Ionospheric and magnetic signatures of a high speed solar wind in low latitudes on 13 October 2012

International audienceThis paper presents the impact of a fast solar wind on the ionosphere, in low latitudes, on 13 October 2012. On that day, the high speed solar wind reached the Earth around 16:00UT, during the recovery phase of a geomagnetic storm which started around 00:00UT. The solar wind speed was determined to be 580km/s, on the same day, around 17:00UT. Its impact was observed in low and equatorial latitudes, in Africa and in Eastern South America, on the F layer and on the geomagnetic field variations. Through the analysis of magnetic indices, ionosonde characteristics and the horizontal component of the geomagnetic field, we found that the 13 October 2012 event exhibited a local impact, affecting the observatories situated in a longitude sector between 315°E and 45°E. Particularly, the F layer in Africa (observed by the ionosonde at Ascension Island) did not present any lift, and there was a delay for approximately two hours of the ascent of the F layer in America (the ionosonde at Fortaleza). In this case, there was an evident inhibition on the development of spread F at the time of the Pre Reversal Enhancement (PRE) in Africa and Eastern America, while the ionograms of the days before and after presented clear spread F traces. The disturbances of the ionospheric equivalent electric current (Diono) deduced from the variations of the geomagnetic field at M'Bour near Dakar (Africa) and at Kourou (Eastern America) exhibited on the dayside, an anti Sq current which is signature of the influence of the Disturbance Dynamo Electric Field (DDEF)