Studies on <i>F</i>‐region Irregularities at Low Latitude From Scintillations of Satellite Signals

Bhar, J. N.; Gupta, Arjun; Basu, S.

doi:10.1029/rs005i006p00939

Cited by 17 publications

(9 citation statements)

References 6 publications

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“…During the post-midnight period, a higher percentage occurrence irrespective of duration is reflected at BOK. The patchy characteristics of scintillation at KNC results from the width tapering nature and evolution of the filamentary structure of NS elongated irregularity clouds (Bhar et al, 1970). VHF scintillation with peak-to-peak fluctuations > 30 dB at RPMC are recorded for 82 % cases, while at KNC fluctuations in excess of 20 dB, lower than the former, are noted for all scintillation cases.…”

Section: General Features Of Scintillation Variabilitymentioning

confidence: 95%

“…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%

“…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. Field alignment is weaker in transition zone than at the equator.…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

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: General Features Of Scintillation Variabilitymentioning

confidence: 95%

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: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

See 2 more Smart Citations

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

Chatterjee¹,

Chakraborty²

2013

Ann. Geophys.

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“…With the help of orbiting satellites, it has been found that the equatorial irregularity belt extends to about ±35°dip [Sinclair and Kelleher, 1969]. Both airglow observations and scintillations with orbiting satellites show that the irregularity clouds may split into several streams as one moves away from the equator [Bhar et al, 1970].…”

Section: Introductionmentioning

confidence: 99%

Equatorial bubbles as observed with GPS measurements over Pune, India

et al. 2006

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[1] Ionospheric total electron content (TEC) and scintillations have been recorded continuously since April 2003 using a dual-frequency GPS receiver at Pune, India (geographic latitude 19.1°N, longitude 74.05°E; 24°N dip), situated in between the magnetic equator and the northern crest of the equatorial anomaly. The TEC often shows bite-outs when severe amplitude scintillations are observed on the GPS L1 carrier level. The apparent duration of the bite-outs may be different from the true east-west duration, as observed with geostationary links, because of the presence of a relative velocity between the irregularity cloud and the satellite. The trajectory of a GPS satellite plays an important role in observing the bubble characteristics. The distributions of amplitude and duration of the bubbles have been obtained during the equinoctial months February through April of 2004. The median values are found to be 9 TEC units (1 TECU = 10 16 el/m 2 ) and 3.3 min, respectively. The range error at GPS L1 frequency corresponding to the median TEC depletion is 1.4 m, while that corresponding to the 95th percentile value is 4.5 m. An asymmetry in the east-west walls of the bubble and sharp edges of the depletions resulting in high range error rates $30 cm/min has been noted.

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Effects of transionospheric signal decorrelation on Global Navigation Satellite Systems (GNSS) performance studied from irregularity dynamics around the northern crest of the EIA

2014

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Transionospheric satellite navigation links operate primarily at L band and are frequently subject to severe degradation of performances arising out of ionospheric irregularities. Various characteristic features of equatorial ionospheric irregularity bubbles like the drift velocity, characteristic velocity, decorrelation time, and decorrelation distance can be determined using spaced aerial measurements at VHF. These parameters measured at VHF from a station Calcutta situated near the northern crest of the Equatorial Ionization Anomaly (EIA) in the geophysically sensitive Indian longitude sector have been correlated with L band scintillation indices and GPS position accuracy parameters for identifying possible proxies to L band scintillations. Good correspondences have been observed between decorrelation times and distances at VHF with GPS S 4 and Position Dilution of Precision during periods of GPS scintillations (S 4

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Studies on F‐region Irregularities at Low Latitude From Scintillations of Satellite Signals

Cited by 17 publications

References 6 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

Equatorial bubbles as observed with GPS measurements over Pune, India

Effects of transionospheric signal decorrelation on Global Navigation Satellite Systems (GNSS) performance studied from irregularity dynamics around the northern crest of the EIA

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