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| Titel |
How to introduce climate change into extreme precipitation predetermination? First attempts to tamper with the MEWP method. |
| VerfasserIn |
Maxime Gérardin, Pierre Brigode, Pietro Bernardara, Joël Gailhard, Rémy Garçon, Emmanuel Paquet, Pierre Ribstein |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082850
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| Zusammenfassung |
| The MEWP (Multi-Exponential Weather Pattern, Garavaglia et al. 2010) distribution is part
of the operational method in use at EDF (Electricité de France) for computing dam spillways
design floods, i.e. the magnitude of the flood that occurs at a given return period.
The return periods of interest lie in the 100 – 10,000 years range. Relying on a
purposely-designed classification of atmospheric circulations into weather patterns, and
assigning a catchment-specific asymptotical coefficient to each of these patterns,
the MEWP distribution provides the daily areal rainfall as a function of the return
period. In its current state, the method relies on the implicit assumption of climate
stationnarity.
In this work we seek to introduce climate change into the MEWP framework. Since the
MEWP distribution basically contains two sorts of parameters, namely frequencies of the
weather patterns, and magnitudes of the events occurring within each of these patterns, we
examine the plausible evolution of these two sets of parameters under climate change, and the
sensitivity of the final result to these two sorts of changes. On the one hand, the future
frequencies are assessed thanks to GCM outputs from CMIP5, and significant, albeit not
greater than the internal variability, changes are observed. On the other hand, the future
magnitudes can be suspected to follow the Clausius-Clapeyron relationship (e.g. Pall et al.,
2007, and Lenderink et van Meijgaard, 2008). We assess the validity of this hypothesis on the
observed daily areal precipitation series for more than a hundred catchments in
France.
The sensitivity analysis shows that, for the return periods at stake, the impact of frequency
changes is small relative to that of magnitude changes, while this would not be true
for smaller return periods. Therefore, we propose to incorporate climate change
into the MEWP distribution in a simple but realistic way, by taking account of the
magnitude change only. We conclude with some insights into the next steps that
will allow a more sophisticated representation of climate change in the MEWP
distribution.
References:
Garavaglia, F., J. Gailhard, E. Paquet, M. Lang, R. Garçon, and P. Bernardara.
2010. “Introducing a Rainfall Compound Distribution Model Based on Weather
Patterns Sub-sampling.” Hydrology and Earth System Sciences 14 (6): 951–964.
doi:10.5194/hess-14-951-2010.
Lenderink, Geert, and Erik van Meijgaard. 2008. “Increase in Hourly Precipitation
Extremes Beyond Expectations from Temperature Changes.” Nature Geoscience 1 (8) (July
20): 511–514. doi:10.1038/ngeo262.
Pall, P., MR Allen, and DA Stone. 2007. “Testing the Clausius–Clapeyron Constraint on
Changes in Extreme Precipitation Under CO 2 Warming.” Climate Dynamics 28 (4):
351–363. |
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