@Article{MuellaPauKanRezSmo:2009:MaQuDi,
               author = "Muella, Marcio Tadeu de Assis Honoroto and Paula, Eurico Rodrigues 
                         de and Kantor, Ivan Jelinek and Rezende, Luiz Felipe Campos de and 
                         Smorigo, Paulo Flabiano",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {Instituto Nacional de Pesquisas Espaciais 
                         (INPE)}",
                title = "Occurrence and zonal drifts of small-scale ionospheric 
                         irregularities over an equatorial station during solar maximum - 
                         Magnetic quiet and disturbed conditions",
              journal = "Advances in Space Research",
                 year = "2009",
               volume = "43",
               number = "12",
                pages = "1957--1973",
                month = "Jun.",
             keywords = "f-region, spread-f, magnetospheric disturbances, electric-fields, 
                         scintillation activity, cachoeira paulista, diagnostic model, 
                         anomaly crest, plasma drifts, system.",
             abstract = "A statistical study of L-band amplitude scintillations and zonal 
                         drift velocity of Fresnel-scale ionospheric irregularities is 
                         presented. Ground-based global positioning system (GPS) data 
                         acquired at the equatorial station of Sao Luis (2.33 degrees S, 
                         44.21 degrees W, dip latitude 1.3 degrees S), Brazil, during the 
                         solar maximum period from March 2001 to February 2002 are used in 
                         the analysis. The variation of scintillations and irregularity 
                         drift velocities with local time, season and magnetic activity are 
                         reported. The results reveal that for the near overhead ionosphere 
                         (satellite elevation angle >45 degrees) a broad maximum in the 
                         occurrence of scintillation is seen from October to February. In 
                         general, weak scintillations (S-4 < 0.4) dominated (>90%) during 
                         equinox (March-April; September-October) and December solstice 
                         (November-February) quiet time conditions and, many of the 
                         scintillations, occurred during pre-midnight hours. The mean zonal 
                         velocities of the irregularities are seen to be similar to 30 in 
                         s(-1) larger near December solstice, while during the equinoctial 
                         period the velocities decay faster and the scintillations tend to 
                         cease earlier. On geomagnetically disturbed nights, scintillation 
                         activity seems to be strongly affected by the prompt penetration 
                         of magnetospheric electric fields and disturbance dynamo effects. 
                         On disturbed days, during the equinox and December solstice 
                         seasons, the scintillations tend to be suppressed in the 
                         pre-midnight hours, whereas during June solstice months 
                         (May-August) the effect is opposite. In the post-midnight period, 
                         the mostly marked increase in the scintillation occurrence is 
                         observed during the equinox months. The results show that during 
                         disturbed conditions only one type of storm (when the main phase 
                         maximum takes place during the daytime hours) agrees with the 
                         Aarons' description, that is the suppression of L-band 
                         scintillations in the first recovery phase night. The results also 
                         reveal that the storm-time irregularity drifts become more spread 
                         in velocity and occasionally may present westward drift. The 
                         present work is important to evaluate the behavior of the 
                         ionospheric irregularities at equatorial latitudes under 
                         geomagnetically quiet and disturbed conditions, which is one of 
                         the most relevant themes in the space weather studies.",
                  doi = "10.1016/j.asr.2009.03.017",
                  url = "http://dx.doi.org/10.1016/j.asr.2009.03.017",
                 issn = "0273-1177",
             language = "en",
           targetfile = "1-s2.0-S0273117709002002-main.pdf",
        urlaccessdate = "03 maio 2024"
}