@Article{SantosWras:2019:CoPhVo,
               author = "Santos, Jean c. and Wrasse, Cristiano Max",
          affiliation = "{Universidade Tecnol{\'o}gica Federal do Paran{\'a} (UFTPR)} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "Converging photospheric vortex flows close to the polarity 
                         inversion line of a fully emerged active region",
              journal = "Annales Geophysicae",
                 year = "2019",
               volume = "37",
               number = "4",
                pages = "603--612",
                month = "July",
             abstract = "We report on the occurrence of vortexes in flow fields obtained 
                         from the evolution of the line-of-sight component of the 
                         photospheric magnetic field in a region around the polarity 
                         inversion line (PIL) of a fully emerged active region. Based on a 
                         local linear approximation for the flow field, we identify the 
                         presence of critical points and classify them according to the 
                         eigenvalues of the Jacobian matrix of the linear transformation. 
                         Converging vortexes are associated with the presence of a 
                         particular kind of critical point, known as the attracting focus. 
                         We identified 12 converging vortexes in the analyzed period and 
                         detected the occurrence of other types of critical points, which 
                         indicate the complexity of the flow field around the PIL. The 
                         detected vortexes show a clockwise preferred sense of rotation 
                         with approximately 67% of the cases. A geometrical analysis of the 
                         velocity structures produced an average value of (D) over bar = 
                         1.63 +/- 0.05 for the fractal dimension, which is very close to 
                         the one obtained for isotropic homogeneous turbulence (D = 5/3). 
                         This suggests that the flow around the PIL is turbulent in 
                         nature.",
                  doi = "10.5194/angeo-37-603-2019",
                  url = "http://dx.doi.org/10.5194/angeo-37-603-2019",
                 issn = "0992-7689",
             language = "en",
           targetfile = "santos_convergins.pdf",
        urlaccessdate = "05 jun. 2024"
}