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| Titel |
Uncertainties in future climate predictions due to convection parameterisations |
| VerfasserIn |
H. Rybka, H. Tost |
| 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 ; 14, no. 11 ; Nr. 14, no. 11 (2014-06-05), S.5561-5576 |
| Datensatznummer |
250118774
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| Publikation (Nr.) |
 copernicus.org/acp-14-5561-2014.pdf |
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| Zusammenfassung |
| In the last decades several convection parameterisations have been developed
to consider the impact of small-scale unresolved processes in Earth System
Models associated with convective clouds. Global model simulations, which
have been performed under current climate conditions with different
convection schemes, significantly differ among each other in the simulated
transport of trace gases and precipitation patterns due to the
parameterisation assumptions and formulations, e.g. the computation of
convective rainfall rates, calculation of entrainment and detrainment rates
etc. Here we address sensitivity studies comparing four different convection
schemes under alternative climate conditions (with doubling of the CO2
concentrations) to identify uncertainties related to convective processes.
The increase in surface temperature reveals regional differences up to 4 K
dependent on the chosen convection parameterisation. These differences are
statistically significant almost everywhere in the troposphere of the
intertropical convergence zone. The increase in upper tropospheric
temperature affects the amount of water vapour transported to the lower
stratosphere, leading to enhanced water vapour contents between 40% and
60% at the cold point temperature in the Tropics. Furthermore, the change
in transporting short-lived pollutants within the atmosphere is highly
ambiguous for the lower and upper troposphere. These results reflect that
different approaches to compute mass fluxes, detrainment levels or trigger
functions determine the transport of short-lived trace gases from the
planetary boundary layer to lower, middle or upper tropospheric levels.
Finally, cloud radiative effects have been analysed, uncovering a shift in
different cloud types in the Tropics, especially for cirrus and deep
convective clouds. These cloud types induce a change in net cloud radiative
forcing varying from 0.5 W m−2 to 2.0 W m−2. |
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