A new insight into the vertical neutral-ion coupling between the mesopause and equatorial ionosphere F-region

Abstract. This letter reports unique observations, illustrating the vertical coupling between the daytime mesopause and F-region of the ionosphere over the magnetic dip equatorial station Trivandrum (8.5° N, 76.5° E, 0.5° N dip lat.) in India. For the "first time", it has been shown that the temporal variations in the mean daytime mesopause temperatures (MPT), during geomagnetically quiet days corroborate well with that of the base height changes (h'F) of the ionospheric F-region. However, there exist some characteristic time delays between these two, which vary from 0 to 90 min. The MPTs are measured using the unique Multi-Wavelength Dayglow Photometer while the h'Fs are derived using a co-located digital Ionosonde. The observed time delays are attributed to the intercompeting roles between the diffusion and wave-dynamical processes in modulating the transport of atomic oxygen at these altitudes.