Characteristics of low latitude ionospheric E-region irregularities linked with daytime VHF scintillations measured from Varanasi

Patel, Kalpana D.; Singh, Ashutosh K.; Patel, Ramesh C.; Singh, R. P.

doi:10.1007/s12040-009-0058-x

Cited by 26 publications

(22 citation statements)

References 29 publications

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“…Low-latitude observations have also indicated a correlation between the occurrence of daytime scintillation and E sb (Huang 1978;Patel et al 2007Patel et al , 2009). Additionally, a few observations of scintillation in the range of GHz have been also investigated for low latitudes.…”

Section: Introductionmentioning

confidence: 94%

“…Nevertheless, daytime GHz scintillation studies attracted as much attention as nighttime scintillation studies, perhaps because daytime scintillation have a relatively lower rate of occurrence and milder nature (Patel et al 2009). For the most part, scintillations are generally believed to be associated with the F layer at night and the blanketing sporadic E (E sb ) layer during the day (Kumar et al 2007;Zou and Wang 2009;Zou 2011;Seif et al 2012;Alfonsi et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

et al. 2015

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Observations made in non-equatorial regions appear to support the hypothesis that the daytime scintillation of radio signals at gigahertz (GHz) frequencies is produced by the gradient-drift instability (GDI) in the presence of a blanketing sporadic E (E sb ) layer. However, the only evidence offered, thus far, to validate this notion, has been some observations of E sb in the vicinity of GHz scintillations. A more comprehensive evaluation requires information about electric field, together with the presence of a steep gradient, which is presumed to be that of E sb . In this regard, the region in the vicinity of the equatorial electrojet (EEJ) appears to be an ideal "laboratory" to conduct such experiments. The dominant driver of electron drift there is the same as that of the EEJ, the vertical polarization electric field, and indications are that the presence of E sb in that vicinity is controlled by a balance in horizontal transport of E sb , between the EEJ electric field and the neutral wind, as described in a model by Tsunoda (On blanketing sporadic E and polarization effects near the equatorial electrojet, 2008). In this paper, we present, for the first time, results from a comprehensive study of daytime GHz scintillations near the magnetic equator. The properties, derived from measurements, are shown, for the first time, to be consistent with a scenario in which E sb presence is dictated by the Tsunoda model, and the plasma-density irregularities responsible for GHz scintillations appear to be produced by the GDI.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

et al. 2015

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“…Thus, for present computation we have taken a = 10 and b = 1. At our low latitude station Varanasi we are recording amplitude scintillations for the signal frequency 250 MHz from FLEETSAT satellite parked at 73°E Singh et al, 2004Singh et al, , 2006Patel et al, 2009). For this source, the distance between the source and the observation plane is 6.6R e and the zenith angle is $2.5°.…”

Section: Data Selection and Modeled Parametersmentioning

confidence: 99%

“…At a low latitude ground station, Varanasi the amplitude scintillations obtained are generally weak and moderate (Singh et al, 1993(Singh et al, , 2004(Singh et al, , 2006Patel et al, 2009). After analyzing scintillations recorded at low latitude station Varanasi, Singh et al (2006) showed that the power law index for irregularity are in the range of À2 to À8 with the mean value of À4.…”

Section: Introductionmentioning

confidence: 99%

“…Depending upon the drift velocity calculated between the 75 m/s and 200 m/s, they have obtained the intermediate scale size of the irregularities. Patel et al (2007Patel et al ( , 2009 showed the fading rate to be slow for the daytime scintillations observed at low latitude station Varanasi, and are associated with sporadic-E irregularities.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of ionospheric scintillation at low-latitude

Patel

Subrahmanyam

Singh

2011

Advances in Space Research

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Morphology of sporadic E layer retrieved from COSMIC GPS radio occultation measurements: Wind shear theory examination

et al. 2014

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On the basis of the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC)-measured fluctuations in the signal-to-noise ratio and excess phase of the GPS signal piercing through ionospheric sporadic E (Es) layers, the general morphologies of these layers are presented for the period from July 2006 to May 2011. It is found that the latitudinal variation in the Es layer occurrence is substantially geomagnetically controlled, most frequent in the summer hemisphere within the geomagnetic latitude region between 10°and 70°and very rare in the geomagnetic equatorial zone. Model simulations show that the summer maximum (winter minimum) in the Es layer occurrence is very likely attributed to the convergence of the Fe + concentration flux driven by the neutral wind. In addition to seasonal and spatial distributions, the height-time variations in the Es layer occurrence in the midlatitude (>30°) region in summer and spring are primarily dominated by the semidiurnal tides, which start to appear at local time around 6 and 18 h in the height range 110-120 km and gradually descend at a rate of about 0.9-1.6 km/h. In the low-latitude (<30°) region, the diurnal tide dominates. The Horizontal Wind Model (HWM07) indicates that the height-time distribution of Es layers at middle latitude (30°-60°) is highly coincident with the zonal neutral wind shear. However, Es layer occurrences in low-latitude and equatorial regions do not correlate well with the zonal wind shear.

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Characteristics of low latitude ionospheric E-region irregularities linked with daytime VHF scintillations measured from Varanasi

Cited by 26 publications

References 29 publications

Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

Modeling of ionospheric scintillation at low-latitude

Morphology of sporadic E layer retrieved from COSMIC GPS radio occultation measurements: Wind shear theory examination

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