@InProceedings{NyassorWGTBKBBFB:2021:CoGrWa,
               author = "Nyassor, Prosper Kwamla and Wrasse, Cristiano Max and Gobbi, 
                         Delano and Takahashi, Hisao and Bageston, Jos{\'e} Valentin and 
                         Kleber, P. N. and Batista, Paulo Prado and Barros, Diego Prado and 
                         Figueiredo, Cosme Alexandre Oliveira Barros and Buriti, R. A.",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {Instituto Nacional de Pesquisas Espaciais 
                         (INPE)} and {Instituto Nacional de Pesquisas Espaciais (INPE)} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Universidade Federal de Campina 
                         Grande (UFCG)}",
                title = "Concentric Gravity waves observed by OH airglow over S{\~a}o 
                         Jo{\~a}o do Cariri",
                 year = "2021",
         organization = "Simp{\'o}sio Brasileiro de Geof{\'{\i}}sica Espacial e 
                         Aeronomia, 8. (SBGEA)",
             abstract = "Observation of concentric/circular gravity waves (CGWs) in the OH 
                         airglow emission over the Brazilian equatorial region. An all-sky 
                         imager located at Sao Joao do Cariri [7.39\◦S, 
                         36.53\◦W] was used in the acquisition of the images. Using 
                         20 years of observational data (between 1998 and 2018), 1052 
                         nights of airglow observations were taken. However, only 5 CGW(s) 
                         cases were found with small-scale wave characteristics. The CGW(s) 
                         events showed horizontal wavelengths between 25 and 31km, 
                         horizontal phase speed between 42 and 75m/s and periods ranging 
                         from 7 to 11 minutes. Most of the CGW structures were well defined 
                         with coherent wave patterns expanding concentrically with all 
                         observed cases having semi-circle or arc-like shapes. The 
                         occurrence of CGWs was found to coincide mostly with the seasons 
                         of strong tropospheric convective activity as well as low 
                         background winds. This suggested a low level of wave breaking or 
                         critical level absorption/filtering/reflection, allowing the CGWs 
                         to propagate up to the mesosphere and lower thermosphere (MLT) 
                         region.",
  conference-location = "Online",
      conference-year = "22-26 mar.",
             language = "en",
        urlaccessdate = "04 maio 2024"
}