Abstract

Empirical orthogonal functions (EOFs) are widely used in climate research to identify dominant patterns of variability and to reduce the dimensionality of climate data. EOFs, however, can be difficult to interpret. Rotated empirical orthogonal functions (REOFs) have been proposed as more physical entities with simpler patterns than EOFs. This study presents a new approach for finding climate patterns with simple structures that overcomes the problems encountered with rotation. The method achieves simplicity of the patterns by using the main properties of EOFs and REOFs simultaneously. Orthogonal patterns that maximise variance subject to a constraint that induces a form of simplicity are found. The simplified empirical orthogonal function (SEOF) patterns, being more 'local', are constrained to have zero loadings outside the main centre of action. The method is applied to winter Northern Hemisphere (NH) monthly mean sea level pressure (SLP) reanalyses over the period 1948–2000. The 'simplified' leading patterns of variability are identified and compared to the leading patterns obtained from EOFs and REOFs. Copyright © 2005 Royal Meteorological Society.

Keywords

Empirical orthogonal functionsConstraint (computer-aided design)ClimatologyCurse of dimensionalitySimplicityNorthern HemisphereSimple (philosophy)Function (biology)Computer scienceMathematicsVariance (accounting)StatisticsGeologyGeometry

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Publication Info

Year
2005
Type
article
Volume
26
Issue
1
Pages
7-28
Citations
85
Access
Closed

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Cite This

Abdel Hannachi, Ian T. Jolliffe, D. B. Stephenson et al. (2005). In search of simple structures in climate: simplifying EOFs. International Journal of Climatology , 26 (1) , 7-28. https://doi.org/10.1002/joc.1243

Identifiers

DOI
10.1002/joc.1243