This project addresses the study of the intraseasonal variability associated to
atmospheric blocking events in the Atlantic basin. The AGCM ARPEGE is used. Control
and time-slice 2xCO2 simulations with different horizontal resolutions are
analysed. The ECMWF reanalysis data are used as a reference for validating
the control run. Then, the response of the climatic variability to the 2xCO2
forcing is extracted by comparing both the control run and the perturbed run features.
With these experiments, the changes in some space-time patterns of variability
could be detected. Furthermore, the mechanisms responsible of these changes
may be hypothesized, allowing a better understanding of the climatic change in this
part of the world. Finally, a downscalling on the Iberian peninsula precipitation
based on changes in persistent modes is going to be made, which will be compared with the
observed and predicted trends of the precipitation. So, the final objective is to
determine the sensibility of the pluviometric regime associated to persistent large-
scale structures over the North Atlantic to the 2xCO2 forcing.