Internal variability in a regional climate model over West Africa

Vanvyve, Emilie;Hall, Nicholas;Messager, Christophe;Leroux, Stephanie;van Ypersele de Strihou, Jean-Pascal
(2008) Climate Dynamics — Vol. 30, n° 2-3, p. 191-202 (2008)

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Authors
  • Vanvyve, EmilieUCLouvain
    Author
  • Hall, Nicholas
    Author
  • Messager, Christophe
    Author
  • Leroux, Stephanie
    Author
  • van Ypersele de Strihou, Jean-Pascalorcid-logoUCLouvain
    Author
Abstract
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.
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Citations

Vanvyve, E., Hall, N., Messager, C., Leroux, S., & van Ypersele de Strihou, J.-P. (2008). Internal variability in a regional climate model over West Africa. Climate Dynamics, 30(2-3), 191-202. https://doi.org/10.1007/s00382-007-0281-6 (Original work published 2008)