@Article{AbduMedeBittBati:1982:VeIoDr,
               author = "Abdu, Mangalathayil Ali and Medeiros, Rui Tertuliano de and 
                         Bittencourt, Jos{\'e} Augusto and Batista, Inez Staciarini",
          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)}",
                title = "Vertical ionization drift velocities and range type spread F in 
                         the evening equatorial ionosphere",
              journal = "Journal of Geophysical Research",
                 year = "1982",
               volume = "Submitted",
                pages = "1--15",
             keywords = "Spread F, vertical ion drift.",
             abstract = "Range type spread F indices in the post sunset hours, determined 
                         from ionograms, are compared with F-layer vertical velocities, 
                         also deduced from ionograms, for a period of one year, over the 
                         magnetic equatorial station Fortaleza (geographic coordinates: 
                         4°S, 38 0W; dip latitude: 1.8°S), Brazil. Besides good correlation 
                         between the two parameters, the results suggest the presence of a 
                         certain threshold value for the vertical ionization velocity and a 
                         corresponding threshold height for the base of the evening 
                         F-layer, as one of the necessary conditions for the occurrence of 
                         spread F irregularities valid for southern solstice (summer) and 
                         equinoctial months. The nature of the possible variabilities in 
                         the amplitude of the initial perturbation in the ionization 
                         (seeding mechanism), which is another prerequisite for the 
                         generation of irregularities, is discussed briefly.",
             language = "en",
           targetfile = "2332.pdf",
        urlaccessdate = "24 jan. 2021"
}