The Earth’s Plasmasphere Structures During Extreme Geomagnetic Disturbance

The earth’s plasmasphere is the core area where the earth’s inner magnetosphere interacts with ionosphere. The significant changes of the plasmasphere structures and the dynamic process strongly affect the structure of the inner magnetosphere and the near-earth space environment during geomagnetic disturbances. However, the formation mechanism of plasmasphere structures at medium-scale is not clear at present. In this thesis, the evolution of the plasmasphere structure during strong geomagnetic disturbance is studied by satellite IMAGE data analysis and simulation based on the single particle trajectory method. The finger-like structures appearing in super geomagnetic storm event are discovered. And then the formation mechanism of the finger-like structure during extreme geomagnetic disturbance is discussed in detail. And the main work and research results are as follows:(1) The evolution of plasmasphere structure during strong geomagnetic disturbance is simulated by Weimer’s mapping electric field model and T04 model. The results show that the evolution of plasmasphere structure during strong geomagnetic disturbance is quite special, especially in late period of evolution, the plasmasphere presents a shape of fans or butterfly wings.(2) The dynamic evolution of plasmasphere structure during extreme geomagnetic disturbance is studied and finger-like structures are discovered based on the IMAGE-EUV data. The change rules of the finger-like structures are analyzed by the comparision of three super geomagnetic storms.(3) The formation and evolution of finger-like structures during extreme geomagnetic disturbance is simulated based on the single particle trajectory method and the results are comparatively unanimous to the observations of satellite IMAGE. The results of simulation show that IMF changes from north to south sharply during the evolution of finger-like structures and component is relative high before it converts.(4) The impacts of solar wind and IMF on finger-like structures are studied in depth. The formation and evolution of finger-like structures with different parameters are analyzed in details.