Characteristics of discrete VLF falling-tone chorus emissions observed at low latitude ground station Jammu

Ashutosh K Singh,A K Singh,R P Patel,K K Singh,R Singh

doi:10.1186/bf03352969

Ashutosh K Singh, A K Singh + Show 3 more

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Abstract The discrete VLF chorus emissions recorded at low latitude ground station Jammu (geomag. lat. = 22°26′N, L = 1.17) are reported and their characteristics based on spectral analysis have been carried out. These discrete chorus emissions are falling tone emissions which are rarely observed at low latitude ground stations. These discrete chorus emissions are generated during a strong geomagnetic storm period of 2–7 May, 1998. We have computed the frequency sweep rate, repetition period and source region of the individual chorus elements. It is observed that the sweep rate increases with time.

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Chorus emissions are one of the most intriguing signals among natural ELF/VLF radiation
We present a detailed spectral analysis of the discrete VLF falling-tone chorus emissions recorded at low latitude ground station Jammu during the routine recording of whistlers from January 1998 to December 1998
Chorus emissions recorded at low latitude ground station Jammu. These discrete chorus emissions are falling tones which were rarely observed at any low latitude ground stations

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Chorus emissions are one of the most intriguing signals among natural ELF/VLF radiation These emissions usually consist of a succession of discrete elements with rising (falling) frequency having repetition period of T ∼ 0.1–1 s and typical duration of chorus events is 0.5–1 h (Helliwell, 1965). It is generally accepted that the generation mechanism of these emissions is connected with the cyclotron instability of whistler-mode waves and radiation belt electrons (Helliwell, 1967), the generation mechanism of these emissions and formation of spectrum of separate elements are still a subject of active experimental and theoretical research (Smith et al, 1996; Trakhtengerts, 1999; Singh et al, 2000; Lauben et al, 2002; Santolik and Gurnett, 2003; Titova et al, 2003; Singh and Singh, 2004; Singh and Ronnmark, 2004; Santolik, 2008; Bortnik et al, 2008; Omura et al, 2008 and references there in).

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