630 nm nightglow observations from 17°N latitude

An investigation of the ionospheric F region near the EIA crest in India using OI 777.4 and 630.0 nm nightglow observations

“…5 and 6. In contrast, Mukherjee et al (2006) observed a large height decent of the F layer in the ∼ 20-60 km range. Overall, hmF2 was found to increase in the pre-midnight hours, attain a maximum around 00:00-02:00 and then decrease beyond 02:00.…”

“…5). Such a feature in the thermospheric nightglow measurements has been linked to the midnight pressure bulge/temperature maximum (MTM) phenomenon (Rao and Sastri, 1994;Batista et al, 1997;Mukherjee et al, 2006;Shepherd, 2016;Figueiredo et al, 2017). MTM refers to an unusual large-scale increase in the thermospheric temperatures in the equatorial region around midnight hours due to convergence of (i) eastward zonal wind driven by the day-night differential heating, (ii) upward propagating tides and (iii) in situ thermospheric tides produced by solar extreme ultraviolet associated heating.…”

“…Studies using Doppler width measurements of OI 630.0 nm nightglow over an equatorial station, Kavalur (12.5 • N), India, during 1992-1993 by Rao and Sastri (1994), indicate MTM to occur usually an hour after midnight during winter. Mukherjee et al (2006) studied the behaviour of OI 630.0 nm nightglow at a low-latitude station, Kolhapur (17 • N), India, during December 2002-April 2003 and found the MTM associated peaks to occur mostly during 02:00-03:00 LT. Overall, the behaviour of Nm during the night was characterized by (i) the signatures of the ionization anomaly in the pre-midnight sector, (ii) a minimum around 00:00-02:00 and (iii) a hump as a consequence of the midnight temperature maximum phenomenon beyond 02:00.…”

“…Sample Nm and hmF2 maps have also been generated to illustrate the usefulness of this technique in understanding ionospheric processes like equatorial plasma bubbles. Earlier, Mukherjee et al (2000Mukherjee et al ( , 2006 reported the nocturnal behaviour of the low-latitude ionosphere over Kolhapur (17 • N), India, using OI 630.0 nm measurements. However, to the best of our knowledge, the observations of OI 777.4 nm emission or its simultaneous measurements with OI 630.0 nm emission over India have not been reported.…”

Simultaneous mesosphere-thermosphere-ionosphere parameter measurements over Gadanki (13.5°N, 79.2°E): First results

“…These measurements have significantly improved our understanding of the gravity‐wave characteristics. At the same time, several studies of 630.0 nm O ( 1 D) thermospheric airglow emission and total electron content (TEC) measurements have strengthened our knowledge of thermosphere‐ionosphere system behavior [e.g., Mukherjee et al , 2000; Sinha et al , 2001; Ogawa et al , 2002; Makela and Miller , 2008].…”