Nonlinear dispersive scale Alfvén waves in magnetosphere-ionosphere coupling:Physical processes and simulation results  

作　　者：ZHAO MingXian LU JianYong 

机构地区：[1]Chinese Academy of Meteorological Sciences,Beijing 100081,China [2]Graduate University of Chinese Academy of Sciences,Beijing 100049,China [3]National Center for Space Weather,China Meteorology Administration,Beijing 100081,China

出　　处：《Chinese Science Bulletin》2012年第12期1384-1392,共9页

基　　金：supported by the National Natural Science Foundation of China(40874087 and 41031063);the China Meteorological Administration(GYHY201106011);the China Public Science and Technology Research Funds Projects of Ocean(201005017)

摘　　要：Dispersive Alfvén waves(DAWs)have been demonstrated to play a significant role in auroral generation of the magnetosphereionosphere coupling system.Starting from a two fluid reduced MHD model,we summarize the frequency,temporal and spatial characteristics of magnetospheric DAWs.Then,the nonlinear kinetic and inertial scale Alfveén waves are studied,and we review some theoretical aspects and simulation results of dispersive Alfve′n waves in Earth's magnetosphere.It is shown that dispersive standing Alfve′n waves can generate the field-aligned currents which transport energy into the auroral ionosphere,where it is dissipated by Joule heating and energy lost due to electron precipitation.The Joule dissipation can heat the ionospheric electron and produce changes in the ionospheric Pedersen conductivity.As a feedback,the conducting ionosphere can also strongly affect the magnetospheric currents. The ponderomotive force can cause the plasma to move along the field line,and generate ionospheric density cavity.The nonlinear structuring can lead to a dispersive scale to accelerate auroral particle,and the Alfvn waves can be trapped within the density cavity. Finally,we show the nonlinear decay of dispersive Alfvén waves related to two anti-propagating electron fluxes observed in the auroral zone.Dispersive Alfven waves （DAWs） have been demonstrated to play a significant role in auroral generation of the magnetosphere- ionosphere coupling system. Starting from a two fluid reduced MHD model, we summarize the frequency, temporal and spatial characteristics of magnetospheric DAWs. Then, the nonlinear kinetic and inertial scale Alfven waves are studied, and we review some theoretical aspects and simulation results of dispersive Alfven waves in Earth＇s magnetosphere. It is shown that dispersive standing Alfven waves can generate the field-aligned currents which transport energy into the auroral ionosphere, where it is dissipated by Joule heating and energy lost due to electron precipitation. The Joule dissipation can heat the ionospheric electron and produce changes in the ionospheric Pedersen conductivity. As a feedback, the conducting ionosphere can also strongly affect the magnetospheric currents. The ponderomotive force can cause the plasma to move along the field line, and generate ionospheric density cavity. The nonlinear structuring can lead to a dispersive scale to accelerate auroral particle, and the Alfven waves can be trapped within the density cavity. Finally, we show the nonlinear decay of dispersive Alfven waves related to two anti-propagating electron fluxes observed in the auroral zone.

关 键 词：ALFVEN波 电离层耦合 非线性色散 磁层 仿真结果 物理过程 阿尔文波 耦合系统 

分 类 号：P352[天文地球—空间物理学]