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Inferring interdependencies in climate networks constructed at inter-annual, intra-season and longer time scales

Deza, J.I.; Barreiro, M.; Masoller, C.

Authors

Ignacio Deza Ignacio.Deza@uwe.ac.uk
Research Fellow in Machine Learning for Building Energy Analysis

M. Barreiro

C. Masoller

Abstract

We study global climate networks constructed by means of ordinal time series analysis. Climate interdependencies among the nodes are quantified by the mutual information, computed from time series of monthly-averaged surface air temperature anomalies, and from their symbolic ordinal representation (OP). This analysis allows identifying topological changes in the network when varying the time-interval of the ordinal pattern. We consider intra-season time-intervals (e.g., the patterns are formed by anomalies in consecutive months) and inter- annual time-intervals (e.g., the patterns are formed by anomalies in consecutive years). We discuss how the network density and topology change with these time scales, and provide evidence of correlations be- tween geographically distant regions that occur at specific time scales. In particular, we find that an increase in the ordinal pattern spacing (i.e., an increase in the timescale of the ordinal analysis), results in climate networks with increased connectivity on the equatorial Pacific area. On the contrary, the number of significant links decreases when the ordinal analysis is done with a shorter timescale (by comparing consecutive months), and interpret this effect as due to more stochasticity in the time-series in the short timescale. As the equatorial Pacific is known to be dominated by El Nin ̃o-Southern Oscillation (ENSO) on scales longer than several months, our methodology allows constructing climate networks where the effect of ENSO goes from mild (monthly OP) to intense (yearly OP), independently of the length of the ordinal pattern and of the thresholding method employed.

Journal Article Type Article
Publication Date Jun 25, 2013
Journal The European Physical Journal Special Topics
Print ISSN 1951-6355
Publisher EDP Sciences
Peer Reviewed Peer Reviewed
Volume 222
Issue 2
Pages 511-523
Institution Citation Deza, J., Barreiro, M., & Masoller, C. (2013). Inferring interdependencies in climate networks constructed at inter-annual, intra-season and longer time scales. European Physical Journal - Special Topics, 222(2), 511-523. https://doi.org/10.1140/epjst/e2013-01856-5
DOI https://doi.org/10.1140/epjst/e2013-01856-5
Keywords climate networks, information theory, symbolic calculus
Publisher URL http://doi.org/10.1140/epjst/e2013-01856-5
Related Public URLs https://link.springer.com/article/10.1140%2Fepjst%2Fe2013-01856-5