Studies of ionospheric variations during geomagnetic activities at the low-latitude station, Ile-Ife, Nigeria

Czasopismo : Acta Geophysica
Tytuł artykułu : Studies of ionospheric variations during geomagnetic activities at the low-latitude station, Ile-Ife, Nigeria

Autorzy :
Eshagh, M.
Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden; Department of Geodesy, K.N.Toosi University of Technology, Tehran, Iran,,
Teisseyre, R.
Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,,
Lizurek, G.
Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,,
Asfahani, J.
Atomic Energy Commission, Damascus, Syria,,
Baddari, K.
Laboratory of Physics of the Earth UMBB, Boumerdes, Algeria,,
Bose, S. K.
Centre for Theoretical Studies, Indian Institute of Technology, Kharagpur, West Bengal, India,,
Romanowicz, R. J.
Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,,
Pagliara, S.
Department of Civil Engineering, University of Pisa, Pisa, Italy,,
Huang, S.
Potsdam Institute for Climate Impact Research, Potsdam, Germany,,
Kubrak, E.
Faculty of Civil and Environmental Engineering, Warsaw University of Life Sciences, Warszawa, Poland,,
Falayi, E. O.
Department of Physics, Tai Solarin University of Education, Ijebu-Ode, Nigeria,,
Ariyibi, E. A.
Department of Physics, Obafemi Awolowo University, Ile-Ife, Nigeria,,
Abstrakty : The dual frequency SCINDA N ovAtel GSV 4004B GPS receiver installed at the Ile-Ife (low-latitude station) has been in operation since December 2009. Data records for the year 2010 were processed to obtain Total Electron Content (TEC) and S4 index. These were interpreted to analyze the ionospheric condition during low geomagnetic activity period (when Dst is from –40 to 0 nT) and during geomagnetic storm events (with Dst about –100 nT). Seasonal variations of the TEC and S4 index were also investigated. The occurrence of scintillations is closely linked to the peak value of TEC during the daytime; this is very evident during the equinox months when TEC ≥ 30 TECu. When the maximumTEC value is below 30 TECu, as shown by most of the days in the summer months, the scintillation phenomenon does not occur. During geomagnetic storms, the daytime segment of the TEC plot experiences fluctuations (even bifurcations) in values with the peak TEC value of about 40 TECu. From the interpreted data, the occurrence of geomagnetic storm does not necessarily suggest an increase in the level of scintillations at a low-latitude region. Also, there is a remarkable difference between the IRI 2007 model and the observed TEC values, as the daytime TEC peak differs in magnitude and time of occurrence from the ob served TEC.

Słowa kluczowe : scintillation, geomagnetic storms, ionosphere, vertical drift,
Wydawnictwo : Instytut Geofizyki PAN
Rocznik : 2013
Numer : Vol. 61, no. 1
Strony : 223 – 239
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Cytuj : Eshagh, M. ,Teisseyre, R. ,Lizurek, G. ,Asfahani, J. ,Baddari, K. ,Bose, S. K. ,Romanowicz, R. J. ,Pagliara, S. ,Huang, S. ,Kubrak, E. ,Falayi, E. O. ,Ariyibi, E. A. , Studies of ionospheric variations during geomagnetic activities at the low-latitude station, Ile-Ife, Nigeria. Acta Geophysica Vol. 61, no. 1/2013