@Article{AbduJayMacCecSob:1998:EqFrZo,
               author = "Abdu, Mangalathyil Ali and Jayachandran, P. T. and MacDougall, J. 
                         and Cecile, J. F. and Sobral, Jos{\'e} Humberto Andrade",
                title = "Equatorial Fregion zonal plasma irregularity drifts under 
                         magnetospheric disturbances",
              journal = "Geophysical Research Letters",
                 year = "1998",
               volume = "25",
               number = "22",
                pages = "4137--4140",
                month = "Nov.",
             keywords = "AERONOMIA, anomalias magn{\'e}ticas, inicio de tempestades 
                         s{\'u}bitas, regi{\~a}o F, ioniza{\c{c}}{\~a}o, ionosfera, 
                         magnetic anomalies, sudden storm commencements, plasma drift, F 
                         region, ionization, ionosphere.",
             abstract = "Equatorial F region plasma drift velocities measured by a digital. 
                         ionosonde (CADI) that was recently installed in Fortaleza, Brazil, 
                         are used to investigate magnetospheric disturbance effects in the 
                         vertical (zonal) and zonal (vertical) velocities (electric 
                         fields). For the first lime we report evidence of large 
                         fluctuations in irregularity zonal drift velocities (similar to 
                         50-180 m/s) associated with magnetospheric disturbances. The 
                         fluctuations in the zonal velocity, anti correlated with those in 
                         vertical velocity, are unlikely to be produced by prompt 
                         penetration of disturbance meridional electric field of high 
                         latitude/magnetospheric origin. A mechanism is proposed to explain 
                         the velocity fluctuations that involves: (1) Hall polarization 
                         vertical electric field in the E-layer that is field line mapped 
                         on to F- layer, and (2) electric field caused by vertical current 
                         arising from divergence in field line integrated zonal Pedersen 
                         current; both produced by the primary disturbance zonal electric 
                         field. Enhanced nighttime E region conductivity with possible 
                         spatial gradients, a requirement for the functioning of this 
                         mechanism, is observed to be present from other simultaneous 
                         measurements, whose source is suggested to be particle induced 
                         ionization in the south Atlantic Magnetic Anomaly (SAMA) zone, as 
                         known also from previous studies.",
                 issn = "0094-8276",
                label = "9580",
           targetfile = "1998_abdu.pdf",
        urlaccessdate = "02 jun. 2024"
}