Abstract:
Simultaneous observations of OI 777.4 and
OI 630.0 nm nightglow emissions were carried at a
low-latitude station, Allahabad (25.5◦ N, 81.9◦ E; geomag.
lat. ∼ 16.30◦ N), located near the crest of the Appleton
anomaly in India during September–December 2009. This
report attempts to study the F region of ionosphere using
airglow-derived parameters. Using an empirical approach put
forward by Makela et al. (2001), firstly, we propose a novel
technique to calibrate OI 777.4 and 630.0 nm emission intensities
using Constellation Observing System for Meteorology,
Ionosphere, and Climate/Formosa Satellite Mission
3 (COSMIC/FORMOSAT-3) electron density profiles. Next,
the electron density maximum (Nm) and its height (hmF2)
of the F layer have been derived from the information of two
calibrated intensities. Nocturnal variation of Nm showed the
signatures of the retreat of the equatorial ionization anomaly
(EIA) and the midnight temperature maximum (MTM) phenomenon
that are usually observed in the equatorial and lowlatitude
ionosphere. Signatures of gravity waves with time
periods in the range of 0.7–3.0 h were also seen in Nm and
hmF2 variations. Sample Nm and hmF2 maps have also been
generated to show the usefulness of this technique in studying
ionospheric processes.
