HF doppler observations on the occurrence of equatorial spread-F
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.
KeywordsHF doppler observations vertical shift velocity group height equatorial spread-F drift velocity layer height
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- Budden K G 1961Radio waves in the ionosphere (London and New York: Cambridge Univ. Press) pp. 153Google Scholar
- Chandra H and Rastogi R G 1972aAnn. Geophys. 28 37Google Scholar
- Chandra H and Rastogi R G 1972bAnn. Geophys. 28 709Google Scholar
- Chandra H and Rastogi R G 1978Indian J. Radio Space Phys. 7 265Google Scholar
- Haerendal G 1974 Report, Max-Planck Inst. fur Phys. und Astrophys., FRGGoogle Scholar