Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 27, 107-111, 2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
06 Jan 2009
Electrodynamics of the equatorial F-region ionosphere during pre-sunrise period
S. R. Prabhakaran Nayar1, T. J. Mathew1, C. V. Sreehari1, S. G. Sumod1, C. V. Devasia2, S. Ravindran2, V. Sreeja2, T. Kumar Pant2, and R. Sridharan2 1Department of Physics, University of Kerala, Kariavattom, Trivandrum, 695 581, India
2Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum 695 022, India
Abstract. The electrodynamics of the pre-sunrise equatorial F-region is investigated using HF Doppler radar and digital ionosonde. The observations are limited to those days for which the radar probing frequency is below the foF2 value. The ionosphere observation using HF Doppler radar exhibit interesting features during pre-sunrise period similar to the post sunset pre-reversal enhancement. The most striking feature observed during pre-sunrise period is the sudden downward excursion in the vertical drift around local sunrise followed by an upward turning. Pre-sunrise observations of vertical plasma drift and the sunrise downward excursion followed by an upward turning after the ground sunrise related to the zonal electric field at the equatorial F-region are the most significant results not reported earlier.

Citation: Prabhakaran Nayar, S. R., Mathew, T. J., Sreehari, C. V., Sumod, S. G., Devasia, C. V., Ravindran, S., Sreeja, V., Kumar Pant, T., and Sridharan, R.: Electrodynamics of the equatorial F-region ionosphere during pre-sunrise period, Ann. Geophys., 27, 107-111, doi:10.5194/angeo-27-107-2009, 2009.
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