Whistlers observed at low-latitude ground-based VLF facility in Fiji

Kumar, Sushil; Anil, D.; Kishore, Amol N.; Ramachandran, Visagaperuman

doi:10.1016/j.jastp.2007.05.001

Cited by 9 publications

(6 citation statements)

References 31 publications

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“…Consequently, there has remained some doubt that low‐latitude whistlers even can exist. Some researchers have proposed a nonducted mode of propagation for low‐latitude whistlers [ James , ; Ceisier , ; Singh and Tantry , ; Hayakawa and Iwai , ; Tanaka and Cairo , ; Kumar et al , ], while others have suggested ducted propagation based on ground data and direction‐finding measurements [ Somayajulu and Tantry , ; Hayakawa et al , , ; Ohta et al , ; Singh et al , ].…”

Section: Introductionmentioning

confidence: 99%

Very low latitude (L = 1.08) whistlers and correlation with lightning activity

Gokani

Singh²,

Cohen

et al. 2015

JGR Space Physics

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We present analysis of more than 2000 lightning‐generated whistlers recorded at a low‐latitude station, located at Allahabad (geographic latitude, 25.40°N; geographic longitude, 81.93°E; L = 1.081), India, during December 2010 to November 2011. The main focus of this work is on the correlation between observed low‐latitude whistlers and lightning activity detected by the World‐Wide Lightning Location Network near the conjugate point (geography 9.87°S, 83.59°E) of Allahabad. Whistler occurrence is higher in the postmidnight period as compared to the premidnight period. Whistlers were observed in the daytime only on 2 days that too before 8:30 LT (morning). Seasonally, occurrence is maximum during winter months, which is due to more lightning activity in the conjugate region and favorable ionospheric conditions. About 63% of whistlers were correlated with lightning strokes in the vicinity of the conjugate point within spatial extent of 1000 km (conjugate area). Most (about 53%) whistlers were found to be associated with lightning strokes that were offset to the southeast of the conjugate point. The results indicate that an energy range of 7.5–17.5 kJ of lightning strokes generate most of whistlers at this station. The L shell calculations show that propagation paths of the observed whistlers were embedded in the topside ionosphere. Based on these results we suggest a possibility of ducted mode of propagation even for such very low latitude whistlers.

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Section: Introductionmentioning

confidence: 99%

Very low latitude (L = 1.08) whistlers and correlation with lightning activity

Gokani

Singh²,

Cohen

et al. 2015

JGR Space Physics

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“…In the absence of a duct, the observation of small dispersion low latitude whistlers are proposed to be due to propagation in the prolongitudinal (PL) mode with the angle between the wave normal and the geomagnetic field almost tending to zero 39 (Singh, 1976;Singh et al, 1992;Singh, 1993). Recently, Kumar et al (2007) reported an observation from the low latitude station Suva, Fiji, and interpreted the propagation mechanism to be PL mode, supported by the negative electron density gradient in the ionosphere that is enhanced during magnetic storms.…”

Section: Ducted Mode Of Propagationmentioning

confidence: 97%

Thunderstorms, Lightning, Sprites and Magnetospheric Whistler-Mode Radio Waves

et al. 2008

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“…We look at the possibility of determining the plasmaspheric parameters from the whistlers shown in Figure 3 . To identify the most likely propagation path of both the whistlers, the latitudinal electron density profiles were calculated using the IRI-2001 model and are plotted in Figure 4 Figure 4a have been reported by Kumar et al (2007). From ray tracing analysis, Bortnik et al (2002) found that the horizontal ionospheric latitudinal electron density gradients can cause whistler wave energy to focus near the geomagnetic equator and can result in a spatially narrow energetic electron precipitation at low L shells values (1.40 < L < 1.65).…”

Section: Plasmaspheric Remote Sensing Using Whistlersmentioning

confidence: 99%

“…Storey (1953) predicted that the path of whistler propagation was more or less aligned with the Earth's magnetic field and extended between the hemispheres. Many researchers have reported a good number of whistlers at the low latitudes from their nighttime observations Hayakawa et al, 1990;Singh et al, 1998;Singh and Hayakawa, 2001;Kumar et al, 2007). However, the propagation characteristics of low latitude whistlers are not properly understood yet and have been the subject of controversy for a long time.…”

Section: Introductionmentioning

confidence: 99%