Swarm satellite observations of the effect of prompt penetration electric fields (PPEFs) on plasma density around noon and midnight side of low latitudes during the 07–08 september 2017 geomagnetic storm

Abstract

In this paper, using plasma density data (Ne) obtained from the Swarm satellite, the effect of prompt penetration electric fields (PPEFs) on the distribution of plasma density at low latitudes during the 07–08 September 2017 geomagnetic storm is discussed. The observations of enhancements and reductions in ionospheric plasma around noon and midnight in association with the orientation of the north–south component of the interplanetary magnetic field (IMF Bz) are presented during the main phase and the recovery phase of geomagnetic storm. The days of 05–06 September 2017 were selected as geomagnetically quiet days, and the plasma density data on these days were plotted as a quiet-time reference. The plasma enhancements and reductions in the low latitudes are found closely related to the magnetic local time (MLT), the orientation of IMF Bz, the main phase and the recovery phase of geomagnetic storm. During the main phase of geomagnetic storm with southward IMF Bz, plasma density increased around noon (10:00–11:00 MLT), while plasma density decreased around midnight (22:00–23:00 MLT). During the recovery phase of geomagnetic storm with northward IMF Bz, plasma density decreased around noon (10:00–11:00 MLT), while plasma density increased around midnight (22:00–23:00 MLT). The plasma density around both noon and midnight after the geomagnetic storm shows a distribution very similar to the distribution of plasma density during the geomagnetically quiet period. It is assumed that PPEFs are responsible for these results. During the main phase of the geomagnetic storm, the eastward PPEFs cause an increase in plasma density around the noon side while the westward PPEFs cause a decrease in plasma density around midnight side.