On the latitudinal variation in OI 630.0 nm dayglow emissions in response to the equatorial electrodynamic processes and neutral winds

Abstract

Earth’s upper atmosphere over low latitudes is influenced by the equatorial electrodynamics. Its influence can also be modulated by the thermospheric winds. The effect of these two forces on the thermospheric neutral behaviour in the daytime can be investigated by measuring the variations in the OI 630.0 nm dayglow emission rates as these serve as effective tracers of the altitude region of their origin. The capability to measure dayglow emissions over a large field-of-view presents a unique opportunity to investigate the upper atmospheric behaviour over large spatial extents. Diurnal measurements of OI 630.0 nm dayglow emission rates have been carried out from two different locations in India using multi-wavelength imaging echelle spectrographs, MISE, which, together cover a spatial range from 5°-18° magnetic latitude. These investigations have been carried out during January-February 2020 (winter season) when solar flux variation was nearly negligible (varied only by 4 solar flux unit from 68–72 solar flux unit). Therefore, latitudinal variations in the daily averaged oxygen dayglow emission intensities have been analyzed to assess their response to the variations in the strength of the equatorial electrodynamics and the meridional winds. The results reveal that these forces show varying effects with the poleward meridional wind contributing to an enhancement in the OI 630.0 nm dayglow emission rates closer to the magnetic equator and a decrement as one moves away from the equator. The equatorial electric field effect, however, continues to be equally effective in the low-latitudes region under consideration.