The variability of low‐latitude ionospheric amplitude and phase scintillation detected by a triple‐frequency GPS receiver

Moraes, Alison de Oliveira; Costa, Emanoel; Abdu, M. A.; Rodrigues, F. S.; Paula, E. R. de; Oliveira, Kelias de; Perrella, Waldecir João

doi:10.1002/2016rs006165

Cited by 61 publications

(44 citation statements)

References 54 publications

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“…Along the period of analysis the mean monthly solar flux values were respectively 155.2, 158.7, 141.7, 128.8, and 126.0 sfu, where 1 sfu = 10 À22 W·m À2 ·Hz À1 at the wavelength of 10.7 cm. This is the same period analyzed by Moraes, Costa, et al (2017), being associated with the equatorial spread F season in the Brazilian sector, according to Abdu et al (1992).…”

Section: Measurementsmentioning

confidence: 79%

Ionospheric Scintillation Fading Coefficients for the GPS L1, L2, and L5 Frequencies

et al. 2018

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The terrestrial ionosphere over low‐latitude regions presents the unique phenomena of the equatorial ionization anomaly (characterized by global maximum in plasma concentration) and plasma‐depleted regions known as equatorial plasma bubbles and associated smaller‐scale plasma irregularities. Transionospheric radio signals such as those from Global Navigation Satellite Systems constellations, traveling across this ambient, may suffer severe scintillation in amplitude and phase due to these plasma structures. Presently, three civilian signals available for GPS users, at L1 (1575.42 MHz), L2C (1227.60 MHz), and L5 (1176.45 MHz) are used to investigate the propagation effects due to these irregularities. The purpose of the present work is to evaluate statistically the distribution of severe fade events for each of these carrier frequencies based on the nonlinear ionospheric propagation effects as represented by the fading coefficients of α‐μ distribution. The results from the analyses of data sets recorded by stations at different geomagnetic latitude locations in Brazil show that regions closer to the equatorial ionization anomaly crest present higher probability of severe fade events. Additionally, the L5 signals, dedicated for safety‐of‐life applications, revealed more unfavorable results when compared to the L1 and L2C frequencies. The results further showed that for 0.8 ≤ S4 ≤ 1.0 the probabilities of fades deeper than −10 dB were between 8.0% and 6.5% depending on the station position. Considering the case of fades deeper than −20 dB, the results reach values near 1%, which is quite concerning. These results show empirically the fading environment that users of the new civilian signals may experience in low‐latitude region. Additionally, the fading coefficients may help in the comprehension of the distribution of amplitude scintillation and its relation with the frequency used, aiding in the future the development of signal processing algorithms capable to mitigate errors for navigation users.

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Section: Measurementsmentioning

confidence: 79%

Ionospheric Scintillation Fading Coefficients for the GPS L1, L2, and L5 Frequencies

et al. 2018

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“…The signature pattern at the scintillation onset time observed here in this work is for GPS-L1 signals. However, as shown in Moraes et al (2017a), the average scintillation onset time value for GPS L2C (1227 MHz) and L5 (1176 MHz) signals are very similar to those for L1. Therefore it is reasonable to expect, by analogy, the same pattern in the scintillation onset time observed for these new civil GPS signals.…”

Section: Resultsmentioning

confidence: 94%

Climatology of the scintillation onset over southern Brazil

et al. 2018

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Abstract. This work presents an analysis of the climatology of the onset time of ionospheric scintillations at low latitude over the southern Brazilian territory near the peak of the equatorial ionization anomaly (EIA). Data from L1 frequency GPS receiver located in Cachoeira Paulista (22.4 • S, 45.0 • W; dip latitude 16.9 • S), from September 1998 to November 2014, covering a period between solar cycles 23 and 24, were used in the present analysis of the scintillation onset time. The results show that the start time of the ionospheric scintillation follows a pattern, starting about 40 min earlier, in the months of November and December, when compared to January and February. The analyses presented here show that such temporal behavior seems to be associated with the ionospheric prereversal vertical drift (PRVD) magnitude and time. The influence of solar activity in the percentage of GPS links affected is also addressed together with the respective ionospheric prereversal vertical drift behavior. Based on this climatological study a set of empirical equations is proposed to be used for a GNSS alert about the scintillation prediction. The identification of this kind of pattern may support GNSS applications for aviation and oil extraction maritime stations positioning.

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“…Thus, we have chosen cases with no occurrence of loss of receiver lock, which was considered a difficult task and reduced the set of data to be analyzed, since loss of lock is a very common process during the occurrence of strong scintillation. Loss of receiver lock during very strong scintillation events tends to occur more frequently when there is a close alignment between the magnetic field lines and the satellite-to-receiver signal paths (DasGupta et al, 2004;Moraes et al, 2017). However, this geometrical factor should not be considered a general rule.…”

Section: Statistical Characterization Of Amplitude Scintillationmentioning

confidence: 99%

“…The work of Aarons (1982) clearly depicts how the scintillation intensities, produced by the smaller-scale irregularity structures coexisting with the plasma bubbles, are maximized in the regions of the Appleton anomaly. More recently, relevant features of ionospheric radio-wave scintillations at the equatorial anomaly region have been extensively investigated for different longitudinal sectors (Spogli et al, 2013;Chatterjee and Chakraborty, 2013;Bhattacharyya et al, 2014;Akala et al, 2015;Cesaroni et al, 2015;Zhang et al, 2015;Srinivasu et al, 2016;Moraes et al, 2017). In the South American sector, particularly for the L-band frequencies, the occurrence characteristics of scintillation-producing irregularities have been demonstrated using ground-based global navigation satellite system (GNSS) receiver networks (e.g., de Akala et al, 2011;Muella et al, 2013Muella et al, , 2014.…”

Section: Introductionmentioning

confidence: 99%

Climatology and modeling of ionospheric scintillations and irregularity zonal drifts at the equatorial anomaly crest region

et al. 2017

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Abstract. In this study the climatology of ionospheric scintillations and the zonal drift velocities of scintillationproducing irregularities are depicted for a station located under the southern crest of the equatorial ionization anomaly. Then, the α−µ ionospheric fading model is used for the firstand second-order statistical characterization of amplitude scintillations. In the statistical analyzes, data are used from single-frequency GPS receivers acquired during ∼ 17 years (September 1997-November 2014 at Cachoeira Paulista (22.4 • S; 45.0 • W), Brazil. The results reveal that the nocturnal occurrence of scintillations follows the seasonal distribution of plasma bubble irregularities observed in the longitudinal sector of eastern South America. In addition to the solar cycle dependence, the results suggest that the occurrence climatology of scintillations is also modulated by the secular variation in the dip latitude of Cachoeira Paulista, since the maximum occurrence of scintillations during the peak of solar cycle 24 was ∼ 20 % lower than that observed during the maximum of solar cycle 23. The dynamics of the irregularities throughout a solar cycle, as investigated from the estimates of the mean zonal drift velocities, presented a good correlation with the EUV and F10.7 cm solar fluxes. Meanwhile, the seasonal behavior showed that the magnitude of the zonal drift velocities is larger during the December solstice months than during the equinoxes. In terms of modeling, the results for the α − µ distribution fit quite well with the experimental data and with the temporal characteristics of fading events independently of the solar activity level.

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The variability of low‐latitude ionospheric amplitude and phase scintillation detected by a triple‐frequency GPS receiver

Cited by 61 publications

References 54 publications

Ionospheric Scintillation Fading Coefficients for the GPS L1, L2, and L5 Frequencies

Ionospheric Scintillation Fading Coefficients for the GPS L1, L2, and L5 Frequencies

Climatology of the scintillation onset over southern Brazil

Climatology and modeling of ionospheric scintillations and irregularity zonal drifts at the equatorial anomaly crest region

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