Interannual Variability, Errors and Biases in a Present Climate Simulation over Southern South America

JOSEFINA BLAZQUEZ; MARIO N. NUÑEZ

Foz do Iguassu, Brazil

Conferencia; The Meeting of the Americas; 2010

American Geophysical Union

This study presents an evaluation of a 20 Km. global atmospheric model JMA/MRI over southern South America. Present-day simulation (1979-2003) of daily temperature and precipitation was analyzed and compared to observations obtained from meteorological stations. Interannual variability, errors and biases are calculated for both variables temperature and precipitation. The calculation of the interannual variability revealed that it is reasonably well capture by the model, showing a general underestimation compared to observations in both variables and in most of regions. The systematic error of the model was also computed calculating the biases. Results show that the region located south of South America has a cold bias with respect to observations during the whole year, while the one which is located over The Andes has a warm bias in almost all the seasons. For precipitation, small biases were found in the south east of Brazil. The mean square error (RMSE) of temperature is less than 3 °C in all the regions, but this value decreases between 1 and 1.5 °C when the RMSE is computed after removal the annual mean bias. In some regions the increase of precipitation error and wet season are in agreement, and in most of regions the RMSE decreases when the error is calculated after removing the annual mean bias. We also find that the more meteorological stations, the less value of error the region had. The results of this work allowed evaluating the ability of the high resolution global model in reproducing the interannual variability and provide an estimation of both errors the random and the systematic one.