Characteristics of equatorial ionization anomaly (EIA) in relation to transionospheric satellite links around the northern crest in the Indian longitude sector

Das, Arijit; Paul, Ashik; Halder, Subhadeep; Basu, Kaustav

doi:10.5194/angeo-32-91-2014

Cited by 16 publications

(19 citation statements)

References 10 publications

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“…The variations of EIA anomaly crest location and intensity have also been reported in the literature [Huang et al, 1989;Rastogi and Klobuchar, 1990]. Sharp latitudinal variability of TEC in the Indian longitude sector has been reported in Paul et al [2011] and Das et al [2014]. Solar cyclic and seasonal variations of TEC have been reported in various literatures such as Rama Rao et al [1977Rao et al [ , 1985, Vertical TEC (VTEC) prediction models have been developed using measured VTEC with the help of artificial neural network (ANN) based models for 77°E, 88°E, and 121°E longitude in the low-latitude regions for different solar activity periods.…”

Section: Introductionsupporting

confidence: 56%

“…The EIA in the equatorial region causes sharp latitudinal gradient of TEC. The highly dynamic ionosphere results in large day-to-day TEC variations [Rastogi and Klobuchar, 1990;Klobuchar et al, 2001;Paul et al, 2011;Das et al, 2014]. The variations of EIA anomaly crest location and intensity have also been reported in the literature [Huang et al, 1989;Rastogi and Klobuchar, 1990].…”

Section: Introductionmentioning

confidence: 86%

“…The variations of EIA anomaly crest location and intensity have also been reported in the literature [ Huang et al , ; Rastogi and Klobuchar , ]. Sharp latitudinal variability of TEC in the Indian longitude sector has been reported in Paul et al [] and Das et al []. Solar cyclic and seasonal variations of TEC have been reported in various literatures such as Rama Rao et al [, ], Bhuyan [], and Bhuyan and Borah [].…”

Section: Introductionmentioning

confidence: 99%

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Response of data‐driven artificial neural network‐based TEC models to neutral wind for different locations, seasons, and solar activity levels from the Indian longitude sector

2017

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The perturbations imposed on transionospheric signals by the ionosphere are a major concern for navigation. The dynamic nature of the ionosphere in the low‐latitude equatorial region and the Indian longitude sector has some specific characteristics such as sharp temporal and latitudinal variation of total electron content (TEC). TEC in the Indian longitude sector also undergoes seasonal variations. The large magnitude and sharp variation of TEC cause large and variable range errors for satellite‐based navigation system such as Global Positioning System (GPS) throughout the day. For accurate navigation using satellite‐based augmentation systems, proper prediction of TEC under certain geophysical conditions is necessary in the equatorial region. It has been reported in the literature that prediction accuracy of TEC has been improved using measured data‐driven artificial neural network (ANN)‐based vertical TEC (VTEC) models, compared to standard ionospheric models. A set of observations carried out in the Indian longitude sector have been reported in this paper in order to find the amount of improvement in performance accuracy of an ANN‐based VTEC model after incorporation of neutral wind as model input. The variations of this improvement in prediction accuracy with respect to latitude, longitude, season, and solar activity have also been reported in this paper.

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Section: Introductionsupporting

confidence: 56%

Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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Response of data‐driven artificial neural network‐based TEC models to neutral wind for different locations, seasons, and solar activity levels from the Indian longitude sector

2017

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“…In contrast, the mid‐latitude ionospheric storm model (ie, the CONUS threat model) was utilized during local daytime, since no significantly large gradient was observed through the Brazilian ionospheric study (see Yoon et al). However, the effects of an equatorial ionospheric anomaly (EIA) that characterizes the daytime equatorial ionosphere all the time with a sharp ionospheric spatial gradient in both the equator‐ward and pole‐ward directions (see Das et al) may still exist. To capture more active ionosphere even in nominal days compared to that in mid‐latitude regions, we assumed that the value of σ vig that bounds nominal ionospheric spatial gradients in low‐latitude regions is twice a σ vig of 4 mm/km in CONUS.…”

Section: Approach I: Worst‐case Epb Threat Assessment and Mitigation mentioning

confidence: 99%

Assessment and mitigation of equatorial plasma bubble impacts on category I GBAS operations in the Brazilian region

et al. 2019

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Prior to initiating GBAS service in equatorial regions, it is vital to evaluate potential integrity threats posed by equatorial plasma bubble (EPB)-induced ionospheric gradients and assess availability when implementing ionospheric threat mitigation methods. Earlier work developed a preliminary EPB model with a gradient bound larger than twice that for mid-latitude ionospheric storms. Position-domain geometry screening (PDGS) with this higher gradient bound decreases availability to 58.3% at the Galeão International Airport, Brazil, during nighttime. A new mitigation method using Monte Carlo simulation randomizes ionospheric scenarios using randomly generated parameter combinations within the threat model and assesses the ensemble impacts. By taking credit for a prior probability of an extreme EPB, this algorithm determines the inflated integrity parameters to meet the safety requirement in the probabilistic definition. This paper shows that with this method, the system availability for category I precision approaches dramatically improved to 89.6% when a datadriven prior probability of 10-5 was applied.

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“…Amplitude scintillation observations and cycle slips at Calcutta located in the northern anomaly crest region have been extensively reported in literature [Ray and DasGupta, 2007;Roy and Paul, 2013] and also from locations beyond the northern crest of the EIA [A. Das et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

Relation of decorrelated transionospheric GPS signal fluctuations from two stations in the northern anomaly crest region with equatorial ionospheric dynamics

Paul

2017

Radio Sci.

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The ionosphere around the northern crest of the equatorial ionization anomaly (EIA) and beyond exhibits rapid temporal as well as spatial development of ionization density irregularities during postsunset hours. A GPS campaign was conducted during September 2012 and April 2013 from the Institute of Radio Physics and Electronics, Calcutta (22.58°N, 88.38°E geographic; magnetic dip: 32°N), and North Bengal University (NBU), Siliguri (26.72°N, 88.39°E geographic, magnetic dip: 39.49°N) in India in order to assess and quantify differences, if any, in the nature of carrier to noise ratio (C/N0) fluctuations observed on the same satellite link around the same time interval from these stations. Significant decorrelation of the received signals was found when tracking the same satellite vehicle (SV) link from these stations during periods of scintillations. Low values of correlation coefficient of C/N0 at L1 frequency recorded on the same SV link at these two stations were found to correspond with high irregularity characteristic velocities. North‐south spatial displacement rates of the impact of ionospheric irregularities were calculated based on coordinated GPS observations which followed an increasing trend with irregularity characteristic velocities measured at VHF. Values of characteristic velocities in excess of 36 m/s were also found to result in large receiver position deviations ~3.5–4.0 m during periods of scintillations. Information related to time lag associated with occurrence of scintillations on the same SV link observed from two stations could be useful for improving performance of transionospheric satellite‐based position determination techniques.

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Characteristics of equatorial ionization anomaly (EIA) in relation to transionospheric satellite links around the northern crest in the Indian longitude sector

Abstract: Abstract. The poleward gradient of the equatorial ionization anomaly (EIA) introduces more intense propagation effects on transionospheric satellite links in comparison to the equatorward gradient.

Cited by 16 publications

References 10 publications

Response of data‐driven artificial neural network‐based TEC models to neutral wind for different locations, seasons, and solar activity levels from the Indian longitude sector

Response of data‐driven artificial neural network‐based TEC models to neutral wind for different locations, seasons, and solar activity levels from the Indian longitude sector

Assessment and mitigation of equatorial plasma bubble impacts on category I GBAS operations in the Brazilian region

Relation of decorrelated transionospheric GPS signal fluctuations from two stations in the northern anomaly crest region with equatorial ionospheric dynamics

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