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| Titel |
A worldwide analysis of trends in water-balance evapotranspiration |
| VerfasserIn |
A. M. Ukkola, I. C. Prentice |
| 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. 10 ; Nr. 17, no. 10 (2013-10-25), S.4177-4187 |
| Datensatznummer |
250085972
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| Publikation (Nr.) |
 copernicus.org/hess-17-4177-2013.pdf |
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| Zusammenfassung |
| Climate change is expected to alter the global hydrological cycle, with
inevitable consequences for freshwater availability to people and
ecosystems. But the attribution of recent trends in the terrestrial water
balance remains disputed. This study attempts to account statistically for
both trends and interannual variability in water-balance evapotranspiration
(ET), estimated from the annual observed streamflow in 109 river basins
during "water years" 1961–1999 and two gridded precipitation data sets. The
basins were chosen based on the availability of streamflow time-series data
in the Dai et al. (2009) synthesis. They were divided into water-limited
"dry" and energy-limited "wet" basins following the Budyko framework. We
investigated the potential roles of precipitation, aerosol-corrected solar
radiation, land use change, wind speed, air temperature, and atmospheric
CO2. Both trends and variability in ET show strong control by
precipitation. There is some additional control of ET trends by vegetation
processes, but little evidence for control by other factors. Interannual
variability in ET was overwhelmingly dominated by precipitation, which
accounted on average for 54–55% of the variation in wet basins (ranging
from 0 to 100%) and 94–95% in dry basins (ranging from 69 to
100%). Precipitation accounted for 45–46% of ET trends in wet basins
and 80–84% in dry basins. Net atmospheric CO2 effects on
transpiration, estimated using the Land-surface Processes and eXchanges
(LPX) model, did not contribute to observed trends in ET because declining
stomatal conductance was counteracted by slightly but significantly
increasing foliage cover. |
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