Browsing by Author "Mito, Collins"

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    Features of the Night-Time F-Region Currents Over Equatorial Africa (August, 2001)
    (2014) Adero, Awuor Ochieng; Baki, Paul; Kotze, Peter; Mito, Collins
    In this paper, we present the features of the equatorial F-region current systems over equatorial Africa during nighttime on 05thAugust, 2001 observed at midnight. The observations have inferred from in situ CHAMP satellite measurements of the vector magnetic field. The magnitudes of the current along all the three magnetic field components of the Earth’s magnetic field varied considerably. The Bx-component recorded a diamagnetic effect of about 8nT, By-component recorded a current density of 5mA/m, and Bz-component reached a value of 3mA/m. The F-region dynamo, gravity dynamo and plasmapressure gradients are the possible mechanisms for the occurrence of these currents. The signatures confined to the equatorial region bounded by the Appleton anomaly.
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    Identification of Night-Time F- Region Currents from CHAMP Satellite Observations over Equatorial Africa
    (2013) Ochieng, Adero Awuor; Baki, Paul; Kotze, Peter; Mito, Collins
    The F-region currents are generally weak and difficult to detect. However, their contributions to the earth’s magnetic field variations are significant and cannot be ignored by the field modelers. CHAMP satellite has therefore provided a perfect opportunity to investigate the in-situ F-region currents on the night side of the equatorial region. The magnitudes of the current along all the three components of the earth’s magnetic field (X, Y, Z) are investigated. However in this paper, we present only the results on the Y-component where interesting magnetic residuals were observed. The X and Z-components were rather masked in much noise and would require further filtering. The currents appear in both the pre-midnight and postmidnight sectors and are spatially confined to the equatorial region bounded by the Appleton anomaly. The magnetic residuals are generally observed in the northern hemisphere of an order of 0.8nT, which gives a height-integrated current density of about 1.3mA/m.
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    A study on the response of the Equatorial Ionization Anomaly over the East Africa sector during the geomagnetic storm of November 13, 2012
    (Elsevier, 2015) Olwendo, Ouko Joseph; Yosuke, Yamazak; Cilliers, Pierre; Baki, Paul; Ngwira, Chigomezyo M; Mito, Collins
    Using a set of up to 12 International GNSS Services (IGS) receivers around the East African region, we present the formation of the peak of ionospheric Equatorial Ionization Anomaly during the geomagnetic storm of 13th November 2012. The diurnal pattern of total electron content (TEC) shows a strong negative storm during the main phase of the storm. Latitudinal variation of TEC shows development of strong Equatorial Ionization Anomaly (EIA) on the recovery phase. Evidence in terms of magnetic variations during the storm period, indicates that the penetration of interplanetary electric fields is the main cause of the negative ionospheric effect during the main phase of the storm. Observation shows the occurrence of very strong westward electric fields arising from the IMF Bz turning southward a few hours after sunset local time. TEC enhancement during the recovery phase on the 16th are attributed to the increased ionospheric disturbance dynamo electric fields. In addition the EIA crest was found to intensify in amplitude as well as expand in latitudinal extent.