Upadhayaya, A.K. and Gupta, Sumedha (2014) A statistical analysis of occurrence characteristics of Spread-F irregularities over Indian region. Journal of Atmospheric and Solar-Terrestrial Physics, 112. pp. 1-9. ISSN 1364-6826

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We investigate the regularities of a change in Spread-F F probability during day-to-day, under varying solar variability, latitudinal behavior and their response to geomagnetic storm in equatorial and low-mid latitude stations. The occurrence characteristics of Spread-F irregularities, is obtained from daily hourly ionosonde data from a low-mid latitude station, Delhi (28.6 degrees N, 77.2 degrees E), for more than half a solar cycle (2001 to 2007). The latitudinal behavior of Spread-F is studied using ionosonde data from anomaly crest station, Ahmedabad (23.01 degrees N, 72.36 degrees E) and equatorial station, Kodaikanal (10.2 degrees N, 77.5 degrees E) for low, moderate and high solar activity periods. The maximum percentage occurrences of Spread-F were observed during the low solar activity year 2007, we believe, the low plasma and neutral density during 23/24 solar cycle minimum could be an important factor leading to the generation and propagation of TIDs and gravity waves. An anti-solar activity correlation to Spread-F occurrence is reported during all the seasons at different stations which are because of instability generated by the trans-equatorial meridional winds. There is a substantial variation during pre and post midnight hours in F region height from equatorial to low latitudes in response to magnetic disturbances. Concurrence was observed in the occurrence time of Spread-F to different storm events during different storm phases. The established irregularities and their behavior in Indian region are qualitatively interpreted and discussed.

Item Type: Article
Additional Information: Copyright for this article belongs to M/S Elsevier B.V.
Uncontrolled Keywords: EquatorialSpread-F Low-latitudeionosphere Geomagnetic storms Ionospheric irregularities
Subjects: Geochemistry/ Geophysics
Meteorology & Atmospheric Sciences
Depositing User: Dr. Rajpal Walke
Date Deposited: 08 Sep 2015 10:55
Last Modified: 08 Sep 2015 10:55
URI: http://npl.csircentral.net/id/eprint/1152

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