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It is well known that circulation models do not properly simulate climatic regional processes. We are therefore, learning about precipitation variations associated with circulation in order to select potential predictors that can be used in a downscaling strategy. The results obtained for spring precipitation will be discussed. A principal component analysis was performed to obtain the spatial and temporal modes of spring precipitation. Dry and wet periods were identified on the principal component time series, and the anomalous periods were compared with composite circulation maps. On the other hand, linear models between precipitation and North Hemisphere circulation indices were proposed. The Arctic Oscillation, East Atlantic/West Russian and Southern Oscillation indices were the most influential. The results suggested that the models are a good approximation to provide information about drought and rainy conditions. The study was carried out using data from different sources: observations and reanalysis projects.

DJF precipitation at several observatories on the Cantabrian Coast is analysed. The interannual variability can be explained by means of two EOFs. The link of both PCs to baroclinic instability is described by means of filtered geopotential, vertically integrated water vapour transport, one-point correlation maps and the maximum Eady growth. Using composites based on PC1 and PC2, it is shown that the overall precipitation (PC1) shows clear differences in all these magnitudes for wet and dry winters. Coastal-continental rainfall differences (PC2) are linked to large-scale moisture transports.

The economic consequences of periods of rain and drought are one of the primary motivations for performing this study which is focused on obtaining stable periodic modes of precipitation and identifying the underlying physical processes involved. Singular Spectral Analysis (SSA) combined with the Maximum Entropy Method (MEM) were applied to some of the longest available precipitation time series located in different climatic regions over the Iberian Peninsula. The spectral analysis of samples, by moving the series starting time, was performed. Once the stable peaks were identified, a cross-spectral analysis between the precipitation time series and the North Hemisphere teleconnection indices was computed. The links in the spectral domain can be of great interest to determine dependence in the short or long term and therefore, to improve statistical prediction models. The North Hemisphere Annular mode and the Southern Oscillation Index were found to covary with spring precipitation observations at the interannual time scale.