ELFT HÍRADÓ

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

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                    ELTE TTK Fizikai Intézet
                STATISZTIKUS FIZIKAI SZEMINÁRIUM


            Éghajlatdinamikai problémák előadássorozat
                     2013. szeptember 23-26.


Valerio Lucarini

Klimacampus, Institute of Meteorology, University of Hamburg, Germany 
Department of Mathematics and Statistics, University of Reading, UK

Mini course on Statistical Mechanics and Thermodynamics for Geophysical Fluid 
Dynamics

1. Sept. 23, 12:15-13:45, É 1.125 
Macroscopic Thermodynamics: Efficiency, Irreversibility, Tipping Points

The climate is a perfect example of a non-equilibrium system which keeps a 
steady state by suitably regulating the fluxes of entropy and energy with the 
surrounding environment. The differential radiation fuels the global 
circulation of the atmosphere and of the ocean, which in turn contributes to 
reducing the temperature gradients across the globe and in generating entropy 
through a variety of processes. In this seminar we will present a 
comprehensive theory of the thermodynamics of our planet able to treat 
comprehensively the Lorenz energy cycle as well as the generation of entropy 
through irreversible processes and we will argue that such theory allows for 
introducing robust, fundamental observables of the climate system and can be 
used for studying more general planetary atmospheres. We will show our these 
thermodynamical tools can be used for studying tipping points and addressing 
issues like the habitability of planets.

References
 Lucarini, V., 2009: Thermodynamic Efficiency and Entropy Production in the 
Climate System. Phys Rev. E, 80, 021118
 Lucarini, V., and F. Ragone, 2011: Energetics of Climate Models: Net Energy 
Balance and Meridional Enthalpy Transport. Rev. Geophys., 49, RG1001, 
doi:10.1029/2009RG00032
 Boschi, R., V. Lucarini, and S. Pascale, 2012: Bistability of the climate 
around the habitable zone: a thermodynamic investigation. Icarus, 
doi:10.1016/j.icarus.2013.03.017
 Lucarini, V., S. Pascale, R. Boschi, E. Kirk, and N. Iro, 2013: Habitability 
and multistablility in earth-like plantets. Astron. Nachr. 334, No. 6, 576-588


2. Sept. 24, 12:15-13:45, É 3.67 
Response, Noise, and Parametrizations

Recent advances of non-equilibrium statistical mechanics provide powerful 
tools for studying basic properties of turbulent geophysical fluids. In 
particular, the response theory developed by Ruelle allows for framing in a 
unified context problems which have been traditionally been dealt with along 
rather separate paths. First, we will discuss the applicability of the 
fluctuation-dissipation theorem in a GFD context and show how response theory 
allows for computing how the statistical properties of a system are altered 
as its parameters are changed, at finite and infinite time horizon. Then, we 
will show how it is possible to derive very general expressions for the 
impact of adding noise (of general form) on an otherwise chaotic 
deterministic system. Finally, we will provide a new framework for the 
construction of parametrizations of unresolved processes in many 
non-equilibrium systems, and most notably in geophysical fluid dynamics. In 
this last effort, we draw a line between
  the Ruelle response theory and the Mori-Zwanzig theory. These results 
generalize various recently proposed methods for constructing a surrogate 
dynamics for the relevant variables, and allows for deriving explicitly 
expressions for stochastic parametrizations.

References
 Lucarini, V., S. Sarno, 2011: A Statistical Mechanical Approach for the 
Computation of the Climatic Response to General Forcings. Nonlin. Processes 
Geophys., 18, 7-28
 Lucarini, V., 2012: Stochastic perturbations to dynamical systems: a 
response theory approach. J Stat Phys, 146, 774-786
 Wouters J. and Lucarini, V., 2012: Disentangling multi-level systems: 
averaging, correlations and memory, J. Stat. Mech. P03003 
doi:10.1088/1742-5468/2012/03/P03003
 Wouters, J., V. Lucarini, 2013: Multi-level dynamical systems: Connecting 
the Ruelle response theory and the Mori-Zwanzig approach. J Stat Phys, DOI: 
10.1007/s10955-013-0726-8


3. Sept. 26, 10:15-11:45, É 7.14
Extreme Events

Extreme Value theory provides a very general mathematical setting for 
studying rare and large fluctuations in time series. While originally the 
theory has been developed in the context of stochastic processes and iid 
variables, recently it has been shown that the extremes of observables of 
chaotic dynamical systems obey the Generalized Extreme Value (GEV) laws 
introduced by Gnedenko. We first consider the case of observables describing 
the recurrence properties of the dynamical system, and show that, given the 
functional form of the observable, we can predict whether its extremes are 
distributed according to Weibull, Gumbel or Frechet statistics. The 
theoretical results are supported by extensive numerical investigations. We 
then treat the case of the so-called physical observables. We prove that 
their extremes are distributed according to the Weibull law and derive 
explicit expressions for the scaling parameter and the shape parameter \xi. 
In particular, we show that \xi<0 h
 as a universal expression which does not depend on the chosen observables. 
The shape parameter is negative and is close to zero when high-dimensional 
systems are considered.

References
 Felici, M., R. Vitolo, V. Lucarini, and A. Speranza, 2007: Extreme Values 
Statistics of the Energy in a Model of Intermediate Complexity Model of the 
Mid-Latitudes Atmospheric jet. Part II: Trend detection and assessment. 
Journal of Atmospheric Sciences, 64, 2159-2175
 Faranda, D., V. Lucarini, G. Turchetti, and S. Vaienti, 2011: Numerical 
convergence of the Block-Maxima approach to the generalized extreme value 
distribution. J. Stat. Phys., DOI 10.1007/s10955-011-0234-7
 Lucarini, V., D. Faranda, and J. Wouters, 2012: Universal behavior of 
extreme value statistics for selected observables of dynamical systems. J 
Stat Phys, 147, 63-73
 Lucarini, V., T. Kuna, D. Faranda, and J. Wouters, 2012: Towards a General 
Theory of Extremes for Observables of Chaotic Dynamical Systems, 
arXiv:1301.0733 [cond-mat.stat-mech]



MTA-ELTE Összehasonlító Társadalmi Dinamika (Peripato) kutatócsoporttal közös 
szervezésben:

Giovanna Gioli

Research Group Climate Change and Security (CLISEC) Institute of Geography, 
KlimaCampus, University of Hamburg

4. Sept. 26, 16:15-17:45, É 0.79
Migration as an adaptation strategy to climatic and environmental change in 
mountain context: a case study from the Upper Indus Basin

Migration in the context of environmental and climatic change is increasingly 
understood as a possible positive adaptation strategy rather than as a last 
resort option (Warner et al 2012; Banerjee et al 2012). 
Especially in resource-dependent and poverty-stricken communities, migration 
can be an important livelihood diversification strategy for reducing 
vulnerability to different sources of (environmental) stress. Many studies 
(e. g. Adger et al. 2002; Tacoli 2009; Banerjee et al 2013) show that labour 
migration may increase the adaptive capacity via remittances, with 
significant consequences for the household's living conditions, social 
security, education and health care. Often, remittance provides a safety net 
for the recipient household in times of environmental hazard (Savage and 
Harvey 2007; World Bank 2009, Tacoli 2009; Gioli et al 2013; World Bank 2009; 
Tacoli 2009 ). 
There is a knowledge gap regarding migration in mountain regions, and the 
upper Indus basin (UIB) is a white spot in terms of available data and 
information. The UIB lies within the Hindu-Kush, Karakoram and Himalayan 
mountains where climate change is already impacting the glacial regime, with 
important consequences on the environment and on local livelihoods. The 
communities of the UIB are highly dependent on ecological goods and services 
and are adapting in various ways to climatic and environmental stressors. 
Though not a new phenomenon, labour migration has emerged as a key livelihood 
strategy and as a core response to environmental pressure to be adopted both 
as an ex ante and ex post adaptive strategy.
In this contribution, we will present some key results of a study recently 
conducted in the Hindu-Kush/Karakoram region of Pakistan and we will try to 
assess under which circumstances migration can be a positive adaptation 
strategy to environmental pressure. We will also propose and discuss a 
methodological framework of analysis.



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