Statistical Relationship Of Ion Upwards With Solar Wind Parameters And Geomagnetic Disturbance Levels

The source of plasma is one of the basic issues in the study of the Earth's magnetosphere.How the ions from the ionosphere are distributed in the source area,and how these ions enter the inner magnetosphere is a hot topic of research.The relationships between the ion upflow and geomagnetic activity,solar wind,and electron deposition in different magnetic storm phases,as well as empirical models have not been studied in detail.This paper uses data from the ascending phase(1997-1998)of the 23rd solar activity cycle,which observed by the ESA instrument of the FAST satellite.We select 183 ion upflow events with energy of 4?300 eV during 20 magnetic storms based on the UFI definition.Then we analysis the statistical relationships between the ion outflow flux and solar wind,geomagnetic activity,and electron deposition,and we also establish empirical models on different phases of magnetic storms,respectively.The results show that:The average ions outflow flux is 7.71×107 eV/(cm2 · s · sr · eV),1.48 × 108 eV/(cm2·s·sr·eV)and 8.12 × 107 eV/(cm2·s·sr·eV)in the initial phase,the main phase and the recovery phase of the magnetic storm,respectively.The ion outflow flux is the largest during the main phase,it shows that a large amount of energy will be injected,which causes the upflow flux to increase exponentially during the main phase of magnetic storm.There are weak correlations between solar wind dynamic pressure,temperature,velocity,and ion upflow flux,which indicates that changes in solar wind parameters will affect the ionospheric ions upflow.Then when the interplanetary magnetosphere deflects southward,the ion upflow flux increases significantly.It shows that when the interplanetary magnetic field deflects southward,high-energy particles of the solar wind are injected into the magnetosphere through magnetic reconnection.The field-direction current generated by the charged particles under the interaction of the solar wind and the magnetosphere penetrates the ionosphere,and local ions are driven upflow by the growing electromotive force in the polar cap area rapidly.On the initial phase,the main phase and the recovery phase of the magnetic storm,the correlation coefficients between the upflow flux and Sym/H are 0.70,-0.69 and-0.50 respectively,and the correlation coefficients with Kp are 0.64,0.71 and 0.53 respectively.On the whole,the correlation between ions upflow and Kp are better than Sym/H on the main phase and the recovery phase.The results of the study indicate that during the initial and main phases of magnetic storm,the levels of geomagnetic disturbance have a greater impact on the ion escape rate.The correlation coefficients of the ion upflow and electron number flux on the initial,main and recovery phase of the storm are 0.88,0.61 and 0.47 respectively.The results show that soft electron deposition during magnetic storm can significantly improve ionospheric ion temperature,plasma friction heating and bipolar electric field in F region are important energy acquisition mechanisms for ion outflow.The ion outflow flux has significant empirical relationships with Sym/H and electron number flux which constructed in this paper and it can be used in magnetic fluid simulation research.