Introduction to the Campfire & NP2 Dynamical Systems Approaches to Problems in Geosciences

Introduction to the Campfire & NP2 Dynamical Systems Approaches to Problems in Geosciences

Welcome to the inaugural event of our Campfire Series within the Nonlinear Processes division of the European Geosciences Union (EGU), taking place on the 14th of November at 10UTC. This first event of the Campfires series promises to be a captivating exploration of Dynamical Systems Approaches to Problems in Geosciences.

Event Schedule:
Introduction to the NP Division: Kickstarting the event, Dr. François G. Schmitt, president of the Nonlinear Processes division, will provide a brief introduction and description of the division. Our Early Career Scientists representatives, Mireia Ginesta and Angel Garcia-Gago, will officially open the Campfires series.

Dr. Christian Franzke will lead the exploration into Dynamical Systems Approaches with two distinguished speakers:

a. Dr. Nick Watkins – LSE & University of Warwick Topic: Some aspects of stochastics

The 20th century saw a revolution in science and technology, when it became possible to accurately model many aspects of real-world complexity by harnessing the power of random processes. The theory of diffusion and Brownian motion due to Einstein, Bachelier, Wiener and others is a particularly visible example where the introduction of stochastic models enhanced (rather than diminished, as is sometimes feared) physical understanding. A very major contribution was made by Langevin in 1908 when he wrote down an equation generalising Newton’s second law to Brownian motion. He exploited a key approximation, the separation of time scales into slowly varying and fast.

This strong assumption has proved remarkably powerful in practise, and demanding applications such as the modelling of stock prices and the Kalman filter so central to rocket guidance systems, have driven many advances. Progress has required blending insights and tools from the fields of stochastic processes, statistical physics and statistical inference, and now forms a very mature body of knowledge. I will talk about this history, and how the Langevin model of Brownian motion inspired Klaus Hasselmann to propose a stochastic paradigm for climate modelling. I will conclude by summarising a recent application of the Hasselmann model in the economics of climate change [Calel et al, Temperature variability implies greater economic damages from climate change, Nature Communications, 11, Article number: 5028 (2020)] and discussing some work in progress on going beyond the separation of time scales.

b. Dr. Yu Huang – Technical University of Munich, Laboratory for Climate and Ocean-Atmosphere Studies China
Topic: A Secular Shift of the Madden-Julian Oscillation and Its Relation to Western Pacific Ocean Warming

In the context of global warming, understanding changes in the Madden-Julian Oscillation
(MJO) is of great importance, because of its worldwide impact on surface weather and
climate. In this report, I would introduce a method to analyze the temporal evolution of the
phase relationship between Kelvin waves and the MJO. Accordingly we find a secular
change in the MJO and Kelvin waves: The MJO activity increased over the Maritime
Continent over the past few decades, which can be observed from the eastward
expansions of both convective activity and Kelvin waves over this region. Further analysis
suggests that the recent Western Pacific Ocean warming plays a role in the secular shift
of the MJO. Our results show that this is an imprint of the effects of global warming on the
atmospheric circulation.

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