Calibration and combination of seasonal forecast over Southern Europe

Abstract

Verification of temperature and precipitation seasonal forecasts from four different operational systems - European Centre for Medium-Range Weather Forecasts (ECMWF) system 4, Météo-France system 3, UK Met Office system 3 and National Center for Environmental Prediction (NCEP) system version 2 - for different seasons, lead times, variables and sub-regions over Southern Europe is computed based on available hindcasts. The impact of calibration and combination of seasonal hindcasts using different setups of a Bayesian scheme has also been discussed. Although results show relatively low skill as a consequence of the low predictability at seasonal scale over mid-latitudes, there is a noticeable consistency among models. As expected over Southern Europe, scores for temperature are better than for precipitation. We also show and discuss windows of opportunity associated to certain seasons/variables/models/regions.