Solar wind-magnetosphere-ionosphere coupling and its impact on
equatorial ionospheric electrodynamics during the 23 March 2023
geomagnetic storm: Effect of sudden decrease of solar wind dynamic
pressure
Abstract
We present a study of the magnetosphere-ionosphere coupling during the
23 March 2023 magnetic storm, focusing on the effect of the drastic
decrease of the solar wind dynamic pressure occurred during the main
phase. Our observations show that the negative pressure pulse had
significant impact to the magnetosphere-ionosphere system. It weakened
large-scale field-aligned currents and paused the progression of the
storm main phase for ~3 hrs. Due to the sudden decrease
of the plasma convection after the negative pressure pulse, the
low-latitude ionosphere was over-shielded and experienced a brief period
of westward penetration electric field, which reversed the direction of
the equatorial electrojet. The counter electrojet was observed both in
space and on the ground. A transient, localized enhancement of downward
field-aligned current was observed near dawn, consistent with the
mechanism for transmitting MHD disturbances from magnetosphere to the
ionosphere after the negative pressure pulse.