The re-splittingδf method(Ye et.al CPC 2020)has been implemented into the global semi-Lagrangian gyrokinetic code NLT(Lei Ye et al.2016,JCP)for the simulations of electromagnetic micro-turbulence in tokamak plasmas.T...The re-splittingδf method(Ye et.al CPC 2020)has been implemented into the global semi-Lagrangian gyrokinetic code NLT(Lei Ye et al.2016,JCP)for the simulations of electromagnetic micro-turbulence in tokamak plasmas.The re-splitting method can be incorporated with the numerical Lie transform method,which is an essential numerical scheme for NLT code,to mitigate the cancellation problem appears in the gyrokinetic pk-formulation with gyrokinetic ions and drift-kinetic electrons.With this method,the ion temperature gradient mode(ITG),the kinetic ballooning mode(KBM)and trapped electron mode(TEM)are simulated by NLT and the results are well benchmarked with other gyrokinetic simulation codes.展开更多
The definition of a reference state close to the realistic atmosphere in an atmospheric model is essential for deriving prognostic deviations and improving numerical accuracy.In this study,a new dynamical framework al...The definition of a reference state close to the realistic atmosphere in an atmospheric model is essential for deriving prognostic deviations and improving numerical accuracy.In this study,a new dynamical framework allowing easy switching between a one-dimensional(1D)and a three-dimensional(3D)time-independent reference state is developed for the semi-implicit semi-Lagrangian solver in a global non-hydrostatic atmospheric model on Yin–Yang grids.The 3D reference state is introduced with consideration of additional horizontal gradient terms of referencestate terms,which is different from the 1D reference state.It is characterized by reduced magnitude of deviations,more accurate pressure gradient force,as well as alleviated numerical noise.Four idealized benchmark tests and multiple full-physics real-case forecasts are carried out to assess the impact of the 3D and 1D reference states.The 3D reference state shows significant advantages in the simulation of atmospheric transport and wave propagation in the idealized experiments.In the real-case forecasts,batched forecasts from June to August 2021 show a comprehensive improvement in medium-range prediction by using the 3D reference state.The new scheme achieves an enhanced prediction skill for large-scale circulation and extends the effective forecast period by 0.8 days in the Northern Hemisphere.展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos.12405275the National MCF Energy R&D Program of China under Grant No.2019YFE03060000 and 2022YFE03060004+2 种基金Collaborative Innovation Program of Hefei Science Center,CAS under Grant 2022HSC-CIP008the Strategic Priority Research Programof the Chinese Academy of Sciences(XDB0790201)the CASHIPS Director’s Fund under Grant No.YZJJ2023QN19.
文摘The re-splittingδf method(Ye et.al CPC 2020)has been implemented into the global semi-Lagrangian gyrokinetic code NLT(Lei Ye et al.2016,JCP)for the simulations of electromagnetic micro-turbulence in tokamak plasmas.The re-splitting method can be incorporated with the numerical Lie transform method,which is an essential numerical scheme for NLT code,to mitigate the cancellation problem appears in the gyrokinetic pk-formulation with gyrokinetic ions and drift-kinetic electrons.With this method,the ion temperature gradient mode(ITG),the kinetic ballooning mode(KBM)and trapped electron mode(TEM)are simulated by NLT and the results are well benchmarked with other gyrokinetic simulation codes.
基金Supported by the National Natural Science Foundation of China(42375153,42075151,and 42205157).
文摘The definition of a reference state close to the realistic atmosphere in an atmospheric model is essential for deriving prognostic deviations and improving numerical accuracy.In this study,a new dynamical framework allowing easy switching between a one-dimensional(1D)and a three-dimensional(3D)time-independent reference state is developed for the semi-implicit semi-Lagrangian solver in a global non-hydrostatic atmospheric model on Yin–Yang grids.The 3D reference state is introduced with consideration of additional horizontal gradient terms of referencestate terms,which is different from the 1D reference state.It is characterized by reduced magnitude of deviations,more accurate pressure gradient force,as well as alleviated numerical noise.Four idealized benchmark tests and multiple full-physics real-case forecasts are carried out to assess the impact of the 3D and 1D reference states.The 3D reference state shows significant advantages in the simulation of atmospheric transport and wave propagation in the idealized experiments.In the real-case forecasts,batched forecasts from June to August 2021 show a comprehensive improvement in medium-range prediction by using the 3D reference state.The new scheme achieves an enhanced prediction skill for large-scale circulation and extends the effective forecast period by 0.8 days in the Northern Hemisphere.
