IJG  Vol.6 No.3 , March 2015
Statistical Study of foF2 Diurnal Variation at Dakar Station from 1971 to 1996: Effect of Geomagnetic Classes of Activity on Seasonal Variation at Solar Minimum and Maximum
ABSTRACT
The statistical study of F2 layer critical frequency at Dakar station from 1971 to 1996 is carried out. This paper shows foF2 statistical diurnal for all geomagnetic activities and all seasons and that during solar maximum and minimum phases. It emerges that foF2 diurnal variation graphs at Dakar station exhibits the different types of foF2 profiles in African EIA regions. The type of profile depends on solar activity, season and solar phase. During solar minimum and under quiet time condition, data show the signature of a strength electrojet that is coupled with intense counter electrojet in the afternoon. Under disturbed conditions, mean intense electrojet is observed in winter during fluctuating and recurrent activities. Intense counter electrojet is seen under fluctuating and shock activities in all seasons coupled with strength electrojet in autumn. In summer and spring under all geomagnetic activity condition, there is intense counter electrojet. During solar maximum, in summer and spring there is no electrojet under geomagnetic activity conditions. Winter shows a mean intense electrojet. Winter and autumn are marked by the signature of the reversal electric field.

Cite this paper
Nour, A. , Frédéric, O. , Louis, Z. , Frédéric, G. , Emmanuel, N. , François, Z. , (2015) Statistical Study of foF2 Diurnal Variation at Dakar Station from 1971 to 1996: Effect of Geomagnetic Classes of Activity on Seasonal Variation at Solar Minimum and Maximum. International Journal of Geosciences, 6, 201-208. doi: 10.4236/ijg.2015.63014.
References
[1]   Legrand, J.P. (1984) Elementary Introduction of Cosmic Physics and Solar Terrestrial Physics, Area of Southern and Antarctic French Land, 306.

[2]   Legrand, J.P. and Simon, P.A. (1989) Solar Cycle and Geomagnetic Activity: A Review for Geophysicists. Part I. The Contributions to Geomagnetic Activity of Shock Waves and of the Solar Wind. Annals of Geophysics, 7, 565-578.

[3]   Simon, P.A., and Legrand, J.P. (1989) Solar Cycle and Geomagnetic Activity: A Review for Geophysicists. Part II. The Solar Sources of Geomagnetic Activity and Their Links with Sunspot Cycle Activity. Annals of Geophysics, 7, 579-594.

[4]   Richardson, I.G., Cliver, E.W. and Cane, H.V. (2000) Sources of Geomagnetic Activity over the Solar Cycle: Relative Importance of Coronal Mass Ejections, High-Speed Streams, and Slow Solar Wind. Journal of Geophysical Research, 105, 18200-18213. http://dx.doi.org/10.1029/1999JA000400

[5]   Richardson, I.G. and Cane, H.V. (2002) Sources of Geomagnetic Activity during Nearly Three Solar Cycles (1972-2000). Journal of Geophysical Research, 107, 1187. Ouattara, F. (2013) IRI-2007 foF2 Predictions at Ouagadougou Station during Quiet Time Periods from 1985 to 1995. Archives of Physics Research, 4, 12-18.

[6]   Ouattara, F. (2009) Contribution à l’étude des relations entre les deux composantes du champ magnétique solaire et l’ionosphère équatoriale. Thèse de Doctorat d’Etat, Université Cheikh Anta Diop, Dakar.

[7]   Ouattara, F. and Zerbo, J.L. (2011) Ouagadougou Station F2 layer Parameters Yearly and Seasonal Variations during Severe Geomagnetic Storms Generated by CMEs and Fluctuating wind Streams. International Journal of Physical Sciences, 6, 4854-4860.

[8]   Ouattara, F., Gnabahou, D.A. and Mazaudier, C.A. (2012) Seasonal, Diurnal and Solar-Cycle Variations of Electron Density at Two West Africa Equatorial Ionization Anomaly Stations. International Journal of Geophysics, 2012, Article ID: 640463. http://dx.doi.org/10.1155/2012/640463

[9]   Ouattara, F. and Mazaudier, C.A. (2012) Statistical Study of the Diurnal Variation of the Equatorial F2 Layer at Ouagadougou from 1966 to 1998. Journal of Space Weather Space Climate, 2, 1-10.
http://dx.doi.org/10.1051/swsc/2012019

[10]   Gnabahou, A. and Ouattara, F. (2012) Ionosphere Variability from 1957 to 1981 at Djibouti Station. European Journal of Scientific Research, 73, 382-390.

[11]   Gnabahou, D.A., Elias, A.G. and Ouattara, F. (2013) Long-Term Trend of foF2 at a West-African Equatorial Station Linked to Greenhouse Gases Increase and Dip Equator Secular Displacement. Journal of Geophysical Research, 118, 3909-3913. http://dx.doi.org/10.1002/jgra.50381

[12]   Gnabahou, D.A., Ouattara, F., Nanéma, E. and Zougmoré, F. (2013) foF2 Diurnal Variability at African Equatorial Stations: Dip Equator Secular Displacement Effect. International Journal of Geosciences, 4, 1145-1150. http://dx.doi.org/10.4236/ijg.2013.48108

[13]   Ouattara, F., Gnabahou, A. and Mazaudier, C.A. (2012) Seasonal, Diurnal and Solar-Cycle Variations of Electron Density at Two West Africa Equatorial Ionization Anomaly Stations. International Journal of Geophysics, 2012, Article ID: 640463, 9 p.

[14]   Ouattara, F., Amory-Mazaudier, C., Fleury, R., Lassudrie-Duchesne, P., Vila, P. and Petitdidier, M. (2009) West African Equatorial Ionospheric Parameters Climatology Based on Ouagadougou Ionosonde Station Data from June 1966 to February 1998. Annales Geophysicae, 27, 2503-2514.
http://dx.doi.org/10.5194/angeo-27-2503-2009

[15]   Mayaud, P.N. (1971) A Measurement of Planetary Magnetic Activity Based on Two Antipodal Observatories. Annales Geophysicae, 27, 67-71.

[16]   Mayaud, P.N. (1972) The aa Indices: A 100-Year Series, Characterizing the Magnetic Activity. Journal of Geophysical Research, 77, 6870-6874. http://dx.doi.org/10.1029/JA077i034p06870

[17]   Faynot, J.M. and Vila, P. (1979) F-Region at the Magnetic Equator. Annales Geophysicae, 35, 1-9.

[18]   Dunford, E. (1967) The Relationship between the Ionosphere Equatorial Anomaly and the E-Region Current System. Journal of Atmospheric and Terrestrial Physics, 29, 1489-1498.
http://dx.doi.org/10.1016/0021-9169(67)90102-X

[19]   Vassal, J.A. (1982) Electrojet, contreélectrojet et région F à Sarh (Tchad), Géophysique. ORSTOM, Paris.

[20]   Vassal, J. (1982) La variation du champ magnétique et ses relations avec I’électrojet équatorial au Sénégal Oriental. Annales Geophysicae, 3, 347-355.

[21]   Acharya, R., Roy, B., Sivaraman, M.R. and Dasgupta, A. (2010) An Empirical Relation of Daytime Equatorial Total Electron Content with Equatorial Electrojet in the Indian Zone. Journal of Atmospheric and Solar-Terrestrial Physics (UK), 72, 774-780. http://dx.doi.org/10.1016/j.jastp.2010.03.023

[22]   Acharya, R., Roy, B., Sivaraman, M.R. and Dasgupta, A. (2011) On Conformity of the EEJ Based Ionospheric Model to the Fountain Effect and Resulting Improvements. Journal of Atmospheric and Solar-Terrestrial Physics (UK), 73, 779-784. http://dx.doi.org/10.1016/j.jastp.2011.01.011

[23]   Farley, D.T., Bonell, E., Fejer, B.G. and Larsen, M.F. (1986) The Prereversal Enhancement of the Zonal Electric Field in the Equatorial Ionosphere. Journal of Geophysical Research, 91, 13723-13728.
http://dx.doi.org/10.1029/JA091iA12p13723

[24]   Rishbeth, H. (1971) The F-Layer Dynamo. Planetary and Space Science, 19, 263-267.
http://dx.doi.org/10.1016/0032-0633(71)90205-4

[25]   Fejer, B.G., Farley, D.T., Woodman, R.F. and Calderon, C. (1979) Dependence of Equatorial F-Region Vertical Drifts on Season and Solar Cycle. Journal of Geophysical Research, 84, 5792-5796.

[26]   Fejer, B.G. (1981) The Equatorial Ionospheric Electric Fields: A Review. Journal of Atmospheric and Terrestrial Physics, 43, 377-386. http://dx.doi.org/10.1016/0021-9169(81)90101-X

 
 
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