Interplanetary Magnetic Field B_y Effects on the Strength and Latitude of Field‐Aligned Currents in Different Magnetic Local Time Sectors

Abstract

In this work, IMF By effects on field‐aligned currents (FACs) are examined in different local time sectors, seasons, and hemispheres. At dusk and 09–14 MLT, when the eastward polar electrojet (PEJ) prevails, the northern FACp (poleward side FACs) are stronger when IMF By < 0 than when IMF By > 0. Conversely, at dawn, 21–02 MLT, and 09–14 MLT with westward PEJ, the northern FACp are stronger with IMF By > 0 compared to IMF By < 0. The southern FACp shows a reversed relationship with IMF By direction. The dependence of FACe (equatorward side FACs) on IMF By is weaker, except for the midday FACe, which shows opposite variations with respect to IMF By when compared to FACp. Stronger IMF By effect is observed in local summer in most of local times. The northern FACs are located at higher latitude for IMF By > 0 than for IMF By < 0 in local times with eastward PEJ, while the opposite trend is observed in other local times and in the Southern Hemisphere. The hemispheric difference in the peak latitude of FACs demonstrates an inverse relationship with its intensity, with stronger FACs located at lower latitudes. Overall, the local time and hemispheric differences in FACs strength and latitude are discussed in the context of interhemispheric field‐aligned currents linked to IMF By.