Ionospheric Response to Strong Geomagnetic Storms During 2000–2005: An IMF Clock Angle Perspective

Abstract

AbstractThis paper presents the equatorial ionospheric response to 11 strong‐to‐severe geomagnetic storms that occurred during the period 2000–2005, the declining phase of the Solar Cycle 23. The analysis has been performed using the global ion density plots of the Defense Meteorological Satellite Program (DMSP). Observations show that for about 91% of the cases, postsunset equatorial irregularities occurred within 3 hr from the time of northward to southward transition of the interplanetary magnetic field (IMF) clock angle, thus bringing out the importance of the role played by IMF By in the process of prompt penetration of electric field (PPEF) in addition to the IMF Bz. This is an improvement from the previously reported (Ray et al., 2015, https://doi.org/10.1002/2014RS005422) 4 hr window of equatorial spread F generation from the southward IMF Bz crossing −10 nT.