Bibliography

The ionospheric response to high-intensity long duration continuous AE activity (HILDCAA) event (13--15 April 2005) over mid-latitude African region

The ionospheric responses to High-Intensity Long Duration Continuous Auroral Electrojet Activity (HILDCAA) event which happened following the CIR-driven storm were studied over the southern hemisphere mid-latitude in the African sector. The 13–15 April 2005 event was analysed to understand some of the mechanisms responsible for the ionospheric changes during HILDCAA event. The ionosonde critical frequency of F2 layer (foF2) and Global Navigation Satellite System (GNSS) Total Electron Content (TEC) were used to analyse the ionospheric responses. The daytime increase in foF2 and TEC values were observed on 13 April 2005. The TEC and foF2 enhancement could be attributed to Large Scale Traveling Ionospheric Disturbances (LSTIDs), increase in thermospheric neutral composition changes, Prompt Penetration Electric Field (PPEF) and an expansion of Equatorial Ionization Anomaly (EIA) to the mid-latitude.

Matamba, Tshimangadzo; Habarulema, John;

Published by: Advances in Space Research      Published on: jan

YEAR: 2021     DOI: 10.1016/j.asr.2020.10.034

CIR; HILDCAA; Ionospheric storm; PPEF; TEC; TIDs

A comparative study of TEC response for the African equatorial and mid-latitudes during storm conditions

The solar wind effects on the Earth\textquoterights environment are studied for their basic scientific values and crucial practical impacts on technological systems. This paper reports results of Total Electron Content (TEC) changes during two successive ionospheric storms of 7\textendash12 November 2004 using GPS data derived from dual frequency receivers located at African equatorial and midlatitudes. In the geographic coordinate system, equatorial TEC variability is considered over Libreville (0.36\textdegreeN, 9.67\textdegreeE), Gabon and Mbarara (0.60\textdegreeS, 30.74\textdegreeE), Uganda. TEC over midlatitude stations Sutherland (32.38\textdegreeS, 20.81\textdegreeE) and Springbok (29.67\textdegreeS, 17.88\textdegreeE), South Africa are analysed. The analysis of the storm time ionospheric variability over South Africa was undertaken by comparing the critical frequency of the F2 layer (foF2) and the peak height of the F2 layer (hmF2) values obtained from Grahamstown (33.30\textdegreeS, 26.53\textdegreeE) and Madimbo (22.4\textdegreeS, 30.9\textdegreeE) ionosonde measurements. During the analysed storm period it is observed that GPS TEC for midlatitudes was depleted significantly with a corresponding depletion in foF2, due to the reduction in GUVI O/N₂ ratio as observed from its global maps. Over the equatorial latitudes, positive storm effects are more dominant especially during the storm main phase. Negative storm effects are observed over both mid and equatorial latitudes during the recovery phase. A shift in equatorial TEC enhancement (from one GPS station to another) is observed during magnetic storms and has been partially attributed to passage of Travelling Ionospheric Disturbances (TIDs). Magnetometer data over the International Real-time Magnetic Observatory Network (intermagnet) station, Addis Ababa, AAE (9.03\textdegreeN, 38.77\textdegreeE) has been used to help with the explanation of possible causes of equatorial ionospheric TEC dynamics during the analysed magnetic storm period.

Habarulema, John; McKinnell, Lee-Anne; a, Dalia; Zhang, Yongliang; Seemala, Gopi; Ngwira, Chigomezyo; Chum, Jaroslav; Opperman, Ben;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 09/2013

YEAR: 2013     DOI: 10.1016/j.jastp.2013.05.008

African equatorial and midlatitude TEC dynamics; Magnetic storms; TIDs