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| Titel |
Sensitivity of the hydrologic cycle to cloud changes in warm climates |
| VerfasserIn |
Henrik Carlson, Rodrigo Caballero |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250133433
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| Publikation (Nr.) |
 EGU/EGU2016-14044.pdf |
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| Zusammenfassung |
| Climates of the deep past have posed the longstanding challenge to understand which
mechanisms maintained very warm climates. Warm climates have been hard to simulate
without very high CO2 concentrations compared to estimates from proxy data. Large climate
sensitivity implies a route to warm temperatures without very high concentrations of CO2. In
at least one model cloud feedbacks play a central role in increasing climate sensitivity with
temperature. However, it is hard to evaluate cloud feedbacks using proxies. On the other
hand, there are proxies that provide information about the hydrologic cycle for
example through estimating aridity and isotope analysis of leaf wax. Cloud feedbacks
could influence the hydrologic cycle through a change in the shortwave radiative
flux at the surface that causes a change in latent heat flux and thereby a change in
precipitation. We study the impact of clouds in a general circulation model for a broad
range of temperatures. One set of simulations with variable clouds is compared
to a set of simulations where clouds are represented by a climatology. Our aim
to provide a constraint for cloud feedbacks based on hydrology proves elusive.
Precipitation change with temperature is very similar regardless of cloud treatment and
there is no saturation effect in precipitation as seen in idealized models. However,
there is a large change in shortwave absorption by atmospheric water vapor. Our
results indicate that the hydrologic cycle is not sensitive to cloud representation in
Eocene-like climates but correct representation of shortwave absorption is essential. |
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