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A STUDY OF EQUATORIAL ELECTROJET OVER AFRICA FROM MAGDAS OBSERVATIONS

A STUDY OF EQUATORIAL ELECTROJET OVER AFRICA FROM MAGDAS OBSERVATIONS. 1 Babatunde Rabiu, 2 Yumoto, K., 2 Yamazaki, Y., 3 Adimula, A. I., 4 Kolawole, L. B., 4 Osinowo, O. M., 5 Baylie Damtie, 6 Paul Baki, 6 Kianji, G. & 2 MAGDAS Group .

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A STUDY OF EQUATORIAL ELECTROJET OVER AFRICA FROM MAGDAS OBSERVATIONS

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  1. A STUDY OF EQUATORIAL ELECTROJET OVER AFRICA FROM MAGDAS OBSERVATIONS 1Babatunde Rabiu, 2Yumoto, K., 2Yamazaki, Y., 3Adimula, A. I., 4Kolawole, L. B., 4Osinowo, O. M., 5Baylie Damtie, 6Paul Baki, 6Kianji, G. & 2MAGDAS Group 1Federal University of Technology, Akure, Nigeria; 2Space Environment Research Centre, Kyushu University, Japan; 3University of Ilorin, Nigeria; 4Reedemer’s University, Nigeria; 5Bahir Dar University, Bahir Dar, Ethiopia ; 6University of Nairobi, Nairobi, Kenya Email: tunderabiu@yahoo.com

  2. Equatorial Electrojet • The E (dynamo) region of the equatorial ionosphere consists of 2 layers of currents responsible for the quiet solar daily variations in Earth’s magnetic field: • Worldwide solar quiet daily variation, WSq (altitude 118  7 km), responsible for the global quiet daily variation observed in the earth’s magnetic field. • Equatorial electrojet, EEJ - an intense current flowing eastward in the low latitude ionosphere within the narrow region flanking the dip equator (altitude 106  2 km) • On disturbed days there is an additional variation, which includes superimposed magnetic storm signatures

  3. Equivalent currents Source: NASA/GSFC & the Danish Space Research Institute (DSRI).

  4. Spatial variation of EEJ Electrojet in ionosphere North 300 km 300 km Dip equator South Geometry of measurement of EEJ as observed on ground

  5. Spatial variation of EEJcontd Satellite view of EEJ has two side lobes with maximum turning points and a minimum turning point between

  6. IGRF model of The Earth’s magnetic field at 400 km altitude due to the ionosopheric current systems. The equatorial intensification of the magnetic field is due to EEJ. (Rabiu et al, 2006)

  7. Coordinates of the Stations Axis B East Axis A West Separation of axes, ∆ L = 33.735° = 3744.585 km

  8. Methods • MAGDAS provides simultaneous near-real time measurements of the Geomagnetic field elements at 13 locations in Africa • Data for 9th October 2008 (A quiet day) [aa = 2] • Midnight Baseline • Hourly departures • Non-cyclic variation • Sq • EEJ

  9. Enhanced Sq at EEJ stations is due to EEJ field

  10. Eastern Sq is greater than western Sq • Longitudinal difference exhibits hour-hour variability

  11. Western EEJ appears weaker than Eastern EEJ! • It is as if there is a process of re-injection of energy as Jet flows eastward

  12. Non constant flow gradient with time • Flow gradient do not follow a definite diurnal pattern • Drastic fluctuation at rising of the Sun/jet • More fluctuations in daytime

  13. Summary • There is a variation in the behaviour of EEJ at the West and East Africa • The EEJ appear stronger in East than West Africa • Need for establishment of more closely spaced pairs of magnetic stations along the Equatorial Africa stations to study the processes that could be responsible for the flow gradient of the EEJ in Africa • Multi-observational techniques should be employed in overland Africa to investigate the drift of electric field

  14. Thank you

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