@Article{CAbduSobr:2004:DaVaUn,
               author = "C, Denardini and Abdu, Mangalathayil Ali and Sobral, Jose Humberto 
                         Andrade",
          affiliation = "Instituto Nacional de Pesquisas Espaciais, Divis{\~a}o de 
                         Aeronomia (INPE. DAE)",
                title = "VHF radar studies of the equatorial electrojet 3-m irregularities 
                         over Sao Luis: day-to-day variabilities under auroral activity and 
                         quiet conditions",
              journal = "Journal of Atmospheric and Solar-Terrestrial Physics",
                 year = "2004",
               volume = "66",
               number = "17",
                pages = "1603--1613",
                month = "Nov.",
             keywords = "equatorial, E-region, equatorial electrojet, VHF coherent scatter 
                         radar echoes, plasma instabilities / DISTURBANCE DYNAMO, FIELD, 
                         IONOSPHERE, FLUCTUATIONS, PENETRATION, VELOCITY, ORIGIN, WAVES.",
             abstract = "We have analyzed the data collected during an observational 
                         campaign of the equatorial electrojet (EEJ) plasma irregularities 
                         using 50MHz coherent back-scatter radar operated at Sao Luis, 
                         Brazil. The 7-day campaign were characterized by a disturbed 3-day 
                         period in the beginning followed by 'quiet' days. A correlative 
                         analysis of the auroral electrojet (AE) indices and radar and 
                         magnetometer data are carried out to investigate the diverse 
                         characteristics of the responses of the EEJ and its instabilities 
                         processes to the disturbance zonal electric fields that penetrate 
                         to equatorial latitudes during auroral disturbance. Large degrees 
                         of day-to-day variability in the EEJ current intensity, 3-m echo 
                         powers and spectral features were observed even under absence of 
                         any auroral disturbances. Among the outstanding results of this 
                         analysis are the following findings: (a) the observed EEJ current 
                         and 3-m irregularity response phases to the intensification/decay 
                         phases of an auroral sub-storm event agree with the prediction by 
                         the existing models; (b) the phase relationship of the EEJ 
                         response versus AE intensification is altered/inverted under the 
                         presence of a ring current (D-st) development; (c) the amplitude 
                         of the EEJ response show clear local time dependence being maximum 
                         around noon; and (d) significant increase in the type-1 
                         (two-stream wave) Doppler velocity exceeding the nominal 
                         ion-acoustic speed is observed under magnetically disturbed 
                         conditions. These results are presented and discussed. (C) 2004 
                         Elsevier Ltd. All rights reserved..",
           copyholder = "SID/SCD",
                 issn = "1364-6826",
             language = "en",
           targetfile = "VHF radar studies.pdf",
        urlaccessdate = "02 maio 2024"
}