NUMERICAL EXPERIMENTS TO THE SUBTROPICAL CYCLONE “ANITA” USING WRF MODEL

• Published in: Ciência e Natura
• Main Authors: Abreu, Rafael Cesario de, Rocha, Rosmeri Porfírio da
• Format: Article in Journal/Newspaper
• Language: Portuguese
• Published: Universidade Federal de Santa Maria 2015
• Subjects: Simulação numérica; ciclone subtropical; WRF.; South Atlantic Ocean
• Online Access: https://periodicos.ufsm.br/cienciaenatura/article/view/16218; https://doi.org/10.5902/2179460X16218

http://dx.doi.org/10.5902/2179460X16218The Weather Research and Forecasting Model (WRF) were used to simulate the subtropical cyclone Anita, which occurred in March of 2010 over southwestern of South Atlantic Ocean. These cyclone instigated weather forecast centers around the world, since numerical models were indicating that it would atypically move to southwest. Therefore, numerical experiments with WRF were conducted in order to evaluate the sensitivity of Anita cyclone by changing different configurations/parameterization: (a) relaxation zone of the model (between 5 and 40 columns); (b) Betts-Miller-Janjic cumulus parameterization; (c) anticipation (24, 48, 72h). Simulations used a 25 km resolution grid, and boundary and initial conditions from FNL/NCEP (Final Analysis/National Centers for Environmental Prediction). Results were compared with the FNL/NCEP analyses and the Tropical Measuring Mission (TRMM). The relaxation zone conditions didn’t seemed to present a large impact in simulating the intensity and position of the cyclone. In general it is simulated a deeper than observed low pressure. In the experiments initiated with 72h before validation date tended to move the cyclone towards the continent, while the experiments initiated 24h before presented better agreement with observed cyclone path. The use of Betts-MillerJanjic cumulus parameterization provides results similar to the observed one, mainly for simulations initiated 72h before. The precipitation was, in general, overestimated in the experiments compared to the TRMM analyses. O modelo Weather Research and Forecasting (WRF) foi utilizado para simular o ciclone subtropical Anita, que ocorreu em março de 2010 no setor sudoeste do Oceano Atlântico Sul. Esse ciclone chamou a atenção, pois previsões numéricas indicavam que ele apresentaria uma trajetória atípica para sudoeste. Portanto, experimentos com o WRF foram realizados para avaliar a sensibilidade do ciclone as diferentes configurações/parametrizações: (a) largura da zona de relaxação (entre 5 e 40 colunas); (b) parametrização convectiva Betts-Miller-Janjic; (c) tempo de antecedência (24, 48 e 72h). As simulações utilizaram uma grade única com 25 km de resolução e condições inicial e de fronteira do FNL/NCEP (Final Analysis/National Centers for Environmental Prediction). Os resultados foram comparados com a análise do FNL/NCEP e do Tropical Rainfall Measuring Mission (TRMM). A alteração da zona de relaxação não apresentou um impacto grande na simulação da posição e intensidade do ciclone. Em geral, as simulações intensificam a baixa pressão do sistema. Os experimentos com 72h de antecedência tenderam a aproximar o centro do ciclone do continente, enquanto que os com antecedência de 24h apresentaram maior concordância com a análise do FNL/NCEP.