@InProceedings{EspinosaSarmientoPadiAlve:2018:EsGeIn,
               author = "Espinosa Sarmiento, Karen Viviana and Padilha, Ant{\^o}nio Lopes 
                         and Alves, Livia Ribeiro",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)}",
                title = "Estimation of geomagnetically Induced Currents at Low Latitude and 
                         Equatorial regions of Brazil during two great magnetic storms of 
                         2015",
                 year = "2018",
         organization = "AGU Fall Meeting",
             abstract = "The South American longitudinal sector presents the unique feature 
                         of the presence of daytime equatorial electrojet currents (EEJ) 
                         and the South Atlantic Magnetic Anomaly (SAMA), where the global 
                         minimum intensity of the geomagnetic field is observed. Enhanced 
                         amplitudes are observed in the horizontal magnetic components 
                         recorded on the ground within the areas of influence of both the 
                         EEJ and the SAMA and therefore it is expected that significant 
                         enhancements of GIC magnitude also occur in these regions. We use 
                         here geomagnetic field variations data recorded by fluxgate 
                         magnetometers from the Brazilian space weather program (EMBRACE) 
                         to evaluate GIC effects during two strong geomagnetic storms in 
                         March (Dst = \−222nT) and June (Dst = \−204nT) 2015. 
                         Among the available geomagnetic stations, we selected those with 
                         information about the underground electrical conductivity 
                         structure and that can be approximated by 1-D models for 
                         calculation of the geoelectric field. GIC levels are estimated 
                         using a realistic local power grid model located in the central 
                         region of Brazil, artificially moved to the sites where the 
                         geomagnetic measurements are available. Maximum GIC amplitude of 
                         about 8 A was estimated at an equatorial station positioned over 
                         high resistivity underground, associated with the arrival of an 
                         interplanetary pressure pulse just behind two other pulses during 
                         the June storm. The results are also interpreted in terms of the 
                         ionospheric currents over the measurement sites and the 
                         conductivity distribution beneath these sites. It is observed that 
                         both EEJ and SAMA increase the GIC amplitudes, with the greatest 
                         effects associated with EEJ. In relation to the underlying 
                         conductivity structure, the higher GIC effects are associated with 
                         low conductance at crustal depths, with upper mantle depths 
                         showing minor effect.",
  conference-location = "Washington, D. C.",
      conference-year = "10-14 dec.",
             language = "en",
           targetfile = "espinosa_estimation.pdf",
        urlaccessdate = "27 abr. 2024"
}