Henk Dijkstra (Utrecht University)
Ergodic Theory of Climate Variability
Climate research deals with changes in the statistics rather than in the exact state of the Earth system. Ergodic theory is aimed to relating the dynamics of a system to its statistical properties and thus particularly suitable for developing a theory of climate variability. In this presentation, concepts of ergodic theory will be used to study climate variability and response to forcing. In particular, it is shown that crucial information on the stability of the climate system can be extracted by approximations of the associated transfer operators and their ergodicity spectrum. The methodology is applied to transitions in spatially-extended models of the El Nino/Southern Oscillation phenomenon, midlatitude atmospheric blocking events and transitions between a snow-free and snow-covered Earth.