Imprint of equatorial electrodynamical processes in the OI 630.0 nm dayglow

Abstract

Results from coordinated measurements of OI 630.0 nm dayglow intensities (centered on ˜220 km altitude), along with VHF (50 MHz) coherent backscatter returns from Thiruvananthapuram, a dip equatorial station in India, revealed that the temporal variability at short periods (< 4 h) of the Doppler frequency of the coherently backscattered 50 MHz radar signal in the electrojet region (˜101 km altitude) preceded the dayglow variations. The time delay was found to be inversely related to the electric field magnitude inferred from the Doppler frequency and also with the independently estimated electrojet strength inferred from the ground magnetic data. These results are presented as direct evidence for the prevailing electrodynamic coupling between the E- and F-region of the ionosphere over the dip equator.