Statistical relationships between ionospheric ion outflows and solar wind and geomagnetic activity parameters during geomagnetic storms

Based on the criteria of choosing ion outflow events, we select 20 ion outflow events within the energy range of 4 similar to 300 eV during the magnetic storm, using the data from the FAST/ESA instrument between 1997 and 1998, and explore the relationships between the ionosphericion outflow and the solar wind, the geomagnetic activity, the precipitating electrons. The results show that: (1) The average ion outflow flux is 6. 08 X 10(7) eV/(cm(2) . s . sr . eV), 5. 75 X 10(7) eV/(cm(2) . s . sr . eV) and 3. 91 X 10(7) eV/(cm(2) . s . sr . eV) on the initial phase, the main phase and the recovery phases, respectively. The ion outflow flux reaches the maximum on the initial phase. (2) The correlation coefficients between the ion outflow flux and the solar wind dynamic pressure and the B, component of the interplanetary magnetic field are 0.47 and -0.38, respectively. (3) The correlation coefficients between the upflow flux and the Sym-H index are 0. 74, -0. 77 and -0. 54 on the initial phase, the main phase and the recovery phase, respectively, and the correlation coefficients with Kp are 0. 53, 0. 75 and 0. 65, respectively. Overall, the correlations between the ion upflow and the Sym-H index are stronger than Kp. (4) The correlation coefficients between the ion upflow and the electron number flux are 0. 74, 0. 52 and O. 32 on the three phases, respectively. Our conclusions are: 1) the soft electron precipitation (<1 keV) contributes significantly to the ion temperature increase and the ion frictional heating; 2) the ambipolar electric field is an important energy source for ion outflows. The empirical relationships of the upflowing ions with the Sym-H and the electron number flux are significant in this study, and these empirical models can be used in magnetic fluid simulation studies.