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A new method to compute the principal components from self-organizing maps: An application to monsoon intraseasonal oscillations

Sahai, AK and Chattopadhyay, R and Joseph, S and Abhilash, S and Borah, N and Goswami, BN (2014) A new method to compute the principal components from self-organizing maps: An application to monsoon intraseasonal oscillations. International Journal of Climatology, 34 (9). pp. 2925-2939.

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The study develops a self-organizing map (SOM)-based local principal component analysis (PCA) to obtain the linearly decorrelated principal components (PCs) of monsoon intraseasonal oscillations (MISOs). Although the SOM-derived feature maps are not orthogonal like empirical orthogonal function (EOFs), we show that in the case of MISOs simple mathematical substitution can make the SOM-derived PCs linearly decorrelated to each other. Thus, the SOM-based local PCA is seen also to be statistically equivalent to extended EOF analysis when applied to MISO analysis. The life cycle and phase evolution of MISO through SOM-based PCA is robust and conforms to the results based on extended EOFs besides having potential to give new information. The remarkable similarity of results with the symmetric SOM configurations shows the effectiveness of these methods for use as empirical reduction models for climate patterns. The asymmetric SOM lattice configurations derive similar phase evolution as compared to a symmetric lattice, but asymmetric temporal evolutions in the PC-defined phase space. The results once again endorse the mathematical basis of PCA through SOM for geophysical applications.

Item Type: Article
Additional Information: Copyright of this article belongs to Royal Meteorological Society.
Uncontrolled Keywords: Atmospheric thermodynamics; Microcomputers; Nanofluidics; Phase space methods; Principal component analysis; Self organizing maps; Tropical engineering, Empirical Orthogonal Function; Eof analysis; Geophysical applications; Intraseasonal oscillations; Lattice configuration; Local principal component analysis; Mathematical basis; Principal Components, Conformal mapping, climate modeling; monsoon; numerical model; principal component analysis; regional climate; seasonal variation; temporal evolution
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 28 Nov 2014 07:03
Last Modified: 28 Nov 2014 07:03

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