04 Oct 2023
 | 04 Oct 2023

Studies on the Propagation Dynamics and Source Mechanism of Quasi-Monochromatic Gravity Waves Observed over São Martinho da Serra (29° S, 53° W), Brazil

Cristiano M. Wrasse, Prosper K. Nyassor, Ligia A. da Silva, Cosme O. A. B. Figueiredo, José V. Bageston, Kleber P. Naccarato, Diego Barros, Hisao Takahashi, and Delano Gobbi

Abstract. Two hundred and nine (209) events of quasi-monochromatic atmospheric gravity waves (QMGWs) were acquired over five (5) years of Gravity Waves (GWs) observation in Southern Brazil. The observations were made using OH all-sky imagers hosted by the Southern Space Observatory (SSO) coordinated by the National Institute for Space Research at São Martinho da Serra (RS) (29.44º S; 53.82º W). A two (2) dimensional Fast Fourier Transform-based spectral analysis shows that the QMGWs have horizontal wavelengths of 10–55 km, periods of 5–74 minutes, and phase speeds up to 100 m/s. The waves exhibited clear seasonal dependence on the propagation direction with anisotropic behavior, propagating mainly toward the southeast during the summer and autumn seasons and mainly toward the northwest during the winter. On the other hand, the propagation directions in the spring season exhibited a wide range from northwest to south. A complimentary backward ray tracing result revealed that the significant factors contributing to the propagation direction of the QMGWs are their source locations and the dynamics of the background winds per season. Three case studies in winter were selected to investigate further the propagation dynamics of the waves and determine their possible source location. We found that the jet-stream associated with cold front and their interaction generated these three GW events.

Cristiano M. Wrasse et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1825', Anonymous Referee #1, 05 Nov 2023
  • RC2: 'Comment on egusphere-2023-1825', Anonymous Referee #2, 07 Nov 2023

Cristiano M. Wrasse et al.

Cristiano M. Wrasse et al.


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Short summary
This present work investigates the propagation dynamics and the sources-source mechanisms of quasi-monochromatic gravity waves (QMGWs) observed between April, 2017 and April, 2022 at São Martinho da Serra. The QMGW parameters were estimated using a 2D spectral analysis, and their source locations were identified using a backward ray tracing model. Furthermore, the propagation conditions, sources, and source mechanisms of the QMGWs were extensively studied.