author = "Abreu, A. J. de and Roberto, M. and Alves, M. A. and Abalde, J. R. 
                         and Nogueira, P. A. B. and Venkatesh, K. and Fagundes, P. R. and 
                         Jesus, Rodolfo de and Gende, M. and Martin, I. M.",
          affiliation = "{Instituto Tecnol{\'o}gico de Aeron{\'a}utica (ITA)} and 
                         {Instituto Tecnol{\'o}gico de Aeron{\'a}utica (ITA)} and 
                         {Instituto Tecnol{\'o}gico de Aeron{\'a}utica (ITA)} and 
                         {Instituto Tecnol{\'o}gico de Aeron{\'a}utica (ITA)} and 
                         Instituto Federal de Educa{\c{c}}{\~a}o, Ci{\^e}ncia e 
                         Tecnologia de S{\~a}o Paulo (IFSP) and {National Atmospheric 
                         Research Laboratory (NARL)} and {Universidade do Vale do 
                         Para{\'{\i}}ba (UNIVAP)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {Universidade do Vale do Para{\'{\i}}ba 
                         (UNIVAP)} and {Instituto Tecnol{\'o}gico de Aeron{\'a}utica 
                title = "Effects of X2-class solar flare events on ionospheric GPS-TEC 
                         andradio waves over Brazilian sector",
              journal = "Advances in Space Research",
                 year = "2019",
               volume = "63",
               number = "11",
                pages = "3586--3605",
                month = "June",
             keywords = "Solar flare, Ionosphere, GPS, Ionosonde.",
             abstract = "In this investigation, we present and discuss the effects of 6 
                         X2-class solar flare events in the ionospheric F region over 
                         Brazilian sector that occurred during 2013 to 2015. For this 
                         investigation, we present the vertical total electron content 
                         (VTEC) observations from nearly 120 Global Positioning System 
                         (GPS) receivers all over the Brazilian sector for each event. 
                         Also, ionospheric sounding observations obtained in Sao Jose dos 
                         Campos (23.2 degrees S, 45.9 degrees W, dip latitude 17.6 degrees 
                         S; hereafter referred to as SJC), under the southern crest of the 
                         equatorial ionospheric anomaly (EIA), Brazil, are presented. The 
                         observations show that the greatest TEC impact occurs with the EUV 
                         fluxes increases lasting for more than one hour and when the solar 
                         active region is located close to the solar disc center. We 
                         present a detailed study of the efficiency of the EUV flux with 
                         wavelengths ranging from 0.1 to 190 nm for the F region 
                         ionization. The largest increase of Delta TEC occurs below the 
                         magnetic equator line, covering mainly the central, northeast, 
                         southeast and south regions, which includes the equatorial 
                         ionospheric anomaly (EIA) region. The ionograms show partial or 
                         total fade out in the echoes traces observed causing blackouts of 
                         radio signals of up to 60 min, which can have serious consequences 
                         to technological systems of public and private agencies around 
                         Brazilian sector. This study can help to better understand the 
                         effects of solar flares in the ionospheric F region.",
                  doi = "10.1016/j.asr.2019.02.020",
                  url = "http://dx.doi.org/10.1016/j.asr.2019.02.020",
                 issn = "0273-1177 and 1879-1948",
             language = "en",
           targetfile = "abreu_effects.pdf",
        urlaccessdate = "29 nov. 2020"