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| Titel |
Changing precipitation in western Europe, climate change or natural variability? |
| VerfasserIn |
Emma Aalbers, Geert Lenderink, Erik van Meijgaard, Bart van den Hurk |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250151462
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| Publikation (Nr.) |
 EGU/EGU2017-16050.pdf |
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| Zusammenfassung |
| Multi-model RCM-GCM ensembles provide high resolution climate projections, valuable for
among others climate impact assessment studies. While the application of multiple
models (both GCMs and RCMs) provides a certain robustness with respect to model
uncertainty, the interpretation of differences between ensemble members – the combined
result of model uncertainty and natural variability of the climate system – is not
straightforward.
Natural variability is intrinsic to the climate system, and a potentially large source of
uncertainty in climate change projections, especially for projections on the local to regional
scale. To quantify the natural variability and get a robust estimate of the forced climate
change response (given a certain model and forcing scenario), large ensembles of climate
model simulations of the same model provide essential information. While for global climate
models (GCMs) a number of such large single model ensembles exists and have been
analyzed, for regional climate models (RCMs) the number and size of single model
ensembles is limited, and the predictability of the forced climate response at the local to
regional scale is still rather uncertain.
We present a regional downscaling of a 16-member single model ensemble over western
Europe and the Alps at a resolution of 0.11 degrees (∼12km), similar to the highest
resolution EURO-CORDEX simulations. This 16-member ensemble was generated by the
GCM EC-EARTH, which was downscaled with the RCM RACMO for the period
1951-2100.
This single model ensemble has been investigated in terms of the ensemble mean response
(our estimate of the forced climate response), as well as the difference between the ensemble
members, which measures natural variability. We focus on the response in seasonal mean
and extreme precipitation (seasonal maxima and extremes with a return period
up to 20 years) for the near to far future. For most precipitation indices we can
reliably determine the climate change signal, given the applied model chain and
forcing scenario. However, the analysis also shows how limited the information in
single ensemble members is on the local scale forced climate response, even for
high levels of global warming when the forced response has emerged from natural
variability.
Analysis and application of multi-model ensembles like EURO-CORDEX should go
hand-in-hand with single model ensembles, like the one presented here, to be able to correctly
interpret the fine-scale information in terms of a forced signal and random noise due to
natural variability. |
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