| Contents |
| We study global climate networks constructed by means of ordinal time series analysis. Climate interdependencies among the nodes are quantified by mutual information, computed from time series of 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. As the equatorial Pacific is known to be dominated by El Ni\~no-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. |
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