Penetrating Electric Field Simulated by the MAGE and Comparison With ICON Observation

Using the newly developed, Multiscale Atmosphere-Geospace Environment (MAGE) model, we simulated the penetrating electric field in the equatorial region under different interplanetary magnetic field (IMF) B-Z conditions during September 2020. Two intervals were selected for detailed analysis and the latter one was compared with the vertical ion drift data from the NASA Ionospheric Connection Explorer (ICON) satellite. The MAGE simulations show that in southward IMF (S-IMF) cases, the dawn-dusk electric potential drop at the equator is about 12% of the cross polar cap potential difference. Based on the MAGE simulation, the dawn-dusk potential drop at the equator varies nearly instantaneously on the order of a few minutes with the changes in the IMF B-Z or interplanetary electric field, which in turn alters the vertical ion drift. The daytime changes of the equatorial vertical ion drift in response to the penetrating electric field related to the IMF B-Z are only half of that during the nighttime. ICON data, though not inconsistent with the simulation, were not able to verify the occurrence of penetrating electric field because of its unfavorable location at the time. The MAGE simulation shows a pre-reversal enhancement (PRE) during southward IMF cases, but the PRE was absent in the ICON IVM observations. Further observations and modeling are needed to resolve this discrepancy.

Automated summary

Using the MAGE model, we simulated the penetrating electric field in the equatorial region under different IMF B-Z conditions. The simulation results showed that the dawn-dusk electric potential drop at the equator is about 12% of the cross polar cap potential difference in southward IMF cases. The simulation also revealed that the dawn-dusk potential drop at the equator varies nearly instantaneously with changes in the IMF B-Z or interplanetary electric field, which in turn affects the vertical ion drift. The ICON data, although inconclusive, were not able to verify the occurrence of the penetrating electric field due to its unfavorable location at the time. Further observations and modeling are needed to resolve this discrepancy.