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Multistation study of nighttime scintillations in low latitudes: Evidence of control by equatorial F region irregularities

Somayajulu, YV and Garg, SC and Dabas, RS and Singh, Lakha and Tyagi, TR and Lokanadham, B and Ramakrishna, S and Navneeth, G (1984) Multistation study of nighttime scintillations in low latitudes: Evidence of control by equatorial F region irregularities. In: Radio Science, 19 (3). pp. 707-718.

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Official URL: http://www.agu.org/pubs/crossref/1984/RS019i003p00...


VHF nighttime scintillations, recorded during a high solar activity period at a meridian chain of stations covering a magnetic latitude belt of 3°–21°N (420 km subionospheric points) are analyzed to investigate the influence of equatorial spread F irregularities on the occurrence of scintillation at latitudes away from the equator. Observations show that saturated amplitude scintillations start abruptly about one and a half hours after ground sunset and their onset is almost simultaneous at stations whose subionospheric points are within 12°N latitude of the magnetic equator, but is delayed at a station whose subionospheric point is at 21°N magnetic latitude by 15 min to 4 hours. In addition, the occurrence of postsunset scintillations at all the stations is found to be conditional on their prior occurrence at the equatorial station. If no postsunset scintillation activity is seen at the equatorial station, no scintillations are seen at other stations also. The occurrence of scintillations is explained as caused by rising plasma bubbles and associated irregularities over the magnetic equator and the subsequent mapping of these irregularities down the magnetic field lines to the F region of higher latitudes through some instantaneous mechanism; and hence an equatorial control is established on the generation of postsunset scintillation-producing irregularities in the entire low-latitude belt.

Item Type: Journal Article
Publication: Radio Science
Publisher: American Geophysical Union
Additional Information: Copyright for this article belongs to American Geophysical Union.
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 20 Jan 2010 11:52
Last Modified: 20 Jan 2010 11:52
URI: http://eprints.iisc.ac.in/id/eprint/23243

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