@InProceedings{Pimenta:2018:StMaAb,
               author = "Pimenta, Alexandre Alvares",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "Study of magnetohydrodynamic absorption of medium-scale traveling 
                         ionospheric disturbances (MSTID'S) under different solar activity 
                         conditions",
                 year = "2018",
         organization = "Simp{\'o}sio Brasileiro de Geof{\'{\i}}sica Espacial e 
                         Aeronomia, 7. (SBGEA)",
             abstract = "Absorption of MSTID's in the F-layer is analyzed using the theory 
                         of magnetohydrodynamic and ground based optical and radio 
                         techniques observations. Depending of solar activity, these 
                         disturbances move horizontally at speeds of approximately 50-250 
                         m/s over distances of several thousands of kilometers. It is 
                         natural to relate these movements with the propagation of a 
                         definite type of wave in the ionosphere. Internal gravity waves 
                         can be regarded as waves of this type. If we consider a gravity 
                         waves to be primarily a neutral wave phenomenon then its 
                         interaction with the ionization in the F-region via ionneutral 
                         collisions can be discussed by the magnetohydrodynamic theory. 
                         Using ground-based all-sky imaging systems, measurements of moving 
                         MSTID's in the OI 630, 0 nm nightglow emission were detected in 
                         the tropical region. Also, digisonde observations, available in 
                         the South Hemisphere, registered abrupt increases in both the 
                         Flayer peak (HmF2) and minimum virtual height (h'F) when the 
                         MSTID's passed over the zenity of instruments. Estimates of the 
                         spatial damping decrements for MSTID's show that the increase in 
                         electron concentration in the F-region is the main parameter for 
                         the MSTID's absorption. From this point of view we can understand 
                         the fact that most moving disturbances covering distances of 
                         several thousand of kilometers during low solar activity. In this 
                         work, we present and discuss the effect of ionization in the 
                         propagation of MSTID's.",
  conference-location = "Santa Maria, RS",
      conference-year = "05-09 nov",
             language = "pt",
        urlaccessdate = "16 maio 2024"
}