DOI: 10.1007/s00382-015-2844-2
Scopus记录号: 2-s2.0-84944562769
论文题名: Different atmospheric moisture divergence responses to extreme and moderate El Niños
作者: Xu G. ; Osborn T.J. ; Matthews A.J. ; Joshi M.M.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2016
卷: 47, 期: 2017-01-02 起始页码: 393
结束页码: 410
语种: 英语
英文关键词: El Niño Southern Oscillation
; Hydrological cycle
; Self-organizing map
英文摘要: On seasonal and inter-annual time scales, vertically integrated moisture divergence provides a useful measure of the tropical atmospheric hydrological cycle. It reflects the combined dynamical and thermodynamical effects, and is not subject to the limitations that afflict observations of evaporation minus precipitation. An empirical orthogonal function (EOF) analysis of the tropical Pacific moisture divergence fields calculated from the ERA-Interim reanalysis reveals the dominant effects of the El Niño-Southern Oscillation (ENSO) on inter-annual time scales. Two EOFs are necessary to capture the ENSO signature, and regression relationships between their Principal Components and indices of equatorial Pacific sea surface temperature (SST) demonstrate that the transition from strong La Niña through to extreme El Niño events is not a linear one. The largest deviation from linearity is for the strongest El Niños, and we interpret that this arises at least partly because the EOF analysis cannot easily separate different patterns of responses that are not orthogonal to each other. To overcome the orthogonality constraints, a self-organizing map (SOM) analysis of the same moisture divergence fields was performed. The SOM analysis captures the range of responses to ENSO, including the distinction between the moderate and strong El Niños identified by the EOF analysis. The work demonstrates the potential for the application of SOM to large scale climatic analysis, by virtue of its easier interpretation, relaxation of orthogonality constraints and its versatility for serving as an alternative classification method. Both the EOF and SOM analyses suggest a classification of “moderate” and “extreme” El Niños by their differences in the magnitudes of the hydrological cycle responses, spatial patterns and evolutionary paths. Classification from the moisture divergence point of view shows consistency with results based on other physical variables such as SST. © 2015, The Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/53633
Appears in Collections: 过去全球变化的重建
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作者单位: Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom; School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom
Recommended Citation:
Xu G.,Osborn T.J.,Matthews A.J.,et al. Different atmospheric moisture divergence responses to extreme and moderate El Niños[J]. Climate Dynamics,2016-01-01,47(2017-01-02)