Improved confidence in regional climate model simulations of precipitation evaluated using drought statistics from the ENSEMBLES models

An ensemble of regional climate model simulations
from the European framework project ENSEMBLES
is compared with observations of low precipitation
events across a number of European regions. We characterize
precipitation deficits in terms of two drought indices,
the Standardized Precipitation Index and the self-calibrated
Palmer Drought Severity Index. Models that robustly
describe the observations for the period 1961–2000 in
given regions are identified and an assessment of the
overall performance of the ensemble is provided. The
results show that in general, models capture the most
severe drought events and that the ensemble mean model
also performs well. Some regions that appear to be more
problematic to simulate well are also identified. These are
relatively small regions and have rather complex topographicalfeatures. The analysis suggests that assessment of future drought occurrence based on climate change experiments in general would appear to be robust. But due to the heterogeneous and often fine-scaled structure of drought occurrence, quantitative results should be used with great care, particularly in regions with complex terrain and limited information about past drought occurrence.