Modeling of VHF scintillation observed at low latitude

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

doi:10.1088/1742-6596/208/1/012065

Cited by 5 publications

(4 citation statements)

References 19 publications

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“…The effects of geomagnetic disturbances on equatorial as well as low latitude ionospheric scintillations have been reported by several workers (Aarons et al 1980;Rastogi et al 1981;Vyas and Ayanandan 2011;Singh et al 2010) who explained that with increase in the magnetic activity, the probability of occurrence of scintillation increases during the post-midnight periods in all longitude sectors, while the pre-midnight phenomenon depends on the season as well as on longitude. By comparing the percentage occurrence of scintillations during quiet and disturbed days, Rama Rao et al (1996Rao et al ( , 1997 and Prasad et al (2004Prasad et al ( , 2012 have reported that the occurrence of nighttime scintillation is inhibited during disturbed days of higher solar activity period.…”

Section: Effect Of Geomagnetic Activitymentioning

confidence: 84%

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Ionospheric irregularities at low latitude using VHF scintillations during extreme low solar activity period (2008–2010)

2016

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In the present study, we have used 250 MHz radio signal radiated by geostationary satellite UFO-02 to study the occurrence characteristics of very high frequency scintillations associated with ionospheric irregularities during recent extreme low solar activity period from 2008 to 2010 at low latitude Indian station Varanasi (Geomag. latitude = 14°55 0 N, long. = 154°E, Dip angle = 37.3°, Sub-ionospheric dip = 34°). The impact of this recent extreme low solar activity period on ionosphere is investigated. It is observed that the scintillation occurrence is low having maximum percentage occurrence during pre-midnight periods. With increasing interest in understanding the behavior of ionospheric irregularities, an effort has been made to examine also the influence of solar and magnetic activity over the occurrence of scintillations. During the extreme low solar activity years the scintillation occurrences do not vary linearly with the sunspot number. The inhibition and generation of irregularities during enhanced magnetic activity period are explained by considering changes in the electric field. The spectral analysis provide spectral index for irregularities which varied between-1.5 and-8 and characteristic length of irregularities varied between 400 and 1200 m which confirms that 250 MHz scintillations observed over Varanasi were associated with intermediate scale irregularities.

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Section: Effect Of Geomagnetic Activitymentioning

confidence: 84%

“…The dynamic range of the receiver was about 20 dB. Most of our scintillation data were recorded on a strip chart which is calibrated as 1 cm equal to 2.54 dB (Singh et al 2010).…”

Section: Discussionmentioning

confidence: 99%

Ionospheric irregularities at low latitude using VHF scintillations during extreme low solar activity period (2008–2010)

2016

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“…Using the flux tube–integrated formalism introduced by Haerendel (Theory of equatorial spread, preprint, 1973), it can readily be shown that, in the absence of unusually strong storm time electric fields at the magnetic equator, the e‐folding growth time for the generalized Rayleigh‐Taylor (GRT) instability is seldom less than about 15–20 min. in the postsunset bottomside F region and seldom for more than one or two e‐folding times under moderate solar flux conditions [see, e.g., Sultan , 1996; Retterer et al , 2005; Krall et al , 2009; Singh et al , 2010]. The time of most rapid wave growth is generally about 1900 SLT, depending on season, solar cycle, and longitude.…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional numerical simulation of equatorial F region plasma irregularities with bottomside shear flow

Aveiro

Hysell

2010

J. Geophys. Res.

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[1] A three-dimensional numerical simulation of plasma density irregularities in the postsunset equatorial F region ionosphere leading to equatorial spread F (ESF) is described. The simulation advances the plasma number density and electrostatic potential forward in time by enforcing the constraints of quasi-neutrality and momentum conservation. The magnetic field lines are not modeled as equipotentials. Simulations are performed for cases with no background winds, with no background electric field or gravity, and with winds, a background electric field, and gravity all working in concert. The first run produced generalized Rayleigh Taylor (GRT) instability, and the second produced collisional shear instability (CSI). The combined run produced an instability which developed into an intense ESF event more quickly and with more realistic characteristics than the other two. Simulation results are compared with incoherent and coherent scatter radar data from the magnetic equator. A number of signature ESF characteristics are shown to be reproduced by the simulation.

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“…Using the flux tube-integrated formalism, it can readily be shown that, in the absence of unusually strong storm time electric fields at the magnetic equator, the e folding growth time for the collisional plasma interchange instability is seldom less than about 15-20 min in the postsunset bottomside F region and seldom for more than one or two e folding times under moderate solar flux conditions [see, for example, Sultan, 1996;Retterer, 2005;Krall et al, 2009;Singh et al, 2010]. The time of most rapid wave growth is generally about 1900 SLT, depending on the season, solar cycle, and longitude.…”

Section: F Region Irregularitiesmentioning

confidence: 99%