Geomagnetically Induced Currents (GICs) related to impulsive Space Weather events at Low Latitudes.

N'GUESSAN KOUASSI, Université Félix Houphouet Boigny -Abidjan Cote d' ivoire

Intense space weather events (geomagnetic storms and sub-storms) are potential sources of electric induction within the earth. These events cause intense geomagnetic field variations which induce electric currents in the conducting layers of the Earth. Disruptions of technological equipments due to “Geomagnetically Induced Currents (GICs)” are experienced in the Scandinavian countries since mid XIX the century (Pulkkinen, 2003). Due to their harmful impacts on technological devices, the GICs have been mostly investigated at high latitudes (Pulkkinen et al., 2001a, 2001b, 2003, 2007). However, Kappenman (2003) demonstrated the risk of large GIC occurrence associated with large geomagnetic impulses like Storm sudden commencement (SSC) at low- and mid-latitudes. There are reports on GIC causing perturbation in technological structures in mid- and low-latitude (Ngwira et al., 2008; Torta et al., 2012, Trivedi et al., 2007). As consequence, intense GICs flow, causing frequent disturbances in technological devices like telecommunication and pipe lines, power grid and transformers. The effect of GICs is assumed to be negligible in low-latitude regions. For this reason, the effect of induced currents is poorly studied. Recently, GICs effects have been recorded in South Africa transformers (Gaunt and Coetzee 2007). Due to these threats, we study the induction effects related to space weather events such as solar flare and ssc at low latitudes. In our study, we estimate the geoelectric field from the magnetic data and compare it to the measured geoelectric field. We note that our results are in good agreement with the measures. Then, we estimate the intensity of the GICs from the geoelectric field calculated on the one hand and on the other hand, from the measured geoelectric field. Thus, participating to CESRA Workshop will be a great opportunity to improve our knowledge and evolve our research work.