An Investigation of the Total Electron Content in the Equatorial Anomaly of East Africa

Radio Science ◽  
1969 ◽  
Vol 4 (9) ◽  
pp. 817-822 ◽  
Author(s):  
A. N. Hunter ◽  
F. Hibberd ◽  
W. Mulokwa
2005 ◽  
Vol 23 (7) ◽  
pp. 2449-2456 ◽  
Author(s):  
N. Dashora ◽  
R. Pandey

Abstract. A GSV 4004A GPS receiver has been operational near the crest of the equatorial anomaly at Udaipur, India for some time now. The receiver provides the line-of-sight total electron content (TEC), the phase and amplitude scintillation index, σφ and S4, respectively. This paper presents the first results on the nighttime TEC depletions associated with the equatorial spread F in the Indian zone. The TEC depletions are found to be very well correlated with the increased S4 index. A new feature of low-latitude TEC is also reported, concerning the observation of isolated and localized TEC enhancements in the nighttime low-latitude ionosphere. The TEC enhancements are not correlated with the S4 index. The TEC enhancements have also been observed along with the TEC depletions. The TEC enhancements have been interpreted as the manifestation of the plasma density enhancements reported by Le et al. (2003). Keywords. Ionosphere (Equatorial ionosphere; Ionospheric irregularities)


2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Takashi Maruyama ◽  
Kornyanat Hozumi ◽  
Guanyi Ma ◽  
Pornchai Supnithi ◽  
Napat Tongkasem ◽  
...  

AbstractA new technique was developed to estimate the ionospheric total electron content (TEC) from Global Navigation Satellite System (GNSS) satellite signals. The vertically distributed electron density was parameterized by two thin-shell layers (double-shell approach). The spatiotemporal variation of TEC (strictly speaking, partial electron content) associated with each shell was approximated by the functional fitting of spherical surface harmonics. The major improvements over the conventional single-shell approach were as follows: (1) the precise estimation of TEC was achieved; (2) the estimated TEC was less dependent on the choice of shell heights; and (3) the equatorial anomaly was captured more correctly. Furthermore, higher and lower shells exhibited a different pattern of local time vs latitude variation, providing information on the ionosphere–thermosphere dynamics.


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