Whistler observations of the quiet time plasmasphere-ionosphere coupling fluxes at low latitude

Abstract

Observations of whistlers during quiet times made at low-latitude ground station Nainital (geomag. lat. 19" 1' N) are used to deduce plasmasphero-ionosphere coupling fluxes. The whistler data from 3 magnetically quiet days are presented that show a smooth decrease in dispersion with time. This decrease in dispersion is interpreted in terms of a corresponding decrease in electron content of tubes of ionization. The electron densities, electron tube contents (1016 el/m2-tube) and coupling fluxes (10 el m-l sT2) are computed by means of an accurate curve fittingmcthod developed by Tarcsai (1975) and are in good agreement with the results reported by other workers.

Simultaneous observation of whistlers and emissions during a geomagnetically quiet period at low latitude

“…The gyro-frequency model N = K 2 R −3 as discussed above has been used in the present computations. The results of equatorial electron density n eq derived from the whistler analysis making use of (7), show the average n eq variations between about 5 × 10 2 electron cm −3 and 1 × 10 3 electron cm −3 , which is in agreement with the result reported earlier from low latitudes during quiet periods (Khosa et al 1990;Lalmani et al 1996;Singh et al 2004b). Moreover, for L > 2.4, there is lower density in the summer than in winter (Singh et al 1998).…”

“…The waves propagating through the plasma medium is dispersed, high frequencies preceding the low frequencies, and the entire signals are called whistlers. The analysis of whistler dispersion yields information about the plasma medium parameters such as electron density, total electron content of a flux tube (Mathur and Rycroft 1972;Park 1973;Rycroft 1973;Ralchovski 1976;Park et al 1978;Lester and Smith 1980;Corcuff and Corcuff 1982;Tarcsai et al 1988;Sazhin et al 1992;Khosa et al 1990;Lalmani et al 1992Lalmani et al , 1996Singh et al 1993Singh et al , 1998Singh et al , 2004b, electron temperature (Scarf 1962;Guthart 1965;Sazhin et al 1990Sazhin et al , 1993, magnetic field and large scale convective electric fields (Wang and Kim 1972;Block and Carpenter 1974;Carpenter and Seely 1976;Park 1976Park , 1978Mishra et al 1980;Ralchovski 1981;Khosa et al 1982;Rash et al1986;Lalmani et al 1996;Singh et al 1998).…”

ESD whistlers from local Thunderstorms observed at Srinagar (L = 1.28) – First observation from Low Latitudes

“…To examine its validity, we have analyzed daytime ESD whistlers from thunderstorms recorded at our ground station Srinagar in magnetically disturbed daytime during thunderstorm activity period, using the curve fitting technique developed by Tarcsai (1975) and the method of Dowden-Allcock linear extended Qtechnique for the determination of exit propagation path latitude. It is to be noted that both these techniques have been applied successfully in the past to the low latitude whistlers whose propagation paths are below L=1.4 (Khosa et al, 1990;Singh, 1993;Lalmani et al, 1992Lalmani et al, ,1996Singh et al, 1999Singh et al, ,2000Singh et al, ,2004Singh et al, ,2006. Both methods yielded results within ±10 percent to that determined value of exit propagation path latitude using empirical relation given by Hayakawa and Tanaka (1978).…”

“…Later, at high, mid and low latitudes, both satellite and ground-based whistler data were exploited to reveal new facts about the structure and dynamics of the ionosphere and magnetosphere. These achievements included the discovery of the plasmaspheric, plasmapause, and bulge (Carpenter and Park, 1973), identification of the mechanisms of the ionosphereprotonoshphere coupling (Park, 1970;Andrews, 1980, Lalmani et al, 1992, 1996, Singh et al, 1998, measurement of magnetospheric electric field (Carpenter et al, 1972;Misra et al, 1980;Lalmani et al, 1982) and electron temperature (Sazhin et al, 1990(Sazhin et al, , 1992(Sazhin et al, , 1993Singh et al, 2008) etc. Further, a wide variety of whistlers recorded during day and nighttimes at low latitude ground stations are markedly different from those recorded at middle and high latitudes.…”