CR 46:197-209 (2011)  -  DOI: https://doi.org/10.3354/cr00984

ABSTRACT: The objective of this study was to explore the ability of 3 regional climate models (RCMs), CNRM-Aladin, C4I-RCA3 and KNMI-RACMO along with their parental global climate models (GCMs), ARPEGE and ECHAM5, to represent the relationship between large-scale atmospheric circulation and climate extremes in the Mediterranean region. Subsequently, an evaluation and inter-comparison of these 3 RCM/GCM couples for the present climate was performed. For this purpose, the Regularised Canonical Correlation Analysis (RCCA) was employed and 4 extreme climate indices of temperature and precipitation were used to define extreme events over the study region. The evaluation of these relationships was carried out against gridded observational and reanalysis datasets. It was found that the observed upper air large scale patterns related to climate extremes in the Mediterranean are not very well reproduced by the RCM/GCM couples in all seasons. In addition, in many cases, the coupled models display patterns of extreme climate indices which are not consistent with the accompanied upper level circulation. Furthermore, all coupled models display substantial deficiencies in simulating precipitation extremes. In the case of summer data, the ability of all 3 models is limited, possibly because the strength of the large-scale atmospheric flow decreases, the control exerted by the lateral boundary conditions is weaker, and the nested models are mainly governed by local processes.

KEY WORDS: Large scale circulation · Extreme climate indices · ENSEMBLES · Circulation patterns · RCCA · Regional climate models · Global climate models