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.

1. INTRODUCTION
2. DATA SET AND METHODOLOGY
    2.1 CHAMP Satellite Data
    2.2 Geomagnetic and OMNI IMF/Solar Wind Data
    2.3 Field-Aligned Currents Density Calculation
    2.4 FAC Range Determination
3. EVENTS STUDY
    3.1 October 2000, 04–06 Storm Event
    3.2 March 2001, 19–21 Storm Event
4. DISCUSSION
5. CONCLUSION
REFERENCES

• Adero Ochieng Awuor(Department of Physics and Space Science, Technical University of Kenya) Corresponding Author
• Paul Baki(Department of Physics and Space Science, Technical University of Kenya)
• Joseph Olwendo(Department of Mathematics and Physical Sciences, Pwani University)
• Pieter Kotze(South Africa National Space Agency, SANSA Space Center)