Impacto de um esquema objetivo de análise nas simulações de eventos meteorológicos num modelo regional. / Impact of an analysis objective scheme to simulate meteorological events regional model.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

An objective scheme of data analysis was implemented in a limited area model for numerical forecast. It is composed of two parts: initialization and continuous data assimilation. The hydrostatic numerical model used was developed by the Japan Meteorology Agency. It is written in flux form using s-p vertical coordinates. The initialization procedure combines the digital filter technique and continuous data assimilation, with the assimilation being carried out using Newtonian relaxation (or nudging). The Newtonian relaxation is an alternative procedure to the variational methods, which enables an efficient and quick data assimilation scheme. The digital filter and the continuous data assimilation (by nudging) create an initial condition close to real state of the atmosphere and avoid the delay between the first-guess and initial conditions. This is a deficiency of the digital filter, when it is applied in its original proposition. This situation has to be prevented particularly in the short-range prediction. This technique has performance similar o initialization by non-linear normal modes, besides it is relative simplicity when used in a regional model. This method and the digital filter are both easily implemented in numerical models. A series of numerical experiments was conducted in order to study the impact of the proposed method in the early steps of the model integration and the sensibility on the simulation of an extratropical cyclone developing at east of the Andes. The method can use any kind of data, but in this study only the NCEP reanalysis and radiosondes are used. The results indicate that the analysis scheme is efficient to produce reliable initial conditions free of high frequency oscillations. The evolution of the extratropical cyclone satisfactorily simulated, and the use of the continuous assimilation showed improvement on the forecast of some meteorological parameters.

ASSUNTO(S)

previsão numérica do tempo modelo de área limitada. key words: data analysis relaxation methods digital filters método de relaxão análise de dados numerical wether forecasting limited area model

ACESSO AO ARTIGO

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