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| Titel |
A comparative study of large-scale atmospheric circulation in the context of a future scenario (RCP4.5) and past warmth (mid-Pliocene) |
| VerfasserIn |
Y. Sun, G. Ramstein, C. Contoux, T. Zhou |
| 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 ; 9, no. 4 ; Nr. 9, no. 4 (2013-07-25), S.1613-1627 |
| Datensatznummer |
250018096
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| Publikation (Nr.) |
 copernicus.org/cp-9-1613-2013.pdf |
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| Zusammenfassung |
The mid-Pliocene warm period (~ 3.3–3.0 Ma) is often considered
as the last sustained warm period with close enough geographic
configurations compared to the present one associated with atmospheric CO2
concentration (405 ± 50 ppm) higher than the modern level. For
this reason, this period is often considered as a potential analogue for the
future climate warming, with the important advantage that for mid-Pliocene
many marine and continental data are available. To investigate this issue,
we selected the RCP4.5 scenario, one of the current available future
projections, to compare the pattern of tropical atmospheric response with the
past warm mid-Pliocene climate.
We use three Atmosphere-Ocean General Circulation Model (AOGCM) simulations (RCP4.5 scenario, mid-Pliocene and present-day simulation) carried out with the IPSL-CM5A model and investigate
atmospheric tropical dynamics through Hadley and Walker cell responses to
warmer conditions, considering that the analysis can provide some assessment
of how these circulations will change in the future. Our results show that
there is a damping of the Hadley cell intensity in the northern tropics and
an increase in both subtropics. Moreover, northern and southern Hadley cells
expand poleward. The response of the Hadley cells is stronger for the RCP4.5 scenario
than for the mid-Pliocene, but in very good agreement with the fact that the
atmospheric CO2 concentration is higher in the future scenario than in the
mid-Pliocene (543 versus 405 ppm). Concerning the response of the Walker
cell, we show that despite very large similarities, there are also some
differences. Common features to both scenarios are: weakening of the
ascending branch, leading to a suppression of the precipitation over the
western tropical Pacific. The response of the Walker cell is stronger in
the RCP4.5 scenario than in the mid-Pliocene but also depicts some major
differences, as an eastward shift of its rising branch in the future scenario
compared to the mid-Pliocene.
In this paper, we explain the dynamics of the Hadley and Walker cells, and
show that despite a minor discrepancy, the mid-Pliocene is certainly an
interesting analogue for future climate changes in tropical areas. |
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