author = "Abdu, Mangalathayil Ali",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "Disturbance electric field effects on equatorial evening vertical 
                         drift and spread F development",
            booktitle = "Proceedings...",
                 year = "2009",
         organization = "Iaga, 2009.",
             keywords = "Disturbance electric fields, Low latitude ionosphere, Equatorial 
                         spread F.",
             abstract = "The most studied and perhaps the most readily verifiable precursor 
                         condition for the growth of post sunset equatorial plasma 
                         instabilities leading to spread F irregularity (ESF) development 
                         is the prereversal enhancement in the zonal electric field (PRE). 
                         Its day-to-day, seasonal and solar flux dependent variabilities 
                         are to the first degree responsible for the corresponding 
                         variabilities in ESF. The day-to-day variability which is the most 
                         challenging problem results from upward propagating atmospheric 
                         waves (especially, gravity- and planetary- waves) as well as from 
                         disturbance electric fields arising from weak to intense 
                         substrom/magnetic storm disturbances. Recent studies have shown 
                         that the evening F region vertical drift/PRE and hence the ESF 
                         suffers drastic modifications due to under-shielding as well as 
                         over-shielding electric fields. The PRE can undergo large 
                         increase, decrease, total suppression or even reversal to downward 
                         depending upon the polarity and intensity of the prompt 
                         penetrating zonal electric field. While the ESF intensity follows 
                         in general moderate increase in the PRE it does not follow very 
                         large increases in vertical drift. This paper will present results 
                         from recent investigations, mainly based on Digisonde observations 
                         in Brazil, on the evening vertical drift and ESF day-to-day 
                         variabilities arising from magnetospherric- and atmospheric- 
  conference-location = "Sopron, Hungary",
      conference-year = "23-30 Aug.",
             language = "en",
        urlaccessdate = "24 jan. 2021"