DOI: 10.1007/s00382-016-3112-9
Scopus记录号: 2-s2.0-84964329783
论文题名: Separation of the atmospheric variability into non-Gaussian multidimensional sources by projection pursuit techniques
作者: Pires C.A.L. ; Ribeiro A.F.S.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2017
卷: 48, 期: 2017-03-04 起始页码: 821
结束页码: 850
语种: 英语
英文关键词: Independent component analysis
; Low-frequency variability
; Non-Gaussianity
; Nonlinear teleconnections
; Source separation
英文摘要: We develop an expansion of space-distributed time series into statistically independent uncorrelated subspaces (statistical sources) of low-dimension and exhibiting enhanced non-Gaussian probability distributions with geometrically simple chosen shapes (projection pursuit rationale). The method relies upon a generalization of the principal component analysis that is optimal for Gaussian mixed signals and of the independent component analysis (ICA), optimized to split non-Gaussian scalar sources. The proposed method, supported by information theory concepts and methods, is the independent subspace analysis (ISA) that looks for multi-dimensional, intrinsically synergetic subspaces such as dyads (2D) and triads (3D), not separable by ICA. Basically, we optimize rotated variables maximizing certain nonlinear correlations (contrast functions) coming from the non-Gaussianity of the joint distribution. As a by-product, it provides nonlinear variable changes ‘unfolding’ the subspaces into nearly Gaussian scalars of easier post-processing. Moreover, the new variables still work as nonlinear data exploratory indices of the non-Gaussian variability of the analysed climatic and geophysical fields. The method (ISA, followed by nonlinear unfolding) is tested into three datasets. The first one comes from the Lorenz’63 three-dimensional chaotic model, showing a clear separation into a non-Gaussian dyad plus an independent scalar. The second one is a mixture of propagating waves of random correlated phases in which the emergence of triadic wave resonances imprints a statistical signature in terms of a non-Gaussian non-separable triad. Finally the method is applied to the monthly variability of a high-dimensional quasi-geostrophic (QG) atmospheric model, applied to the Northern Hemispheric winter. We find that quite enhanced non-Gaussian dyads of parabolic shape, perform much better than the unrotated variables in which concerns the separation of the four model’s centroid regimes (positive and negative phases of the Arctic Oscillation and of the North Atlantic Oscillation). Triads are also likely in the QG model but of weaker expression than dyads due to the imposed shape and dimension. The study emphasizes the existence of nonlinear dyadic and triadic nonlinear teleconnections. © 2016, Springer-Verlag Berlin Heidelberg. 资助项目: FCT, Fundação para a Ciência e a Tecnologia
; FCT, Fundação para a Ciência e a Tecnologia
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/53377
Appears in Collections: 过去全球变化的重建
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作者单位: Instituto Dom Luiz (IDL), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
Recommended Citation:
Pires C.A.L.,Ribeiro A.F.S.. Separation of the atmospheric variability into non-Gaussian multidimensional sources by projection pursuit techniques[J]. Climate Dynamics,2017-01-01,48(2017-03-04)