http://nopr.niscpr.res.in/handle/123456789/35930 2026-10-11T01:54:35Z http://nopr.niscpr.res.in/handle/123456789/36017 Title: Small ion mean lifetimes at five typical locations in Indian region Authors: Manohar, G K; Kandalgaonkar, S S Abstract: Small ion mean lifetimes at five typical locations (rural, oceanic, hilltop, urban and industrial) in the Indian region have been obtained using Aitken nuclei concentrations. It is noted that the derived values of mean lifetimes at urban and industrial locations are much less than those at rural and oceanic locations. Page(s): 347-348 1993-10-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/36016 Title: Study of field-aligned irregularities by VLF whistlers and VHF scintillations Authors: Singh, R P; Singh, A K; Singh, R N Abstract: Whistler wave ducting and VHF wave scintillations are known to be due to the plasma irregularities in the ambient medium. The whistler waves from natural origin and amplitude scintillations of FLEETSAT geostationary satellite signals are simultaneously recorded at Varanasi, to study the morphology of irregularities present in the ionosphere. In this paper are presented the preliminary results of these investigations. It has been found that there is no positive correlation between whistler occurrence and VHF scintillations. Page(s): 342-346 1993-10-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/36015 Title: Response of F-region vertical drift at the magnetic equator to the interplanetary magnetic field fluctuations Authors: Nayar, S R Prabhakaran; Thomas, Rachel; Bala, B; Varma, Meena V K; Yamini, S Abstract: The response of fluctuations in the vertical drift (<i>V</i>_d) in the equatorial F-region to the fluctuations in the IMF north-south component (<i>B_Z</i>) has been studied. It is found that, in general, there exists fluctuations of periodicity 3-4h in both <i>V</i>_d and IMF <i>B_Z</i>. To study the relationship between the short period fluctuations in <i>V</i>_d and IMF <i>B</i>_Z component, the power spectrum of both the parameters were evaluated using 5-min averaged values. Both the parameters showed somewhat similar spectrum with a strong peak around 37 min, implying a good correlation between the two parameters on a short time scale also. Page(s): 338-341 1993-10-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/36014 Title: Dispersion in ionospheric drifts over Patiala Authors: Singh, Darshan; Gurm, H S; Singh, Manjit Abstract: The cross-spectral analysis has been applied to ionospheric drift records obtained at Patiala during the years 1987-88 and 1989-90. Positive dispersion is predominant in the E region and random dispersion in the F region. About 10% of the records show no dispersion and only in these cases the drift motion can be described by single velocity parameter given by similar fade and full correlation analysis. Negative dispersion is observed only in 4% of cases in the E region and 5% of cases in the F region. Characteristic velocity is high in case of random or large positive dispersion. The positive dispersion is probably due to two or more scale size structures moving with different speeds in the same direction, while random dispersion is due to several scale size structures moving with different speeds and in different directions. Page(s): 331-337 1993-10-01T00:00:00Z