Study of Response of Extreme Meso-Scale Field-Aligned Current to Interplanetary Magnetic Field Components B X , B Y and B Z During Geomagnetic Storm

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 ≤ 30 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 -BZ 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 BX when BZ is negative. This interesting observation can further be investigated.