WRF model sensitivity to choice of parameterization for simulations over state of rio grande do sul in 2014

Abstract

In this study, a sensitivity test was performed, based on the change of parameterizations in the simulations of the mesoscale model Weather Research and Forecast in the 2014 summer and winter of on the State of Rio Grande do Sul. For this purpose, six experiments were configured with different combinations of parametrizations, alternating with complexity for the treatment of cumulus physics, cloud microphysics and solar radiation, and subdivided into two groups, which differ in relation to the Planetary Boundary Layer (PBL) parameterization - the Yonsei University (YSU) and Mellor-Yamada-Janjic (MYJ) schemes. The meteorological variables wind speed at 10m and air temperature at 2m were simulated and compared from the systematic errors (bias) and total errors (RMSE) calculation, with historical data from meteorological stations of the Banco de Dados Meteorológicos para Ensino e Pesquisa (BDMEP) of the Instituto Nacional de Meteorologia (INMET). The results showed that the model was sensitive to the alteration of the physical schemes in both the hourly and seasonal analyzes. Sensitivities were observed regarding the complexity of the schemes, but mainly from the change in CLP schemes. Experiments (EXP) with the YSU scheme showed a positive (hot) mean bias during the two seasons of the year, while the MYJ experiments had negative bias (cold) in summer and positive (warm) bias in winter. In the calculations of the systematic errors of the wind speed there were overestimations in all the experiments, but with greater accumulation during the nocturnal period. Considering the results of the indices, it was verified that the combination between the more complex convective and radiative physics added to the CLP scheme with nonlocal closure YSU, represented better the atmospheric state in Rio Grande do Sul state during summer and winter of 2014.