@Article{CostaVilaFons:2004:GPToEl,
               author = "Costa, Aracy Mendes da and Vilas Boas, Jos{\'e} Williams dos 
                         Santos and Fonseca Junior, Edvaldo S. da",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and EPUSP",
                title = "GPS total electron content measurements at low latitudes in Brazil 
                         for low solar activity",
              journal = "Geof{\'{\i}}sica Internacional",
                 year = "2004",
               volume = "43",
               number = "1",
                pages = "129--137",
             keywords = "GPS, Total Electron Content, equatorial anomaly.",
             abstract = "Variations of ionospheric Total Electron Content (TEC) have been 
                         calculated using GPS data at station Presidente Prudente, Brazil 
                         (22.1° S; 51.4° W) in 1997, a period of low solar activity. Two 
                         hourly TEC averages are presented for the period. Diurnal, 
                         seasonal, solar activity variations and Equatorial Anomaly effects 
                         are discussed. TEC diurnal means compared with IRI 95 predictions 
                         for equinox and solstice months show that IRI-95 systematically 
                         overestimates the observed values. Pre-midnight TEC enhancements 
                         were observed all over the year, except in May and June. The TEC 
                         values reproduce the same general trend of TEC observations over 
                         Cachoeira Paulista, Brazil (22.5° S; 45° W). The fountain effect 
                         seems to be more effective at Presidente Prudente because of its 
                         lower magnetic dip latitude. A correlation between TEC 
                         experimental values and low solar flux (62 < F10.7 < 116 flux 
                         units) emphasizes the inadequacy of IRI to model low latitude TEC 
                         values at low solar activity periods. These are the first results 
                         obtained using TEC-GPS technique for total electron content 
                         measurement in southwestern Brazil.",
                 issn = "0016-7169",
             language = "en",
           targetfile = "mendes.pdf",
        urlaccessdate = "16 jun. 2024"
}