http://nopr.niscpr.res.in/handle/123456789/36933 2026-10-13T04:06:55Z http://nopr.niscpr.res.in/handle/123456789/37319 Title: A Measurement of Ionospheric Irregularity from Radio Star Scintillations Authors: Lokanadham, B; Ray, Shubhra; Bhonsle, R V Abstract: The hourly variations of scintillation index and scintillation fate are studied during the nights of a summer month, June 1970, from the radio star scintillation data recorded at Ahmedabad. The variation of scintillation index showed a peak occurrence around 0200-0400 hrs local time and the variation of scintillation rate correlated well with that of the vertical component (V) of earth's magnetic field. The power spectral analysis carried out for different samples of data gave velocity of ionospheric of irregularity ranging from 95 to 133 m/sec at F-region heights. Page(s): 216-218 1978-08-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/37318 Title: 30-Day Periodicity in Sunspot Activity & Rainfall Authors: Reddy, R S; Murty, BH V Ramana Abstract: An attempt is made to examine short term periodicities, if any, in the sunspot activity and rainfall. The daily mean relative sunspot numbers for July-Sep. during 1961-70 and the daily sunspot means for July-Sep. 1889-1938, as well as the rainfall series of Tamil Nadu for July-Sep. during 1961-70 have been analyzed by power spectrum. The study has suggested that the sunspot activity and the rainfall contain a concurrent 30-day periodicity which is highly significant during the southwest monsoon period (July-Sep.) when the sun remains at all times in the northern hemisphere. Page(s): 215-216 1978-08-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/37317 Title: Average Anisotropy Characteristics of High Energy Cosmic Ray Particles Approaching Solar Minimum Authors: Sharma, R M; Nigam, S K; Singh, R L; Agrawal, S P Abstract: Long-term variability of the daily variation of cosmic ray intensity is discussed in terms of two hypotheses: the 22-yr field-aligned sinusoidal wave proposed by S E Forbush [J. geophys. Res., 74 (1969), 3451] and the radial or field-aligned anisotropy mainly effective during alternate sunspot cycle superimposed on normal corotational anisotropy. As expected, no evidence is found for a positive cycle of 22-yr wave around 1964-65 minima as well as of complete phase reversal in diurnal vector even for a complete solar rotation in 1976 in contrast to that in 1954 at neutron monitor energies. Comparison of diurnal and semidiurnal variations with the available solar wind velocity measurements provide further evidence of significant changes since 1971and better understanding of the nature of semi-diurnal anisotropy. It is shown that the semi-diurnal anisotropy observed during days of higher <i>A_p</i> index may not be due to extra-terrestrial effect but of local origin. Page(s): 210-214 1978-08-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/37316 Title: Prediction of Atmospheric Radio Noise Field Strengths for the Indian Subcontinent Authors: Ghosh, B B; Saksena, R C Abstract: An attempt has been made to predict atmospheric radio noise field strengths (ARN-FS) for frequencies up to 30 MHz, for different time blocks and seasons at any place in the Indian subcontinent. These are in the form of contour diagrams at 5 MHz for 1 kHz bandwidth. A relation has been given to predict ARN-FS values for any given frequency for any given location using these contour diagrams. Page(s): 205-209 1978-08-01T00:00:00Z