Recent advances in studies of the middle and upper atmosphere and their coupling with the lower atmosphere in China are briefly reviewed. This review emphasizes four aspects: (1) Development of instrumentation for mid...Recent advances in studies of the middle and upper atmosphere and their coupling with the lower atmosphere in China are briefly reviewed. This review emphasizes four aspects: (1) Development of instrumentation for middle and upper atmosphere observation; (2) Analyses and observation of middle and upper atmosphere; (3) Theoretical and modeling studies of planetary wave and gravity wave activities in the middle atmosphere and their relation to lower atmospheric processes; (4) Study on the coupling between the stratosphere and the troposphere.展开更多
This paper summarizes the research results obtained by Chinese scientists and/or through international collaborations during 2004 to 2006. Within the context of COSPAR, the progresses in the studies of the middle and ...This paper summarizes the research results obtained by Chinese scientists and/or through international collaborations during 2004 to 2006. Within the context of COSPAR, the progresses in the studies of the middle and upper atmosphere in China in the past two years are introduced with focusing the developments in facilities and instruments, and the advancements in scientific issues, e.g., dynamics related processes, atmospheric constituents, and the coupling with the lower atmosphere.展开更多
Propagation of the surface waves along a two-dimensional plasma column and the far-field radiation patterns are studied in thin column approximation. Wave phase and attenuation coefficients are calculated for various ...Propagation of the surface waves along a two-dimensional plasma column and the far-field radiation patterns are studied in thin column approximation. Wave phase and attenuation coefficients are calculated for various plasma parameters. The radiation patterns are shown. Results show that the radiation patterns are controllable by flexibly changing the plasma length and other parameters in comparison to the metal monopole antenna. It is meaningful and instructional for the optimization of the plasma antenna design.展开更多
In this paper advances on study of middle and upper atmosphere and their cou pling with lower atmosphere in China in recent two years are briefly reviewed.This review emphasized three aspects, ie. (1) analysis and obs...In this paper advances on study of middle and upper atmosphere and their cou pling with lower atmosphere in China in recent two years are briefly reviewed.This review emphasized three aspects, ie. (1) analysis and observation of mid and upper atmosphere over China; (2) theoretical and modelling study of grav ity wave activities in middle atmosphere and their relation to lower atmospheric processes; (3) coupling between the stratosphere and troposphere.展开更多
Along with the introduction of the concept of dual-channel communication,we utilized the finite-difference time-domain（FDTD） method to simulate and measure the radiation pattern under certain plasma densities and pl...Along with the introduction of the concept of dual-channel communication,we utilized the finite-difference time-domain（FDTD） method to simulate and measure the radiation pattern under certain plasma densities and plasma collision frequencies.Results show that under certain settings,the radiation pattern of a plasma antenna resembles that of a metallic antenna.In contrast to a metallic antenna,a plasma antenna possesses other functionalities,such as dynamic reconfiguration and digital controllability.The data from simulation are similar to the measurement results,indicating that column plasma antenna can realize dual-channel communication.This work confirms the viability of realizing dual-channel communication by column plasma antenna,which adds a new but promising method for modern intelligent communication.展开更多
This paper focuses on the application of plasma as wireless antenna. In order to reveal the radiation characteristics of column plasma antenna, we chose the finite-difference time- domain （FDTD） numerical analysis m...This paper focuses on the application of plasma as wireless antenna. In order to reveal the radiation characteristics of column plasma antenna, we chose the finite-difference time- domain （FDTD） numerical analysis method to simulate radiation impedance and efficiencies of each channel for a few sets of plasma densities and plasma collision frequencies. Simulation results demonstrate that a plasma antenna shares similar characteristics with a metallic antenna in radiation impedance and efficiency of each channel when an appropriate setting is adopted. Unlike a metallic antenna, a plasma antenna is capable of realizing such functions as dynamic reconfiguration, digital control and dual-channel communication. Thus it is possible to carry out dual-channel communication by plasma antenna, indicating a new path for modern intelligent communication.展开更多
As well known, the magnetic cross-tail component By in the magnetotail is in direct proportion to the in-terplanetary magnetic field (IMF) By component. And the polarity of IMF and plasmoid / flux rope By components d...As well known, the magnetic cross-tail component By in the magnetotail is in direct proportion to the in-terplanetary magnetic field (IMF) By component. And the polarity of IMF and plasmoid / flux rope By components do indeed agree. This results indicate that the IMF By penetrates plasmoids and the magnetic structures must therefore be three-dimensional. In this note, the dynamical processes of magnetotail in the course of a substorm are studied using a MHD code with two-dimensions and three components on the basis of two types of initial equilibrium solutions of the quiet magnetotail. The numerical results of two cases illustrate various features of time evolution of By component that correspond to two kinds of plasmoid-like structures: one is associated with a flux rope core and the other resembles a 'closed loop' plamoid. Therefore, the occurrence of various magnetic structures in the magnetotail might be related to nonsteady driven reconnection with different distributions of the By component.展开更多
Ⅰ. SOLAR-TERRESTRIAL SCIENCESThe solar-terrestrial sciences study how the solar energy, momentum and mass transfer through the interplanetary space, the earth magnetosphere, the ionosphere and the neutral atmosphere,...Ⅰ. SOLAR-TERRESTRIAL SCIENCESThe solar-terrestrial sciences study how the solar energy, momentum and mass transfer through the interplanetary space, the earth magnetosphere, the ionosphere and the neutral atmosphere, and their influence on earth environment. The solar-terrestrial sciences are also called, sometimes, the solar-terrestrial physics, solar-terrestrial relations,展开更多
Chaotic phenomena in the magnetopause boundary region are studied in the MHD framework by using the Fourier truncation method. The MHD system is considered as a one-dimensional current sheet with a co-existing velocit...Chaotic phenomena in the magnetopause boundary region are studied in the MHD framework by using the Fourier truncation method. The MHD system is considered as a one-dimensional current sheet with a co-existing velocity shear and continuous energy transfer. The nonlinearity of the system, the evolution processes and properties of its different attractors are analysed. The possible routs and parameter conditions for chaos onset are also investigated. Numerical solutions show that when the Reynolds number (R) and the magnetic Reynolds number (Km) are very large, chaos appears in the system and its onset may provide a physical mechanism leading to turbulent reconnection at the magnetopause.展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos.40333034,40075007,and 40175002the.Chinese Academy of Sciences under Grant No.KZCX-SW-217.
文摘Recent advances in studies of the middle and upper atmosphere and their coupling with the lower atmosphere in China are briefly reviewed. This review emphasizes four aspects: (1) Development of instrumentation for middle and upper atmosphere observation; (2) Analyses and observation of middle and upper atmosphere; (3) Theoretical and modeling studies of planetary wave and gravity wave activities in the middle atmosphere and their relation to lower atmospheric processes; (4) Study on the coupling between the stratosphere and the troposphere.
基金Supported by the National Natural Science Foundation of China (40374056, 40333034) and Chinese Academy of Science KZCX3-SW-217, KGCX2-SW-408, KGCX3-SYW-403
文摘This paper summarizes the research results obtained by Chinese scientists and/or through international collaborations during 2004 to 2006. Within the context of COSPAR, the progresses in the studies of the middle and upper atmosphere in China in the past two years are introduced with focusing the developments in facilities and instruments, and the advancements in scientific issues, e.g., dynamics related processes, atmospheric constituents, and the coupling with the lower atmosphere.
文摘Propagation of the surface waves along a two-dimensional plasma column and the far-field radiation patterns are studied in thin column approximation. Wave phase and attenuation coefficients are calculated for various plasma parameters. The radiation patterns are shown. Results show that the radiation patterns are controllable by flexibly changing the plasma length and other parameters in comparison to the metal monopole antenna. It is meaningful and instructional for the optimization of the plasma antenna design.
基金Supported by the National Natural Science Foundation of China(No. 40175002, 40075007) and The Chinese Academy of Sciences.
文摘In this paper advances on study of middle and upper atmosphere and their cou pling with lower atmosphere in China in recent two years are briefly reviewed.This review emphasized three aspects, ie. (1) analysis and observation of mid and upper atmosphere over China; (2) theoretical and modelling study of grav ity wave activities in middle atmosphere and their relation to lower atmospheric processes; (3) coupling between the stratosphere and troposphere.
文摘Along with the introduction of the concept of dual-channel communication,we utilized the finite-difference time-domain（FDTD） method to simulate and measure the radiation pattern under certain plasma densities and plasma collision frequencies.Results show that under certain settings,the radiation pattern of a plasma antenna resembles that of a metallic antenna.In contrast to a metallic antenna,a plasma antenna possesses other functionalities,such as dynamic reconfiguration and digital controllability.The data from simulation are similar to the measurement results,indicating that column plasma antenna can realize dual-channel communication.This work confirms the viability of realizing dual-channel communication by column plasma antenna,which adds a new but promising method for modern intelligent communication.
文摘This paper focuses on the application of plasma as wireless antenna. In order to reveal the radiation characteristics of column plasma antenna, we chose the finite-difference time- domain （FDTD） numerical analysis method to simulate radiation impedance and efficiencies of each channel for a few sets of plasma densities and plasma collision frequencies. Simulation results demonstrate that a plasma antenna shares similar characteristics with a metallic antenna in radiation impedance and efficiency of each channel when an appropriate setting is adopted. Unlike a metallic antenna, a plasma antenna is capable of realizing such functions as dynamic reconfiguration, digital control and dual-channel communication. Thus it is possible to carry out dual-channel communication by plasma antenna, indicating a new path for modern intelligent communication.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 49874035 and 49834040) and the Space Physics Fund of the First-rate University Program.
文摘As well known, the magnetic cross-tail component By in the magnetotail is in direct proportion to the in-terplanetary magnetic field (IMF) By component. And the polarity of IMF and plasmoid / flux rope By components do indeed agree. This results indicate that the IMF By penetrates plasmoids and the magnetic structures must therefore be three-dimensional. In this note, the dynamical processes of magnetotail in the course of a substorm are studied using a MHD code with two-dimensions and three components on the basis of two types of initial equilibrium solutions of the quiet magnetotail. The numerical results of two cases illustrate various features of time evolution of By component that correspond to two kinds of plasmoid-like structures: one is associated with a flux rope core and the other resembles a 'closed loop' plamoid. Therefore, the occurrence of various magnetic structures in the magnetotail might be related to nonsteady driven reconnection with different distributions of the By component.
文摘Ⅰ. SOLAR-TERRESTRIAL SCIENCESThe solar-terrestrial sciences study how the solar energy, momentum and mass transfer through the interplanetary space, the earth magnetosphere, the ionosphere and the neutral atmosphere, and their influence on earth environment. The solar-terrestrial sciences are also called, sometimes, the solar-terrestrial physics, solar-terrestrial relations,
基金Project supported by the National Natural Science Foundation of China,and partly by the NationalBasic Research Program(Nonlinear Science).
文摘Chaotic phenomena in the magnetopause boundary region are studied in the MHD framework by using the Fourier truncation method. The MHD system is considered as a one-dimensional current sheet with a co-existing velocity shear and continuous energy transfer. The nonlinearity of the system, the evolution processes and properties of its different attractors are analysed. The possible routs and parameter conditions for chaos onset are also investigated. Numerical solutions show that when the Reynolds number (R) and the magnetic Reynolds number (Km) are very large, chaos appears in the system and its onset may provide a physical mechanism leading to turbulent reconnection at the magnetopause.
