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SUMMARY:Stochastic methods for understanding palaeoclimates - Crucifix\, M
  (Universit Catholique de Louvain)
DTSTART:20100824T090000Z
DTEND:20100824T100000Z
UID:TALK25881@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:We review the fundamental basis of palaeoclimate theory : astr
 onomical control on insolation\, climate models as (stochastic) dynamical 
 systems and statistical frameworks for model selection and model calibrati
 on\, accounting for the specificities of the palaeoclimate problem : spars
 e data\, dating uncertainties and phenomenological character. \n\nIn the s
 pirit of the workshop\, we emphasise the stochastic aspects of the theory.
  Stochastic methods intervene in model design\, in order to parameterise c
 limatic events at shorter time scales than the dynamics deterministically 
 represented in the model. As stochastic parameterisations are introduced\,
  the notions of synchronisation and climatic attractor have to be revisite
 d\, but modern mathematics provide the tools to this end (pullback and ran
 dom attractors). In a specific example\, we show how the synchronisation p
 atterns on astronomical forcing evolve as the complexity of the astronomic
 al forcing is gradually taken into account\, and then when stochastic para
 meterisations are introduced. \n\nStochastic methods naturally occur in st
 atistical problems of model calibration and selection\, via Monte-Carlo Sa
 mpling methods. We give an overview of what has been attempted so far\, in
 cluding particle filter for state and parameter estimation methods\, altho
 ugh we still are in uncharted territory. \n\nFinally\, we conclude on more
  philosophical attempts at understanding the meaning of stochastic paramet
 erisations ('sub-grid parameterisations' or 'model error').
LOCATION:Seminar Room 1\, Newton Institute
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