POM97, an oceanic model, has been used for the first time to the numerical study on the tidal waves of the as Regions around Taiwan. In this paper, we have got the result that the semidiurnal tidal waves of these area...POM97, an oceanic model, has been used for the first time to the numerical study on the tidal waves of the as Regions around Taiwan. In this paper, we have got the result that the semidiurnal tidal waves of these area mainly are the co-operating tides which come from the south of 23'N of the western Pacific. Those semidiurnal tidal waves affecting the Taiwan Straits come respectively from the south and the north entrance of the channel, and the north tidal wave is stronger than the south one. The strongest tidal field is the area from the Meizhou Bay to the Xinhua Bay along the coast of Fujian Province, where the biggest amplitude of the M2 partial tide can reach 240 cm. The strongest tidal cur- rent fields lie in the Penghu watercourse, where the maximum velocity of the M2 partial tide can arrive at 196 m/s. In the horizontal structure of the tidal currets, we have found that there is a stream dot in the north of the channel, besides, there still exist four new ones. As for the vertical structure, it mainly is biassed to the right at the surface, and to the left near the bottom layer.展开更多
A storm surge is an abnormal sharp rise or fall in the seawater level produced by the strong wind and low pressure field of an approaching storm system.A storm tide is a water level rise or fall caused by the combined...A storm surge is an abnormal sharp rise or fall in the seawater level produced by the strong wind and low pressure field of an approaching storm system.A storm tide is a water level rise or fall caused by the combined effect of the storm surge and an astronomical tide.The storm surge depends on many factors,such as the tracks of typhoon movement,the intensity of typhoon,the topography of sea area,the amplitude of tidal wave,the period during which the storm surge couples with the tidal wave.When coupling with different parts of a tidal wave,the storm surges caused by a typhoon vary widely.The variation of the storm surges is studied.An once-in-a-century storm surge was caused by Typhoon 7203 at Huludao Port in the north of the Liaodong Bay from July 26th to 27th,1972.The maximum storm surge is about 1.90 m.The wind field and pressure field used in numerical simulations in the research were derived from the historical data of the Typhoon 7203 from July 23rd to 28th,1972.DHI Mike21 is used as the software tools.The whole Bohai Sea is defined as the computational domain.The numerical simulation models are forced with sea levels at water boundaries,that is the tide along the Bohai Straits from July 18th to 29th（2012）.The tide wave and the storm tides caused by the wind field and pressure field mentioned above are calculated in the numerical simulations.The coupling processes of storm surges and tidal waves are simulated in the following way.The first simulation start date and time are 00：00 July 18th,2012; the second simulation start date and time are 03：00 July 18th,2012.There is a three-hour lag between the start date and time of the simulation and that of the former one,the last simulation start date and time are 00：00 July 25th,2012.All the simulations have a same duration of 5 days,which is same as the time length of typhoon data.With the first day and the second day simulation output,which is affected by the initial field,being ignored,only the 3rd to 5th day simulation results are used to study the rules of the storm surges in the north of the Liaodong Bay.In total,57 cases are calculated and analyzed,including the coupling effects between the storm surge and a tidal wave during different tidal durations and on different tidal levels.Based on the results of the 57 numerical examples,the following conclusions are obtained：For the same location,the maximum storm surges are determined by the primary vibration（the storm tide keeps rising quickly） duration and tidal duration.If the primary vibration duration is a part of the flood tidal duration,the maximum storm surge is lower（1.01,1.05 and 1.37 m at the Huludao Port,the Daling Estuary and the Liaohe Estuary respectively）.If the primary vibration duration is a part of the ebb tidal duration,the maximum storm surge is higher（1.92,2.05 and 2.80 m at the Huludao Port,the Daling Estuary and the Liaohe Estuary respectively）.In the mean time,the sea level restrains the growth of storm surges.The hour of the highest storm tide has a margin of error of plus or minus 80 min,comparing the high water hour of the astronomical tide,in the north of the Liaodong Bay.展开更多
Many observations show that in the Yellow Sea internal tidal waves (ITWs) possess the remarkable characteristics of internal Kelvin wave, and in the South Yellow Sea (SYS) the nonlinear evolution of internal tidal wav...Many observations show that in the Yellow Sea internal tidal waves (ITWs) possess the remarkable characteristics of internal Kelvin wave, and in the South Yellow Sea (SYS) the nonlinear evolution of internal tidal waves is one of the mechanisms producing internal solitary waves (ISWs), which is different from the generation mechanism in the case where the semidiurnal tidal current flows over topographic drops. In this paper, the model of internal Kelvin wave with continuous stratification is given, and an elementary numerical study of nonlinear evolution of ITWs is made for the SYS, using the generalized KdV model (GKdV model for short) for a continuous stratified ocean, in which the different effects of background barotropic ebb and flood currents are considered. Moreover, the parameterization of vertical turbulent mixing caused by ITWs and ISWs in the SYS is studied, using a parameterization scheme which was applied to numerical experiments on the breaking of ISWs by Vlasenko and Hutter in 2002. It is found that the vertical turbulent mixing caused by internal waves is very strong within the upper layer with depth less than about 30m, and the vertical turbulent mixing caused by ISWs is stronger than that by ITWs.展开更多
In this paper, geoelectrical field anomalies at Changli and Xingji station in Hebei Province were analyzed before five remote earthquakes. It was found that the anomalies mainly occurred two or three months before ear...In this paper, geoelectrical field anomalies at Changli and Xingji station in Hebei Province were analyzed before five remote earthquakes. It was found that the anomalies mainly occurred two or three months before earthquakes, which is of importance to short-term and impendent earthquake prediction. There exhibited different characteristics in geoelectrical field anomalies, but they were closely related to tidal waves, for example, the increasing in ampli- tude at semidiurnal and semimonthly periods of tidal waves; the decreasing or disappearing in amplitude of tidal waves that should have been recorded normally at that time; while there accompanied incremental signals with high frequency, such as jump variations. It was thought that the formation mechanism of the geoelectrical anoma- lies before strong earthquakes resulted from stress-strain resonance effects when rock was weakened during the preparation process in seismic area, and then signals of electric field propagated to remote stations in free space or crust, and superposed on the geoelectric field tidal waves recorded at the stations, leading to increasing or decreasing in amplitude of geoelectrical tidal waves. The high frequency signals may be related to the variation of rock porosity, permeability and so on beneath the stations, as a result of the dynamic effects of remote earthquakes.展开更多
Tidal waves in the East China Sea are simulated numerically with POM(Princeton Ocean Model) model for normal mean sea level, 30 cm higher, 60 cm higher, and 100 cm higher, respectively, and the simulated result is com...Tidal waves in the East China Sea are simulated numerically with POM(Princeton Ocean Model) model for normal mean sea level, 30 cm higher, 60 cm higher, and 100 cm higher, respectively, and the simulated result is compared with the harmonic analysis result of hourly sea level data from 19 tide gauges for more than 19 years. It is indicated that the long-term mean sea level variation affects notably tidal waves in this region. Generally, the tidal amplitude increases when the mean sea level rises, but this relationship may be inverse for some sea areas. The maximal variation of tidal amplitude takes place in the zones near the Fujian coast and the Zhejiang coast, rather than the shallowest Bohai Sea. The maximum increase of M2 amplitude can exceed about 15 cm corresponding to the 60 cm rise of the mean sea level along the Fujian coast. The other regions with large variations of tidal amplitude are those along the Jiangsu coast, the south-east coast of Shandong, and the south-east coast of Dalian. The propagation of tidal waves is also related to mean sea level variation, and the tidal phase-lag decreases generally when the mean sea level rises. Almost all the regions where the tidal phase-lag increases with rising mean sea level are close to amphidromic points, meanwhile the spatial area of such regions is very small. Because the influence of mean sea level variation upon tidal waves is spatially marked, such spatial effect should be considered in calculation of the tidal characteristic value and engineering water level. In the region where the amplitudes of the major tidal constituents increase, the probable maximum high water level becomes higher, the probable maximum low water level becomes lower, and both design water level andcheck water level increase obviously. For example, the design water level at Xiamen increases by 13.5 cm due to the variation of tidal waves when the mean sea level rises 60 cm, the total increase of design water level being 73.5 cm.展开更多
Analysis of tidal current and sea level has been made based on the observations from the summer of 2006 to the winter of 2007,respectively.The result indicates that a two-layer structure of residual current exists in ...Analysis of tidal current and sea level has been made based on the observations from the summer of 2006 to the winter of 2007,respectively.The result indicates that a two-layer structure of residual current exists in summer,with its upper layer going northwestward and the lower layer southeastward.In addition,some strong residuals exist in the neighboring depth of the pycnocline during the current period of astronomical tide.In winter,except some individual layersthe residual currents mostly direct to the northwest,from which we can see the fluctuation of abnormal sea-level and the appearance of associated current because of the changes of the wind field.The analysis of tidal ellipse indicates that the direction of the maximum semidiurnal component is clockwise from summer to winter,with an angle of 16-18.Moreover,in summer the semidiurnal component rotates with depth clockwise while the diurnal component counterclockwise.However,the vertical structure is almost homogeneous in winter.展开更多
Natural and human-induced changes may exert considerable impacts on the seasonal and nodal dynamics of M2 and K1 tidal constituents.Therefore,quantifying the influences of these factors on tidal regime changes is esse...Natural and human-induced changes may exert considerable impacts on the seasonal and nodal dynamics of M2 and K1 tidal constituents.Therefore,quantifying the influences of these factors on tidal regime changes is essential for sustainable water resources management in coastal environments.In this study,the enhanced harmonic analysis was applied to extract the seasonal variability of the M2 and K1 tidal amplitudes and phases at three gauging stations along Lingdingyang Bay of the Zhujiang River Delta.The seasonal dynamics in terms of tidal wave celerity and amplification/damping rate were used to quantify the impacts of human-induced estuarine morphological alterations on M2 and K1 tidal hydrodynamics in inner and outer Lingdingyang Bay.The results show that both tidal amplification/damping rate and wave celerity were considerably increased from the pre-anthropogenic activity period(Pre-AAP)to the post-anthropogenic activity period(Post-AAP)excepting the tidal amplification/damping rate in outer Lingdingyang Bay,and the variations in outer Lingdingyang Bay was larger than those in inner Lingdingyang Bay.The alterations in these two parameters were more significant in flood season than in dry season in both inner and outer Lingdingyang Bay.The seasonal variability of M2 and K1 tidal amplitudes were further quantified using a regression model accounting for the 18.61-year lunar nodal modulation,where this study observes a considerable alteration in M2 constituent owing to human interventions.During the Post-AAP,the M2 amplitudes at the downstream station were larger than those that would have occurred in the absence of strong human interventions,whereas the opposite was true for the upstream station,leading to a substantial decrease in tidal amplification in outer Lingdingyang Bay.However,it is opposite in inner Lingdingyang Bay.The underlying mechanism can be primarily attributed to channel deepening and narrowing caused by human interventions,that resulted in substantial enlargement of the bay volume and reduced the effective bottom friction,leading to faster wave celerity and stronger amplified waves.展开更多
To study the Taiwan Strait （TS）, an unusual sea area, the numerical model in marginal seas of China is used to simulate and analyze the tidal wave motion in the strait. The numerical modeling experiments reproduce t...To study the Taiwan Strait （TS）, an unusual sea area, the numerical model in marginal seas of China is used to simulate and analyze the tidal wave motion in the strait. The numerical modeling experiments reproduce the amphidromic system of the M2 tide in the south end of the Taiwan strait, and consequently confirm the existence of the degenerate amphidromic system. On this basis, further discussion is conducted on the M2 system and its formation mechanism. It can be concluded that the tidal waves of the TS is consisted of the progressing wave from the north entrance and the degenerate amphidromic system from the south entrance, in which the progressing wave from the north entrance dominates the tidal wave motion in the strait. Except for the convergent effect caused by the landform and boundary, the degenerate amphidromic system produced in the south of the strait is another important factor for the following phenomena： the large tidal range in the middle of the strait, the concentrative zone of co-amplitude and co-phase line in the south of the strait. The degenerate amphidromic system is mainly produced by the incident Pacific Ocean tidal wave from the Luzon strait and the action by the shoreline and landform. The position of the amphidromic point is compelled to move toward southwest until degenerating by the powerful progressing wave from the north entrance.展开更多
This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surf...This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surface wave radar(HFSWR) systems. The analysis shows that the tidal current pattern in the southwestern Taiwan Strait is primarily semi-diurnal and influenced significantly by shallow water constituents. The spatial distribution of tidal current ellipses of M2 is probably affected by the interaction between two different systems of tide wave, one from the northern mouth of Taiwan Strait and the other from the Bashi Channel. The directions of the major axes of M2 tidal current ellipses coincide roughly with the axis of the Taiwan Strait. The spatial distribution of the magnitudes of the probable maximum current velocity(PMCS) shows gradual increase of the velocity from northeast to southwest, which is in accordance with the spatial distribution of the measured maximum current velocity(MMCS). The directions of the residual currents are in accordance with the direction of the prevailing monsoon wind at the Taiwan Strait and the direction of the Taiwan warm current during summer. The bathymetry also shows a significant effect on the spatial distribution characteristics of tidal currents.展开更多
A three dimensional hydrodynamic was developed for the Dubai coastal zone including the Dubai Creek. The model is based on DHI （Danish Hydraulic Institute＇s） MIKE 3 HD （FM） modeling software. The model was subjec...A three dimensional hydrodynamic was developed for the Dubai coastal zone including the Dubai Creek. The model is based on DHI （Danish Hydraulic Institute＇s） MIKE 3 HD （FM） modeling software. The model was subjected to extensive calibration making use of recorded water levels, currents, water temperature and salinity. A high level of accuracy in calibration was achieved as indicated by the computed statistical error parameters at all recording stations. The model results combined with field recording of water levels were used to ascertain tidal wave propagation pattern in the Dubai coastal zone and in and out of the Dubai creek. This model will be a very useful tool in assessing impacts of planned connection of artificial waterways to the Dubai Creek.展开更多
This work analyzes the quality of crustal tilt and strain observations during 2014, which were acquired from 269 sets of ground tiltmeters and 212 sets of strainmeters. In terms of data quality, the water tube tiltmet...This work analyzes the quality of crustal tilt and strain observations during 2014, which were acquired from 269 sets of ground tiltmeters and 212 sets of strainmeters. In terms of data quality, the water tube tiltmeters presented the highest rate of excellent quality,approximately 91%, and the pendulum tiltmeters and ground strainmeters yielded rates of81% and 78%, respectively. This means that a total of 380 sets of instruments produced high-quality observational data suitable for scientific investigations and analyses.展开更多
Wave equation model(WEM)first developed by Lynch and Gray [2]is one of accurate and effective numerical methods to resolve shallow water equations.This paper shows the numerical consistency of the second- order wave e...Wave equation model(WEM)first developed by Lynch and Gray [2]is one of accurate and effective numerical methods to resolve shallow water equations.This paper shows the numerical consistency of the second- order wave equation and the first- order continuity equation, analyzes the error between them. This paper also shows that the numerical friction factor τo appearing in wave equation is of key importance to the numerical solutions and mass conservation of wave equation model.Numerical calculations of M2 tidal waves in rectangular harbor and a quarter annular harbor are made to demonstrate that it is possible to find a proper numerical friction factor τowith which accurate solutions and satisfactory mass conservation can be achieved by wave equation model.展开更多
Marine energy developmenthas been drownedout by Suco ssful clean power projects on land.Can new government policies give tidal and wave power generators the jump start they need?
文摘POM97, an oceanic model, has been used for the first time to the numerical study on the tidal waves of the as Regions around Taiwan. In this paper, we have got the result that the semidiurnal tidal waves of these area mainly are the co-operating tides which come from the south of 23'N of the western Pacific. Those semidiurnal tidal waves affecting the Taiwan Straits come respectively from the south and the north entrance of the channel, and the north tidal wave is stronger than the south one. The strongest tidal field is the area from the Meizhou Bay to the Xinhua Bay along the coast of Fujian Province, where the biggest amplitude of the M2 partial tide can reach 240 cm. The strongest tidal cur- rent fields lie in the Penghu watercourse, where the maximum velocity of the M2 partial tide can arrive at 196 m/s. In the horizontal structure of the tidal currets, we have found that there is a stream dot in the north of the channel, besides, there still exist four new ones. As for the vertical structure, it mainly is biassed to the right at the surface, and to the left near the bottom layer.
文摘A storm surge is an abnormal sharp rise or fall in the seawater level produced by the strong wind and low pressure field of an approaching storm system.A storm tide is a water level rise or fall caused by the combined effect of the storm surge and an astronomical tide.The storm surge depends on many factors,such as the tracks of typhoon movement,the intensity of typhoon,the topography of sea area,the amplitude of tidal wave,the period during which the storm surge couples with the tidal wave.When coupling with different parts of a tidal wave,the storm surges caused by a typhoon vary widely.The variation of the storm surges is studied.An once-in-a-century storm surge was caused by Typhoon 7203 at Huludao Port in the north of the Liaodong Bay from July 26th to 27th,1972.The maximum storm surge is about 1.90 m.The wind field and pressure field used in numerical simulations in the research were derived from the historical data of the Typhoon 7203 from July 23rd to 28th,1972.DHI Mike21 is used as the software tools.The whole Bohai Sea is defined as the computational domain.The numerical simulation models are forced with sea levels at water boundaries,that is the tide along the Bohai Straits from July 18th to 29th（2012）.The tide wave and the storm tides caused by the wind field and pressure field mentioned above are calculated in the numerical simulations.The coupling processes of storm surges and tidal waves are simulated in the following way.The first simulation start date and time are 00：00 July 18th,2012; the second simulation start date and time are 03：00 July 18th,2012.There is a three-hour lag between the start date and time of the simulation and that of the former one,the last simulation start date and time are 00：00 July 25th,2012.All the simulations have a same duration of 5 days,which is same as the time length of typhoon data.With the first day and the second day simulation output,which is affected by the initial field,being ignored,only the 3rd to 5th day simulation results are used to study the rules of the storm surges in the north of the Liaodong Bay.In total,57 cases are calculated and analyzed,including the coupling effects between the storm surge and a tidal wave during different tidal durations and on different tidal levels.Based on the results of the 57 numerical examples,the following conclusions are obtained：For the same location,the maximum storm surges are determined by the primary vibration（the storm tide keeps rising quickly） duration and tidal duration.If the primary vibration duration is a part of the flood tidal duration,the maximum storm surge is lower（1.01,1.05 and 1.37 m at the Huludao Port,the Daling Estuary and the Liaohe Estuary respectively）.If the primary vibration duration is a part of the ebb tidal duration,the maximum storm surge is higher（1.92,2.05 and 2.80 m at the Huludao Port,the Daling Estuary and the Liaohe Estuary respectively）.In the mean time,the sea level restrains the growth of storm surges.The hour of the highest storm tide has a margin of error of plus or minus 80 min,comparing the high water hour of the astronomical tide,in the north of the Liaodong Bay.
基金supported by the Key Program of the National Natural Science Foundation of China under contract No.41030855
文摘Many observations show that in the Yellow Sea internal tidal waves (ITWs) possess the remarkable characteristics of internal Kelvin wave, and in the South Yellow Sea (SYS) the nonlinear evolution of internal tidal waves is one of the mechanisms producing internal solitary waves (ISWs), which is different from the generation mechanism in the case where the semidiurnal tidal current flows over topographic drops. In this paper, the model of internal Kelvin wave with continuous stratification is given, and an elementary numerical study of nonlinear evolution of ITWs is made for the SYS, using the generalized KdV model (GKdV model for short) for a continuous stratified ocean, in which the different effects of background barotropic ebb and flood currents are considered. Moreover, the parameterization of vertical turbulent mixing caused by ITWs and ISWs in the SYS is studied, using a parameterization scheme which was applied to numerical experiments on the breaking of ISWs by Vlasenko and Hutter in 2002. It is found that the vertical turbulent mixing caused by internal waves is very strong within the upper layer with depth less than about 30m, and the vertical turbulent mixing caused by ISWs is stronger than that by ITWs.
基金National Key Project of Science and Technology (2004BA601B010503)
文摘In this paper, geoelectrical field anomalies at Changli and Xingji station in Hebei Province were analyzed before five remote earthquakes. It was found that the anomalies mainly occurred two or three months before earthquakes, which is of importance to short-term and impendent earthquake prediction. There exhibited different characteristics in geoelectrical field anomalies, but they were closely related to tidal waves, for example, the increasing in ampli- tude at semidiurnal and semimonthly periods of tidal waves; the decreasing or disappearing in amplitude of tidal waves that should have been recorded normally at that time; while there accompanied incremental signals with high frequency, such as jump variations. It was thought that the formation mechanism of the geoelectrical anoma- lies before strong earthquakes resulted from stress-strain resonance effects when rock was weakened during the preparation process in seismic area, and then signals of electric field propagated to remote stations in free space or crust, and superposed on the geoelectric field tidal waves recorded at the stations, leading to increasing or decreasing in amplitude of geoelectrical tidal waves. The high frequency signals may be related to the variation of rock porosity, permeability and so on beneath the stations, as a result of the dynamic effects of remote earthquakes.
文摘Tidal waves in the East China Sea are simulated numerically with POM(Princeton Ocean Model) model for normal mean sea level, 30 cm higher, 60 cm higher, and 100 cm higher, respectively, and the simulated result is compared with the harmonic analysis result of hourly sea level data from 19 tide gauges for more than 19 years. It is indicated that the long-term mean sea level variation affects notably tidal waves in this region. Generally, the tidal amplitude increases when the mean sea level rises, but this relationship may be inverse for some sea areas. The maximal variation of tidal amplitude takes place in the zones near the Fujian coast and the Zhejiang coast, rather than the shallowest Bohai Sea. The maximum increase of M2 amplitude can exceed about 15 cm corresponding to the 60 cm rise of the mean sea level along the Fujian coast. The other regions with large variations of tidal amplitude are those along the Jiangsu coast, the south-east coast of Shandong, and the south-east coast of Dalian. The propagation of tidal waves is also related to mean sea level variation, and the tidal phase-lag decreases generally when the mean sea level rises. Almost all the regions where the tidal phase-lag increases with rising mean sea level are close to amphidromic points, meanwhile the spatial area of such regions is very small. Because the influence of mean sea level variation upon tidal waves is spatially marked, such spatial effect should be considered in calculation of the tidal characteristic value and engineering water level. In the region where the amplitudes of the major tidal constituents increase, the probable maximum high water level becomes higher, the probable maximum low water level becomes lower, and both design water level andcheck water level increase obviously. For example, the design water level at Xiamen increases by 13.5 cm due to the variation of tidal waves when the mean sea level rises 60 cm, the total increase of design water level being 73.5 cm.
基金The Public Science and Technology Research Funds Projects of Ocean under contract Nos 200905001 and 201005019the State Basic Research Program of China under contract No.2005CB422303the National Natural Science Foundation of China under contract No.41006002
文摘Analysis of tidal current and sea level has been made based on the observations from the summer of 2006 to the winter of 2007,respectively.The result indicates that a two-layer structure of residual current exists in summer,with its upper layer going northwestward and the lower layer southeastward.In addition,some strong residuals exist in the neighboring depth of the pycnocline during the current period of astronomical tide.In winter,except some individual layersthe residual currents mostly direct to the northwest,from which we can see the fluctuation of abnormal sea-level and the appearance of associated current because of the changes of the wind field.The analysis of tidal ellipse indicates that the direction of the maximum semidiurnal component is clockwise from summer to winter,with an angle of 16-18.Moreover,in summer the semidiurnal component rotates with depth clockwise while the diurnal component counterclockwise.However,the vertical structure is almost homogeneous in winter.
基金The National Key R&D Program of China under contract No.2016YFC0402600the National Natural Science Foundation of China under contract No.51979296the Guangzhou Science and Technology Program of China under contract No.202002030452。
文摘Natural and human-induced changes may exert considerable impacts on the seasonal and nodal dynamics of M2 and K1 tidal constituents.Therefore,quantifying the influences of these factors on tidal regime changes is essential for sustainable water resources management in coastal environments.In this study,the enhanced harmonic analysis was applied to extract the seasonal variability of the M2 and K1 tidal amplitudes and phases at three gauging stations along Lingdingyang Bay of the Zhujiang River Delta.The seasonal dynamics in terms of tidal wave celerity and amplification/damping rate were used to quantify the impacts of human-induced estuarine morphological alterations on M2 and K1 tidal hydrodynamics in inner and outer Lingdingyang Bay.The results show that both tidal amplification/damping rate and wave celerity were considerably increased from the pre-anthropogenic activity period(Pre-AAP)to the post-anthropogenic activity period(Post-AAP)excepting the tidal amplification/damping rate in outer Lingdingyang Bay,and the variations in outer Lingdingyang Bay was larger than those in inner Lingdingyang Bay.The alterations in these two parameters were more significant in flood season than in dry season in both inner and outer Lingdingyang Bay.The seasonal variability of M2 and K1 tidal amplitudes were further quantified using a regression model accounting for the 18.61-year lunar nodal modulation,where this study observes a considerable alteration in M2 constituent owing to human interventions.During the Post-AAP,the M2 amplitudes at the downstream station were larger than those that would have occurred in the absence of strong human interventions,whereas the opposite was true for the upstream station,leading to a substantial decrease in tidal amplification in outer Lingdingyang Bay.However,it is opposite in inner Lingdingyang Bay.The underlying mechanism can be primarily attributed to channel deepening and narrowing caused by human interventions,that resulted in substantial enlargement of the bay volume and reduced the effective bottom friction,leading to faster wave celerity and stronger amplified waves.
文摘To study the Taiwan Strait （TS）, an unusual sea area, the numerical model in marginal seas of China is used to simulate and analyze the tidal wave motion in the strait. The numerical modeling experiments reproduce the amphidromic system of the M2 tide in the south end of the Taiwan strait, and consequently confirm the existence of the degenerate amphidromic system. On this basis, further discussion is conducted on the M2 system and its formation mechanism. It can be concluded that the tidal waves of the TS is consisted of the progressing wave from the north entrance and the degenerate amphidromic system from the south entrance, in which the progressing wave from the north entrance dominates the tidal wave motion in the strait. Except for the convergent effect caused by the landform and boundary, the degenerate amphidromic system produced in the south of the strait is another important factor for the following phenomena： the large tidal range in the middle of the strait, the concentrative zone of co-amplitude and co-phase line in the south of the strait. The degenerate amphidromic system is mainly produced by the incident Pacific Ocean tidal wave from the Luzon strait and the action by the shoreline and landform. The position of the amphidromic point is compelled to move toward southwest until degenerating by the powerful progressing wave from the north entrance.
基金supported by the National High Technology Research and Development Program (‘863’ Program) of China under contract No. 2012AA091701the Fundamental Research Fund for the Central University of China under the contract No. 2012212020211
文摘This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surface wave radar(HFSWR) systems. The analysis shows that the tidal current pattern in the southwestern Taiwan Strait is primarily semi-diurnal and influenced significantly by shallow water constituents. The spatial distribution of tidal current ellipses of M2 is probably affected by the interaction between two different systems of tide wave, one from the northern mouth of Taiwan Strait and the other from the Bashi Channel. The directions of the major axes of M2 tidal current ellipses coincide roughly with the axis of the Taiwan Strait. The spatial distribution of the magnitudes of the probable maximum current velocity(PMCS) shows gradual increase of the velocity from northeast to southwest, which is in accordance with the spatial distribution of the measured maximum current velocity(MMCS). The directions of the residual currents are in accordance with the direction of the prevailing monsoon wind at the Taiwan Strait and the direction of the Taiwan warm current during summer. The bathymetry also shows a significant effect on the spatial distribution characteristics of tidal currents.
文摘A three dimensional hydrodynamic was developed for the Dubai coastal zone including the Dubai Creek. The model is based on DHI （Danish Hydraulic Institute＇s） MIKE 3 HD （FM） modeling software. The model was subjected to extensive calibration making use of recorded water levels, currents, water temperature and salinity. A high level of accuracy in calibration was achieved as indicated by the computed statistical error parameters at all recording stations. The model results combined with field recording of water levels were used to ascertain tidal wave propagation pattern in the Dubai coastal zone and in and out of the Dubai creek. This model will be a very useful tool in assessing impacts of planned connection of artificial waterways to the Dubai Creek.
基金supported by Special Foundation of Earthquake Science(201408006)Director Foundation of Institute of Seismology,China Earthquake Administration(201516214)
文摘This work analyzes the quality of crustal tilt and strain observations during 2014, which were acquired from 269 sets of ground tiltmeters and 212 sets of strainmeters. In terms of data quality, the water tube tiltmeters presented the highest rate of excellent quality,approximately 91%, and the pendulum tiltmeters and ground strainmeters yielded rates of81% and 78%, respectively. This means that a total of 380 sets of instruments produced high-quality observational data suitable for scientific investigations and analyses.
文摘Wave equation model(WEM)first developed by Lynch and Gray [2]is one of accurate and effective numerical methods to resolve shallow water equations.This paper shows the numerical consistency of the second- order wave equation and the first- order continuity equation, analyzes the error between them. This paper also shows that the numerical friction factor τo appearing in wave equation is of key importance to the numerical solutions and mass conservation of wave equation model.Numerical calculations of M2 tidal waves in rectangular harbor and a quarter annular harbor are made to demonstrate that it is possible to find a proper numerical friction factor τowith which accurate solutions and satisfactory mass conservation can be achieved by wave equation model.
文摘Marine energy developmenthas been drownedout by Suco ssful clean power projects on land.Can new government policies give tidal and wave power generators the jump start they need?
