ELFT HÍRADÓ

[StatFizSzeminar <statfiz AT glu.elte.hu>]

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           ELTE TTK Fizikai Intézet
       STATISZTIKUS FIZIKAI SZEMINÁRIUM


             2019. október 2.

                   szerda 

                   11.00

                Ulrike Feudel

        Carl von Ossietzky University


     "Tipping phenomena and resilience: 
        two sides of the same coin?"
 


Many systems in nature are characterized by 
the coexistence of different stable states
for a given set of environmental parameters
and external forcing. Examples for such 
behavior can be found in different fields of
science ranging from mechanical or chemical
systems to ecosystem and climate dynamics. 
As a consequence of the coexistence of a 
multitude of stable states, the final state 
of the system depends strongly on the initial
condition. Perturbations, applied to those 
natural systems can lead to a critical 
transition from one stable state to another.
Such critical transitions are called tipping
phenomena in climate science, regime shifts 
in ecology or phase transitions in physics.
Such critical transitions can happen in 
various ways: (1) due to bifurcations, i.e. 
changes in the dynamics when external forcing
or parameters are varied extremely slow (2) 
due to fluctuations which are always inevitable
in natural systems, (3) due to rate-induced
transitions, i.e. when external forcing changes
on characteristic time scale comparable to the
time scale of the considered dynamical system 
and (4) due to shocks or extreme events. We 
discuss these critical transitions and their
characteristics and illustrate them with 
examples from natural systems. Moreover, we 
discuss the concept of resilience, which has 
been originally introduced by C.S. Holling in 
ecology, and formulate it in terms of dynamical
systems theory. This formulation offers 
mathematical and numerical tools to use it as
a measure of the persistence of a function of
a dynamical system. 



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        honlap: http://glu.elte.hu/~statfiz

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