Springtime coupled modes of regional wind in the Iberian Peninsula and large‐scale variability patterns

Abstract

Abstract This paper investigates the relationships between the Global Circulation Model (GCM)‐simulated 1000 hPa geopotential heights (taken from the ERA40 reanalysis) over the North Atlantic and the regional wind over the Iberian Peninsula for springtime (March to May). The main goal is to recognize the atmospheric circulation patterns linked to wind anomaly configurations. The method used for the downscaling is singular value decomposition (SVD). After applying a Monte Carlo approach to assess the statistical significance of the obtained modes, the SVD analysis highlighted that the covariability is dominated by three main large‐scale features of the atmospheric circulation over the North Atlantic: (1) a first mode that relates local wind to the Scandinavian pattern (SCAN), by which a blocking pattern is linked to below‐normal winds, (2) a second covariability mode associated with the North Atlantic Oscillation (NAO) pattern that correlates with wind over Iberia. An enhanced spring NAO pattern is related to positive (negative) wind correlations over the northern (southern) Iberia and (3) a third SVD mode that relates wind to the East Atlantic (EA) pattern promoting a dissimilar behaviour in the Iberian wind with positive (negative) wind correlations in the western (eastern) part of Iberia. To conclude, composite maps were built up to give an average circulation associated with coherent wind variability over Iberia. Copyright © 2010 Royal Meteorological Society