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| Titel |
Assessing changes in drought characteristics with standardized indices |
| VerfasserIn |
Jean-Philippe Vidal, Julien Najac, Eric Martin, Laurent Franchisteguy, Jean-Michel Soubeyroux |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040938
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| Zusammenfassung |
| Standardized drought indices like the Standardized Precipitation Index (SPI) are more and
more frequently adopted for drought reconstruction, monitoring and forecasting, and the
SPI has been recently recommended by the World Meteorological Organization
to characterize meteorological droughts. Such indices are based on the statistical
distribution of a hydrometeorological variable (e.g., precipitation) in a given reference
climate, and a drought event is defined as a period with continuously negative index
values.
Because of the way these indices are constructed, some issues may arise when using them
in a non-stationnary climate. This work thus aims at highlighting such issues and
demonstrating the different ways these indices may – or may not – be applied and interpreted
in the context of an anthropogenic climate change.
Three major points are detailed through examples taken from both a high-resolution
gridded reanalysis dataset over France and transient projections from the ARPEGE general
circulation model downscaled over France. The first point deals with the choice of the
reference climate, and more specifically its type (from observations/reanalysis or from
present-day modelled climate) and its record period. Second, the interpretation of actual
changes are closely linked with the type of the selected drought feature over a future period:
mean index value, under-threshold frequency, or drought event characteristics (number, mean
duration and magnitude, seasonality, etc.). Finally, applicable approaches as well as
related uncertainties depend on the availability of data from a future climate, whether
in the form of a fully transient time series from present-day or only a future time
slice.
The projected evolution of drought characteristics under climate change must inform
present decisions on long-term water resources planning. An assessment of changes in
drought characteristics should therefore provide water managers with appropriate
information that can help building effective adaptation strategies. This work thus aims
at showing the potential of standardized indices to describe changes in drought
characteristics, but also possible pitfalls and potentially misleading interpretations. |
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