@Article{SahaiFaguBitt:1999:SoCyEf,
               author = "Sahai, Yogeshwar and Fagundes, Paulo Roberto and Bittencourt, 
                         Jos{\'e} Augusto",
                title = "Solar cycle effects on large scale equatorial F-region plasma 
                         depletions",
              journal = "Advances in Space Research",
                 year = "1999",
               volume = "24",
               number = "11",
                pages = "1477--1480",
             keywords = "AERONOMIA, ciclo solar, efeitos, regi{\~a}o F, 
                         propaga{\c{c}}{\~a}o transequatorial, bolhas de plasma, 
                         atividade solar, solar cycle, effects, F region, transequatorial 
                         propagation, plasma bubbles, solar activity.",
             abstract = "In recent years, scientists have used wide-angle imaging 
                         observations of F-region nightglow emissions (e.g., OI630 nm and 
                         OI777.4 nm) to map the F-region equatorial ionospheric 
                         irregularity structures, characterized by large scale plasma 
                         depletions, generally known as transequatorial plasma bubbles. In 
                         Brazil, an OI630 nm all-sky imaging system has been in operation 
                         at Cachoeira Paulista (22.7 degrees S, 45.0 degrees W) since March 
                         1987. This has provided an extensive data-base of the OI630 nm 
                         all-sky imaging observations in the equatorial ionospheric anomaly 
                         region. In this paper, the morphology of large scale equatorial 
                         F-region plasma depletions under sunspot maximum and minimum 
                         conditions is presented and discussed. It has been observed that 
                         the occurrences of plasma depleted regions are relatively lesser 
                         during low solar activity than during high solar activity. The 
                         seasonal occurrence pattern is fairly similar for high and low 
                         solar activities.",
                 issn = "0273-1177",
                label = "9393",
             language = "en",
           targetfile = "1-s2.0-S0273117799007097-main.pdf",
        urlaccessdate = "08 maio 2024"
}