1. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea A STUDY OF EQUATORIAL ELECTROJET OVER AFRICA FROM MAGDAS OBSERVATIONS 1 Federal University of Technology, Akure, Nigeria; 2 Space Environment Research Centre, Kyushu University, Japan; 1 Federal University of Technology, Akure, Nigeria; 2 Space Environment Research Centre, Kyushu University, Japan; 3 University of Ilorin, Nigeria; 4 Reedemer’s University, Nigeria; 5 Bahir Dar University, Bahir Dar, Ethiopia ; 6 University of Nairobi, Nairobi, Kenya Email: tunderabiu@yahoo.com tunderabiu@yahoo.com 1 Babatunde Rabiu, 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 1

2. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea 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 2

3. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea Equivalent currents Source: NASA/GSFC & the Danish Space Research Institute (DSRI).

4. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea Dip equator South North Electrojet in ionosphere 300 km Geometry of measurement of EEJ as observed on ground Spatial variation Spatial variation of EEJ

5. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea Satellite view of EEJ has two side lobes with maximum turning points and a minimum turning point between Spatial variation contd Spatial variation of EEJ contd

6. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea (Rabiu et al, 2006) 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.

7. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea Coordinates of the Stations OBSGMLat◦GLong ◦ E GLat◦ ILR-1.824.678.50 ◦ N LAG3.436.48 ◦ N AAB0.1838.779.04 ◦ N NAB36.801.16 ◦ S Separation of axes, ∆ L = 33.735° = 3744.585 km Axis A West Axis B East 7

8. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea Methods Data for 9 th October 2008 (A quiet day) [aa = 2] Midnight Baseline Hourly departures Non-cyclic variation Sq EEJ MAGDAS provides simultaneous near-real time measurements of the Geomagnetic field elements at 13 locations in Africa 8

9. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea Enhanced Sq at EEJ stations is due to EEJ field 9

10. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea  Eastern Sq is greater than western Sq  Longitudinal difference exhibits hour-hour variability

11. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea  Western EEJ appears weaker than Eastern EEJ!  It is as if there is a process of re-injection of energy as Jet flows eastward 11

12. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea  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 12

13. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea 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 13

14. UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea THANK YOU 14