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| Titel |
Potential evaporation trends over land between 1983–2008: driven by radiative fluxes or vapour-pressure deficit? |
| VerfasserIn |
C. Matsoukas, N. Benas, N. Hatzianastassiou, K. G. Pavlakis, M. Kanakidou, I. Vardavas |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 15 ; Nr. 11, no. 15 (2011-08-01), S.7601-7616 |
| Datensatznummer |
250009964
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| Publikation (Nr.) |
 copernicus.org/acp-11-7601-2011.pdf |
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| Zusammenfassung |
| We model the Penman potential evaporation (PE) over all land areas of the
globe for the 25-yr period 1983–2008, relying on radiation transfer models
(RTMs) for the shortwave and longwave fluxes. Penman's PE is determined by
two factors: available energy for evaporation and ground to atmosphere vapour
transfer. Input to the PE model and RTMs comprises satellite cloud and
aerosol data, as well as data from reanalyses. PE is closely linked to pan
evaporation, whose trends have sparked controversy in the community, since
the factors responsible for the observed pan evaporation trends are not
determined with consensus. Our particular interest is the temporal evolution
of PE, and the provided insight to the observed trends of pan evaporation. We
examine the decadal trends of PE and various related physical quantities,
such as net solar flux, net longwave flux, water vapour saturation deficit
and wind speed. Our findings are the following: Global warming has led to a
larger water vapour saturation deficit. The periods 1983–1989, 1990–1999,
and 2000–2008 were characterised by decreasing, increasing, and slightly
decreasing PE, respectively. In these last 25 yr, global
dimming/brightening cycles generally increased the available energy for
evaporation. PE trends seem to follow more closely the trends of energy
availability than the trends of the atmospheric capability for vapour
transfer, at most locations on the globe, with trends in the Northern
hemisphere significantly larger than in the Southern. These results support
the hypothesis that global potential evaporation trends are attributed
primarily to secular changes in the radiation fluxes, and secondarily to
vapour transfer considerations. |
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