TRR 181 Seminar "Universality of extreme events in atmospheric models"

The TRR 181 seminar is held by  Vera Melinda Galfi (Universität Hamburg, new Postdoc in M1) on November 8, 11 am at Universität Hamburg, Bundesstr. 53, Room 22/23.

"Universality of extreme events in atmospheric models"

 Abstract

We study extremes of atmospheric observables (total energy and near-surface temperature) in two numerical models, a quasi-geostrophic (QG) two-layer atmospheric model and a simplified general circulation model of the atmosphere (PUMA - Portable University Model of the Atmosphere), by applying two rigorous mathematical frameworks: Extreme Value Theory and Large Deviations Theory. In both cases, we connect properties of extreme or rare events to general properties of the system (or of the system state) producing these events, by taking perspectives based on dynamical systems theory and statistical mechanics. In case of energy extremes in the QG model, we search for the universality of extreme events, and find a connection between statistical properties of extremes of different energy observables and general dynamical properties of the system. This is in accordance with theoretical results developed for chaotic dynamical systems. In case of extremes of temperature averages in the PUMA model, we aim at analysing persistent temperature extreme events (like heat waves or cold spells) based on Large Deviations Theory. Here, we also find universal characteristics in form of a connection between temporal and spatial (and spatiotemporal) averages, while the spatial averaging is performed along the selected latitude.