Investigation of ionospheric response to two moderate geomagnetic storms using GPS?TEC measurements in the South American and African sectors during the ascending phase of solar cycle 24

A. J. DE ABREU; FAGUNDES, P.R.; GENDE, M.; BOLAJI, O. S.; DE JESUS, R.; BRUNINI, C.

ADVANCES IN SPACE RESEARCH

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2014 vol. 53 p. 1313 - 1328

0273-1177

In this paper, we have investigated the responses of the ionospheric F-region during two moderate geomagnetic storms, one of which is followed by a storm of small intensity, occurred in May 2010 during the ascending phase of solar cycle 24. The first geomagnetic storm the Dst index reached a minimum of -64nT at 1500 UT on 02 May and the second geomagnetic storm the Dst index reached a minimum of -85nT at 1400 UT on 29 May.In this paper, we present vertical total electron content (VTEC) and phase fluctuations (in TECU/min) from Global Positioning System (GPS) observations, covering from equatorial to mid-latitude regions in the South American and African sectors. The results obtained during the two moderate geomagnetic storms in both sectors show that an expressive positive phase at equatorial, low- and mid-latitude regions is observed. This positive phase é possibly linked to the equatorward extent of the wind and the electric field strength. The traveling ionospheric disturbances (TIDs) can also contribute similar mechanical effects as the equatorward wind. The observations show a pre-storm occurred from low- to mid-latitude regions on the 01 May in the African sector. The results also show that occurred suppression of equatorial ionospheric irregularities during the 02-04 May in the African sector, possibly due the geomagnetic storm.