Effect of equatorial ionization anomaly on the occurrence of spread-F

Jayachandran, P. T.; Ram, P. Sri; Somayajulu, V. V.; Rao, P. V. S. Rama

doi:10.1007/s00585-997-0255-3

Cited by 40 publications

(26 citation statements)

References 17 publications

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“…The result is statistically significant at 95 % confidence level. Thus, the locations of the resurgence peak latitude along with CTR, which is a measure of the strength of EIA, may play a significant role for forecasting scintillation at places away from the EIA crest (Jayachandran et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

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: Discussionmentioning

confidence: 99%

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

Chatterjee¹,

Chakraborty²

2013

Ann. Geophys.

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“…However, higher midnight to morning scintillation was detected at the March equinox compared with the September equinox by Ackah et al (2011). The seasonal variation in scintillation is related to the seasonal variation in spread F. According to Mendillo and Aarons (2005) and Jayachandran et al (1997), the seasonal variation in spread F is caused by the alignment of the Earth's magnetic field with the solar day terminator. Thus, when the Earth's magnetic field becomes aligned with the solar day terminator around the location of the GPS receiver, the local eastward electric field and the magnetic field are positioned at 90°to each other.…”

Section: Daily and Monthly Variationmentioning

confidence: 99%

Characterization of ionospheric scintillation at a geomagnetic equatorial region station

Seba

Gogie

2015

Advances in Space Research

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“…By a careful analysis of ground based ionospheric data, a close linkage between EIA and ESF was shown by Raghavarao et al (1988), Alex et al (1989) and Jayachandran et al (1997). The basic mechanism responsible for the generation of ESF is the Collisional Rayleigh-Taylor (CRT) plasma instability.…”

Section: Introductionmentioning

confidence: 96%

Observational evidence for the plausible linkage of Equatorial Electrojet (EEJ) electric field variations with the post sunset F-region electrodynamics

et al. 2009

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Abstract. The paper is based on a detailed observational study of the Equatorial Spread F (ESF) events on geomagnetically quiet (A p ≤ 20) days of the solar maximum (2001), moderate (2004) and minimum (2006) years using the ionograms and magnetograms from the magnetic equatorial location of Trivandrum (8.5 • N; 77 • E; dip lat ∼0.5 • N) in India. The study brings out some interesting aspects of the daytime Equatorial Electrojet (EEJ) related electric field variations and the post sunset F-region electrodynamics governing the nature of seasonal characteristics of the ESF phenomena during these years. The observed results seem to indicate a plausible linkage of daytime EEJ related electric field variations with pre-reversal enhancement which in turn is related to the occurrence of ESF. These electric field variations are shown to be better represented through a parameter, termed as "E", in the context of possible coupling between the Eand F-regions of the ionosphere. The observed similarities in the gross features of the variations in the parameter "E" and the F-region vertical drift (V z ) point towards the potential usage of the EEJ related parameter "E" as an useful index for the assessment of V z prior to the occurrence of ESF.

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Effect of equatorial ionization anomaly on the occurrence of spread-F

Abstract: Abstract. The unique geometry of the geomagnetic field lines over the equatorial ionosphere coupled with the

Cited by 40 publications

References 17 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

Characterization of ionospheric scintillation at a geomagnetic equatorial region station

Observational evidence for the plausible linkage of Equatorial Electrojet (EEJ) electric field variations with the post sunset F-region electrodynamics

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