UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea A STUDY OF EQUATORIAL ELECTROJET OVER AFRICA...
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UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea A STUDY OF EQUATORIAL A STUDY OF EQUATORIAL ELECTROJET OVER AFRICA ELECTROJET OVER AFRICA FROM MAGDAS OBSERVATIONS FROM MAGDAS OBSERVATIONS 1 Federal University of Technology, Akure, Nigeria; Federal University of Technology, Akure, Nigeria; 2 Space Environment Space Environment Research Centre, Kyushu University, Japan; 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: Email: [email protected] 1 Babatunde Rabiu, 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
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Transcript of UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea A STUDY OF EQUATORIAL ELECTROJET OVER AFRICA...
UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea
A STUDY OF EQUATORIAL A STUDY OF EQUATORIAL ELECTROJET OVER AFRICA ELECTROJET OVER AFRICA
FROM MAGDAS FROM MAGDAS OBSERVATIONSOBSERVATIONS
11Federal University of Technology, Akure, Nigeria; Federal University of Technology, Akure, Nigeria; 22Space Space Environment Research Centre, Kyushu University, Japan; Environment Research Centre, Kyushu University, Japan;
3University of Ilorin, Nigeria; 4Reedemer’s University, Nigeria; 5Bahir Dar University, Bahir Dar, Ethiopia ; 6University of
Nairobi, Nairobi, KenyaEmail: Email: [email protected]
11Babatunde Rabiu, Babatunde Rabiu, 2Yumoto, K., 2Yamazaki, Y., 3Adimula, A. I., 4Kolawole, L. B., 4Osinowo, O. M., 5Baylie Damtie, 6Paul Baki,
6Kianji, G. & 2MAGDAS Group
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UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea
Equatorial ElectrojetEquatorial Electrojet The E (dynamo) region of the equatorial ionosphere consists of The E (dynamo) region of the equatorial ionosphere consists of
2 layers of currents responsible for the quiet solar daily 2 layers of currents responsible for the quiet solar daily variations in Earth’s magnetic field: variations in Earth’s magnetic field:
Worldwide solar quiet daily variation, WSq (altitude 118 Worldwide solar quiet daily variation, WSq (altitude 118 7 7 km), responsible for the global quiet daily variation observed in km), responsible for the global quiet daily variation observed in the earth’s magnetic field. the earth’s magnetic field.
Equatorial electrojet, EEJ - an intense current flowing eastward Equatorial electrojet, EEJ - an intense current flowing eastward in the low latitude ionosphere within the narrow region flanking in the low latitude ionosphere within the narrow region flanking the dip equator (altitude 106 the dip equator (altitude 106 2 km) 2 km)
On disturbed days there is an additional variation, which On disturbed days there is an additional variation, which includes superimposed magnetic storm signaturesincludes superimposed magnetic storm signatures
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UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea
Equivalent
currents
Source: NASA/GSFC & the Danish Space Research Institute (DSRI).
UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea
Dip equatorSouth
North
Electrojet in ionosphere
300 km
300 km
Geometry of measurement of EEJ as observed on ground
Spatial variation Spatial variation of EEJ
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 Spatial variation of EEJ contdcontd
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.
UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea
Coordinates of the StationsCoordinates of the StationsOBS GMLat
◦GLong◦ E
GLat◦
ILR -1.82 4.67 8.50◦N
LAG 3.43 6.48◦N
AAB 0.18 38.77 9.04◦N
NAB 36.80 1.16◦S
Separation of axes, ∆ L = 33.735° = 3744.585 km
Axis A
West
Axis B
East
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UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea
MethodsMethods
Data for 9th October 2008 (A quiet day) [aa = 2]Midnight BaselineHourly departuresNon-cyclic variationSqEEJ
MAGDAS provides simultaneous near-real time measurements of the Geomagnetic field elements at 13 locations in Africa
L
EEJEastEEJWestGradientEEJ
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UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea
Enhanced Sq at EEJ stations is due to EEJ field
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UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea
Eastern Sq is greater than western Sq
Longitudinal difference exhibits hour-hour variability
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
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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
UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea
SummarySummary• 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
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UN/ESA/NASA/JAXA 2009 21-25 Sept., 2009 Daejeon, Korea
THANK YOUTHANK YOU
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