Determination of Total Electron Content at Equatorial Region—Thailand Using Radio Occultation Technique

Abstract. This study developed a model of Total Electron Content (TEC) over the African region. The TEC data were derived from radio occultation measurements done by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. Geomagnetically quiet time (Kp −20 nT) data during the years 2008–2011, and 2013–2017 were binned according to local time, seasons, solar flux level, geographic longitude, and dip latitude. Cubic B splines were fitted to the binned data to obtain the model. The model was validated using TEC data of the years 2012 and 2018. The validation exercise revealed that, approximation of observed TEC data by our model produces root mean squared error of 4.8 TECU. Moreover, the modeled TEC data correlated highly with the observed TEC data (r = 0.93). Our model is the first attempt to predict TECs over the entire African region by using extensive COSMIC TEC measurements. Due to the extensive input data and the good modeling technique, we were able to reproduce the well-known features such as local time, seasonal, solar activity, and spatial variations of TEC over the African region.

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On the validity of the ionospheric pierce point (IPP) altitude of 350 km in the Indian equatorial and low-latitude sector

Annales Geophysicae ◽

10.5194/angeo-24-2159-2006 ◽

2006 ◽

Vol 24 (8) ◽

pp. 2159-2168 ◽

Cited By ~ 87

Author(s):

P. V. S. Rama Rao ◽

K. Niranjan ◽

D. S. V. V. D. Prasad ◽

S. Gopi Krishna ◽

G. Uma

Keyword(s):

Elevation Angle ◽

Equatorial Region ◽

Indian Region ◽

Electron Content ◽

Total Electron ◽

Gps Satellites ◽

Lower Elevation ◽

Pierce Point ◽

L1 And L2

Abstract. The GPS data provides an effective way to estimate the total electron content (TEC) from the differential time delay of L1 and L2 transmissions from the GPS. The spacing of the constellation of GPS satellites in orbits are such that a minimum of four GPS satellites are observed at any given point in time from any location on the ground. Since these satellites are in different parts of the sky and the electron content in the ionosphere varies both spatially and temporally, the ionospheric pierce point (IPP) altitude or the assumed altitude of the centroid of mass of the ionosphere plays an important role in converting the vertical TEC from the measured slant TEC and vice versa. In this paper efforts are made to examine the validity of the IPP altitude of 350 km in the Indian zone comprising of the ever-changing and dynamic ionosphere from the equator to the ionization anomaly crest region and beyond, using the simultaneous ionosonde data from four different locations in India. From this data it is found that the peak electron density height (hpF2) varies from about 275 to 575 km at the equatorial region, and varies marginally from 300 to 350 km at and beyond the anomaly crest regions. Determination of the effective altitude of the IPP employing the inverse method suggested by Birch et al. (2002) did not yield any consistent altitude in particular for low elevation angles, but varied from a few hundred to one thousand kilometers and beyond in the Indian region. However, the vertical TEC computed from the measured GPS slant TEC for different IPP altitudes ranging from 250 to 750 km in the Indian region has revealed that the TEC does not change significantly with the IPP altitude, as long as the elevation angle of the satellite is greater than 50 degrees. However, in the case of satellites with lower elevation angles (<50°), there is a significant departure in the TEC computed using different IPP altitudes from both methods. Therefore, the IPP altitude of 350 km may be taken as valid even in the Indian sector but only in the cases of satellite passes with elevation angles greater than 50°.

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GPS Total Electron Content (TEC) Prediction at Ionosphere Layer over the Equatorial Region

Trends in Telecommunications Technologies ◽

10.5772/8474 ◽

2010 ◽

Cited By ~ 3

Author(s):

Norsuzila Yaacob ◽

Mardina Abdullah ◽

Mahamod Ismail

Keyword(s):

Total Electron Content ◽

Equatorial Region ◽

Electron Content ◽

Total Electron

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Geometric determination of ionospheric total electron content from dual frequency radar sounding measurements

Planetary and Space Science ◽

10.1016/j.pss.2019.07.010 ◽

2019 ◽

Vol 178 ◽

pp. 104696 ◽

Cited By ~ 2

Author(s):

Kirk M. Scanlan ◽

Cyril Grima ◽

Gregor Steinbrügge ◽

Scott D. Kempf ◽

Duncan A. Young ◽

...

Keyword(s):

Total Electron Content ◽

Electron Content ◽

Dual Frequency ◽

Total Electron ◽

Ionospheric Total Electron Content

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Storm-time total electron content and its response to penetration electric fields over South America

Annales Geophysicae ◽

10.5194/angeo-29-1765-2011 ◽

2011 ◽

Vol 29 (10) ◽

pp. 1765-1778 ◽

Cited By ~ 16

Author(s):

P. M. de Siqueira ◽

E. R. de Paula ◽

M. T. A. H. Muella ◽

L. F. C. Rezende ◽

M. A. Abdu ◽

...

Keyword(s):

South America ◽

Total Electron Content ◽

Electric Fields ◽

Equatorial Region ◽

Electron Content ◽

The South ◽

Low Latitude ◽

Total Electron ◽

Vertical Drift ◽

Magnetometer Data

Abstract. In this work the response of the ionosphere due to the severe magnetic storm of 7–10 November 2004 is investigated by analyzing GPS Total Electron Content (TEC) maps constructed for the South America sector. In order to verify the disturbed zonal electric fields in South America during the superstorm, ionospheric vertical drift data obtained from modeling results are used in the analysis. The vertical drifts were inferred from ΔH magnetometer data (Jicamarca-Piura) following the methodology presented by Anderson et al. (2004). Also used were vertical drifts measured by the Jicamarca ISR. Data from a digisonde located at São Luís, Brazil (2.33° S, 44.2° W, dip latitude 0.25°) are presented to complement the Jicamarca equatorial data. Penetration electric fields were observed by the comparison between the equatorial vertical drifts and the Interplanetary Electric Field (IEF). The TEC maps obtained from GPS data reflect the ionospheric response over the South America low-latitude and equatorial region. They reveal unexpected plasma distributions and TEC levels during the main phase of the superstorm on 7 November, which is coincident with the local post-sunset hours. At this time an increase in the pre-reversal enhancement was expected to develop the Equatorial Ionization Anomaly (EIA) but we observed the absence of EIA. The results also reveal well known characteristics of the plasma distributions on 8, 9, and 10 November. The emphasized features are the expansion and intensification of EIA due to prompt penetration electric fields on 9 November and the inhibition of EIA during post-sunset hours on 7, 8, and 10 November. One important result is that the TEC maps provided a bi-dimensional view of the ionospheric changes offering a spatial description of the electrodynamics involved, which is an advantage over TEC measured by isolated GPS receivers.

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