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

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

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 between 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 Niño-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. © 2013 EDP Sciences and Springer.

• Journal Article Type: Article
• Acceptance Date: Apr 25, 2013
• Online Publication Date: Jun 25, 2013
• Publication Date: Jun 1, 2013
• Deposit Date: Mar 19, 2019
• Journal: European Physical Journal: Special Topics
• Print ISSN: 1951-6355
• Electronic ISSN: 1951-6401
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 222
• Issue: 2
• Pages: 511-523
• DOI: https://doi.org/10.1140/epjst/e2013-01856-5
• Keywords: climate networks, information theory, symbolic calculus
• Public URL: https://uwe-repository.worktribe.com/output/930784
• 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
• Contract Date: Mar 19, 2019