author = "Moro, Juliano and Xu, J and Denardin, Clezio Marcos and Resende, 
                         Laysa Cristina Ara{\'u}jo and Silva, R{\'e}gia Pereira da and 
                         Liu, Z. and Li, H. and Yan, C. and Wang, C. and Schuch, Nelson 
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Chinese 
                         Academy of Sciences (CAS)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {} and {Chinese Academy of Sciences (CAS)} 
                         and {Chinese Academy of Sciences (CAS)} and {Chinese Academy of 
                         Sciences (CAS)} and {Instituto Nacional de Pesquisas Espaciais 
                title = "On the Sources of the Ionospheric Variability in the South 
                         American Magnetic Anomaly During Solar Minimum",
              journal = "Journal of Geophysical Research: Space Physics",
                 year = "2019",
               volume = "124",
                pages = "1",
             abstract = "t We investigate for the first time the variability of the F2 
                         layer critical frequency (foF2), its peak height (hmF2), the 
                         thickness parameter B0, and the E region critical frequency (foE) 
                         over Santa Maria (29.7 S, 53.7 W, dip angle = \−37), a 
                         station located in the central region of the South American 
                         Magnetic Anomaly. The selected ionospheric parameters were 
                         obtained from ionograms recorded by a recent Digisonde Portable 
                         Sounder 4\‐D. The time period covers 309 days from 1 
                         September 2017 to 30 August 2018. The diurnal analyses revealed a 
                         large day\‐to\‐day ionospheric variability, with 
                         some peculiarities as a strong semiannual pattern superimposed to 
                         expected ionospheric behavior. Furthermore, the results show 
                         significant differences between the averaged foF2 in December and 
                         June solstices, revealing a possible presence of the annual 
                         asymmetry. The coefficient of variation (CV) is used as a 
                         quantitative description of the variability of each parameter 
                         versus time and season. Considering low solar flux and 
                         geomagnetically quiet days only, we note that CV is smaller during 
                         the daytime and larger during nighttime for all parameters. The 
                         least variable ionospheric parameter in our study is foE, while 
                         the most variable one is B0. Regarding the F2 layer parameters, we 
                         observe that foF2 is much more variable than hmF2. We attribute 
                         the observed CV to the neutral atmosphere source over Santa Maria. 
                         The ionospheric variability is in general enhanced during 
                         geomagnetically disturbed periods. The estimated CV is higher over 
                         Santa Maria than Wuhan, China (30.5 N, 114.4 E, dip angle = 
                         46), a station with no influence of the South American Magnetic 
                  doi = "10.1029/2019ja026780",
                  url = "http://dx.doi.org/10.1029/2019ja026780",
                 issn = "2169-9402",
                label = "lattes: 0549130828972280 10 MoroXNRSLLYWS:2019:SoIoVa",
             language = "en",
           targetfile = "moro_sources.pdf",
        urlaccessdate = "13 abr. 2021"