@MastersThesis{Fernandes:2014:PaTeRe,
               author = "Fernandes, Alex de Almeida",
                title = "Paraleliza{\c{c}}{\~a}o do termo de reatividade qu{\'{\i}}mica 
                         do modelo ambiental CCATT-BRAMS utilizando um solver baseado em 
                         estima{\c{c}}{\~a}o linear {\'o}tima",
               school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                 year = "2014",
              address = "S{\~a}o Jos{\'e} dos Campos",
                month = "2014-11-28",
             keywords = "CCATT-BRAMS, OpenMP, qu{\'{\i}}mica atmosf{\'e}rica, 
                         estima{\c{c}}{\~a}o linear {\'o}tima, atmospheric chemistry, 
                         optimal linear estimation.",
             abstract = "O Centro de Previs{\~a}o de Tempo e Estudos Clim{\'a}ticos 
                         (CPTEC/INPE) desenvolveu e utiliza o modelo ambiental CCATT-BRAMS 
                         que acopla um modelo de transporte de gases tra{\c{c}}o ao modelo 
                         regional BRAMS. Este modelo ambiental possui um termo de 
                         reatividade qu{\'{\i}}mica que atualiza a composi{\c{c}}{\~a}o 
                         qu{\'{\i}}mica da atmosfera para o passo de tempo considerado. 
                         Este termo modela as rea{\c{c}}{\~o}es qu{\'{\i}}micas entre 
                         componentes da atmosfera e deve ser resolvido para cada ponto da 
                         grade espacial. A composi{\c{c}}{\~a}o qu{\'{\i}}mica da 
                         atmosfera influi na absor{\c{c}}{\~a}o de radia{\c{c}}{\~a}o 
                         solar pela atmosfera impactando seu balan{\c{c}}o t{\'e}rmico. 
                         Entretanto, seu custo computacional ao ser executado a cada passo 
                         de tempo {\'e} uma ordem de grandeza superior ao do modelo BRAMS, 
                         de forma que seu uso operacional {\'e} poss{\'{\i}}vel com sua 
                         execu{\c{c}}{\~a}o a cada 4 passos de tempo. Esse custo deve-se 
                         {\`a} resolu{\c{c}}{\~a}o de um sistema linear de 
                         equa{\c{c}}{\~o}es para cada ponto de grade. O solver utilizado 
                         correntemente tem uma implementa{\c{c}}{\~a}o sequencial e sua 
                         paraleliza{\c{c}}{\~a}o demandaria altera{\c{c}}{\~o}es 
                         significativas do c{\'o}digo correspondente. Assim, este trabalho 
                         prop{\~o}e o uso de um solver baseado em estima{\c{c}}{\~a}o 
                         linear {\'o}tima que possui um c{\'o}digo mais simples e mais 
                         apropriada {\`a} paraleliza{\c{c}}{\~a}o. Testes demonstraram 
                         que o solver proposto fornece resultado numericamente equivalentes 
                         {\`a}queles do solver original e que possibilita um ganho de 
                         desempenho ao ser paralelizado com a biblioteca OpenMP. 
                         Investigou-se tamb{\'e}m a possibilidade de port{\'a}-lo para 
                         execu{\c{c}}{\~a}o em placa aceleradora gr{\'a}fica (GPU) 
                         prevendo a disponibilidade desses aceleradores num futuro 
                         supercomputador do CPTEC/INPE. ABSTRACT: The Center for Weather 
                         Forecasting and Climate Studies (CPTEC/INPE) developed and employs 
                         the environmental model CCATT-BRAMS that couples a pollutant 
                         transport model and the regional numerical model BRAMS. This 
                         environmental model includes a chemical reactions module that 
                         updates the chemical composition of the atmosphere for the 
                         considered timestep. This module models the chemical reactions 
                         between atmospheric components and must be solved for each 
                         gridpoint. The atmospheric chemical composition influences the 
                         absorption of solar radiation by the atmosphere thus affecting it 
                         is thermal balance. However the computational cost of executing 
                         this module at every timestep is one order of magnitude higher 
                         than that of the BRAMS model. Therefore, its operational use is 
                         feasible with an execution every 4 timesteps. Such computational 
                         cost is due to the resolution of a linear system of equations for 
                         each gridpoint. The currently employed solver has a serial version 
                         and would demand large modifications of the code in order to be 
                         parallelized. This work proposes the use of a solver based on 
                         optimal linear estimation that has a code that is simpler and more 
                         suitable for parallelization. Numerical tests show that the 
                         proposed solver achieved results that are numerically equivalent 
                         to those of the original solver. In addition, the OpenMP parallel 
                         version of the proposed solver achieved reasonable speed-up. This 
                         work also investigated the portability of the proposed solver for 
                         execution in a graphics processing unit (GPU) since such 
                         accelerators may be available in a future supercomputer of 
                         CPTEC/INPE.",
            committee = "Carvalho, Solon Ven{\^a}ncio de (presidente) and Stephany, 
                         Stephan (orientador) and Panetta, Jairo (orientador) and Velho, 
                         Haroldo Fraga de Campos and Sanches, Carlos Alberto Alonso",
           copyholder = "SID/SCD",
         englishtitle = "Parallelization of the chemical reactions module of the 
                         CCATT-BRAMS environmental model using a solver based on optimal 
                         linear estimation",
             language = "pt",
                pages = "103",
                  ibi = "8JMKD3MGP3W34P/3HG84GL",
                  url = "http://urlib.net/ibi/8JMKD3MGP3W34P/3HG84GL",
           targetfile = "publicacao_.pdf",
        urlaccessdate = "27 abr. 2024"
}