• A F ZILLE

      Articles written in Journal of Earth System Science

    • Geomagnetically-induced effects related to disturbed geomagnetic field variations at low latitude

      N KOUASSI V DOUMBIA K BOKA Z TUO O D F GRODJI A A KASSAMBA A F ZILLE

      More Details Abstract Fulltext PDF

      In this paper, we analyzed low latitude geoelectric field variations and Geomagnetically Induced Current (GIC), associated with disturbed geomagnetic field variations in West Africa. For this purpose, variations of geomagnetic field components H, D and Z, and geoelectric field horizontal components Ey and Ex were examined during geomagnetically disturbed periods, with the daily means of the Ap index higher than 20 nT. Variations of geoelectric field components Ey and Ex were identified as associated with disturbed variations of the geomagnetic field. The GIC was estimated from the observed Ey and Exbased on system parameters configuration with a=b=50 Akm/V. The disturbance fluctuations in the geoelectric field components and the estimated GIC exhibit a diurnal trend, with higher amplitudes during the daytime. The impulses in the geoelectric field components and the estimated GIC are stronger in the southern stations than in the northern stations. On the average, these impulses decrease from LAM to TOM, with a slight enhancement near the magnetic equator.

      $\bf{Highlights}$

      $\bullet$ Similar fluctuations in the time derivatives dH/dt and dD/dt of the geomagnetic field components were observed in the horizontal components Ey and Ex of the geoelectric field and the GIC variations.

      $\bullet$ The disturbance fluctuations in the geoelectric field components and the GIC exhibit higher amplitudes during the daytime, especially between about 8:00 and 16:00 LT.

      $\bullet$ The impulses in the geoelectric field components and the estimated GIC during this daytime are stronger in the southern stations than in the northern stations.

      $\bullet$ On the average, the impulses in geoelectric field components and the estimated GIC exhibit a slight enhancement near the magnetic equator.

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