Aspectos metodológicos del uso del análisis de componentes principales en campos de anomalias de altura geopotencial en el sur de sudamerica

摘要

This paper presents a discussion of methodological aspects of the use of the principal component analysis (PCA) to verify its efficacy synthesis for the daily 1000 and 500 hPa anomalies of geopotential height fields of the October to May 1979-2001 NCEP reanalyses II in southern South America. This analysis was performed in order to obtain a representative data base for future synoptic classifications. The need of orthogonal rotations and their efficacy was analyzed showing that the explained variance redistribution was not improved. A random sub-sample of 100 days was used to study the influence of the persistence effect of consecutive daily fields. This effect did not significantly modify the PCA results and did not introduce other significant PCs. The set of geopotential height data may be considerably reduced using PCA as a synthesis technique. This result was corroborated using Bartlett?s sphericity test and an empirical test on the modified correlation matrix. Finally, to represent a real field and thus facilitate a physical sense, it is found that the combination of two or more PCs is necessary.