Magnetometer observations recorded in 2008 from geomagnetic stations deployed across Africa under the Magnetic Data Acquisition System (MAGDAS) were utilized to investigate the ionospheric solar quiet (Sq) current system at the mid- and high-latitude regions of Europe. To effectively distinguish between the internal and external magnetic field and current contributions associated with Sq variations, a spherical harmonic analysis (SHA) technique was employed. The results indicate that the Sq current system exhibits a pronounced dawn-to-dusk behavior. Notably, the external current variations differ markedly from the internal current components in both magnitude and phase characteristics. Seasonal analysis reveals that the external current attains its maximum intensity during the June solstice at the HRN and LER stations, while at the DOU station the peak occurs during the September equinox. The corresponding peak current strengths are approximately 4.0 × 10³ A, 3.5 × 10³ A, and 0.9 × 10³ A, respectively.
(PhD) et al. (Sun,) studied this question.