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Hour-to-hour & Day-to-day Variations of Ionospheric Absorption over Udaipur

1985-12-01T00:00:00Z

Title: Hour-to-hour & Day-to-day Variations of Ionospheric Absorption over Udaipur Authors: Acharya, B L; Rai, R K Abstract: Hour-to-hour and day-to-day variations at Udaipur (24°35'N) of ionospheric absorption during moderate and high solar activity periods (1978-80) are presented. The occurrence of two maxima in the diurnal variation of absorption due to solar flare, due to nearness of the working frequency to the critical frequency of the reflecting region and in the presence of sporadic- E (blanketing or flat type) is discussed. The day-to-day variations of absorption in the light of day-to-day variations of 10.7-cm solar flux, sunspot number and 1-8 Å X-ray flux have also been discussed. Page(s): 171-174

Dispersion in Ionospheric Drift-Comparison of Filter Method with Cross-spectral Method

1985-12-01T00:00:00Z

Title: Dispersion in Ionospheric Drift-Comparison of Filter Method with Cross-spectral Method Authors: Vyas, G D; Chandra, H Abstract: Spaced fading records obtained at Tiruchirapalli are analyzed by filtering the data employing low pass and high pass filters with varying cut-off frequencies and the variation of the apparent and true drift velocities with fading frequency obtained by full-correlation analysis studied. The variation of the apparent drift velocity obtained is similar to that obtained from cross spectral method. Page(s): 169-170

Study of Ionospheric Drifts during Partial Solar Eclipses

1985-12-01T00:00:00Z

Title: Study of Ionospheric Drifts during Partial Solar Eclipses Authors: Vyas, B M; Mathur, S; Rai, R K Abstract: Horizontal drift measurements in E- and F-region have been made at Udaipur during partial solar eclipses of 31 July 1981 and 15 Dec 1982. The results obtained on the eclipse day have been compared with the normal day values. It is found that during the main phase of the eclipse, the E- and F-region drift velocity, in the direction of totality, increases. Page(s): 165-168

Earth-Space Path Rain Attenuation Estimation up to 50 GHz from Radiometric Measurements at K-Band Frequencies

1985-12-01T00:00:00Z

Title: Earth-Space Path Rain Attenuation Estimation up to 50 GHz from Radiometric Measurements at K-Band Frequencies Authors: Bhattacharya, C K; Uppal, G S Abstract: Radiometric observations at 18 and 22.235 GHz have been utilized to obtain relationship between average excess of attenuation with rain rate over New Delhi, Effective path length is obtained at 18 GHz for different rain rates, using published values of attenuation coefficients [T Oguchi & Y Hosoya, J Radio Res Lab (Japan), 21 (1974)105; 181]. It has been found that the effective path length is independent of frequency. Computed effective path lengths have been used for estimating earth-space path attenuation values up to 50GHz. Page(s): 162-164