Computation of growth rate of VLF hiss emissions recorded at Indian Antarctic station, Maiyri, Antarctica (l = 4.5)

VLF hiss emissions are the naturally occurring phenomena in audio frequency range electromagnetic signal propagating in whistler mode and readily detectable at middle and high latitudes. They have constant spectral density in the limited frequency band with right hand polarization. In this paper, we present some VLF hiss data were observed for the first time at the Indian Antarctic Station, Maitri, Antarctica (geographic latitude 700 46/ S, longitude 110 50/ E, geomagnetic latitude 660 03/ S, longitude 530 21/E) during February 17, 2001 has been analyzed. The typical dynamic spectra of VLF hiss emissions in the frequency range of 11 to 13 kHz and three harmonic lines in different frequency range at 6.2, 8.0 and 9.2 kHz are presented. The lower frequency harmonic line is stronger intensity in comparison to higher frequency harmonic line. To explain about these emissions, we propose that the hiss emissions are generated through Doppler – shifted cyclotron interaction near the geomagnetic equator and propagate towards the Earth in the whistler – mode. We have computed growth rate of the waves for different anisotropies and present the results.