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| Titel |
Comparison of 20th century and pre-industrial climate over South America in regional model simulations |
| VerfasserIn |
S. Wagner, I. Fast, F. Kaspar |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 8, no. 5 ; Nr. 8, no. 5 (2012-10-16), S.1599-1620 |
| Datensatznummer |
250005845
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| Publikation (Nr.) |
 copernicus.org/cp-8-1599-2012.pdf |
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| Zusammenfassung |
In this study, we assess how the anthropogenically induced increase in
greenhouse gas concentrations affects the climate of central and southern
South America. We utilise two regional climate simulations for present day
(PD) and pre-industrial (PI) times. These simulations are compared to
historical reconstructions in order to investigate the driving processes
responsible for climatic changes between the different periods. The regional
climate model is validated against observations for both re-analysis data
and GCM-driven regional simulations for the second half of the 20th
century. Model biases are also taken into account for the interpretation of
the model results. The added value of the regional simulation over
global-scale modelling relates to a better representation of hydrological
processes that are particularly evident in the proximity of the Andes
Mountains.
Climatic differences between the simulated PD minus PI period agree
qualitatively well with proxy-based temperature reconstructions, albeit the
regional model overestimates the amplitude of the temperature increase. For
precipitation the most important changes between the PD and PI simulation
relate to a dipole pattern along the Andes Mountains with increased
precipitation over the southern parts and reduced precipitation over the
central parts. Here only a few regions show robust similarity with studies
based on empirical evidence. However, from a dynamical point-of-view,
atmospheric circulation changes related to an increase in high-latitude
zonal wind speed simulated by the regional climate model are consistent with
numerical modelling studies addressing changes in greenhouse gas
concentrations.
Our results indicate that besides the direct effect of greenhouse gas
changes, large-scale changes in atmospheric circulation and sea surface
temperatures also exert an influence on temperature and precipitation
changes in southern South America. These combined changes in turn affect the
relationship between climate and atmospheric circulation between PD and PI
times and should be considered for the statistical reconstruction of climate
indices calibrated within present-day climate data. |
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