Generation mechanism for VLF chorus emissions observed at a low-latitude ground station

Abstract

Abstract.A detailed spectral analysis of VLF chorus emissions observed at the low-latitude ground station Gulmarg (geomag. lat., 24 • 26 N, geomag. long., 147 • 9 E, L=1.28) during the strong magnetic activity on 7-8 March 1986 have been carried out, which shows that each chorus element originates from the upper edge of the underlying hiss band. To explain various temporal and spectral features of these emissions, a possible generation mechanism has been presented based on the backward wave oscillator regime of the magnetospheric cyclotron maser. On the basis of this model, we have computed various chorus parameters as well as some magnetospheric parameters affecting the generation process. A comparison of the observed chorus characteristics with the proposed generation mechanism shows a good agreement.

Search for gravitational waves from low mass compact binary coalescence in LIGO’s sixth science run and Virgo’s science runs 2 and 3

“…Environmental signal levels at our observatories and at external electromagnetic weather observatories were typical of quiet times. Mechanisms that could cause coincident signals among widely separated detectors -such as earthquakes, microseismic noise due to large weather systems, and electromagnetic disturbances in the ionosphere [25,26] -were therefore ruled out.…”

Search for Gravitational Waves from Low Mass Compact Binary Coalescence in LIGO's Sixth Science Run and Virgo's Science Runs 2 and 3

“…Environmental signal levels at our observatories and at external electromagnetic weather observatories were typical of quiet times. Mechanisms that could cause coincident signals among widely separated detectors -such as earthquakes, microseismic noise due to large weather systems, and electromagnetic disturbances in the ionosphere [25,26] -were therefore ruled out.…”

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

“…Triggered emissions exhibit a bewildering variety of dynamic spectral forms (Helliwell, 1965;Nagano et al, 1996;Nunn et al, 1997;Smith and Nunn, 1998;Singh et al, 2003a;Singh and Patel, 2004;Siingh et al, 2005b) and follow a source which could be a whistler (Storey, 1953;Nunn and Smith, 1996), discrete emissions (Helliwell, 1965), signals from VLF transmitters (Helliwell, 1965;Bell et al, 1982), power line radiation from the world's power grids (Helliwell et al, 1975;Park and Change, 1978;Luette et al, 1979) and the upper frequency boundary of hiss (Helliwell, 1969;Reeve and Rycroft, 1976 a,b;Koons, 1981;Hattori et al, 1989Hattori et al, , 1991Singh et al, 2000;Singh and Ronnmark, 2004). The observations in general support the idea that strong VLF emissions may be triggered by a very weak signal.…”