Assessment and applications of precipitation Extreme Forecast Index (EFI) from ECMWF to Anhui province

In this study, the precipitation Extreme Forecast Index (EFI) from ECMWF global ensemble prediction system (EPS) from October 2012 to September 2014, including 1d, 5d and 10 d accumulated precipitation EFI, were used to evaluate the statistical relationship between EFI and severe precipitation and its anomaly, respectively. Results indicate that the high value center of EFI corresponds to severe precipitation zone. The greater the EFI is, the higher the probability that severe precipitation events occurred is. But as the forecast time length increases, the indicative significance of EFI becomes less evident. TS scores of the high value center of EFI for daily precipitation and the precipitation area show that to obtain the best TS score, the thresholds of EFI increase with the increase of precipitation grades and decrease with the increase of forecast time length. The indicative significance of EFI for 5 d and 10 d accumulated precipitation to heavy rainfall in the cold seasons (from October to March the following year) is better than that in the warm seasons (from April to September). When EFI is greater than 0.4, the precipitation climate anomalies increase quickly with the increase both 5 d and 10 d accumulated precipitation. In addition, the indicative significance of EFI for 5 d accumulated precipitation is better than that for 10 d accumulated precipitation.