This paper examines the simplification strategy of retaining only the nonhydrostatic effect of local acceleration in a three-dimensional fully nonhydrostatic model regarding the submesoscale wave phenomenon in the oce...This paper examines the simplification strategy of retaining only the nonhydrostatic effect of local acceleration in a three-dimensional fully nonhydrostatic model regarding the submesoscale wave phenomenon in the ocean.Elaborate scale analysis of the vertical component of the Reynold-averaged Navier-Stokes(RANS)equation was performed,confirming the rationalization of this simplification.Then,the simplification was implemented in a RANS equation-based nonhydrostatic model NHWAVE(nonhydrostatic WAVE)to make a simplified nonhydrostatic model.Numerical examples were taken to test its performance,including surface sinusoidal waves propagating on an idealized East China Sea topography,tidally induced internal lee waves and small-scale solitary waves.The results show that in a considerably wide range of nonlinear strengths,the simplified nonhydrostatic model can obtain similar results as those in the fully nonhydrostatic model,even for smaller-scale solitary waves.Nonlinearity influences the applicability of the simplification.The stronger the nonlinearity is,the worse the simplified model describes the nonhydrostatic phenomenon.In general,the simplified nonhydrostatic model can simulate surface waves better than internal waves.Improvement of computational efficiency in the simplified nonhydrostatic model is reasonable,reducing the central processing unit time duration in the fully nonhydrostatic model by 16.4%–20.6%.The specially designed algorithm based on the simplified nonhydrostatic equation can remarkably reduce the computational time.展开更多
The equations of state(EOSs)of materials are the cornerstone of condensed matter physics,material science,and geophysics.However,acquiring an accurate EOS in diamond anvil cell(DAC)experiments continues to prove probl...The equations of state(EOSs)of materials are the cornerstone of condensed matter physics,material science,and geophysics.However,acquiring an accurate EOS in diamond anvil cell(DAC)experiments continues to prove problematic because the current lack of an accurate pressure scale with clarified sources of uncertainty makes it difficult to determine a precise pressure value at high pressure,and nonhydrostaticity affects both the volume and pressure determination.This study will discuss the advantages and drawbacks of various pressure scales,and propose an absolute pressure scale and correction methods for the effects of non-hydrostaticity.At the end of this paper,we analyze the accuracy of the determined EOS in the DAC experiments we can achieve to date.展开更多
Nonlinear internal waves(NIWs) are ubiquitous around the Kara Sea, a part of the Arctic Ocean that is north of Siberia. Three hot spot sources for internal waves, one of which is the Kara Strait, have been identified ...Nonlinear internal waves(NIWs) are ubiquitous around the Kara Sea, a part of the Arctic Ocean that is north of Siberia. Three hot spot sources for internal waves, one of which is the Kara Strait, have been identified based on Envisat ASAR. The generation and evolution of the NIWs through the interactions of the tide and topography across the strait is studied based on a nonhydrostatic numerical model. The model captures most wave characteristics shown by satellite data. A typical inter-packets distance on the Barents Sea side is about 25 km in summer, with a phase speed about 0.65 m/s. A northward background current may intensify the accumulation of energy during generation, but it has little influence on the other properties of the generated waves. The single internal solitary wave(ISW) structure is a special phenomenon that follows major wave trains, with a distance about 5–8 km. This wave is generated with the leading wave packets during the same tidal period. When a steady current toward the Kara Sea is included, the basic generation process is similar, but the waves toward the Kara Sea weaken and display an internal bore-like structure with smaller amplitude than in the control experiment. In winter, due to the growth of sea ice, stratification across the Kara Strait is mainly determined by the salinity, with an almost uniform temperature close to freezing. A pycnocline deepens near the middle of the water depth(Barents Sea side), and the NIWs process is not as important as the NIWs process in summer. There is no fission process during the simulation.展开更多
A 3D compressible nonhydrostatic dynamic core based on a three-point multi-moment constrained finite-volume (MCV) method is developed by extending the previous 2D nonhydrostatic atmospheric dynamics to 3D on a terrain...A 3D compressible nonhydrostatic dynamic core based on a three-point multi-moment constrained finite-volume (MCV) method is developed by extending the previous 2D nonhydrostatic atmospheric dynamics to 3D on a terrainfollowing grid. The MCV algorithm defines two types of moments: the point-wise value (PV) and the volume-integrated average (VIA). The unknowns (PV values) are defined at the solution points within each cell and are updated through the time evolution formulations derived from the governing equations. Rigorous numerical conservation is ensured by a constraint on the VIA moment through the flux form formulation. The 3D atmospheric dynamic core reported in this paper is based on a three-point MCV method and has some advantages in comparison with other existing methods, such as uniform third-order accuracy, a compact stencil, and algorithmic simplicity. To check the performance of the 3D nonhydrostatic dynamic core, various benchmark test cases are performed. All the numerical results show that the present dynamic core is very competitive when compared to other existing advanced models, and thus lays the foundation for further developing global atmospheric models in the near future.展开更多
An adaptive 2 D nonhydrostatic dynamical core is proposed by using the multi-moment constrained finite-volume(MCV) scheme and the Berger-Oliger adaptive mesh refinement(AMR) algorithm. The MCV scheme takes several poi...An adaptive 2 D nonhydrostatic dynamical core is proposed by using the multi-moment constrained finite-volume(MCV) scheme and the Berger-Oliger adaptive mesh refinement(AMR) algorithm. The MCV scheme takes several pointwise values within each computational cell as the predicted variables to build high-order schemes based on single-cell reconstruction. Two types of moments, such as the volume-integrated average(VIA) and point value(PV), are defined as constraint conditions to derive the updating formulations of the unknowns, and the constraint condition on VIA guarantees the rigorous conservation of the proposed model. In this study, the MCV scheme is implemented on a height-based, terrainfollowing grid with variable resolution to solve the nonhydrostatic governing equations of atmospheric dynamics. The AMR grid of Berger-Oliger consists of several groups of blocks with different resolutions, where the MCV model developed on a fixed structured mesh can be used directly. Numerical formulations are designed to implement the coarsefine interpolation and the flux correction for properly exchanging the solution information among different blocks. Widely used benchmark tests are carried out to evaluate the proposed model. The numerical experiments on uniform and AMR grids indicate that the adaptive model has promising potential for improving computational efficiency without losing accuracy.展开更多
The Global-Regional Integrated forecast System(GRIST)is the next-generation weather and climate integrated model dynamic framework developed by Chinese Academy of Meteorological Sciences.In this paper,we present sever...The Global-Regional Integrated forecast System(GRIST)is the next-generation weather and climate integrated model dynamic framework developed by Chinese Academy of Meteorological Sciences.In this paper,we present several changes made to the global nonhydrostatic dynamical(GND)core,which is part of the ongoing prototype of GRIST.The changes leveraging MPI and PnetCDF techniques were targeted at the parallelization and performance optimization to the original serial GND core.Meanwhile,some sophisticated data structures and interfaces were designed to adjust flexibly the size of boundary and halo domains according to the variable accuracy in parallel context.In addition,the I/O performance of PnetCDF decreases as the number of MPI processes increases in our experimental environment.Especially when the number exceeds 6000,it caused system-wide outages(SWO).Thus,a grouping solution was proposed to overcome that issue.Several experiments were carried out on the supercomputing platform based on Intel x86 CPUs in the National Supercomputing Center in Wuxi.The results demonstrated that the parallel GND core based on grouping solution achieves good strong scalability and improves the performance significantly,as well as avoiding the SWOs.展开更多
Intergranular fluids within the nonhydrostatically stressed solids are a sort of important fluids in the crust. Research on the mechanical and chemical behavior of the intergranular fluids in nonhydrostatically stress...Intergranular fluids within the nonhydrostatically stressed solids are a sort of important fluids in the crust. Research on the mechanical and chemical behavior of the intergranular fluids in nonhydrostatically stressed rocks at low temperature is a key for understanding deformation and syntectonic geochemical processes in mid to shallow crust. Theoretically, it is suggested that the fluid film sandwiched between solid grains is one of the main states of intergranular fluids in the nonhydrostatically stressed solids. Their superthin thickness makes the fluid films have the mechanical and chemical behavior very different from the common fluids. Because of hydration force, double layer repulsive force or osmotic pressure due to double layer, the fluid films can transmit nonhydrostatic stress. The solid minerals intergranular fluids interaction and mass transfer by intergranular fluids is stress related, because the stress in solid minerals can enhance the free energy of solid matter on the interfaces. The thermodynamic and kinetic equations for the simple case of stress induced processes are derived.展开更多
All solutions of the Korteweg-de Vries(K-dV) equation that are bounded on the real line are physically relevant, depending on the application area of interest. Usually, both analytical and numerical approaches conside...All solutions of the Korteweg-de Vries(K-dV) equation that are bounded on the real line are physically relevant, depending on the application area of interest. Usually, both analytical and numerical approaches consider solution profiles that are either spatially localized or (quasi) periodic. The development of numerical techniques for obtaining approximate solution of partial differential equations has very much increased in the finite element and finite difference methods. Recently, new auxiliary equation method introduced by PANG, BIAN and CHAO is applied to the analytical solution of K-dV equation and wavelet methods are applied to the numerical solution of partial differential equations. Pioneer works in this direction are those of Beylkin, Dahmen, Jaffard and Glowinski, among others. In this research we employ the new auxiliary equation method to obtain the effect of dispersion term on travelling wave solution of K-dV and their numerical estimation as well. Our approach views the limit behavior as an invariant measure of the fast motion drifted by the slow component, where the known constants of motion of the fast system are employed as slowly evolv- ing observables;averaging equations for the latter lead to computation of the characteristic features of the motion.展开更多
The newly developed nonhydrostatic(NH)global spectral dynamical core is evaluated by using three-dimensional(3D)benchmark tests with/without moisture.This new dynamical core differs from the original Aladin-NH like on...The newly developed nonhydrostatic(NH)global spectral dynamical core is evaluated by using three-dimensional(3D)benchmark tests with/without moisture.This new dynamical core differs from the original Aladin-NH like one in the combined use of a dry-mass vertical coordinate and a new temperature variable,and thus,it inherently conserves the dry air mass and includes the mass sink effect associated with precipitation flux.Some 3D dry benchmark tests are first conducted,including steady state,dry baroclinic waves,mountain waves in non-sheared and sheared background flows,and a dry Held–Suarez test.The results from these test cases demonstrate that the present dynamical core is accurate and robust in applications on the sphere,especially for addressing the nonhydrostatic effects.Then,three additional moist test cases are conducted to further explore the improvement of the new dynamical core.Importantly,in contrast to the original Aladin-NH like one,the new dynamical core prefers to obtain simulated tropical cyclone with lower pressure,stronger wind speeds,and faster northward movement,which is much closer to the results from the Model for Prediction Across Scales(MPAS),and it also enhances the updrafts and provides enhanced precipitation rate in the tropics,which partially compensates the inefficient vertical transport due to the absence of the deep convection parameterization in the moist Held–Suarez test,thus demonstrating its potential value for full-physics global NH numerical weather prediction application.展开更多
The Global/Regional Assimilation and PrEdiction System(GRAPES) is a newly developed global non-hydrostatic numerical prediction model,which will become the next generation medium-range opera-tional model at China Mete...The Global/Regional Assimilation and PrEdiction System(GRAPES) is a newly developed global non-hydrostatic numerical prediction model,which will become the next generation medium-range opera-tional model at China Meteorological Administration(CMA).The dynamic framework of GRAPES is featuring with fully compressible equations,nonhydrostatic or hydrostatic optionally,two-level time semi-Lagrangian and semi-implicit time integration,Charney-Phillips vertical staggering,and complex three-dimensional pre-conditioned Helmholtz solver,etc.Concerning the singularity of horizontal momentum equations at the poles,the polar discretization schemes are described,which include adoption of Arakawa C horizontal grid with ν at poles,incorporation of polar filtering to maintain the computational stability,the correction to Helmholtz equation near the poles,as well as the treatment of semi-Lagrangian interpolation to improve the departure point accuracy,etc.The balanced flow tests validate the rationality of the treatment of semi-Lagrangian departure point calculation and the polar discretization during long time integration.Held and Suarez tests show that the conservation proper-ties of GRAPES model are quite good.展开更多
During the period of 3—5 August 1996(for short “96.8”),an extraordinary rainstorm eventoccurred in Henan,Hebei and Shanxi Provinces in China,resulting in severe flood catastrophe.Synoptic analyses indicated that th...During the period of 3—5 August 1996(for short “96.8”),an extraordinary rainstorm eventoccurred in Henan,Hebei and Shanxi Provinces in China,resulting in severe flood catastrophe.Synoptic analyses indicated that the stable gross col field and the interaction between a northwardmoving typhoon(down into low pressure)and its east lateral Pacific subtropical high were thelarge-and meso-scale circulation conditions of the “96.8” extraordinary rainstorm.The mesoscaletyphoon-low and its specific dynamical and thermodynamical structures were directly related to thisrainstorm event.The nonhydrostatic version of mesoscale numerical model MM5 was used toconduct investigation of numerical simulation for this case.The simulation with the full physicalprocesses of nonhydrostatic version MM5 was basically possessed of a capability to reproduce thegenesis,development and evolution of the large-scale and meso-α scale synoptic systems.Thesimulative results using a two-way interactive nesting procedure revealed that the typhoon-low waspossessed of an intensive coupled mechanism between the dynamical and thermodynamical fields,namely,the developing typhoon-low was possessed of a structure of the.cyclonic vorticity columnwith warm center and high humidity,the vorticity column on the lower levels was the moistconvective instability and negative moist potential vorticity structure:the intensive ascendingvertical motion and the intense divergence on upper levels and intensive convergence on the lowerlevels as well as the development of the convective cloud cluster were intercoupling:the intensesouthern wind jet companied by the typhoon-low was not only the interaccompanying andintercoupling condition of the development and maintenance of the typhoon-low and convectivecloud cluster,but also was the transportable belt of the moisture source and heat energy of the“96.8”extraordinary rainstorm.The analysis of simulative results of precipitation indicated thatthe distribution of the rainfall belt and rainfall rate was basically consistent with that of theobservation in spite of some rainfall centers less or larger than those of the observation for coarseor fine mesh domain,respectively.展开更多
A three-dimensional elastic nonhydrostatic mesoscale(β-γ)model with nested-grid is presented.It uses a set of fullequations in terrain-following coordinates as its basic dynamic frame,which is solved with a time-spl...A three-dimensional elastic nonhydrostatic mesoscale(β-γ)model with nested-grid is presented.It uses a set of fullequations in terrain-following coordinates as its basic dynamic frame,which is solved with a time-splitting algorithmfor acoustic and gravity waves.The model physical parameterization includes a K-theory subgrid eddy mixing for cloudand free atmosphere,a bulk planetary boundary layer parameterization,and three types of sofisticated cloudmicrophysics schemes with double-parameters for hail-bearing clouds,warm clouds and snowing clouds respectively.The model is designed to be used flexibly for simulations of a variety of meso-and small-scale atmospheric processes,and can be improved as a regional and local operational NWP system in future.展开更多
基金The National Natural Science Foundation of China under contract No.41676003.
文摘This paper examines the simplification strategy of retaining only the nonhydrostatic effect of local acceleration in a three-dimensional fully nonhydrostatic model regarding the submesoscale wave phenomenon in the ocean.Elaborate scale analysis of the vertical component of the Reynold-averaged Navier-Stokes(RANS)equation was performed,confirming the rationalization of this simplification.Then,the simplification was implemented in a RANS equation-based nonhydrostatic model NHWAVE(nonhydrostatic WAVE)to make a simplified nonhydrostatic model.Numerical examples were taken to test its performance,including surface sinusoidal waves propagating on an idealized East China Sea topography,tidally induced internal lee waves and small-scale solitary waves.The results show that in a considerably wide range of nonlinear strengths,the simplified nonhydrostatic model can obtain similar results as those in the fully nonhydrostatic model,even for smaller-scale solitary waves.Nonlinearity influences the applicability of the simplification.The stronger the nonlinearity is,the worse the simplified model describes the nonhydrostatic phenomenon.In general,the simplified nonhydrostatic model can simulate surface waves better than internal waves.Improvement of computational efficiency in the simplified nonhydrostatic model is reasonable,reducing the central processing unit time duration in the fully nonhydrostatic model by 16.4%–20.6%.The specially designed algorithm based on the simplified nonhydrostatic equation can remarkably reduce the computational time.
基金supported by the National Natural Science Foundation of China under Grant No.11504354Research Foundation of National Key Laboratory of Shock Wave and Detonation Physics under Grants No.9140C6703010703 and 9140C6703010803.
文摘The equations of state(EOSs)of materials are the cornerstone of condensed matter physics,material science,and geophysics.However,acquiring an accurate EOS in diamond anvil cell(DAC)experiments continues to prove problematic because the current lack of an accurate pressure scale with clarified sources of uncertainty makes it difficult to determine a precise pressure value at high pressure,and nonhydrostaticity affects both the volume and pressure determination.This study will discuss the advantages and drawbacks of various pressure scales,and propose an absolute pressure scale and correction methods for the effects of non-hydrostaticity.At the end of this paper,we analyze the accuracy of the determined EOS in the DAC experiments we can achieve to date.
基金The National Key Research and Development Program of China under contract No.2016YFC1402705the National Natural Science Foundation of China under contract No.41576189
文摘Nonlinear internal waves(NIWs) are ubiquitous around the Kara Sea, a part of the Arctic Ocean that is north of Siberia. Three hot spot sources for internal waves, one of which is the Kara Strait, have been identified based on Envisat ASAR. The generation and evolution of the NIWs through the interactions of the tide and topography across the strait is studied based on a nonhydrostatic numerical model. The model captures most wave characteristics shown by satellite data. A typical inter-packets distance on the Barents Sea side is about 25 km in summer, with a phase speed about 0.65 m/s. A northward background current may intensify the accumulation of energy during generation, but it has little influence on the other properties of the generated waves. The single internal solitary wave(ISW) structure is a special phenomenon that follows major wave trains, with a distance about 5–8 km. This wave is generated with the leading wave packets during the same tidal period. When a steady current toward the Kara Sea is included, the basic generation process is similar, but the waves toward the Kara Sea weaken and display an internal bore-like structure with smaller amplitude than in the control experiment. In winter, due to the growth of sea ice, stratification across the Kara Strait is mainly determined by the salinity, with an almost uniform temperature close to freezing. A pycnocline deepens near the middle of the water depth(Barents Sea side), and the NIWs process is not as important as the NIWs process in summer. There is no fission process during the simulation.
基金supported by the National Key Research and Development Program of China (Grant Nos. 2017YFC1501901 and 2017YFA0603901)the Beijing Natural Science Foundation (Grant No. JQ18001)
文摘A 3D compressible nonhydrostatic dynamic core based on a three-point multi-moment constrained finite-volume (MCV) method is developed by extending the previous 2D nonhydrostatic atmospheric dynamics to 3D on a terrainfollowing grid. The MCV algorithm defines two types of moments: the point-wise value (PV) and the volume-integrated average (VIA). The unknowns (PV values) are defined at the solution points within each cell and are updated through the time evolution formulations derived from the governing equations. Rigorous numerical conservation is ensured by a constraint on the VIA moment through the flux form formulation. The 3D atmospheric dynamic core reported in this paper is based on a three-point MCV method and has some advantages in comparison with other existing methods, such as uniform third-order accuracy, a compact stencil, and algorithmic simplicity. To check the performance of the 3D nonhydrostatic dynamic core, various benchmark test cases are performed. All the numerical results show that the present dynamic core is very competitive when compared to other existing advanced models, and thus lays the foundation for further developing global atmospheric models in the near future.
基金supported by The National Key Research and Development Program of China(Grants Nos.2017YFA0603901 and 2017YFC1501901)The National Natural Science Foundation of China(Grant No.41522504)。
文摘An adaptive 2 D nonhydrostatic dynamical core is proposed by using the multi-moment constrained finite-volume(MCV) scheme and the Berger-Oliger adaptive mesh refinement(AMR) algorithm. The MCV scheme takes several pointwise values within each computational cell as the predicted variables to build high-order schemes based on single-cell reconstruction. Two types of moments, such as the volume-integrated average(VIA) and point value(PV), are defined as constraint conditions to derive the updating formulations of the unknowns, and the constraint condition on VIA guarantees the rigorous conservation of the proposed model. In this study, the MCV scheme is implemented on a height-based, terrainfollowing grid with variable resolution to solve the nonhydrostatic governing equations of atmospheric dynamics. The AMR grid of Berger-Oliger consists of several groups of blocks with different resolutions, where the MCV model developed on a fixed structured mesh can be used directly. Numerical formulations are designed to implement the coarsefine interpolation and the flux correction for properly exchanging the solution information among different blocks. Widely used benchmark tests are carried out to evaluate the proposed model. The numerical experiments on uniform and AMR grids indicate that the adaptive model has promising potential for improving computational efficiency without losing accuracy.
基金This work was supported by the National Key Research and Development Program of China under Grant No.2017YFC1502203.
文摘The Global-Regional Integrated forecast System(GRIST)is the next-generation weather and climate integrated model dynamic framework developed by Chinese Academy of Meteorological Sciences.In this paper,we present several changes made to the global nonhydrostatic dynamical(GND)core,which is part of the ongoing prototype of GRIST.The changes leveraging MPI and PnetCDF techniques were targeted at the parallelization and performance optimization to the original serial GND core.Meanwhile,some sophisticated data structures and interfaces were designed to adjust flexibly the size of boundary and halo domains according to the variable accuracy in parallel context.In addition,the I/O performance of PnetCDF decreases as the number of MPI processes increases in our experimental environment.Especially when the number exceeds 6000,it caused system-wide outages(SWO).Thus,a grouping solution was proposed to overcome that issue.Several experiments were carried out on the supercomputing platform based on Intel x86 CPUs in the National Supercomputing Center in Wuxi.The results demonstrated that the parallel GND core based on grouping solution achieves good strong scalability and improves the performance significantly,as well as avoiding the SWOs.
文摘Intergranular fluids within the nonhydrostatically stressed solids are a sort of important fluids in the crust. Research on the mechanical and chemical behavior of the intergranular fluids in nonhydrostatically stressed rocks at low temperature is a key for understanding deformation and syntectonic geochemical processes in mid to shallow crust. Theoretically, it is suggested that the fluid film sandwiched between solid grains is one of the main states of intergranular fluids in the nonhydrostatically stressed solids. Their superthin thickness makes the fluid films have the mechanical and chemical behavior very different from the common fluids. Because of hydration force, double layer repulsive force or osmotic pressure due to double layer, the fluid films can transmit nonhydrostatic stress. The solid minerals intergranular fluids interaction and mass transfer by intergranular fluids is stress related, because the stress in solid minerals can enhance the free energy of solid matter on the interfaces. The thermodynamic and kinetic equations for the simple case of stress induced processes are derived.
文摘All solutions of the Korteweg-de Vries(K-dV) equation that are bounded on the real line are physically relevant, depending on the application area of interest. Usually, both analytical and numerical approaches consider solution profiles that are either spatially localized or (quasi) periodic. The development of numerical techniques for obtaining approximate solution of partial differential equations has very much increased in the finite element and finite difference methods. Recently, new auxiliary equation method introduced by PANG, BIAN and CHAO is applied to the analytical solution of K-dV equation and wavelet methods are applied to the numerical solution of partial differential equations. Pioneer works in this direction are those of Beylkin, Dahmen, Jaffard and Glowinski, among others. In this research we employ the new auxiliary equation method to obtain the effect of dispersion term on travelling wave solution of K-dV and their numerical estimation as well. Our approach views the limit behavior as an invariant measure of the fast motion drifted by the slow component, where the known constants of motion of the fast system are employed as slowly evolv- ing observables;averaging equations for the latter lead to computation of the characteristic features of the motion.
基金Supported by the National Natural Science Foundation of China(42275062,41875121,and 41975066).
文摘The newly developed nonhydrostatic(NH)global spectral dynamical core is evaluated by using three-dimensional(3D)benchmark tests with/without moisture.This new dynamical core differs from the original Aladin-NH like one in the combined use of a dry-mass vertical coordinate and a new temperature variable,and thus,it inherently conserves the dry air mass and includes the mass sink effect associated with precipitation flux.Some 3D dry benchmark tests are first conducted,including steady state,dry baroclinic waves,mountain waves in non-sheared and sheared background flows,and a dry Held–Suarez test.The results from these test cases demonstrate that the present dynamical core is accurate and robust in applications on the sphere,especially for addressing the nonhydrostatic effects.Then,three additional moist test cases are conducted to further explore the improvement of the new dynamical core.Importantly,in contrast to the original Aladin-NH like one,the new dynamical core prefers to obtain simulated tropical cyclone with lower pressure,stronger wind speeds,and faster northward movement,which is much closer to the results from the Model for Prediction Across Scales(MPAS),and it also enhances the updrafts and provides enhanced precipitation rate in the tropics,which partially compensates the inefficient vertical transport due to the absence of the deep convection parameterization in the moist Held–Suarez test,thus demonstrating its potential value for full-physics global NH numerical weather prediction application.
基金Supported by the Ministry of Science and Technology of China (Grant Nos 2006BAC02B01 and 2006BAC03B03)the National High Technology Research and Development Program of China (863 Program) (Grant No 2006AA01A123)
文摘The Global/Regional Assimilation and PrEdiction System(GRAPES) is a newly developed global non-hydrostatic numerical prediction model,which will become the next generation medium-range opera-tional model at China Meteorological Administration(CMA).The dynamic framework of GRAPES is featuring with fully compressible equations,nonhydrostatic or hydrostatic optionally,two-level time semi-Lagrangian and semi-implicit time integration,Charney-Phillips vertical staggering,and complex three-dimensional pre-conditioned Helmholtz solver,etc.Concerning the singularity of horizontal momentum equations at the poles,the polar discretization schemes are described,which include adoption of Arakawa C horizontal grid with ν at poles,incorporation of polar filtering to maintain the computational stability,the correction to Helmholtz equation near the poles,as well as the treatment of semi-Lagrangian interpolation to improve the departure point accuracy,etc.The balanced flow tests validate the rationality of the treatment of semi-Lagrangian departure point calculation and the polar discretization during long time integration.Held and Suarez tests show that the conservation proper-ties of GRAPES model are quite good.
基金This study was funded by the National Key Program for Developing Basic Sciences(G1998040907)and the National Natural Science Foundation of China.
文摘During the period of 3—5 August 1996(for short “96.8”),an extraordinary rainstorm eventoccurred in Henan,Hebei and Shanxi Provinces in China,resulting in severe flood catastrophe.Synoptic analyses indicated that the stable gross col field and the interaction between a northwardmoving typhoon(down into low pressure)and its east lateral Pacific subtropical high were thelarge-and meso-scale circulation conditions of the “96.8” extraordinary rainstorm.The mesoscaletyphoon-low and its specific dynamical and thermodynamical structures were directly related to thisrainstorm event.The nonhydrostatic version of mesoscale numerical model MM5 was used toconduct investigation of numerical simulation for this case.The simulation with the full physicalprocesses of nonhydrostatic version MM5 was basically possessed of a capability to reproduce thegenesis,development and evolution of the large-scale and meso-α scale synoptic systems.Thesimulative results using a two-way interactive nesting procedure revealed that the typhoon-low waspossessed of an intensive coupled mechanism between the dynamical and thermodynamical fields,namely,the developing typhoon-low was possessed of a structure of the.cyclonic vorticity columnwith warm center and high humidity,the vorticity column on the lower levels was the moistconvective instability and negative moist potential vorticity structure:the intensive ascendingvertical motion and the intense divergence on upper levels and intensive convergence on the lowerlevels as well as the development of the convective cloud cluster were intercoupling:the intensesouthern wind jet companied by the typhoon-low was not only the interaccompanying andintercoupling condition of the development and maintenance of the typhoon-low and convectivecloud cluster,but also was the transportable belt of the moisture source and heat energy of the“96.8”extraordinary rainstorm.The analysis of simulative results of precipitation indicated thatthe distribution of the rainfall belt and rainfall rate was basically consistent with that of theobservation in spite of some rainfall centers less or larger than those of the observation for coarseor fine mesh domain,respectively.
文摘A three-dimensional elastic nonhydrostatic mesoscale(β-γ)model with nested-grid is presented.It uses a set of fullequations in terrain-following coordinates as its basic dynamic frame,which is solved with a time-splitting algorithmfor acoustic and gravity waves.The model physical parameterization includes a K-theory subgrid eddy mixing for cloudand free atmosphere,a bulk planetary boundary layer parameterization,and three types of sofisticated cloudmicrophysics schemes with double-parameters for hail-bearing clouds,warm clouds and snowing clouds respectively.The model is designed to be used flexibly for simulations of a variety of meso-and small-scale atmospheric processes,and can be improved as a regional and local operational NWP system in future.
