<b>Rainfall data from the European center for medium-range weather forecast for monitoring meteorological drought in the state of São Paulo

Abstract

 This study evaluated the use of rainfall data from the European Center for Medium-Range Weather Forecast (ECMWF) for monitoring meteorological drought in the state of São Paulo, based on rainfall data and on the Standardized Precipitation Index (SPI). Rainfall data from ECMWF were obtained from pixels corresponding to 24 meteorological stations of the state of São Paulo. The consistency of the surface data was evaluated by the following tests: Standard Normal Homogeneity Test (SNHT), Buishand and Pettitt. In order to evaluate the agreement between the surface data and the ECMWF data, for cumulative rainfall and SPI values, the following measures of accuracy were used: Willmott index of agreement (d2), modified Willmott index of agreement (d1), and mean absolute error (MAE). Higher concordances were found in the dry period (June to September). In the wet period (December to March), the ECMWF overestimated rainfall data in up to 75% of localities when compared to meteorological station data. The results indicated that the use of SPI increases the agreement between data from the ECMWF and the meteorological stations, compared to rainfall series. The highest correlations were found in the dry period leading to the conclusion that the ECMWF performs better during this period.