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| Titel |
ENSO and multi-decadal 'trends' in continental evaporation |
| VerfasserIn |
Diego Miralles, Ryan Teuling, Martinus van den Berg, John Gash, Robert Parinussa, Richard de Jeu, Hylke Beck, Thomas Holmes, Carlos Jimenez, Niko Verhoest, Wouter Dorigo, Han Dolman |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250090778
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| Publikation (Nr.) |
 EGU/EGU2014-5034.pdf |
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| Zusammenfassung |
| While the hydrological cycle is expected to intensify in response to global warming,
little unequivocal evidence of such an acceleration has yet been found on a global
scale. This holds in particular for terrestrial evaporation, the crucial return flow
of water from continents to atmosphere. Counterintuitively, the few studies that
have applied satellite and in situ observations to evaluate multi-decadal trends have
uncovered prolonged declines in global average continental evaporation. A priori, these
reductions contradict the expectations of an intensifying water cycle. Up to date, the
question of whether these declines in evaporation reflect a more permanent feature
of global warming or they result from internal climate variability, has been left
unanswered.
Here, we attempt to answer that question by analyzing global satellite-based datasets of
evaporative fluxes, soil moisture and NDVI. Our findings reveal that the reported recent
declines in global continental evaporation are not a consequence of a persistent reorganization
of the water cycle, but a consequence of internal climate variability. During El Niño,
limitations in the supply of moisture in central Australia, southern Africa and eastern South
America cause vegetation water-stress and reduced terrestrial evaporation. These regional
terrestrial evaporation declines are so pronounced that that determine the total annual
volumes of water vapour from continental land surfaces into the atmosphere. Meanwhile, in
northern latitudes (where the effects of ENSO are weaker) continental evaporation has raised
since the ’80s at rates that are consistent with the expectations calculated from air
temperature trends. Future changes in continental evaporation will be determined by the
response of ENSO to changes in global radiative forcing, which still remains highly
uncertain. Opportunely, the increasing timespan of satellite observation records will
enable a more significant assessment of the trends in global evaporation in coming
years. |
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