Preprints
https://doi.org/10.5194/angeo-2023-34
https://doi.org/10.5194/angeo-2023-34
30 Nov 2023
 | 30 Nov 2023
Status: this preprint is currently under review for the journal ANGEO.

The Role of Gravity Waves in the Mesosphere Inversion Layers (MILs) over low-latitude (3–15° N) Using SABER Satellite Observations

Chalachew Lingerew and Jaya Prakash Raju

Abstract. The Mesosphere transitional region over low latitude is a distinct and highly turbulent zone of the atmosphere. A transition MLT region is connected with dynamic processes, particularly gravity waves, as a causative of an inversion phenomenon. MLT inversions have been the subject of numerous investigations, but their formation mechanisms are still poorly understood. In this article, an attempt has been made to investigate the upper and lower inversion phenomena and their causative mechanisms using long-term SABER observations in the height range of 60–100 km during the period of 2005–2020 over a low-latitude region (3–15° N). The results indicate that the frequency of occurrence rate for the upper inversion is below 40 %, whereas for the lower inversion, it is below 20 %, indicating that the upper inversion is dominant over the lower inversion. The upper inversion exists in the height range of 78–91 km with an inversion amplitude of ~20–80 k and a thickness of ~3–12 km, whereas the lower inversion is confined in the height range of 70–80 km with an inversion amplitude of ~10–60 k and a thickness of ~4–10 km. The gravity wave indicator potential energy depicts high energy (below 100 J/kg) in the upper MLT region (90 and 85 km) compared to the lower MLT region (75 and 70 km) with less than 50 J/kg. The stability criteria from Brunt-Vaisala frequency (N2) indicate instability in the upper MLT region (90 and 85 km) with very low values relative to the lower MLT region (75 and 70 km), which supports the higher frequency of upper inversion compared to lower inversion. This result leads us to the conclusion that a high amount of gravity wave potential energy is a consequence of the high instability in the upper inversion relative to the lower inversion.

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Chalachew Lingerew and Jaya Prakash Raju

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-2023-34', Olga Zorkaltseva, 05 Dec 2023
  • RC2: 'Comment on angeo-2023-34', Anonymous Referee #2, 22 Dec 2023
    • AC2: 'Reply on RC2: I will include your comment in the next revised version, and I thank you for your constructive comment.', chalachew lingerew, 05 Jan 2024
      • EC1: 'Reply on AC2', Igo Paulino, 06 Jan 2024
    • AC4: 'Reply on RC2', chalachew lingerew, 11 Jan 2024
  • RC3: 'Comment on angeo-2023-34', Anonymous Referee #3, 05 Jan 2024
    • AC3: 'Reply on RC3: I will include your comment in the next revised version, and I thank you for your constructive comment.', chalachew lingerew, 05 Jan 2024
      • EC2: 'Reply on AC3', Igo Paulino, 06 Jan 2024
    • AC5: 'Reply on RC3', chalachew lingerew, 11 Jan 2024
Chalachew Lingerew and Jaya Prakash Raju
Chalachew Lingerew and Jaya Prakash Raju

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Short summary
The study uses SABER data to analyze the MIL phenomenon and its causative gravity wave potential energy and instability. The upper MLT inversion frequency is below 40 %, while lower inversions are below 20 %. The high potential energy (~100 J/kg) of gravity waves in the upper MLT region (85 and 90 km) is due to instability, causing large inversion phenomena. while the reverse is true in the lower MLT regions.