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le 17/07/2013. Evidences of chaos from the dynamics of snow cover. in Pyrenees, Lebanon and High-Atlas mountains. approach. Global Modelling. Phenomenological approach of the dynamics well adapted to low-dimensionnal system several underlying hypothesis.
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le 17/07/2013 Evidences of chaos from the dynamics of snow cover in Pyrenees, Lebanon and High-Atlas mountains
approach Global Modelling • Phenomenological approach of the dynamics • well adapted to low-dimensionnal system • several underlying hypothesis Few knowledge about the dynamics is required The dynamics is directly investigated from a time series It can provide a strong evidence of chaotic behaviour System should be ergodic, deterministic, autonomous and stationnary
approach Global Modelling Gouesbet & Letellier (1994) • Reformulation Polynomial approximation
approach Previous applications to ‘‘real world’’ systems Letellier et al. 2006 • - natural • - ecological • - human • agricultural • climatic • .. systems • Sunspot cycles • Canadian lynx cycles • Human respiration • Rainfed wheat • Snow cover Maquet et al. 2007 Letellier et al. 2013 Mangiarotti et al. 2011, 2013 .. this work !
Takens’theorem (1981) example: attracteur de Lorenz(1963) z(t) (1941-2010) x(t) y(t)
Takens’theorem (1981) z(t) x(t +2 τ ) (1941-2010) x(t + τ ) x(t) y(t) x(t) (differentiable & differentiable inverse) diffeomorphism
Takens’theorem (1981) z(t) x(t +2 τ ) x(t + τ ) x(t) y(t) x(t) (differentiable & differentiable inverse) diffeomorphism
approach Phase Space Portrait NDVI(t) On dérive n fois
Pyrénées (0-40000km²) Mt Liban (0-12000km²) Atlas (0-30000km²)
2000-2012 Portraits dynamiques Pyrénées Mt Liban Atlas
approach Algorithmic tools R-packages PoMoS GloMo Models selection algorithm interaction Main GloMo Interface Packages available on CRAN: http://cran.cict.fr
2000-2012 Pyrénées (…) Mt Liban (…) Atlas (…)
Pyreneous yearly analysis Pyrénées
Pyreneous 2000-2001
Pyreneous 2001-2002
Pyreneous 2002-2003
Pyreneous 2003-2004
Pyreneous 2010-2011
Mt Liban yearly analysis Mont Liban
Mt Liban 2001-2002
Mt Liban 2003-2004
Mt Liban 2005-2006
Mt Liban 2006-2007
Mt Liban 2007-2008
Mt Liban 2009-2010
Atlas yearly analysis Atlas
Atlas 2001-2002
Atlas 2002-2003
Atlas 2004-2005
Atlas 2005-2006
Atlas 2006-2007
Atlas 2009-2010