54~74.8 are measured between among the four bivalves, sequencing decently Saccostrea cucullata > Sinonoracula construta > Mytilus vlrulis > Ruditapes philippznarum;(2)The relationship between filtration rate and individual size shows a negative exponential function(FR=aWb, FR'=aWb-1),with b-1=-0.435 6 and -0.392; (3)Filtration rates on Skeletonema costatum are much higher than on Alzzandrium tamarensis and Scrippsilla trochoidea) in Soccostrea cucullata and Ruditapes philippinarum;(4)FR' on algal densities is also showed a negative function(FR'=aDb-1),with b-1=-0.143 and -0.215 2 in Saccostrea cucullata and Ruditapes philippinarum,respectively.
2003, 25(1): 93-99.
Abstract:
Three populations of two different geographic areas in Chlamys farreri from Russian and China and the Ft hybrids derived from Chinese wild population (CW)♀×Russian population (R)♂,Chinese cultural population (CC)♀×Russian population (R)♂,Russian population (R)♂Chinese wild population (CW)♂,from each group 40-50 individuals were selected for the research on the growth characteristics.The three determined results indicate that there existed different extent heterosis (or hybrid vigour) for growth of shell height, shell length, shell thickness and live weight, and that growth of hybrid in CW♀×R♂ has a stronger heterosis among the crosses at the end of send month, and no significant difference at the end of third month among the crosses, and growth of hybrid in R♀×CC♂ has a stronger heterosis among the crosses at the end of fourth month,.Russian population can be recognized as excellent parent in growth at the first 3 months and Chines culture population is better at the end of fourth month; Chines wild population has a better growth than Chinese culture population at the second month and no sienificant difference at the end of third month, and reverses at the fourth month.
Three populations of two different geographic areas in Chlamys farreri from Russian and China and the Ft hybrids derived from Chinese wild population (CW)♀×Russian population (R)♂,Chinese cultural population (CC)♀×Russian population (R)♂,Russian population (R)♂Chinese wild population (CW)♂,from each group 40-50 individuals were selected for the research on the growth characteristics.The three determined results indicate that there existed different extent heterosis (or hybrid vigour) for growth of shell height, shell length, shell thickness and live weight, and that growth of hybrid in CW♀×R♂ has a stronger heterosis among the crosses at the end of send month, and no significant difference at the end of third month among the crosses, and growth of hybrid in R♀×CC♂ has a stronger heterosis among the crosses at the end of fourth month,.Russian population can be recognized as excellent parent in growth at the first 3 months and Chines culture population is better at the end of fourth month; Chines wild population has a better growth than Chinese culture population at the second month and no sienificant difference at the end of third month, and reverses at the fourth month.
2003, 25(1): 100-109.
Abstract:
The interaction of obliquely incident waves with infinite number of perforated caissons is investigated under the linear assumption that the velocity inside the perforated wall is linearly correlated with the pressure difference between the two sides of wall.The fluid domain is divided into infinite sub-domains according to the wnfiguration of structures, and eigenfunction expansion is applied to expand velocity potentials in each domain.A phase relation is introduced for wave oscillation in each caisson, and structure geometry is considered in constructing the models of reflection waves.The numerical results are compared with the experimental data, and a good agreement between them can be found.The numerical examinations show that velocities at the inner and outer sides of front walls of caissons are close to each other when porous effect parameter is infinite.The wave forces normal to caissons decrease with wave incident angle, and the longitudinal wave forces increase with the wave incident angle when the incident wave frequency is small.
The interaction of obliquely incident waves with infinite number of perforated caissons is investigated under the linear assumption that the velocity inside the perforated wall is linearly correlated with the pressure difference between the two sides of wall.The fluid domain is divided into infinite sub-domains according to the wnfiguration of structures, and eigenfunction expansion is applied to expand velocity potentials in each domain.A phase relation is introduced for wave oscillation in each caisson, and structure geometry is considered in constructing the models of reflection waves.The numerical results are compared with the experimental data, and a good agreement between them can be found.The numerical examinations show that velocities at the inner and outer sides of front walls of caissons are close to each other when porous effect parameter is infinite.The wave forces normal to caissons decrease with wave incident angle, and the longitudinal wave forces increase with the wave incident angle when the incident wave frequency is small.
2003, 25(1): 110-119.
Abstract:
In the curvilinear coordinates, a numerical simulation model for wave propagation in water of slowly varying topography is presented.The model is suitable to complicated loundary shapes and overcomes the limitation of other models with algorithm transfomtation.In the model, the time-dependent parabolic equation, deduced from the original elliptic type of mild-slope equation, is used as the governing equation.The present governing equation not only avoids the drawback to common parabolic form of mild-slope equation but also is convenient for solution.Based on the general conditions for open and fixed natural boundaries with an arbitrary reflection coefficient and phase shift, the boundary conditions for the present model are treated.The alternative direction implicit method is used to solve the governing equation.The numerical results of the present model are in agreement with those of physical models.Systematical tests show that the present model can reasonably simulate the wave transformation, such as shoaling, refraction, diffraction and reflection.So the present model is able to be used in coastal engineering with complicated boundary shapes extensively.
In the curvilinear coordinates, a numerical simulation model for wave propagation in water of slowly varying topography is presented.The model is suitable to complicated loundary shapes and overcomes the limitation of other models with algorithm transfomtation.In the model, the time-dependent parabolic equation, deduced from the original elliptic type of mild-slope equation, is used as the governing equation.The present governing equation not only avoids the drawback to common parabolic form of mild-slope equation but also is convenient for solution.Based on the general conditions for open and fixed natural boundaries with an arbitrary reflection coefficient and phase shift, the boundary conditions for the present model are treated.The alternative direction implicit method is used to solve the governing equation.The numerical results of the present model are in agreement with those of physical models.Systematical tests show that the present model can reasonably simulate the wave transformation, such as shoaling, refraction, diffraction and reflection.So the present model is able to be used in coastal engineering with complicated boundary shapes extensively.
2003, 25(1): 120-127.
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2003, 25(1): 128-131.
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2003, 25(1): 132-137.
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2003, 25(1): 138-142.
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