@InProceedings{FagundesAbalSahaBitt:2009:ObDaVa,
               author = "Fagundes, Paulo R. and Abalde, J. R. and Sahai, Y. and 
                         Bittencourt, Jos{\'e} Augusto",
          affiliation = "{Universidade do Vale do Para{\'{\i}}ba} and {Universidade do 
                         Vale do Para{\'{\i}}ba} and {Universidade do Vale do 
                         Para{\'{\i}}ba} and {Instituto Nacional de Pesquisas Espaciais 
                         (INPE)}",
                title = "Observation of day-to-day variability in equatorial spread-F",
            booktitle = "Proceedings...",
                 year = "2009",
         organization = "Iaga, 2009.",
             keywords = "Ionosphere, Spread-F, Equatorial region.",
             abstract = "It is well established that Rayleigh -Taylor instability mechanism 
                         is fundamental for the generation of large scale equatorial 
                         ionospheric irregularities. The pre-reversal enhancement (PRE) of 
                         zonal electric field, which uplifts the ionosphere after the 
                         sunset, is one of the most important ingredients in the day-to-day 
                         variability of equatorial spread-F (ESF). Although, ESF have been 
                         studied since late 1930s, nevertheless it continues to attract 
                         considerable attention because still debate is going on regarding 
                         the onset conditions and their influence on trans-ionospheric 
                         radio-wave communications, location and navigation systems in the 
                         equatorial and low latitude regions. However, up to now there is 
                         not a good explanation for the day-to-day ESF variability during 
                         geomagnetically quiet and disturbed conditions. Observations from 
                         mult-instruments both ground (optical, ionosondes, and radars) and 
                         space (satellites) have been utilized for these studies. In this 
                         paper we show that a planetary wave type oscillation affects the 
                         PRE and then consequentially the variability of ESF. Also, the 
                         strength of the PRE plays an important role in the generation of 
                         fresh spread-F, where fresh spread-F are those observed between 
                         19:00 and 21:00 LT (post-sunset conditions).",
  conference-location = "Sopron, Hungary",
      conference-year = "23-30 Aug.",
             language = "en",
        urlaccessdate = "12 maio 2024"
}