On the covariability of seasonal temperature and precipitation in Spain, 1956-2005

摘要

In this work, the covariability between the standardized anomalies of seasonal mean temperature and total rainfall in four Spanish sites during the periods 1956-1980 and 1981-2005 is analysed. Original data are standardized using the reference period 1971-2000. Using the hypothesis of bivariate normal distribution, the climate states corresponding to each period may be characterized by the confidence ellipses at the 95% confidence level. Movements of the ellipses indicate changes in the vector mean (translations), changes in the sign of the correlation coefficient (rotations) and in the variance-covariance matrix (deformations). Significance of these changes is assessed by Hotelling's, difference between correlation coefficients, and Barlett's tests, respectively. Results indicate a general translation towards higher (lower) mean temperature (precipitation) in the second period. Significant changes in the variance-covariance matrix did not show a clear pattern. Future developments of this methodology are outlined.