@Article{SilvaSCSCWWBV:2022:GeAlMo,
               author = "Silva, Jos{\'e} Alexandre de Oliveira e and Selhorst, Caius 
                         Lucius and Costa, Joaquim Eduardo Rezende and Sim{\~o}es, Paulo 
                         J. A. and Castro, Carlos Guillermo Gimenez de and Wedemeyer, Sven 
                         and White, Stephen M. and Brajsa, Roman and Valio, Adriana",
          affiliation = "{Universidade de S{\~a}o Paulo (USP)} and {Universidade de 
                         S{\~a}o Paulo (USP)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {Universidade Presbiteriana Mackenzie} and 
                         {Universidade Presbiteriana Mackenzie} and {University of Oslo} 
                         and {Air Force Research Laboratory} and {University of Zagreb} and 
                         {Universidade Presbiteriana Mackenzie}",
                title = "A Genetic Algorithm to Model Solar Radio Active Regions From 3D 
                         Magnetic Field Extrapolations",
              journal = "Frontiers in Astronomy and Space Sciences",
                 year = "2022",
               volume = "9",
                pages = "e911118",
                month = "June",
             keywords = "Sun, radio radiation, atmosphere, magnetic fields, force-free 
                         field extrapolation, Sun-active regions.",
             abstract = "In recent decades our understanding of solar active regions (ARs) 
                         has improved substantially due to observations made with better 
                         angular resolution and wider spectral coverage. While prior AR 
                         observations have shown that these structures were always brighter 
                         than the quiet Sun at centimeter wavelengths, recent observations 
                         at millimeter and submillimeter wavelengths have shown ARs with 
                         well defined dark umbrae. Given this new information, it is now 
                         necessary to update our understanding and models of the solar 
                         atmosphere in active regions. In this work, we present a 
                         data-constrained model of the AR solar atmosphere, in which we use 
                         brightness temperature measurements of NOAA 12470 at three radio 
                         frequencies: 17, 100 and 230 GHz. The observations at 17 GHz were 
                         made by the Nobeyama Radioheliograph (NoRH), while the 
                         observations at 100 and 230 GHz were obtained by the Atacama Large 
                         Millimeter/submillimeter Array (ALMA). Based on our model, which 
                         assumes that the radio emission originates from thermal free-free 
                         and gyroresonance processes, we calculate radio brightness 
                         temperature maps that can be compared with the observations. The 
                         magnetic field at distinct atmospheric heights was determined in 
                         our modelling process by force-free field extrapolation using 
                         photospheric magnetograms taken by the Helioseismic and Magnetic 
                         Imager (HMI) on board the Solar Dynamics Observatory (SDO). In 
                         order to determine the best plasma temperature and density height 
                         profiles necessary to match the observations, the model uses a 
                         genetic algorithm that modifies a standard quiet Sun atmospheric 
                         model. Our results show that the height of the transition region 
                         (TR) of the modelled atmosphere varies with the type of region 
                         being modelled: for umbrae the TR is located at 1080 +/- 20 km 
                         above the solar surface; for penumbrae, the TR is located at 1800 
                         +/- 50 km; and for bright regions outside sunspots, the TR is 
                         located at 2000 +/- 100 km. With these results, we find good 
                         agreement with the observed AR brightness temperature maps. Our 
                         modelled AR can be used to estimate the emission at frequencies 
                         without observational coverage.",
                  doi = "10.3389/fspas.2022.911118",
                  url = "http://dx.doi.org/10.3389/fspas.2022.911118",
                 issn = "2296-987X",
             language = "en",
           targetfile = "fspas-09-911118.pdf",
        urlaccessdate = "07 maio 2024"
}