Talks

Critical transitions, relatively sudden transitions between qualitatively different dynamics, are due to various distinct mechanisms. So far, bifurcation induced, noise- induced, shock-induced or rate-induced transitions have been studied extensively. In complex systems like the climate system or ecosystems, particularly in coupled versions of them, the dynamics of different components or different subsystems is characterized by different timescales. One simple example are ecosystems exhibiting allometric slowing down, that means that the duration of lifecycles increases with the trophic level. Coupling different compartments of the climate system involves also different timescales as the intrinsic timescales of flow patterns in the atmosphere are much faster than in the ocean. To study the dynamics of such systems requires the use of the methodology of slow-fast systems to account properly for such timescale separation. We will discuss the concept of critical manifolds in slow-fast sy...

Complex networks have revolutionised the way non-linear dynamical (deterministic and stochastic) systems are represented and analysed. This paradigm shift owes itself to the ability to encode non-linear relationships in a hierarchical manner from the skeletal structure to deeper and subtle spatio-temporal dependencies. This talk aims to provide an overview of a class of complex networks known as causal networks that draw ideas from various fields including econometrics, social sciences, neuroscience, sciences, ecology and engineering. Of specific interest and relevance are the causal climate networks. The first half of the talk shall be devoted the overview and mathematical formalism of different types of (climate) causal networks with focus on Granger causal and convergent cross-mapping (CCM) class of networks, both of which are constructed from time-series data. The second part of this talk is devoted to a presentation of applications to reconstructing climate networks from data and ...

As part of PI’s ongoing initiative aimed at enhancing the skills of our graduate students and post docs, we're introducing a training program designed to equip them with practical insights for delivering compelling non-technical presentations. The sessions will be facilitated by PI's training and outreach personnel.

The operator algebraic approach to quantum field theory is called algebraic quantum field theory. In this setting, we consider a family of operator algebras generated by observables in spacetime regions. This has been particularly successful in 2-dimensional conformal field theory. We present roles of tensor categories, modular invariance, classification theory, induction machinery and connections to vertex operator algebras.

A brief tour of Chaos in 1-dimensional maps followed by a quick primer on Machine Learning. This will help researchers in Climate Science as there is an increasing use of AI/ML methods in this domain.

Climate networks defined on a regular grid of geographic locations (nodes) covering the Earth's surface, built from the analysis of statistical interdependencies of climate time series, can provide useful information on large-scale patterns of climate variability. In this talk, I will discuss climate networks constructed from surface air temperature time series, using different methods such as Hilbert analysis, mutual information and Granger causality.

The research aimed at wind-wave interaction study in a big range of wind speeds, from light and moderate at a regional scale up to high wind speeds at hurricane wind conditions is performed. The regional model based on the WAVEWATCH III spectral wave model is adapted to the conditions of an inland water body using the WRF atmospheric model. Adaptation and verification of the models was carried out on the basis of the results of a series of field experiments to study the wind-wave regime of the Gorky reservoir performed in 2012–2019 using an autonomous buoy station based on the Froude oceanographic buoy. Within the framework of the WAVEWATCH III model, an analysis of the influence on the simulation result and subsequent adjustment of the parameters of the WAM 3 wind input parameterization was made, as well as the scheme for the approximate calculation of the Boltzmann integral Discrete Interaction Approximation (DIA) is adapted. Within the framework of the WRF model, calculations were c...