How IMF-By controls the Equatorial Electrodynamics during Storm time?

Abstract:

The control of north south component of solar wind magnetic field (IMF-Bz) is well known on the global storm time electrodynamics of the Sun-Earth system. Over high latitudes the prompt penetration electric field, driven mainly by IMF Bz, modifies the plasma convection giving rise to DP2 cells. Over low to equatorial latitudes it enhances the eastward zonal electric field on the day side and does the opposite on the night side. In contrast, the knowledge about the effects of east west component of solar wind magnetic field (IMF-By) is known up to a great extent at the high latitudes only. It is known to rotate the convection cells, and modify the potential distributions, winds, and even thermospheric density. Such effects also show hemispheric asymmetries. But the influence of IMF-By at lower or up to equatorial latitudes has rarely been observed/studied. This is primarily because it is very difficult to distinguish the impact of IMF-By from the huge dominance of IMF-Bz in dictating the storm time electrodynamics. Only a few studies have observationally indicated the influence of IMF-By on storm time electrodynamics beyond polar latitudes. Using previous observations and simulations, our research shows that IMF-By can alter the equatorial electrodynamics and winds up to a great extent which is hitherto to be understood and have never been accounted for in evaluation of space weather events. This study will elaborate the different findings about the impact of IMF-By on equatorial storm time electrodynamics. The shortcoming of our present approach of evaluating space weather events and importance of upgrading our understandings will be discussed.