Signatures of solar event at middle and low latitudes in the Europe-African sector, during geomagnetic storms, October 2013
Résumé
In this study we investigate the ionospheric and magnetic disturbances during four magnetic storms of October 2013. The Earth was under the influence of solar events as CMEs, interplanetary shock wave and high speed solar wind stream flowing from coronal holes. The variation of the disturbed magnetic observations and GPS-TEC are compared with the variation of quiet days during the same month in order to obtain the characteristics of GPS_TEC, GPS_ROTI (Rate of TEC Index) and magnetic disturbances due to the solar events. We use multi-instruments as GPS station at middle and low latitudes for Africa longitudes. At the beginning of each storm our data highlight the effect of the prompt penetration of the magnetosphere electric field which strongly increases the TEC. During the recovery phase of the storms, we observe on TEC and magnetic data, the signature of the ionospheric disturbance dynamo due to wind produced by Joule heating in the auroral zone. We observe the time variation of the ROTI index during these consecutive days associated to magnetic data. We see the disappearance of the scintillations (low values of ROTI) in Africa at all longitudes on the day of October 14, 2013. The 2 possible causes to explain this observation (large scale disturbance due to the solar wind magnetosphere dynamo source or local physical source) are investigated.