27 Jul 2023
 | 27 Jul 2023
Status: a revised version of this preprint is currently under review for the journal ANGEO.

Simultaneous OI 630 nm imaging observations of thermospheric gravity waves and associated revival of fossil depletions around midnight near the EIA crest

Navin Parihar, Saranya Padincharapad, and Anand Kumar Singh

Abstract. We report the F-region airglow imaging of fossil plasma depletions around midnight that revived afresh under the persisting thermospheric gravity wave (GW) activity. An all-sky imager recorded these events in OI 630 nm imaging over Ranchi (23.3º N, 85.3º E, mlat. ~19º N), India, on 16 April 2012. Northward propagating and east-west aligned GWs (λ ~210 km, ~64 m/s, and τ ~0.91 h) were seen around midnight. Persisting for ~2 hours, this GW activity revived two co-existing and eastward drifting fossil depletions, DP1 and DP2. GWs-driven revival was prominently seen in depletion DP1, wherein its apex height grew from ~600 km to >800 km, and the level of intensity depletion increased from ~17 % to 50 %. Present study is novel in the sense that simultaneous observations of thermospheric GWs activity and associated evolution of depletion in OI 630 nm airglow imaging, and that too around local midnight, have not been reported earlier. Current understanding is that GW phase fronts aligned parallel to the geomagnetic field lines and eastward propagating are more effective in seeding Rayleigh-Taylor (RT) instability. Here, GW fronts were east-west aligned (i.e. perpendicular to the geomagnetic field lines) and propagated northward, yet they revived fossil depletions.

Navin Parihar, Saranya Padincharapad, and Anand Kumar Singh

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on angeo-2023-26', Anonymous Referee #1, 22 Aug 2023
    • CC1: 'Reply on RC1', Navin Parihar, 29 Aug 2023
    • AC1: 'Reply on RC1', Navin Parihar, 18 Sep 2023
  • RC2: 'Comment on angeo-2023-26', Anonymous Referee #2, 24 Aug 2023
    • CC2: 'Reply on RC2', Navin Parihar, 29 Aug 2023
    • AC2: 'Reply on RC2', Navin Parihar, 18 Sep 2023
  • RC3: 'Comment on angeo-2023-26', Anonymous Referee #3, 29 Aug 2023
    • CC3: 'Reply on RC3', Navin Parihar, 29 Aug 2023
    • AC3: 'Reply on RC3', Navin Parihar, 18 Sep 2023
Navin Parihar, Saranya Padincharapad, and Anand Kumar Singh

Data sets

OI 630 nm Airglow Images for 20120416 Navin Parihar

Navin Parihar, Saranya Padincharapad, and Anand Kumar Singh


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Short summary
Gravity waves are well known to deform the bottomside plasma of the F-region into the wavelike ionization structures which then act as a seed to Rayleigh-Taylor instability, which, in turn, generates irregularities. Present study features midnight fossil airglow depletions that revived due to undergoing GW activity and turned into an active depletion.