Concepción Rodríguez-Puebla

Spatial and temporal patterns of annual precipitation variability over the Iberian Peninsula

In this study we have examined the spatial and temporal variability of the annual precipitation observations over the Iberian Peninsula (IP) for 47 years and 51 stations. Empirical orthogonal functions (EOFs) were obtained in order to characterise the variability. Four regional precipitation regimes have been identified and the corresponding principal components (PCs) were subjected to spectral analysis in order to obtain the structure of the temporal variations. The relationship between the precipitation and circulation patterns is also investigated. The four leading PCs of annual precipitation are associated with the following patterns: East Atlantic (EA); North Atlantic Oscillation (NAO); Southern Oscillation Index (SOI); Scandinavia (SCAND). The spectra of the precipitation PCs show statistically significant oscillations coherent with those found in the time series of the teleconnection indices. A reconstruction of the time series as a function of the PCs is provided in order to obtain a characterisation of precipitation climatology over the IP.

Comparison of Precipitation from Observed Data and General Circulation Models over the Iberian Peninsula

Abstract In this paper, the ability of model outputs from the Intergovernmental Panel on Climate Change (IPCC) to describe the natural internal variability of precipitation observations is evaluated. The analysis is focused on the Iberian Peninsula for December–February (DJF). The study was performed with observed data from National Meteorological Institutes, reanalysis data from the National Centers for Environmental Prediction–National Center for Atmospheric Research, teleconnection indices, and model simulations. First, the seasonal cycle, mean winter pattern, and tendency for nine model simulations were evaluated. Then, four models were selected to obtain interannual variability and to diagnose the links between precipitation and large-scale circulation. This intercomparison is based on the modes obtained by the empirical orthogonal function (EOF) and spectral analyses to investigate the temporal properties of the most significant spatial patterns. The models well reproduce the observed seasonal cycle...

Operational predictability of monthly average maximum temperature over the Iberian Peninsula using DEMETER simulations and downscaling

The multi-model ensemble for seasonal to interannual prediction developed in the European Union project DEMETER has been used to quantify the predictability of monthly average maximum temperature that could be achieved operationally over the Iberian Peninsula. Statistical downscaling based on canonical correlation analysis is applied to increase the spatial resolution available from the global models. The downscaling is based on empirical connections between the North Atlantic sea level pressure and monthly average maximum temperature over the Iberian Peninsula. The maximum temperature estimated from the multi-model ensemble and the single models is compared to the observations. The statistical downscaling model skill is characterized by means of the correlation, variance fraction and the Brier skill score. The results suggest the following: the downscaling model works properly when driven by observed large-scale fields in terms of the correlation and the variance fraction scores, despite some problems owing to sample degeneracy; the predictability is almost limited to February, which is one of the initialization months of the DEMETER ensemble, and it is lost when this month is not considered as starting month. This result is supported by the fact that the areally averaged reproducibility is lower during non-initialization months. In any case, the analysis of the variance test performed reveals that the monthly average maximum temperature is scarcely predictable. Finally, the results also support the advantage of using a multi-model ensemble approach instead of single models participating in DEMETER.

Relationships between Dry and Wet Periods in Spring Precipitation over the Iberian Peninsula and Atmospheric Circulation

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.

Baroclinic Activity and Interannual Variability of Winter Precipitation in the Northern Iberian Peninsula

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.