Interdecadal changes in atmospheric connectivity using complex networks
Abstract
Improving our understanding of the Earth complex climate phenomena, such as El Niño-Southern Oscillation, has a huge economic and social impact for present and future generations, and can underpin advances in areas as diverse as energy, environment, agricultural and marine sciences. To contribute in this direction we have analyzed the teleconnection patterns from a complex network perspective, using both linear and nonlinear time series symbolic analysis techniques. Specifically, we construct global climate networks by studying the monthly average eddy geopotential height anomalies at 200 mb since 1900 (NCEP/NCAR reanalysis data and NOAA 20th Century Reanalysis) and calculate the fraction of the Earth that each geographical point is connected to (area weighted connectivity function). Mutual information with the ordinal patterns and the classical probability density function methodologies, and linear correlation are used to measure the interconnection degree between nodes. The threshold, to avoid randomness, is varied to establish the strength of the links. The map of area weighted connectivity shows larger connectivity in the tropics with every methodology which agrees with our current understanding of tropical dynamics. Likewise with lower thresholds there are some extratropical regions that stand out for their number of connections, such as the south and north Pacific, which reflect the teleconnection patterns in both hemispheres through the propagation of Rossby waves. Moreover the results also show some differences between linear and nonlinear methodologies, specifically in the central tropical Pacific, where the nonlinear methods using ordinal patterns shows significantly fewer connections than with the others methods. Further analysis of the dynamics of the connectivities in strategic locations shows clear interdecadal changes in the area weighted connectivity function, which suggests changes in the dynamics of the atmospheric teleconnection processes in different decades.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2013
- Bibcode:
- 2013AGUSMGC23B..05A
- Keywords:
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- 1616 GLOBAL CHANGE / Climate variability;
- 3309 ATMOSPHERIC PROCESSES / Climatology;
- 1620 GLOBAL CHANGE / Climate dynamics