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CR 20:271-279 (2002)  -  doi:10.3354/cr020271

Simplified EOFs‹three alternatives to rotation

I. T. Jolliffe1,*, M. Uddin2, S. K. Vines3

1Department of Mathematical Sciences, University of Aberdeen, Meston Building, King¹s College, Aberdeen AB24 3UE, Scotland, United Kingdom
2Department of Statistics, University of Karachi, Karachi 75270, Pakistan
3Department of Statistics, Faculty of Mathematics and Computing, The Open University, Walton Hall, Milton Keynes MK7 6AA, United Kingdom

ABSTRACT: Principal component analysis (PCA) is widely used in atmospheric science, and the resulting empirical orthogonal functions (EOFs) are often rotated to aid interpretation. In this paper 3 methods are described which provide alternatives to the standard 2-stage procedure of PCA followed by rotation. The techniques are illustrated on a small example involving sea-surface temperatures in the Mediterranean. Each method is shown to give different simplified interpretations for the major sources of variation in the data set. All 3 techniques have advantages over standard rotation.

KEY WORDS: EOFs · Simplification · Interpretation · Rotation · LASSO · Mediterranean · SST

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