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| Titel |
Seasonal hydrologic prediction in the United States: understanding the role of initial hydrologic conditions and seasonal climate forecast skill |
| VerfasserIn |
S. Shukla, D. P. Lettenmaier |
| 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 ; 15, no. 11 ; Nr. 15, no. 11 (2011-11-22), S.3529-3538 |
| Datensatznummer |
250013029
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| Publikation (Nr.) |
 copernicus.org/hess-15-3529-2011.pdf |
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| Zusammenfassung |
| Seasonal hydrologic forecasts derive their skill from knowledge of initial
hydrologic conditions and climate forecast skill associated with seasonal
climate outlooks. Depending on the type of hydrological regime and the
season, the relative contributions of initial hydrologic conditions and
climate forecast skill to seasonal hydrologic forecast skill vary. We seek
to quantify these contributions on a relative basis across the Conterminous
United States. We constructed two experiments – Ensemble Streamflow
Prediction and reverse-Ensemble Streamflow Prediction – to partition the
contributions of the initial hydrologic conditions and climate forecast
skill to overall forecast skill. In ensemble streamflow prediction (first
experiment) hydrologic forecast skill is derived solely from knowledge of
initial hydrologic conditions, whereas in reverse-ensemble streamflow
prediction (second experiment), it is derived solely from atmospheric
forcings (i.e. perfect climate forecast skill). Using the ratios of root
mean square error in predicting cumulative runoff and mean monthly soil
moisture of each experiment, we identify the variability of the relative
contributions of the initial hydrologic conditions and climate forecast
skill spatially throughout the year. We conclude that the initial hydrologic
conditions generally have the strongest influence on the prediction of
cumulative runoff and soil moisture at lead-1 (first month of the forecast
period), beyond which climate forecast skill starts to have greater
influence. Improvement in climate forecast skill alone will lead to better
seasonal hydrologic forecast skill in most parts of the Northeastern and
Southeastern US throughout the year and in the Western US mainly during
fall and winter months; whereas improvement in knowledge of the initial
hydrologic conditions can potentially improve skill most in the Western US
during spring and summer months. We also observed that at a short lead time
(i.e. lead-1) contribution of the initial hydrologic conditions in soil
moisture forecasts is more extensive than in cumulative runoff forecasts
across the Conterminous US. |
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