@InProceedings{NyassorWGPTBNBBFB:2019:CoGrWa,
               author = "Nyassor, Prosper Kwamla and Wrasse, Cristiano Max and Gobbi, 
                         Delano and Paulino, Igo and Takahashi, Hisao and Bageston, 
                         Jos{\'e} Valentin and Naccarato, Kleber Pinheiro and Batista, 
                         Paulo Prado and Barros, Diego and Figueiredo, Cosme Alexandre 
                         Oliveira Barros and Buriti, Ricardo",
          affiliation = "{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)} 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 Brazil",
                 year = "2019",
         organization = "AGU Fall Meeting",
             abstract = "We present first statistical results of concentric/circular 
                         gravity waves (CGWs) observed in the OH airglow emission over the 
                         Brazilian equatorial and low latitude regions. All-sky imagers 
                         located at S{\~a}o Jo{\~a}o do Cariri [7.39°S, 36.53°W], 
                         Petrolina [9.39°S, 40.50°W], Cachoeira Paulista [22.66°S, 45.00°W] 
                         and S{\~a}o Martinho da Serra [29.48°S, 53.87°W] were used in the 
                         acquisition of the images. Using 20 years of observational data 
                         (between 1998 and 2018), 3525 nights of airglow observations were 
                         taken. However, only 40 CGW(s) cases were found with small-scale 
                         wave characteristics. The CGW(s) events showed horizontal 
                         wavelengths between 20 and 40 km, horizontal phase speed between 
                         40 and 107 m/s and periods ranging from 6 to 11 minutes. Most of 
                         the CGW(s) structures were well defined with coherent wave 
                         patterns expanding concentrically with 97.5% 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, which corresponded to 
                         non-solstice months. This suggested a low level of wave breaking 
                         or critical level absorption/filtering, allowing the CGWs to 
                         propagate up to the mesosphere and lower thermosphere (MLT) 
                         region. The yearly latitudinal distribution of CGWs showed higher 
                         occurrence in the subtropics (28°S), followed by the equatorial 
                         latitudes (7°S) with the tropical latitudes (23°S) recording the 
                         lowest occurrence.",
  conference-location = "San Francisco, CA",
      conference-year = "09-13 dec.",
             language = "en",
           targetfile = "nyassor_concentric.pdf",
        urlaccessdate = "19 abr. 2024"
}