Time-frequency variability of spring precipitation associated with teleconnection indices over the Iberian peninsula.

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.