Statistical Relationships between Ionospheric Upflows and Various Parameters during Geomagnetic Storms

A collection of data from 149 orbits by the Fast Auroral SnapshoT (FAST) mission during 34 geomagnetic storms from 1997 to 2006 is used to analyze the energy flux of upflowing ions as a function of storm phases, and analyze the relationships between the flux and the parameters, including Sym-H index, Kp index, and the Poynting flux to construct empirical models. Results show that, in the main phase of the storm, the energy flux exceeds 10⁸ eV·cm^–2·s^–1·sr^–1·eV ^–1, and in the initial and recovery phases, the energy flux can exceed 10⁷ eV·cm^–2·s^–1·sr^–1·eV ^–1. The averaged energy flux in the main phase is higher than that in the initial and recovery phases. In the initial phase, the flux is significantly positively correlated to Sym-H, Kp and the Poynting flux. The correlation coefficients are 0.890, 0.664 and 0.660, respectively. In the main phase, the correlation coefficients are 0.858, 0.823 and 0.541, respectively. Empirical formulas for the energy flux as functions of the Sym-H and the Poynting flux are constructed. In the main phase,

,

$ {J}_{{i}^{+}}={10}^{6.469 \pm 0.798}\times  $

$  {{S}_{\mathrm{d}\mathrm{c}}}^{0.888 \pm 0.703} $

. In the initial phase, due to the rapid injection of the energy during geomagnetic disturbance and the rapid energy acquisition of ionospheric ions, the ion energy flux is highly correlated with the geomagnetic disturbance indices. Meanwhile, the energy flux increases by two orders of magnitude in the main phase. The Joule dissipation caused by the downward Poynting flux is one of the important sources of ion energy acquisition, and a strong correlation is observed.