NOPR Collection:

D-Region Model Study for Udaipur

2016-11-04T05:15:33Z

Title: D-Region Model Study for Udaipur Authors: Bansal, T C; Vijayvergia, S K; Pal, R K Abstract: On the basis of a simplified ion-chemical scheme a D-region model is prepared. Multifrequency absorption results measured at Udaipur match with the electron density profile obtained from the scheme. The results are compared with positive ion and electron concentrations measured at the same solar zenith angle position over Thumba. The scheme used is slightly different from that of the existing ones in both negative and positive ion sides. Page(s): 97-99

F-Region Vertical Velocity & Its Fluctuations at the Magnetic Equator

2016-11-04T05:13:11Z

Title: F-Region Vertical Velocity & Its Fluctuations at the Magnetic Equator Authors: Subbarao, K S V; Murthy, B V Krishna Abstract: F-region vertical velocities in the evening time have been estimated at two levels from simultaneous phase-path observations on two frequencies, 2.2 and 4.1 MHz. It is found that electrodynamic drift is greater at lower level than that at higher level. Wave-type disturbances with a period of 9 min have also been observed. Page(s): 94-96

Ionospheric Electron Content Measurements at a Northern Low Midlatitude Station through Half a Solar Cycle

2016-11-04T05:11:53Z

Title: Ionospheric Electron Content Measurements at a Northern Low Midlatitude Station through Half a Solar Cycle Authors: Bhuyan, P K; Tyagi, Tuhi Ram; Singh, Lakha; Somayajulu, Y V Abstract: Ionospheric electron content (IEC) measurements with the help of geostationary satellite radio beacon have been made at Delhi during the period 1975-80. Results for three 1-yr periods representing low medium and high solar activity conditions are presented. Detailed study of the diurnal seasonal and solar cycle variations has revealed a number of new features which were not observed earlier from observations made with low orbiting satellites. The IEC, its early morning build-up rate and nighttime decay rate of ionization show seasonal as well as semiannual variations with peak in equinoctial months which indicates that response of the ionosphere to solar radiations is greatest in this season. A secondary enhancement was observed in the evening hours frequently during winter and equinox of medium and high solar activity period. The seasonal anomaly, i.e. when IEC in winter exceeds that in summer appears during medium and high solar activity period only. Another interesting observation is that IEC shows nonlinear dependence with 10.7 cm solar flux. After increasing linearly up to about 200 units, it decreases with varying rates in all the three seasons with the result that at about 230 units, winter IEC becomes lower than the summer values. Study of the behaviour of IEC during different hours of the day with season and solar activity has revealed that IEC behaves differently in daytime and nighttime. Also the harmonic components beyond the third one do not show any significant values. Page(s): 84-93

Low Latitude Integrated Production & Loss Rates from Faraday Rotation Experiment Using ATS-6 & ETS-II Satellite Transmissions

2016-11-04T05:10:23Z

Title: Low Latitude Integrated Production & Loss Rates from Faraday Rotation Experiment Using ATS-6 & ETS-II Satellite Transmissions Authors: Dabas, R S; Bhuyan, P K; Tyagi, T R; Singh, Lakha; Somayajulu, Y V Abstract: Faraday fading records obtained near sunrise at Gauhati and Delhi using ATS-6 transmissions( 1975-76) and at Delhi using ETS-II transmissions (1979-80) have been analyzed to obtain the integrated production rate for the overhead sun (Q₀) and the effective loss rate (). The results of Q₀ and are quite dissimilar for the two stations. An attempt has been made to explain qualitatively the observed variations with the neutral composition changes of the (N₂O) ratio. Page(s): 81-83