Signature of ionospheric irregularities under different geophysical conditions on SBAS performance in the western African low-latitude region

Abstract. Rate of change of TEC (ROT) and its index (ROTI) are considered a good proxy to characterize the occurrence of ionospheric plasma irregularities like those observed after sunset at low latitudes. SBASs (satellite-based augmentation systems) are civil aviation systems that provide wide-area or regional improvement to single-frequency satellite navigation using GNSS (Global Navigation Satellite System) constellations. Plasma irregularities in the path of the GNSS signal after sunset cause severe phase fluctuations and loss of locks of the signals in GNSS receiver at low-latitude regions. ROTI is used in this paper to characterize plasma density ionospheric irregularities in central–western Africa under nominal and disturbed conditions and identified some days of irregularity inhibition. A specific low-latitude algorithm is used to emulate potential possible SBAS message using real GNSS data in the western African low-latitude region. The performance of a possible SBAS operation in the region under different ionospheric conditions is analysed. These conditions include effects of geomagnetic disturbed periods when SBAS performance appears to be enhanced due to ionospheric irregularity inhibition. The results of this paper could contribute to a feasibility assessment of a European Geostationary Navigation Overlay System-based SBAS in the sub-Saharan African region.

[1]  H. Chandra,et al.  Equatorial spread-F over a solar cycle , 1972 .

[2]  Xiaoqing Pi,et al.  Monitoring of global ionospheric irregularities using the Worldwide GPS Network , 1997 .

[3]  M. A. Abdu,et al.  Magnetic declination control of the equatorial F region dynamo electric field development and spread F , 1981 .

[4]  P. K. Purohit,et al.  Study of GPS based ionospheric scintillation and its effects on dual frequency receiver , 2010 .

[5]  Todd Walter,et al.  Availability Impact on GPS Aviation due to Strong Ionospheric Scintillation , 2011, IEEE Transactions on Aerospace and Electronic Systems.

[6]  E. R. Paula,et al.  Effects of the vertical plasma drift velocity on the generation and evolution of equatorial spread F , 1999 .

[7]  Juan Blanch,et al.  Estimating ionospheric delay using kriging: 1. Methodology , 2011 .

[8]  R. Sridharan,et al.  On the seasonal variations of the threshold height for the occurrence of equatorial spread F during solar minimum and maximum years , 2007 .

[9]  B. Fejer,et al.  Correction [to “Ionospheric irregularities”] , 1981 .

[10]  Jiyun Lee,et al.  Assessment of Nominal Ionosphere Spatial Decorrelation for LAAS , 2006, 2006 IEEE/ION Position, Location, And Navigation Symposium.

[11]  Rolland Fleury,et al.  Middle‐ and low‐latitude ionosphere response to 2015 St. Patrick's Day geomagnetic storm , 2016 .

[12]  A. D. Sarma,et al.  Modelling of GAGAN TEC data using Spherical Harmonic Functions , 2009, 2009 4th International Conference on Computers and Devices for Communication (CODEC).

[13]  A. D. Sarma,et al.  Investigation of suitability of grid-based ionospheric models for GAGAN , 2006 .

[14]  Takuya Tsugawa,et al.  Occurrence characteristics of plasma bubble derived from global ground‐based GPS receiver networks , 2007 .

[15]  Larry J. Paxton,et al.  Morphology of the equatorial anomaly and equatorial plasma bubbles using image subspace analysis of Global Ultraviolet imager data , 2005 .

[16]  R. Tsunoda,et al.  Control of the seasonal and longitudinal occurrence of equatorial scintillations by the longitudinal gradient in integrated E region Pedersen conductivity , 1985 .

[17]  R. Fleury,et al.  Seasonal TEC Variability in West Africa Equatorial Anomaly Region , 2012 .

[18]  D. A. Gnabahou,et al.  Seasonal, Diurnal, and Solar-Cycle Variations of Electron Density at Two West Africa Equatorial Ionization Anomaly Stations , 2012 .

[19]  Russell Stoneback,et al.  Identifying equatorial ionospheric irregularities using in situ ion drifts , 2014 .

[20]  P. V. S. Rama Rao,et al.  Study of spatial and temporal characteristics of L-band scintillations over the Indian low-latitude region and their possible effects on GPS navigation , 2006 .

[21]  Brent M. Ledvina,et al.  Characteristics of the ionospheric F-region plasma irregularities over brazilian longitudinal sector , 2007 .

[22]  S. Sunda,et al.  Improvement of Position Accuracy with GAGAN and the Impact of Scintillation on GNSS , 2013 .

[23]  Keith M. Groves,et al.  A comparison of TEC fluctuations and scintillations at Ascension Island , 1999 .

[24]  J. O. Adeniyi,et al.  Variability of foE in the equatorial ionosphere with solar activity , 2013 .

[25]  Bodo W. Reinisch,et al.  The effects of the pre-reversal ExB drift, the EIA asymmetry, and magnetic activity on the equatorial spread F during solar maximum , 2005 .

[26]  K. Pathak,et al.  A study of L band scintillations during the initial phase of rising solar activity at an Indian low latitude station , 2013 .

[27]  D. Venkata Ratnam,et al.  Performance evaluation of selected ionospheric delay models during geomagnetic storm conditions in low‐latitude region , 2011 .

[28]  T. Walter,et al.  Protecting Against Unsampled Ionospheric Threats , 2005 .

[29]  L. C. Gentile,et al.  Equatorial plasma bubbles observed by DMSP satellites during a full solar cycle: Toward a global climatology , 2002 .

[30]  D. Venkata Ratnam,et al.  Modelling of low-latitude ionosphere using modified planar fit method for GAGAN , 2009 .