@Article{NyassorWPGYTBNBPSF:2022:InCoGr,
               author = "Nyassor, Prosper Kwamla and Wrasse, Cristiano Max and Paulino, Igo 
                         and Gobbi, Delano and Yigit, E. and Takahashi, Hisao and Batista, 
                         Paulo Prado and Naccarato, Kleber Pinheiro and Buriti, R. A. and 
                         Paulino, A. R. and Silva, Diego Barros and Figueiredo, Cosme 
                         Alexandre Oliveira Barros",
          affiliation = "{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 {George Mason University} 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)} and {Universidade Estadual da Para{\'{\i}}ba (UEPB)} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)}",
                title = "Investigations on Concentric Gravity Wave Sources Over the 
                         Brazilian Equatorial Region",
              journal = "Journal of Geophysical Research: Atmospheres",
                 year = "2022",
               volume = "127",
               number = "17",
                pages = "e2021JD035149",
                month = "Sept.",
             keywords = "concentric gravity waves, convective source, ray tracing.",
             abstract = "Observations of concentric gravity waves (CGWs) in the OH airglow 
                         emission over the Brazilian equatorial region are presented. An 
                         all-sky imager installed at Sao Joao do Cariri [7.4 degrees S, 
                         36.5 degrees W] was used to acquire near-infrared OH images. Using 
                         over 19 years of observational data from 2000 to 2019, more than 
                         1,052 clear sky nights of airglow data were acquired with a total 
                         of 25 observed CGW cases. Three CGW events were selected for this 
                         study. These waves had small-scale characteristics and 
                         well-defined concentric structures. The selected CGW events showed 
                         horizontal wavelengths lambda(H) similar to 31.9, 42.5, and 30.9 
                         km, horizontal phase speeds c(H) similar to 49.2, 57.6, and 74.1 
                         m/s, and periods tau similar to 10.8, 12.3, and 7.0 min, 
                         respectively. The CGW structures were well defined, with coherent 
                         wave patterns expanding concentrically from the source point, with 
                         the observed events having semi-circle or arc-like and 
                         semi-elliptical shapes. We found the occurrence of the CGWs to 
                         coincide with the seasons of intense tropospheric convective 
                         activity and low background winds. This suggests little or no wave 
                         breaking, critical level absorption, and filtering or reflection, 
                         thereby allowing the CGWs to propagate up to the mesosphere and 
                         lower thermosphere region. Using backward ray tracing, we also 
                         found the positions and times where and when the ray paths reached 
                         the tropopause. The tropopause positions and times of two of the 
                         CGW events coincide with active convective systems with cold cloud 
                         top temperatures. However, the tropopause position of one of the 3 
                         CGW events did not coincide with any active convective system, 
                         suggesting that this CGW was most likely generated in-situ.",
                  doi = "10.1029/2021JD035149",
                  url = "http://dx.doi.org/10.1029/2021JD035149",
                 issn = "2169-8996 and 2169-897X",
             language = "en",
           targetfile = "JGR Atmospheres - 2022 - Nyassor - Investigations on Concentric 
                         Gravity Wave Sources Over the Brazilian Equatorial Region.pdf",
        urlaccessdate = "15 jun. 2024"
}