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Thesis/Dissertation: BibTeX citation key:  Ali2004a
Ali, A. (2004) Modélisation de l’invariance d’échelle des champs de pluie sahéliens. Application aux algorithmes d’estimation et aux études de variabilité climatique. Thesis. Institut National Polytechnique de Grenoble.
Added by: Fanny Lefebvre 2010-09-16 16:14:15    Last Edited by: Fanny Lefebvre 2010-12-01 13:43:33
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Categories: General
Keywords: Modelling
Creators: Ali
Publisher: Institut National Polytechnique de Grenoble

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Abstract
This thesis concerns an integrated modeling approach to Sahelian rainfields by considering rain events as the basic elements of rainfall variability. The first part relates to the development of a geostatistical model, allowing the characterization of the spatial variability of rainfields over a broad range
of time scales. For this, the internal and external variability of rain events have been identified as climatological invariants and have been characterized by their respective variograms e and I. From these two elements which constitute the core of the model, an analytical relation makes it possible to deduce the variogram Z of the multi-event rainfields as a function of the number of events. The second part combines the theoretical expression of the kriging variance deduced from the model developed in the first part and the result of an intercomparison of optimal interpolation methods to extend an estimation error function initially established on the EPSAT-Niger experiment region to all the Sahelian region. This error function has been used to evaluate the rainfall networks in the Sahelian countries and to intercompare various satellite rainfall products for the region. The third part presents the basis of a conceptual simulation model for Sahelian rainfields at regional scale, taking into account the initiation and the dynamics of convective rain systems. The model is based on the formalism of the point processes and uses a satellite data base established from an automatic tracking of meso-scale convective systems. Upon completion, this model will be used to produce rainfall scenarios at regional scales in order to test the hydrological or agronomic impact of climatic variability.
Added by: Fanny Lefebvre    Last Edited by: Fanny Lefebvre