The influence of IMF components on meso-scale field-aligned currents (FACs) is investigated with an aim to establish how different IMF components influence the occurrence and distribution of FACs. The field-aligned currents (FACs) are calculated from the curl of the Ampere's law to the magnetic field recorded by CHAMP satellite during 24 major geomagnetic storms. To determine the field-aligned currents at extreme mesoscale range ∼150-250 km, a low-pass filter to FACs with a cutoff period of 20s is applied. The peak-to-peak amplitude of FAC density, with the maximum difference ≤ 3 0 MLAT, is determined and used to define the FAC range. The results indicate high occurrence of FACs centered about IMF ≈ 0, for large values of Dst. The magnitude of FACs is in general affected by all the three IMF components, alongside other ionospheric factors such as solar wind speed and density. Magnetic reconnection, under-B Z is a major FACs drivers and is significant in the dayside northern hemisphere. The reconnection is not symmetric in both hemispheres. We find a possible electrodynamic similarity between the dayside northern hemisphere and nightside southern hemisphere, prominent along B X when B Z is negative. This interesting observation can further be investigated.

Challenging Minisatellite Payload (CHAMP) satellite magnetic data are used to investigate the latitudinal variation of the storm-time meso-scale field-aligned currents by defining a new metric called the FAC range. Three major geomagnetic storm events are considered. Alongside SymH, the possible contributions from solar wind dynamic pressure and interplanetary magnetic field (IMF) BZ are also investigated. The results show that the new metric predicts the latitudinal variation of FACs better than previous studies. As expected, the equatorward expansion and poleward retreat are observed during the storm main phase and recovery phase respectively. The equatorward shift is prominent on the northern duskside, at ~58° coinciding with the minimum SymH and dayside at ~59° compared to dawnside and nightside respectively. The latitudinal shift of FAC range is better correlated to IMF BZ in northern hemisphere dusk-dawn magnetic local time (MLT) sectors than in southern hemisphere. The FAC range latitudinal shifts responds better to dynamic pressure in the duskside northern hemisphere and dawnside southern hemisphere than in southern hemisphere dusk sector and northern hemisphere dawn sector respectively. FAC range exhibits a good correlation with dynamic pressure in the dayside (nightside) southern (northern) hemispheres depicting possible electrodynamic similarity at day-night MLT sectors in the opposite hemispheres.