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| Titel |
On the sources of global land surface hydrologic predictability |
| VerfasserIn |
S. Shukla, J. Sheffield, E. F. Wood, 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 ; 17, no. 7 ; Nr. 17, no. 7 (2013-07-16), S.2781-2796 |
| Datensatznummer |
250018936
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| Publikation (Nr.) |
 copernicus.org/hess-17-2781-2013.pdf |
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| Zusammenfassung |
Global seasonal hydrologic prediction is crucial to mitigating the impacts
of droughts and floods, especially in the developing world. Hydrologic
predictability at seasonal lead times (i.e., 1–6 months) comes from knowledge
of initial hydrologic conditions (IHCs) and seasonal climate forecast skill
(FS). In this study we quantify the contributions of two primary components
of IHCs – soil moisture and snow water content – and FS (of precipitation
and temperature) to seasonal hydrologic predictability globally on a
relative basis throughout the year. We do so by conducting two model-based
experiments using the variable infiltration capacity (VIC) macroscale
hydrology model, one based on ensemble streamflow prediction (ESP) and
another based on Reverse-ESP (Rev-ESP), both for a 47 yr re-forecast period
(1961–2007). We compare cumulative runoff (CR), soil moisture (SM) and snow
water equivalent (SWE) forecasts from each experiment with a VIC model-based
reference data set (generated using observed atmospheric forcings) and
estimate the ratio of root mean square error (RMSE) of both experiments for
each forecast initialization date and lead time, to determine the relative
contribution of IHCs and FS to the seasonal hydrologic predictability. We
find that in general, the contributions of IHCs to seasonal hydrologic
predictability is highest in the arid and snow-dominated climate (high
latitude) regions of the Northern Hemisphere during forecast periods
starting on 1 January and 1 October. In mid-latitude regions, such as the
Western US, the influence of IHCs is greatest during the forecast period
starting on 1 April. In the arid and warm temperate dry winter regions of
the Southern Hemisphere, the IHCs dominate during forecast periods starting
on 1 April and 1 July. In equatorial humid and monsoonal climate regions,
the contribution of FS is generally higher than IHCs through most of the
year.
Based on our findings, we argue that despite the limited FS (mainly for
precipitation) better estimates of the IHCs could lead to improvement in the
current level of seasonal hydrologic forecast skill over many regions of the
globe at least during some parts of the year. |
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