Investigating the Spatiotemporal Evolution of midlatitude trough with Subauroral Ion Drifts Using Multiple DMSP satellites

Utilizing data from multiple Defense Meteorological Satellite Program (DMSP) satellites, we examine the spatiotemporal evolution of Subauroral Ion Drifts (SAID) and midlatitude trough. We observed consecutive SAID events at intervals of 25 minutes using the satellites for 8 Southern Hemisphere passes between dusk and midnight sector. Our findings reveal that SAID is present in the absence of a well-defined midlatitude trough during the initial expansion phase of substorms. After the SAID event, the plasmapause emerges as the ion density cut off at the near-by location. The plasmapause develops into a deep trough which is also observed in Double SAID (DSAID). There is a detachment of hot ion flux towards the SAID region in the initial phase. These detached hot ions remain colocated until the deep trough appears, while the edges of ion and electron precipitation are separated from the SAID events. These results suggest that the presence of a midlatitude trough near the E and F region may play a crucial role in the formation of SAID from the lower to topside ionosphere. In other words, the formation of SAID in topside ionosphere may not be directly linked to the midlatitude trough in the same region.