Networks in the climate system: Research gap is closed

02/24/2014 - There are networks within the climate system of the earth: Changes at one point can trigger changes at another, far away point – so an El Niño-event in South America can interfere with the Asian monsoon. Up to now, these correlations could only be determined statistically by comparing observation data and time series. A study now for the first time reveals the physical mechanisms behind the statistics. According to an article published by scientists of the Potsdam Institute for Climate Impact Research in the journal Scientific Reports, a new open access journal of the renowned Nature group, flows are of prime interest here.
Networks in the climate system: Research gap is closed
Networks in the climate system in the Pacific region. Graph: Molkenthin et al (2014)

“One can picture this as a bucket of water in which nothing happens unless for instance one spot gets heated up,” says Nora Molkenthin, lead author of the study. “The heat diffuses over time. It decreases at its place of origin, and it depends on flows, or currents, how strongly and fast this happens.” So the scientists have observed changes of parameters over time and space. To start with, this was done first in an exemplary simple physical system. Then they put it into a formula that can be filled with almost any data. “In fact I was a little surprised that this has not yet been done by anybody in this way before,” says Molkenthin.

The findings can for instance be applied to ocean currents. A comparison of the results of the formula with observation data confirms this new method. But since in nature a huge number of factors have an influence, the application of the results presented now can again be seen as an additional layer of complexity. In the real world, the bucket of water is very large and very much is happening in it at the same time. The application of the new approach thus is still very complex, say the scientists.

The research approach with complex networks has in the beginning often been met with doubt, says Jürgen Kurths, co-chair of the PIK research domain Transdisciplinary Concepts & Methods and co-author of the study – he is one of the pioneers in the research of complex, non-linear systems. “It is a new field to which our group indeed significantly contributed to”. This approach has meanwhile gained recognition with its research work on the Monsoon for instance. “The new study shows the link between the junctions within the networks and the systems of currents – it is thus the last still missing conceptual building block in this intellectual edifice”.


Article: Molkenthin, N., Rehfeld, K., Marwan, N., Kurths, J. (2014): Networks from Flows - From Dynamics to Topology. Scientific Reports 4, 4119 [doi: 10.1038/srep04119]



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