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HF doppler observations on the occurrence of equatorial spread-F

  • B. T. Vikram Kumar
  • P. Velayudhan Nair
  • P. B. Rao
Article

Abstract

HF doppler observations of the vertical drift velocity and group height of the 5.5 MHz plasma frequency level of the post-sunset bottomside F-region obtained on a fewESF (equatorial spread-F) and non-ESF days at Trivandrum are presented. The results show that on the non-ESF days, the maximum group height attained is about 400 km and the maximum velocity is less than 30 m/sec. On theESF days, however, the corresponding values are found to be in the range of 400–650 km and 30–50 m/sec. TheESF onset is found to be significantly delayed relative to the velocity peak indicating that it is more closely linked to the layer height than to the drift velocity.

Keywords

HF doppler observations vertical shift velocity group height equatorial spread-F drift velocity layer height 

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References

  1. Anderson D N and Haerendal G 1979J. Geophys. Res. 84 4251CrossRefGoogle Scholar
  2. Basu S and Kelley M C 1979Radio Sci. 14 471CrossRefGoogle Scholar
  3. Budden K G 1961Radio waves in the ionosphere (London and New York: Cambridge Univ. Press) pp. 153Google Scholar
  4. Chandra H and Rastogi R G 1972aAnn. Geophys. 28 37Google Scholar
  5. Chandra H and Rastogi R G 1972bAnn. Geophys. 28 709Google Scholar
  6. Chandra H and Rastogi R G 1978Indian J. Radio Space Phys. 7 265Google Scholar
  7. Farley D T, Balsley B B, Woodman R F and Mc Clure J P 1970J. Geophys. Res. 75 7199CrossRefGoogle Scholar
  8. Fejer B G and Kelley M C 1980Rev. Geophys. Space Phys. 18 401CrossRefGoogle Scholar
  9. Haerendal G 1974 Report, Max-Planck Inst. fur Phys. und Astrophys., FRGGoogle Scholar
  10. Hudson M K and Kennel C F 1975J. Geophys. Res. 80 4581CrossRefGoogle Scholar
  11. Ossakow S L, Zalesak S T, Mc Donald B E and Chaturvedi P K 1979J. Geophys. Res. 84 17CrossRefGoogle Scholar
  12. Ossakow S L 1981J. Atmos. Terr. Phys. 43 437CrossRefGoogle Scholar
  13. Rastogi R G and Woodman R F 1978J. Atmos. Terr. Phys. 40 485CrossRefGoogle Scholar

Copyright information

© Indian Academy of Sciences 1985

Authors and Affiliations

  • B. T. Vikram Kumar
    • 1
  • P. Velayudhan Nair
    • 1
  • P. B. Rao
    • 1
  1. 1.Department of PhysicsUniversity of KeralaKariavattom, TrivandrumIndia

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