On the use of weather regimes to forecast meteorological drought over Europe

摘要

An early warning system for drought events can provide valuable informationfor decision makers dealing with water resources management and internationalaid. However, predicting such extreme events is still a big challenge. Inthis study, we compare two approaches for drought predictions basedon forecasted precipitation derived from the Ensemble extended forecast model?(ENS) of the ECMWF, and on forecasted monthly occurrence anomalies of weatherregimes?(MOAWRs), also derived from the ECMWF model. Results show that the MOAWRs approach outperforms the one based on forecastedprecipitation in winter in the north-eastern parts of the European continent,where more than 65% of droughts are detected 1 month in advance. The approachbased on forecasted precipitation achieves better performance inpredicting drought events in central and eastern Europe in both spring andsummer, when the local atmospheric forcing could be the key driver of theprecipitation. Sensitivity tests also reveal the challenges in predictingsmall-scale droughts and drought onsets at longer lead times. Finally, the results show that the ENS model of the ECMWF successfullyrepresents most of the observed linkages between large-scale atmosphericpatterns, depicted by the weather regimes and drought events over Europe.