Identification of Night-Time F- Region Currents from CHAMP Satellite Observations over Equatorial Africa

Abstract

The F-region currents are generally weak and difficult to detect. However, their contributions to the earth’s magnetic field variations are significant and cannot be ignored by the field modelers. CHAMP satellite has therefore provided a perfect opportunity to investigate the in-situ F-region currents on the night side of the equatorial region. The magnitudes of the current along all the three components of the earth’s magnetic field (X, Y, Z) are investigated. However in this paper, we present only the results on the Y-component where interesting magnetic residuals were observed. The X and Z-components were rather masked in much noise and would require further filtering. The currents appear in both the pre-midnight and postmidnight sectors and are spatially confined to the equatorial region bounded by the Appleton anomaly. The magnetic residuals are generally observed in the northern hemisphere of an order of 0.8nT, which gives a height-integrated current density of about 1.3mA/m.