author = "Pietrella, M. and Pezzopane, M. and Fagundes, P. R. and Jesus, 
                         Rodolfo de and Supnithi, P. and Klinngam, S. and Ezquer, R. G. and 
                         Cabrera, M. A.",
          affiliation = "{Istituto Nazionale di Geofisica e Vulcanologia} and {Istituto 
                         Nazionale di Geofisica e Vulcanologia} and {Universidade do Vale 
                         do Para{\'{\i}}ba (UNIVAP)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {King Mongkut's Institute of Technology 
                         Ladkrabang (KMITL)} and {King Mongkut's Institute of Technology 
                         Ladkrabang (KMITL)} and {Universidad Tecnol{\'o}gica Nacional} 
                         and {Universidad Tecnol{\'o}gica Nacional}",
                title = "Equinoctial spread-F occurrence at low latitudes in different 
                         longitude sectors under moderate and high solar activity",
              journal = "Journal of Atmospheric and Solar-Terrestrial Physics",
                 year = "2017",
               volume = "164",
                pages = "149--162",
                month = "Nov.",
             keywords = "IonosphereEquatorial ionosphereIonospheric irregularitiesWave 
             abstract = "A comparative study aimed to investigate the equatorial and 
                         low-latitude spread-F occurrences for moderate solar activity 
                         (MSA) and high solar activity (HSA), was carried out considering 
                         concurrent observations made in some ionospheric stations, which 
                         identify three separate longitudinal sectors: Chiang Mai (CGM; 
                         18.8 N, 98.9 E, mag. Lat. 13.2 N) and Chumphon (CPN; 10.7 N, 
                         99.4 E, mag. Lat. 3.2 N), Thailand; Palmas (PAL; 10.2 S, 311.8 
                         E, mag. Lat. 0.9 S) and S{\~a}o Jos{\'e} dos Campos (SJC; 23.2 
                         S, 314.1 E, mag. Lat. 14.0 S), Brazil; Tucum{\'a}n (TUC; 26.9 
                         S, 294.6 E, mag. Lat. 16.8 S), Argentina. Spread-F phenomena 
                         recorded during the equinoctial months of September and October 
                         2010, March and April 2011, for MSA, March and April 2014, 
                         September and October 2014, for HSA, were classified in two 
                         different modes: range spread-F (RSF) and frequency spread-F 
                         (FSF). The satellite trace (ST) occurrence was also investigated 
                         as possible precursor of spread-F events. When comparing the 
                         results of equatorial (CPN and PAL) and low-latitude (CGM, SJC, 
                         and TUC) stations, some common features independently of the solar 
                         activity emerge: (1) a prevalence of RSF signatures is observed in 
                         the time interval 20:0003:00 LT, while FSF occurrences prevail in 
                         the time interval 03:0006:00 LT; (2) STs are confirmed to be a 
                         possible precursor of RSF occurrences. For HSA, at equatorial 
                         latitudes, spread-F occurrences in the Thai sector (CPN) are 
                         higher than those observed in the Brazilian sector (PAL). When 
                         comparing the results of low-latitude stations of CGM, SJC, and 
                         TUC some unusual aspects characterizing the morphology of spread-F 
                         occurrences emerge: (1) contrary to the Thai and Argentine 
                         sectors, in the Brazilian sector (SJC), RSF and FSF appearances in 
                         September, for HSA, are observed with relatively long persistence 
                         times between about 03:00-06:00 LT and 01:00-03:00 LT 
                         respectively, while balanced RSF and FSF occurrences with short 
                         persistence times are observed for months for MSA; (2) a 
                         prevalence of FSF at CGM during the first half of September for 
                         MSA, never observed in the Brazilian and Argentine areas. During 
                         years of LSA and MSA common morphological aspects are found at CGM 
                         and SJC, that is a predominance of FSF, with the lowest 
                         persistence times characterizing SJC. This suggests that the 
                         low-latitude behaviour of spread-F occurrences, under different 
                         levels of solar activity, at least in the longitude sectors here 
                         analysed, can be to a some extent generalized.",
                  doi = "10.1016/j.jastp.2017.07.007",
                  url = "http://dx.doi.org/10.1016/j.jastp.2017.07.007",
                 issn = "1364-6826",
             language = "en",
           targetfile = "pietrella_equinoctial.pdf",
        urlaccessdate = "26 nov. 2020"