Comparison of Transient Variation of Total Electron Content within and Outside Equatorial Ionization Anomaly Region
O. R. Oladosu
Department of Physics, Federal University of Technology Akure, Nigeria and African Regional Centre for Space Science and Technology Education in (ARCSSTE-E), Obafemi Awolowo University, Ile-Ife, Nigeria.
A. A. Agoyi *
Department of Physics, Federal University of Technology Akure, Nigeria.
A. O. Adewale
Department of Physics, University of Lagos, Nigeria.
R. S. Fayose
Department of Physics, Adekunle Ajasin University, Akungba Akoko, Nigeria.
A. B. Rabiu
Centre for Atmospheric Research of National Space Research and Development Agency, Anyigba, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
This research analyzed the Transient (Quiet and disturbed conditions) variation of Total Electron Content (TEC) within the Equatorial Ionization Anomaly (EIA) region and outside the anomaly region in the area of ground Global Positioning System (GPS) stations at Federal University of Technology Akure (FUTA) in Nigeria (a station in the EIA region) and Matera in Italy (a station in the middle latitude region) for period of 2008 to 2010. The work shows variation of TEC in function of the daily timing, geographical positioning of the studied area and seasons. The study correlates the TEC to the development of the investigated regions and to the variation of ultraviolet solar radiation and neutral winds. The data were collected using special equipment (Novatel GSV 4004B GPS SCINDA system installed at FUTA Nigeria by the US Air Force Research Laboratory (AFRL) USA (PI-keith Groves)) and the International GNSS Service (IGS) GPS system at Matera Italy. The diurnal variation shows TEC maximum on afternoon, for quiet days and almost similar variations, with small changes for the disturbed days. The difference observed between quiet and disturbed days are correlated with different space weather conditions. A predawn minimum (low in EIA region) and pre-midnight enhancement (higher at EIA region) were observed in each area investigated. Similarly the monthly and seasonal variations were analyzed. The study shows that TEC value is usually higher at the EIA region than the middle latitude region. But when storms occurs TEC Value at the middle latitude is higher. It observed from the study that TEC in the EIA region is mainly controlled by the EIA development, while the TEC variation in the middle latitude region is controlled by extreme ultraviolet solar radiation and neutral winds.
Keywords: Transient variation, total electron content, equatorial ionization anomaly, Akure.
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Leonard K, Daniel M, Pryse SE, Candar LjR, Bamford RA, Belehaki A, Leitinger R, Radicella SM, Mitchell CN, Spencer PSJ. Total electron content- A key parameter in propagation: Measurement and use in ionospheric imaging. Ann. Geophys. 2004;24(Sup.):1067-1091.
Huang YN, Cheng K, Chen SW. Equatorial anomaly of the ionospheric electron content near the northern anomaly crest. J. Geophys. Res. (USA). 1989;94:13515-13525.
Rastogi RG, Klobuchar JA. Ionospheric electron content within the equatorial F2 layer anomaly belt. J. Geophys. Res. 1990;95:19045.
Chakrabarty D, Mala SB, Smitha VT, Iyer KN. Solar EUV flux (0.1-50 nm), F10.7 cm flux, sunspot number and the total electron content in the crest region of equatorial ionization anomaly during the deep minimum between solar cycle 23 and 24. India J. Radio and Space Phys. 2012;41: 110-120.
Golton E, Walker GO. Observation of ionospheric electron content across the equatorial anomaly at sunspot minimum. J. Atmos. Terr. Phys. (UK). 1971;33:1-11.
Biqiang Zhao, Weixing Wan, Libo Liu, Zhipeng Ren. Characteristics of the ionospheric total electron content of the equatorial ionization anomaly in the Asian-Australian Region during 1996–2004. Ann. Geophys. 2009;27:3861–3873.
Huang YN, Cheng K. Solar cycle variation of the equatorial ionosphere anomaly in total electron content in the Asian Region. J. Geophs. Res. 1996;101:24513-24520.
Wu CC, Fry CD, Liu JY, Liou K, Tseng CL. Annual TEC variation in the equatorial anomaly region during the solar minimum: September 1996-August 1997. J. Atmos. and Solar-Terr. Phys. 2004;66:199-207.
Wu CC, Liou K, Shan SJ, Tseng CL. Variation of ionospheric total electron content in Taiwan region of the equatorial anomaly from 1994 to 2003. Adv. Space Res. 2008;41:611–616.
Liu H, Stolle C, Forster M, Watanabe S. Solar activity dependence of the electron density in the equatorial anomal regions observed by CHAMP. J. Geophys. Res. 2007;112:A11311.
Groves K, Basu S, Weber E, Smitham M, Kuenzler H, Valladares C. Sheehan anomaly region. J. Geophys. Res. 1997;106(A12):30363-30369.
Rabiu AB, Mamukuyomi AI, Joshua EO. Variability of the equatorial ionosphere inferred from geomagnetic field measurements. Bull. Astr. Soc. India. 2007;35:607-618.
Ho-Fang T, Jann-Yeny L, Wei-Hsiung T, Chao-Han L, Ching-Liang T, Chin-Chun W. Seasonal variation of the ionospheric total electron content in Asian equatorial anomaly regions. J. Geophys. Res. 2001;106:30363-30369.
Mala SB, Joshi HP, Iyer KN, Aggarwa Ml, Ravindran S, Pathan BM. TEC variations during low solar activity period (2005–2007) near the equatorial ionospheric anomaly crest region in India. Ann. Geophys. 2009;27:1047–1057.
Rama Rao PVS, Gopi KS, Niranjan K, Prasad DSVVD. Temporal and spatial variation in TEC using simultaneous measurements from the India GPS network of receivers during the low solar activity period of 2004-2005. Ann. Geophys. (Germany). 2006;24:3279-329.
Rishbeth H. F-region storms and thermospheric circulation. J. Atmos. Terr. Phys. 1975;37:1055–1064.
Abdu MA. Major phenomena of the equatorial ionosphere thermosphere system under disturbed conditions. J. Atmos. Sol. Terr. Phys. 1997;59:1505–1519.
Nirvikar Dashora, Pandey R. Variations in the total electron content near the crest of the equatorial ionization anomaly during the November 2004 geomagnetic storm. Earth Planets Space. 2007;59:127–131.
Su YZ, Bailey GJ, Balan N. Modeling studies of the longitudinal variations in TEC at equatorial-anomaly latitudes. J. Atmos. Terr. Phys.1995;57:433-442.
Mendes da Costa AJ, Williams Vilas Boas, Edvaldo S. da Fonseca Junior. GPS total electron content measurements at low latitudes in Brazil for low solar activity. Geofísica Internacional. 2004;43:1129-1137.
Abdu MA, Muralikrishna P, Batista IS, Sobral JHA. Rocket observations of equatorial plasma bubbles over Natal, Brazil, using a high frequency capacitance probe. J. Geophys. Res. 1991;96:7689-7695.
Kumar S, Gwal AK. VHF ionospheric scintillations near the equatorial anomaly crest: Solar and magnetic activity effects. J. Atmos. Terr. Phys. 2000;62:157-167.
Horvath I, Essex EA. Using observations from GPS and TOPEX satellites to investigate night-time TEC enhancements at mid-latitudes in the southern hemisphere during a low sunspot number period. J. Atmos. Terr. Phys. 2000;62:371-391.
Karia SP, Pathak KN. GPS based TEC measurements for a period August 2008 – December 2009 near the northern crest of Indian equatorial ionospheric anomaly region. J. Earth Syst. Sci. 2011;120:5851–5858.
Essex EA, Klobuchar JA. Mid-latitude winter night-time increases in the total electron content of the ionosphere. Journal of Geophysical Res. 1980;85(A11):6011-6020.