Long-term morphological and power spectral studies of VHF amplitude scintillations recorded over Waltair (17.7°N, 83.3°E), India

  • Author(s): V. K. D Srinivasu, P. S. Brahmanandam, G. Uma, D. S. V. V. D. Prasad, P. V. S. Rama Rao, and S. Mukherjee
  • DOI: 10.3319/TAO.2016.11.08.01
  • Keywords: Scintillations, Equatorial ionization anomaly, Low-latitude station, Power spectral characteristics
  • Presented recently recorded amplitude scintillations over Waltair, India
  • Studied morphological features and spectral characteristics of scintillations
  • The plausible mechanisms of the observational results are discussed
Abstract

This research reports recently recorded 250 MHz amplitude scintillations at Waltair (17.70N, 83.30E), a low-latitude station in India, by using the signals radiated from a geostationary satellite (FLEETSAT, 73o E) during a six-year period (2008 -2013), which covers an extremely low and higher solar activity years (2008 and 2013). The morphological features in terms of local time, month, and season and during different geophysical conditions are presented. The scintillation patches (segregated based on their occurrence durations) have shown an increasing trend with the increasing sunspot activity. The scintillation patches with 30- minute duration are not only showing increasing trends with the increasing sunspot activity, but their occurrence frequencies also show increasing trends with increasing sunspot activity. The scintillation activity during disturbed epochs (Kp index lies between 3+ and 9) is found to be less compared to its quiet day counterparts. The plausible mechanisms for these observational results are discussed. In addition, power spectral characteristics, including Fresnel frequency, upper role of frequency and spectral slope of scintillations are calculated and the salient results of them are presented.

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