Important Roles of IMF By and Substorms on Ionospheric Electric Fields: New Results

The strong electrodynamic polar to equator coupling during geomagnetically disturbed times remains a subject of intense research. After decades of research, we understand the effects of IMF Bz on global ionosphere, perhaps up to a great extent. However, our understanding about the effects of the azimuthal component of IMF (By) esp., up to the equatorial latitudes is still at a very nascent stage. Similarly, the impact of substorm on the Magnetosphere-Ionosphere system and their transmission to low latitudes remains poorly understood. A large azimuthal component under comparable southward IMF Bz conditions can substantially modify the electric field effects from polar to equatorial latitudes resulting into unexpected distribution of ionospheric plasmas in the Ionosphere-Thermosphere system. In the first part, using observations from multiple instruments from auroral to equatorial latitudes on a unique space weather event this work addresses the importance and impacts of IMF By on disturbed time ionospheric electric fields over equatorial latitudes. In the second part, the work will address the issue of polarity of substorm induced penetration electric field over low latitudes and how they compare with the storm induced penetration electric field. Observations show that substorms can induce westward fields, contrary to recent claims that such substorms produce only eastward fields, and that their effects on low latitudes can compete with storm induced fields at times. These results strongly suggest a very crucial role of IMF By and substorms when evaluating strom-time effects on global Ionosphere-Thermosphere systems.