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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 17, issue 4
Ann. Geophys., 17, 519–525, 1999
https://doi.org/10.1007/s00585-999-0519-1
© European Geosciences Union 1999
Ann. Geophys., 17, 519–525, 1999
https://doi.org/10.1007/s00585-999-0519-1
© European Geosciences Union 1999

  30 Apr 1999

30 Apr 1999

Sequential sporadic-E layers at low latitudes in the Indian sector

P. T. Jayachandran*,1, P. Sri Ram1, P. V. S. Rama Rao1, and V. V. Somayajulu2 P. T. Jayachandran et al.
  • 1Department of Physics, Andhra University Visakhapatnam - 530 003, India
  • 2Space Physics Laboratory, V.S.S.C Trivandrum - 695 022, India
  • *Presently Department of Physics and Astronomy University of Western Ontario London, Ontario, Canada
  • e-mail: jaya@danlon.physics.uwo.ca

Abstract. A study of the formation and movement of sequential Sporadic-E layers observed during the night-time hours at two Indian low-latitude stations, SHAR (dip 10°N) and Waltair (dip 20°N) shows that the layer are formed around 19:00 h. IST at altitudes of ~180 km. They descend to the normal E-region altitude of about 100 km in three to four hours and becomes blanketing type of Es before they disappear. However, the absence of these descending layers at an equatorial station, Trivandrum (dip 2°N) gives the experimental evidence for wind shear theory. The meridional neutral wind derived from the height variation of the F-layer showed significant poleward wind during the descent of these layers. Hence it is inferred that these layers are formed as a consequence of the convergence of plasma by the poleward wind and the equatorward propagating gravity waves (inferred from the height fluctuations of F-layer).

Key words. Ionosphere (active experiments; equatorial ionosphere · ionospheric irregularities)

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