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Internal variability in a regional climate model over West Africa

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Vanvyve, Emilie [UCL] Hall, Nicholas Messager, Christophe Leroux, Stephanie van Ypersele de Strihou, Jean-Pascal [UCL]

Sensitivity studies with regional climate models are often performed on the basis of a few simulations for which the difference is analysed and the statistical significance is often taken for granted. In this study we present some simple measures of the confidence limits for these types of experiments by analysing the internal variability of a regional climate model run over West Africa. Two I-year long simulations, differing only in their initial conditions, are compared. The difference between the two runs gives a measure of the internal variability of the model and an indication of which timescales are reliable for analysis. The results are analysed for a range of timescales and spatial scales, and quantitative measures of the confidence limits for regional model simulations are diagnosed for a selection of study areas for rainfall, low level temperature and wind. As the averaging period or spatial scale is increased, the signal due to internal variability gets smaller and confidence in the simulations increases. This occurs more rapidly for variations in precipitation, which appear essentially random, than for dynamical variables, which show some organisation on larger scales.

Document type Article de périodique (Journal article) – Article de recherche
Access type Accès restreint
Publication date 2008
Language Anglais
Journal information "Climate Dynamics : observational, theoretical and computational research on the climate system" - Vol. 30, no. 2-3, p. 191-202 (2008)
Peer reviewed yes
Publisher Springer (New York)
issn 0930-7575
e-issn 1432-0894
Publication status Publié
Affiliation UCL
Links
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Bibliographic reference Vanvyve, Emilie ; Hall, Nicholas ; Messager, Christophe ; Leroux, Stephanie ; van Ypersele de Strihou, Jean-Pascal. Internal variability in a regional climate model over West Africa. In: Climate Dynamics : observational, theoretical and computational research on the climate system, Vol. 30, no. 2-3, p. 191-202 (2008)
Permanent URL http://hdl.handle.net/2078.1/36890