The effects of sea surface temperature（SST）,cloud radiative and microphysical processes,and diurnal variations on rainfall statistics are documented with grid data from the two-dimensional equilibrium cloud-resolvin...The effects of sea surface temperature（SST）,cloud radiative and microphysical processes,and diurnal variations on rainfall statistics are documented with grid data from the two-dimensional equilibrium cloud-resolving model simulations.For a rain rate of higher than 3 mm.h 1,water vapor convergence prevails.The rainfall amount decreases with the decrease of SST from 29℃ to 27℃,the inclusion of diurnal variation of SST,or the exclusion of microphysical effects of ice clouds and radiative effects of water clouds,which are primarily associated with the decreases in water vapor convergence.However,the amount of rainfall increases with the increase of SST from 29℃ to 31℃,the exclusion of diurnal variation of solar zenith angle,and the exclusion of the radiative effects of ice clouds,which are primarily related to increases in water vapor convergence.For a rain rate of less than 3 mm.h 1,water vapor divergence prevails.Unlike rainfall statistics for rain rates of higher than 3 mm.h 1,the decrease of SST from 29℃ to 27℃ and the exclusion of radiative effects of water clouds in the presence of radiative effects of ice clouds increase the rainfall amount,which corresponds to the suppression in water vapor divergence.The exclusion of microphysical effects of ice clouds decreases the amount of rainfall,which corresponds to the enhancement in water vapor divergence.The amount of rainfall is less sensitive to the increase of SST from 29℃ to 31℃ and to the radiative effects of water clouds in the absence of the radiative effects of ice clouds.展开更多
The action of the wind field and the influence of topography can cause divergence or convergence of surface current. The existence of the divergence-convergence effect is proved and the dynamical significance of the d...The action of the wind field and the influence of topography can cause divergence or convergence of surface current. The existence of the divergence-convergence effect is proved and the dynamical significance of the divergent or convergent state and its link with many marine phenomena are pointed out. Divergence fields of surface current in the Bohai Sea in winter and summer are obtained by numerical modelling describing the divergence-convergence character of seasonally wind-driven current. The relation between the effect and seasonal marine phenomena is discussed. Study on the divergence-convergence effect of surface current (DCESC)can be an indirect method for testing the calculated results.展开更多
Two cruises for multi discipline investigation were conducted in October and November, 1998 in Daya Bay to collect: (1) samples from five levels including sea surface microlayer (SML), subsurface (SSL), surface, body ...Two cruises for multi discipline investigation were conducted in October and November, 1998 in Daya Bay to collect: (1) samples from five levels including sea surface microlayer (SML), subsurface (SSL), surface, body (mid column) and bottom water; and (2) observational data on chlorophyll a and nutrients, and important factors such as turbidity, BOD, COD, TN, TP and phytoplankton. Results showed that there was no enrichment of chlorophyll a in the SML, but quite notable enrichment of some organic matter and nutrients. Compared with the findings in earlier researches, PO 4 P and SiO 3 Si have decreased, and the N/P ratio has increased obviously to even more than 100 in the SML. It is concluded preliminarily that PO 4 P and SiO 3 Si mainly determine phytoplankton growth in Daya Bay at present.展开更多
Sea surface wind stress variabilities near and off the east coast of Korea, are examined using 7 kinds of wind datasets from measurements at 2 coastal (land) stations and 2 ocean buoys,satellite scatterometer (QuikSCA...Sea surface wind stress variabilities near and off the east coast of Korea, are examined using 7 kinds of wind datasets from measurements at 2 coastal (land) stations and 2 ocean buoys,satellite scatterometer (QuikSCAT), and global reanalyzed products (ECMWF,NOGAPS,and NCEP/NCAR). Temporal variabilities are analyzed at 3 frequency bands; synoptic (2-20 d), intra-seasonal (20-90 d),and seasonal (>90 d).Synoptic and intra-seasonal variations are predominant near and off the Donghae City due to the passage of the mesoscale weather system. Seasonal variation is caused by southeastward wind stress during Asian winter monsoon. The sea surface wind stress from reanalyzed datasets.QuikSCAT and KMA-B measurements off the coast show good agreement in the magnitude and direction,which are strongly aligned with the alongshore direction.At the land-based sites,wind stresses are much weaker by factors of 3-10 due to the mountainous landmass on the east parts of Korea Peninsula.The first EOF modes(67%-70%) of wind stresses from reanalyzed and QuikSCAT data have similar structures of the strong southeastward wind stress in winter along the coast but show different curl structures at scales less than 200 km due to the orographic effects.The second EOF modes (23%-25%) show southwestward wind stress in every September along the east coast of the North Korea展开更多
Nowadays, Autonomous Underwater Vehicles(AUVs) are frequently used for exploring the oceans. The hydrodynamics of AUVs moving in the vicinity of the water surface are significantly different at higher depths. In this ...Nowadays, Autonomous Underwater Vehicles(AUVs) are frequently used for exploring the oceans. The hydrodynamics of AUVs moving in the vicinity of the water surface are significantly different at higher depths. In this paper, the hydrodynamic coefficients of an AUV in non-dimensional depths of 0.75, 1, 1.5, 2, and 4D are obtained for movement close to the free-surface. Reynolds Averaged Navier Stokes Equations(RANS) are discretized using the finite volume approach and the water-surface effects modeled using the Volume of Fraction(VOF) method. As the operating speeds of AUVs are usually low, the boundary layer over them is not fully laminar or fully turbulent, so the effect of boundary layer transition from laminar to turbulent flow was considered in the simulations. Two different turbulence/transition models were used: 1) a full-turbulence model, the k-ε model, and 2) a turbulence/transition model, Menter's Transition-SST model. The results show that the Menter's Transition-SST model has a better consistency with experimental results. In addition, the wave-making effects of these bodies are studied at different immersion depths in the sea-surface vicinity or at finite depths. It is observed that the relevant pitch moments and lift coefficients are non-zero for these axi-symmetric bodies when they move close to the sea-surface. This is not expected for greater depths.展开更多
In considering the vertical heat boundary approximation for the free surface applied. However, due to the existence of the transport problems in the upper ocean, the flat upper and the horizontal homogenous hypothesis...In considering the vertical heat boundary approximation for the free surface applied. However, due to the existence of the transport problems in the upper ocean, the flat upper and the horizontal homogenous hypothesis are usually wave motion, the application of this approximation may result in some errors to the solar irradiation since it decays quickly in respect to the actual thickness of the water layer below the surface; on the other hand, due to the fluctuation of the water layer depth, it is improper to neglect the effects of the horizontal advection and turbulent diffusion since they also contribute to the vertical heat transport. A new model is constructed in this study to reflect these effects. The corresponding numerical simulations show that the wave motion may remarkably accelerate the vertical heat transferring process and the variation of the temperature in the wave affected layer appears in an oscillating manner.展开更多
In the context of a model of tropical cyclone intensity based on an improved meso-scale atmospheric model, numerical simulation is performed of the track and intensity variation of tropical cyclones (TC) arising from ...In the context of a model of tropical cyclone intensity based on an improved meso-scale atmospheric model, numerical simulation is performed of the track and intensity variation of tropical cyclones (TC) arising from sea surface temperature (SST) variation over a specified sea region. Evidence suggests that the model is capable of modeling quite welt the track and intensity of TC: SST variation leads to an abrupt change in the cyclone intensity: the response of the cyclone to the abrupt SST change lasts 8—12 h.展开更多
A tropical cyclone-marine mixed layer model including air-sea interaction is established to conduct numerical experiment with the effects of SST on the cyclone's intensity,Evidence suggests that with air-sea inter...A tropical cyclone-marine mixed layer model including air-sea interaction is established to conduct numerical experiment with the effects of SST on the cyclone's intensity,Evidence suggests that with air-sea interaction involved,SST rise causes a drop of central pressure of the storm and SST impact on the intensity is weaker in the coupling case.Moreover,study is undertaken of the intensity variation of another tropical cyclone moving in the cyclone's cold-tail sector,with the results in good agreement with the observational fact.展开更多
A coastal historical evolution of the Yangtze River Delta was discussed in this paper on the basis of the historical data of the coastal zone and an estimation was made for the future change of the coast The emphasi...A coastal historical evolution of the Yangtze River Delta was discussed in this paper on the basis of the historical data of the coastal zone and an estimation was made for the future change of the coast The emphasis was put on the future climate change that will have influence on the sea wall, coastal navigation and freshwater resources in the Delta It was also pointed out that the global warming and precipitation increase in the Yangtze River Valley may exert more impact on the zone In addition, some measures describing how to adapt to the climate change and reduce its impact were put forward展开更多
In this paper, the p-σ five layer primitive equation model segmented by mountains and physical parameterizations including short wave radiation; long wave radiation; large-scale and convective condensation; heat and ...In this paper, the p-σ five layer primitive equation model segmented by mountains and physical parameterizations including short wave radiation; long wave radiation; large-scale and convective condensation; heat and moisture transport from surface to the first model level is used. The horizonial resolution is 5° lat. ×5° long. with the integration region from 25°S to 55°N and from 5°W eastward to 175°W. The model was spun up with perpetual June boundary conditions and forcing starting with June zonal mean heights and geostrophic wind field. In order to investigate the effects of SST (sea surface tempefuture) over the equatorial Western Pacific and the Indian Ocean on the Asian summer monsoon, four sets of numerical experments with positive anomalies over the equatorial Western Pacific, and positive and negative anomalies over the Western Indian Ocean, and zonal mean SST (the control case) are performed. The experimental results show that the South Asian low in the lower troposphere and the anticyclone over the South Asia in the uppet troposphere intensified when positive SST anomalies over the equatorial Western Pacific is included. A statistical test method for simulations is proposed. Finally, the influence mechanism of the SST anomalies over the equatorial oceans is discussed. It is worth stressing that the effects of the SST over the equatorial oceans on the Asian summer monsoon can arise as a result of interaction of SST anomalies, atmospheric flow field and heat sources and sinks in the atmosphere.展开更多
A set of equations was derived for a non-Boussinesq ocean model in thispaper. A new time-splitting scheme was introduced which incorporates the 4th-order Runge-Kuttaexplicit scheme of low-frequency mode and an implici...A set of equations was derived for a non-Boussinesq ocean model in thispaper. A new time-splitting scheme was introduced which incorporates the 4th-order Runge-Kuttaexplicit scheme of low-frequency mode and an implicit scheme of high-frequency mode. With thismodel, potential temperature, salinity fields and sea surface height were calculated simultaneouslysuch that the numerical error of extrapolation of density field from the current time level to thenext one could be reduced while using the equation of mass conservation to determine sea surfaceheight. The non-Bouss-inesq effect on the density field and sea surface height was estimated bynumerical experiments in the final part of this paper.展开更多
基金Project supported by the National Basic Research Program of China (Grant No. 2012CB417201)the National Natural Science Foundation of China (Grant Nos. 41075034,40930950,40975034,and 41075044)
文摘The effects of sea surface temperature（SST）,cloud radiative and microphysical processes,and diurnal variations on rainfall statistics are documented with grid data from the two-dimensional equilibrium cloud-resolving model simulations.For a rain rate of higher than 3 mm.h 1,water vapor convergence prevails.The rainfall amount decreases with the decrease of SST from 29℃ to 27℃,the inclusion of diurnal variation of SST,or the exclusion of microphysical effects of ice clouds and radiative effects of water clouds,which are primarily associated with the decreases in water vapor convergence.However,the amount of rainfall increases with the increase of SST from 29℃ to 31℃,the exclusion of diurnal variation of solar zenith angle,and the exclusion of the radiative effects of ice clouds,which are primarily related to increases in water vapor convergence.For a rain rate of less than 3 mm.h 1,water vapor divergence prevails.Unlike rainfall statistics for rain rates of higher than 3 mm.h 1,the decrease of SST from 29℃ to 27℃ and the exclusion of radiative effects of water clouds in the presence of radiative effects of ice clouds increase the rainfall amount,which corresponds to the suppression in water vapor divergence.The exclusion of microphysical effects of ice clouds decreases the amount of rainfall,which corresponds to the enhancement in water vapor divergence.The amount of rainfall is less sensitive to the increase of SST from 29℃ to 31℃ and to the radiative effects of water clouds in the absence of the radiative effects of ice clouds.
基金Contribution No.2110 from the Institute of Oceanology,Academia SinicaProject supported by the National Natural Science Foundation of China
文摘The action of the wind field and the influence of topography can cause divergence or convergence of surface current. The existence of the divergence-convergence effect is proved and the dynamical significance of the divergent or convergent state and its link with many marine phenomena are pointed out. Divergence fields of surface current in the Bohai Sea in winter and summer are obtained by numerical modelling describing the divergence-convergence character of seasonally wind-driven current. The relation between the effect and seasonal marine phenomena is discussed. Study on the divergence-convergence effect of surface current (DCESC)can be an indirect method for testing the calculated results.
文摘Two cruises for multi discipline investigation were conducted in October and November, 1998 in Daya Bay to collect: (1) samples from five levels including sea surface microlayer (SML), subsurface (SSL), surface, body (mid column) and bottom water; and (2) observational data on chlorophyll a and nutrients, and important factors such as turbidity, BOD, COD, TN, TP and phytoplankton. Results showed that there was no enrichment of chlorophyll a in the SML, but quite notable enrichment of some organic matter and nutrients. Compared with the findings in earlier researches, PO 4 P and SiO 3 Si have decreased, and the N/P ratio has increased obviously to even more than 100 in the SML. It is concluded preliminarily that PO 4 P and SiO 3 Si mainly determine phytoplankton growth in Daya Bay at present.
文摘Sea surface wind stress variabilities near and off the east coast of Korea, are examined using 7 kinds of wind datasets from measurements at 2 coastal (land) stations and 2 ocean buoys,satellite scatterometer (QuikSCAT), and global reanalyzed products (ECMWF,NOGAPS,and NCEP/NCAR). Temporal variabilities are analyzed at 3 frequency bands; synoptic (2-20 d), intra-seasonal (20-90 d),and seasonal (>90 d).Synoptic and intra-seasonal variations are predominant near and off the Donghae City due to the passage of the mesoscale weather system. Seasonal variation is caused by southeastward wind stress during Asian winter monsoon. The sea surface wind stress from reanalyzed datasets.QuikSCAT and KMA-B measurements off the coast show good agreement in the magnitude and direction,which are strongly aligned with the alongshore direction.At the land-based sites,wind stresses are much weaker by factors of 3-10 due to the mountainous landmass on the east parts of Korea Peninsula.The first EOF modes(67%-70%) of wind stresses from reanalyzed and QuikSCAT data have similar structures of the strong southeastward wind stress in winter along the coast but show different curl structures at scales less than 200 km due to the orographic effects.The second EOF modes (23%-25%) show southwestward wind stress in every September along the east coast of the North Korea
文摘Nowadays, Autonomous Underwater Vehicles(AUVs) are frequently used for exploring the oceans. The hydrodynamics of AUVs moving in the vicinity of the water surface are significantly different at higher depths. In this paper, the hydrodynamic coefficients of an AUV in non-dimensional depths of 0.75, 1, 1.5, 2, and 4D are obtained for movement close to the free-surface. Reynolds Averaged Navier Stokes Equations(RANS) are discretized using the finite volume approach and the water-surface effects modeled using the Volume of Fraction(VOF) method. As the operating speeds of AUVs are usually low, the boundary layer over them is not fully laminar or fully turbulent, so the effect of boundary layer transition from laminar to turbulent flow was considered in the simulations. Two different turbulence/transition models were used: 1) a full-turbulence model, the k-ε model, and 2) a turbulence/transition model, Menter's Transition-SST model. The results show that the Menter's Transition-SST model has a better consistency with experimental results. In addition, the wave-making effects of these bodies are studied at different immersion depths in the sea-surface vicinity or at finite depths. It is observed that the relevant pitch moments and lift coefficients are non-zero for these axi-symmetric bodies when they move close to the sea-surface. This is not expected for greater depths.
基金Supported by the National High Technology Research and Development Program of China (863 Program, No. 2006AA09A309)China Postdoctoral Science Foundation (No. 20070411111)the Fund of Shandong Province for the Excellent Post-Doctors (No. 200603056)
文摘In considering the vertical heat boundary approximation for the free surface applied. However, due to the existence of the transport problems in the upper ocean, the flat upper and the horizontal homogenous hypothesis are usually wave motion, the application of this approximation may result in some errors to the solar irradiation since it decays quickly in respect to the actual thickness of the water layer below the surface; on the other hand, due to the fluctuation of the water layer depth, it is improper to neglect the effects of the horizontal advection and turbulent diffusion since they also contribute to the vertical heat transport. A new model is constructed in this study to reflect these effects. The corresponding numerical simulations show that the wave motion may remarkably accelerate the vertical heat transferring process and the variation of the temperature in the wave affected layer appears in an oscillating manner.
基金This study was supported by the China National Key Project under Contract 85-906-07-03-05
文摘In the context of a model of tropical cyclone intensity based on an improved meso-scale atmospheric model, numerical simulation is performed of the track and intensity variation of tropical cyclones (TC) arising from sea surface temperature (SST) variation over a specified sea region. Evidence suggests that the model is capable of modeling quite welt the track and intensity of TC: SST variation leads to an abrupt change in the cyclone intensity: the response of the cyclone to the abrupt SST change lasts 8—12 h.
基金the China National Key Project under Contract 85-906-07-03-05.
文摘A tropical cyclone-marine mixed layer model including air-sea interaction is established to conduct numerical experiment with the effects of SST on the cyclone's intensity,Evidence suggests that with air-sea interaction involved,SST rise causes a drop of central pressure of the storm and SST impact on the intensity is weaker in the coupling case.Moreover,study is undertaken of the intensity variation of another tropical cyclone moving in the cyclone's cold-tail sector,with the results in good agreement with the observational fact.
文摘A coastal historical evolution of the Yangtze River Delta was discussed in this paper on the basis of the historical data of the coastal zone and an estimation was made for the future change of the coast The emphasis was put on the future climate change that will have influence on the sea wall, coastal navigation and freshwater resources in the Delta It was also pointed out that the global warming and precipitation increase in the Yangtze River Valley may exert more impact on the zone In addition, some measures describing how to adapt to the climate change and reduce its impact were put forward
文摘In this paper, the p-σ five layer primitive equation model segmented by mountains and physical parameterizations including short wave radiation; long wave radiation; large-scale and convective condensation; heat and moisture transport from surface to the first model level is used. The horizonial resolution is 5° lat. ×5° long. with the integration region from 25°S to 55°N and from 5°W eastward to 175°W. The model was spun up with perpetual June boundary conditions and forcing starting with June zonal mean heights and geostrophic wind field. In order to investigate the effects of SST (sea surface tempefuture) over the equatorial Western Pacific and the Indian Ocean on the Asian summer monsoon, four sets of numerical experments with positive anomalies over the equatorial Western Pacific, and positive and negative anomalies over the Western Indian Ocean, and zonal mean SST (the control case) are performed. The experimental results show that the South Asian low in the lower troposphere and the anticyclone over the South Asia in the uppet troposphere intensified when positive SST anomalies over the equatorial Western Pacific is included. A statistical test method for simulations is proposed. Finally, the influence mechanism of the SST anomalies over the equatorial oceans is discussed. It is worth stressing that the effects of the SST over the equatorial oceans on the Asian summer monsoon can arise as a result of interaction of SST anomalies, atmospheric flow field and heat sources and sinks in the atmosphere.
文摘A set of equations was derived for a non-Boussinesq ocean model in thispaper. A new time-splitting scheme was introduced which incorporates the 4th-order Runge-Kuttaexplicit scheme of low-frequency mode and an implicit scheme of high-frequency mode. With thismodel, potential temperature, salinity fields and sea surface height were calculated simultaneouslysuch that the numerical error of extrapolation of density field from the current time level to thenext one could be reduced while using the equation of mass conservation to determine sea surfaceheight. The non-Bouss-inesq effect on the density field and sea surface height was estimated bynumerical experiments in the final part of this paper.
