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    • Keywords


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

    • 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.

    • Author Affiliations


      B T Vikram Kumar1 P Velayudhan Nair1 P B Rao1

      1. Department of Physics, University of Kerala, Kariavattom, Trivandrum - 695581, India
    • Dates

  • Journal of Earth System Science | News

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      Posted on July 25, 2019

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