Latitudinal and Local Time Variation of Ionospheric Turbulence Parameters during the Conjugate Point Equatorial Experiment in Brazil

Carrano, Charles S.; Valladares, C. E.; Groves, K. M.

doi:10.1155/2012/103963

Cited by 34 publications

(46 citation statements)

References 37 publications

(105 reference statements)

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“…While strong scintillation was reported (Valladares et al, 2004) during most of the days at the EIA region, at the magnetic equator strong scintillation is rarely observed. The strength of turbulence is reported (Carrano et al, 2012) to be larger near the crest of EIA and at early post-sunset hours.…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 94%

“…The ionosphere near the anomaly crest exhibits extreme variability under various geophysical and geomagnetic conditions. Though much study has been done (Bhar et al, 1970;Somayajulu et al, 1984;Reddy, 1986, 1990;Kil et al, 2002;Valladares et al, 2001Valladares et al, , 2004Carrano et al, 2012) on the spatial variations of scintillation in the low latitude zone, space-time variability of the same within a short latitudinal span around the crest of the equatorial ionization anomaly is yet to be explored. The study may throw some light on the fine structures of the space-time variability of scintillation, and results obtained may fruitfully utilized to decide the system vulnerability and corresponding solutions for adaptivity.…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

“…Several observations pertaining to climatology and dynamics of irregularities near the equatorial low-latitude zone have been made (Bhar et al, 1970;Somayajulu et al, 1984;Reddy, 1986, 1990;Chakraborty et al, 1999;Kil et al, 2002;Valladares et al, 2001Valladares et al, , 2004Carrano et al, 2012). Bhar et al (1970), using transit satellites BEB and BEC, showed that the irregularities in the low-to midlatitude transition zone are embedded in N-S elongated clouds with the width tapering off towards north.…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

“…A reduction in fade rates may be dictated by lower values of horizontal drift velocities and its larger spatial/temporal variability. The decorrelation time characterizes the rate of fluctuations of a signal (Carrano et al, 2012) that is estimated by the time at which the autocorrelation function of the signal falls to 50 % of its peak value. It is a very good measure of the strength of scattering when the first-order statistics, as represented by the S 4 index, are completely saturated (Basu et al, 1983).…”

Section: General Features Of Scintillation Variabilitymentioning

confidence: 99%

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Variability of ionospheric scintillation near the equatorial anomaly crest of the Indian zone

Chatterjee¹,

Chakraborty²

2013

Ann. Geophys.

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Multistation observations of ionosphere scintillation at VHF (250 MHz) and GNSS L1 frequency from three locations – (i) Bokkhali (BOK) (geographic 21.6° N, 88.2° E, dip 31.48°, (ii) Raja Peary Mohan College Centre (RPMC) (geographic 22.66° N, 88.4° E, dip 33.5°) and (iii) Krishnath College Centre (KNC), Berhampore (geographic 24.1° N, 88.3° E, dip 35.9°) – at ~ 1° latitudinal separations near the northern crest of the equatorial ionization anomaly (EIA) of the Indian longitude sector are investigated in conjunction with total electron content (TEC) data and available ionosonde data near the magnetic equator to study fine structure in spatial and temporal variability patterns of scintillation occurrences. The observations are carried out in the autumnal equinoctial months of a high solar activity year (2011). In spite of smaller latitudinal/spatial separation among the observing stations, conspicuous differences are reflected in the onset time, duration, fade rate and fade depth of VHF scintillations as well as in spectral features. Scintillations are mostly associated with depletion in TEC around the anomaly crest and occurrence of ESF near the magnetic equator at an earlier time. Not only the strength of EIA, but also the locations of observing stations with respect to the post-sunset resurgence peak of EIA seem to play dominant role in dictating the severity of scintillation activity. A secondary enhancement in diurnal TEC in the post-sunset period seems to accentuate the irregularity activities near the anomaly crest, and a threshold value of the same may fruitfully be utilized for the prediction of scintillation around the locations. An idea regarding latitudinal extent of scintillation is developed by considering observations at L1 frequency from the GPS and GLONASS constellation of satellites. A critical value of h'F near the magnetic equator for the occurrence of simultaneous scintillation at the three centres is suggested. The observations are discussed considering electrodynamical aspect of equatorial irregularities

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Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 94%

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

Section: General Features Of Scintillation Variabilitymentioning

confidence: 99%

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Variability of ionospheric scintillation near the equatorial anomaly crest of the Indian zone

Chatterjee¹,

Chakraborty²

2013

Ann. Geophys.

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“…2 of the work of Oliveira et al (2014). Additionally to the fading rate, the τ 0 parameter may be used to characterize the turbulent ionospheric medium (Carrano et al, 2012) and to predict GPS receiver cycle slipping rates (Humphreys et al, 2010). For example, in Moraes et al (2011), the typical values of probability of cycle slip for GPS users at low latitudes under amplitude scintillation conditions were up to 35 %.…”

Section: Ionospheric Fading Modelmentioning

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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Satellite‐beacon Ionospheric‐scintillation Global Model of the upper Atmosphere (SIGMA) I: High‐latitude sensitivity study of the model parameters

et al. 2014

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Complex magnetosphere‐ionosphere coupling mechanisms result in high‐latitude irregularities that are difficult to characterize using only Global Navigation Satellite System (GNSS) scintillation measurements. However, GNSS observations combined with physical parameters derived from modeling can be used to study the physics of these irregularities. We have developed a full three‐dimensional electromagnetic wave propagation model called “Satellite‐beacon Ionospheric‐scintillation Global Model of the upper Atmosphere” (SIGMA), to simulate GNSS scintillations. This model eliminates the most significant approximation made by the previous simulation approaches about the correlation length of the irregularity. Thus, for the first time, using SIGMA, we can accomplish scintillation simulations of significantly high fidelity. While the model is global, it is particularly applicable at high latitudes as it accounts for the complicated geometry of the magnetic field lines in these regions. Using SIGMA, we simulate the spatial and temporal variations in the GNSS signal phase and amplitude on the ground. In this paper, we present the model and results from a study to determine the sensitivity of the SIGMA outputs to different input parameters. We have deduced from our sensitivity study that the peak to peak (P2P) power gets most affected by the spectral index and line of sight direction, while the P2P phase and standard deviation of the phase (σφ) are more sensitive to the anisotropy of the irregularity. The sensitivity study of SIGMA narrows the parametric space to investigate when comparing the modeled results to the observations.

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Latitudinal and Local Time Variation of Ionospheric Turbulence Parameters during the Conjugate Point Equatorial Experiment in Brazil

Cited by 34 publications

References 37 publications

Variability of ionospheric scintillation near the equatorial anomaly crest of the Indian zone

Variability of ionospheric scintillation near the equatorial anomaly crest of the Indian zone

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

Satellite‐beacon Ionospheric‐scintillation Global Model of the upper Atmosphere (SIGMA) I: High‐latitude sensitivity study of the model parameters

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