DATE2016-05-31 19:19:53
AUTHORSJosé Manuel Hidalgo-muñoz (1), Matilde García-valdecasas-ojeda (2), Sonia Raquel Gámiz-fortis (2), Yolanda Castro-díez (2), María Jesús Esteban-parra (2)
  1. Met Office Hadley Centre Exeter (United Kingdom)
  2. Department Of Applied Physics, University Of Granada Granada (Spain)
ABSTRACTThe goal of this work is to improve the understanding of the climate drivers for winter streamflow variability in the Iberian Peninsula (IP). For this purpose, the lagging singular value decomposition (SVD) technique was used for the combined fields of streamflow and the potential predictor variables sea surface temperature (SST), geopotential high (Z500), air temperature (TMP) and precipitation (RR). The SVD was performed considering the atmospheric and oceanic fields leading the winter streamflow from the previous four seasons, i.e. seasonal Atlantic and Pacific SST, Z500, TMP and RR corresponding to the previous winter, spring, summer and autumn. After an exhaustive quality control of data, the compiled dataset of streamflow comprises 325 gauge stations in Spain, 9 in Portugal, and 170 reservoir entrances in Spain, totalling 504 data series, covering the period from October 1975 to September 2008. In all SVD analyses only the three first modes were evaluated, because of they account for 70% or more of the square covariance fraction (SCF) in most cases, and the SCF for the fourth and subsequent modes usually drops below 10%, which means that the amount of information accounted for these modes respecting the two fields is not very relevant. The significance of the covariability coupled modes obtained by SVD was also evaluated and the main physical bases supporting them are discussed by using teleconnection indices. Among all coupling modes determined in SVD, only those modes in which the predictability skill (COR) is significant at 90% of confidence level (0.29) have been considered and described. The results show eight significant modes for winter streamflow with strength of the coupling ranging between 0.44, associated to the second mode of air temperature of previous winter, and 0.83 for the third mode of previous winter SST. The found relationships could indicate a potential predictability for winter streamflow in the Iberian Peninsula based on these global fields. Acknowledgements: This work has been financed by the projects P11-RNM-7941 (Junta de Andalucía-Spain) and CGL2013-48539-R (MINECO-Spain, FEDER).