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| Titel |
Monitoring and quantifying future climate projections of dryness and wetness extremes: SPI bias |
| VerfasserIn |
F. Sienz, O. Bothe, K. Fraedrich |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 16, no. 7 ; Nr. 16, no. 7 (2012-07-18), S.2143-2157 |
| Datensatznummer |
250013370
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| Publikation (Nr.) |
 copernicus.org/hess-16-2143-2012.pdf |
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| Zusammenfassung |
| The adequacy of the gamma distribution (GD) for monthly precipitation
totals is reconsidered. The motivation for this study is the observation
that the GD fails to represent precipitation in considerable areas of
global observed and simulated data.
This misrepresentation may lead to erroneous estimates of the
Standardised Precipitation Index (SPI), evaluations of models, and
assessments of climate change.
In this study, the GD is compared to the Weibull (WD), Burr Type III
(BD), exponentiated Weibull (EWD) and generalised gamma (GGD) distribution.
These distributions extend the GD in terms of possible
shapes (skewness and kurtosis) and the behaviour for large arguments.
The comparison is based on the Akaike information criterion, which
maximises information entropy and reveals a trade-off between
deviation and the numbers of parameters used. We use monthly sums of
observed and simulated precipitation for 12 calendar months of the year.
Assessing observed and simulated data,
(i) the Weibull type distributions give distinctly improved fits
compared to the GD and
(ii) the SPI resulting from the GD overestimates
(underestimates) extreme dryness (wetness). |
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