Statistical Study of Convection Electric Field in the Inner Magnetosphere Responding to the Southward Turnings of Interplanetary Magnetic Field

Abstract This study presents a statistical analysis of the convection electric field in the inner magnetosphere responding to sudden southward turnings of the interplanetary magnetic field (IMF), based on electric field data from the Van Allen Probes (September 2012–July 2019) and IMF data from the NASA/GSFC OMNI database. In total, events of the southward turning of the IMF are analyzed. Individual events exhibit enhancement of convection after turning with a range of response times from nearly instantaneous to delays of about 10 min. Statistical results reveal an average increase in E y of approximately 0.1 mV/m within 30 min after southward turning, showing significant variation with magnetic local time (MLT). The response is earliest and strongest in the pre‐noon (9–12 MLT) sector, and subsequently propagates toward other MLT sectors at a speed of approximately 0.6 MLT/min. These findings provide statistical in situ evidence consistent with the dayside‐driven convection scenario recently proposed by Dai et al. (2024, https://doi.org/10.1038/s41467‐024‐44992‐y ), thereby improving our understanding of solar wind–magnetosphere coupling processes.