@Article{EssienFTWBKLAGB:2021:LoStMe,
               author = "Essien, Patrick and Figueiredo, Cosme Alexandre Oliveira Barros 
                         and Takahashi, Hisao and Wrasse, Cristiano Max and Barros, Diego 
                         and Klutse, N. A. B. and Lomotey, Solomon Otoo and Ayorinde, 
                         Toyese Tunde and Gobbi, Delano and Bilibio, Anderson Vestena",
          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 {African Institute for Mathematical Sciences (AIMS)} 
                         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)}",
                title = "Long-term study on medium-scale traveling ionospheric disturbances 
                         observed over the south american equatorial region",
              journal = "Atmosphere",
                 year = "2021",
               volume = "12",
               number = "11",
                pages = "e1409",
                month = "Nov.",
             keywords = "Detrended TEC, Equatorial, Medium-scale traveling ionospheric 
                         disturbances.",
             abstract = "Using data collected by the GNSS dual-frequency receivers network, 
                         de-trended TEC maps were generated to identify and characterize 
                         the medium-scale traveling ionospheric disturbances (MSTIDs) over 
                         the South American equatorial region (latitude: 0\◦ to 
                         15\◦ S and longitude: 30\◦ to 55\◦ W) during 
                         solar cycle 24 (from January 2014 to December 2019). A total of 
                         712 MSTIDs were observed during quiet geomagnetic conditions. The 
                         Frequency of occurrence of MSTID is high during the solar maximum 
                         and low in the minimum phase. This might be due to the solar cycle 
                         dependence of gravity wave activity in the lower atmosphere and 
                         gravity wave propagation conditions in the thermosphere. The 
                         predominant daytime MSTIDs, representing 80% of the total 
                         observations, occurred in winter (June-August season in the 
                         southern hemisphere) with the secondary peak in the equinox; while 
                         the evening time MSTIDs, representing 18% of the entire events, 
                         occurred in summer (December to February season) and equinox 
                         (March to May and September to November), and the remaining 2% of 
                         the MSTIDs were observed during nighttime. The seasonal variation 
                         of the MSTID events was attributed to the source mechanisms 
                         generating them, the wind filtering and dissipation effects, and 
                         the local time dependency. The horizontal wavelengths of the 
                         MSTIDs were mostly concentrated between 500 and 800 km, with the 
                         mean value of 667 ± 131 km. The observed periods ranged from 30 to 
                         45 min with the mean value of 36 ± 7 min. The observed horizontal 
                         phase speeds were distributed around 200 to 400 m/s, with the 
                         corresponding mean of 301 ± 75 m/s. The MSTIDs in the winter 
                         solstice and equinoctial months preferentially propagated 
                         northeastward and northwestward. Meanwhile, during the summer 
                         solstice, they propagated in all directions. The anisotropy of the 
                         propagation direction might be due to several reasons: the wind 
                         and dissipative filtering effects, ion drag effects, the primary 
                         source region, and the presence of the secondary or tertiary 
                         gravity waves in the thermosphere. Atmospheric gravity waves from 
                         strong convective sources might be the primary precursor for the 
                         observed equatorial MSTIDs. In all seasons, we noted that the 
                         MSTIDs propagating southeastward were probably excited by the 
                         likely gravity waves generated by the intertropical convergence 
                         zone (ITCZ).",
                  doi = "10.3390/atmos12111409",
                  url = "http://dx.doi.org/10.3390/atmos12111409",
                 issn = "2073-4433",
             language = "en",
           targetfile = "essien_atmosphere.pdf",
        urlaccessdate = "04 maio 2024"
}