Intérêts de la méthode des analogues pour la génération de scénarios de précipitations à l'échelle de la France métropolitaine : Cohérence spatiale et adaptabilité du lien d'échelle

Abstract : Hydrological scenarios required for the impact studies need to have unbiased meteorological scenarios adapted to the space and time scales of the considered hydro-systems. Hence, meteorological scenarios obtained from global climate models and/or numerical weather prediction models are not really appropriated. Outputs of these models have to be post-processed, which is often carried out thanks to Statistical Downscaling Methods (SDMs). Since the 2000's, SDMs are widely used for the generation of scenarios at a single site. The generation of relevant precipitation fields over large regions or hydro-systems is conversely not straightforward, in particular when the spatial consistency has to be satisfied. One strategy to fulfill this constraint is to use a SDM based on the search of past analog situations. In this PhD, we evaluate the ability of an Analog Model (AM) – where the analogy is applied to the geopotential heights 1000 and 500 hPa – for the generation of spatially coherent precipitation scenarios over the French metropolitan territory. In a first part, the spatial transferability of an AM is evaluated: the model appears to be usable for the generation of spatial coherent scenarios over territories covering several tens of thousands squared kilometers if no climatological barrier is met in between. In a second part, we evaluate the sensitivity of the prediction performance to the spatial aggregation of the predictand. The performance increases with the aggregation level as long as the large scale variables are good predictors of precipitation for the region under consideration. This performance increase has to be related to the decrease of the predictand variability. We finally explore the possibility of improving the local performance of the AM using additional local scale predictors. For each prediction day, the prediction is obtained from a parametric regression model, for which predictors and parameters are estimated from the analog dates. The resulting combined model noticeably allows increasing the prediction performance by adapting the downscaling link for each prediction day. The selected predictors for a given prediction depend on the large scale situation and on the considered region.
Document type :
Theses
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-01230438
Contributor : Abes Star <>
Submitted on : Wednesday, November 18, 2015 - 12:03:27 PM
Last modification on : Sunday, July 14, 2019 - 2:11:19 AM
Long-term archiving on : Saturday, April 29, 2017 - 12:37:41 AM

File

CHARDON_2014_archivage.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-01230438, version 1

Collections

Citation

Jérémy Chardon. Intérêts de la méthode des analogues pour la génération de scénarios de précipitations à l'échelle de la France métropolitaine : Cohérence spatiale et adaptabilité du lien d'échelle. Sciences de la Terre. Université de Grenoble, 2014. Français. ⟨NNT : 2014GRENU044⟩. ⟨tel-01230438⟩

Share

Metrics

Record views

281

Files downloads

262