@Article{SahaiFaguBitt:2000:SoCyEf,
               author = "Sahai, Yogeshwar and Fagundes, Paulo Roberto and Bittencourt, 
                         Jos{\'e} Augusto",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and Instituto 
                         de Pesquisas e Desenvolvimento (IP\&D), Universidade do Vale do 
                         Para",
                title = "Transequatorial F-region ionospheric plasma bubbles: solar cycle 
                         effects",
              journal = "Journal of Atmospheric and Solar-Terrestrial Physics",
                 year = "2000",
               volume = "62",
               number = "15",
                pages = "1377--1383",
                month = "Oct.",
             keywords = "AERONOMIA, ciclos solar, efeitos da atividade solar, regi{\~a}o 
                         F, bolhas de plasma, solar cycles, solar activity effects, F 
                         region, plasma bubbles.",
             abstract = "During the recent past, wide-angle optical imaging observations of 
                         F-region nightglow emissions (e.g. OI 630 nm)have provided 
                         excellent results related to the occurrence, evolution and 
                         dynamics of large-scale range spread-F irregularities, as they are 
                         characterized by large-scale ionospheric plasma depletions, 
                         generally known as transequatorial plasma bubbles, which result in 
                         quasi north-south aligned intensity depleted bands. The intensity 
                         depletions seen in the airglow images are the optical signature, 
                         at the height range of the emitting layer of transequatorial 
                         magnetic field-aligned plasma bubbles. An all-sky imaging system, 
                         observing the OI 630 nm emission, was operational at Cachoeira 
                         Paulista (22.7 degree S, 45.0 degree W; similar to 16 degreesS dip 
                         latitude), Brazil, during the period March 1987 to October 1991. 
                         It was put back in operation again in September 1994 and 
                         observations are continuing. These observations have provided an 
                         extensive data-base of OI 630 nm images which permitted us to 
                         address several aspects related to the formation and development 
                         of large-scale spread-F plasma irregularities during both high- 
                         and low solar activity periods. An analysis of about 11,000 images 
                         from these investigations are presented and discussed in this 
                         paper. The seasonal occurrence characteristics are fairly similar 
                         for both low and high solar activities. However, the occurrences 
                         of intensity depleted bands are much less during low solar 
                         activity (33 percent ) as compared with high solar activity (55 
                         percent ). Also, some of the intensity depleted bands in the 
                         images (which show the optical signatures at the height of the 
                         emitting layer around 250-300 km)indicating that plasma bubbles 
                         attaining very high altitudes (>1500 km)at the magnetic equator 
                         (by mapping the depletion bands along geomagnetic field lines to 
                         the equatorial plane (e.g., Mendillo and Tyler, J. Geophys. Res. 
                         88 (1983)5778), are much less during low solar activity (34 
                         percent of the images with intensity depleted bands)as compared 
                         with high solar activity (66 percent of the images with intensity 
                         depleted bands). The average nocturnal variations of intensity 
                         depleted regions show different characteristics during the high 
                         and low solar activity periods.",
                 issn = "1364-6826",
                label = "9632",
             language = "en",
           targetfile = "1-s2.0-S1364682600001796-main.pdf",
        urlaccessdate = "23 maio 2024"
}