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| Titel |
Simulated enhancement of ENSO-related rainfall variability due to Australian dust |
| VerfasserIn |
L. D. Rotstayn, M. A. Collier, R. M. Mitchell, Y. Qin, S. K. Campbell, S. M. Dravitzki |
| 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 ; 11, no. 13 ; Nr. 11, no. 13 (2011-07-12), S.6575-6592 |
| Datensatznummer |
250009904
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| Publikation (Nr.) |
 copernicus.org/acp-11-6575-2011.pdf |
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| Zusammenfassung |
| Australian dust emissions are highly episodic, and this may increase
the importance of Australian dust as a climate feedback agent. We
compare two 160-year coupled atmosphere-ocean simulations of
modern-day climate using the CSIRO Mark 3.6 global climate model
(GCM). The first run (DUST) includes an interactive treatment of
mineral dust and its direct radiative effects. The second run (NODUST)
is otherwise identical, but has the Australian dust source set to
zero. We focus on the austral spring season, when the correlation
between rainfall and the El Niño Southern Oscillation (ENSO) is
strongest over Australia. The ENSO-rainfall relationship over eastern
Australia is stronger in the DUST run: dry (El Niño) years tend to
be drier, and wet (La Niña) years wetter. The amplification of
ENSO-related rainfall variability over eastern Australia represents an
improvement relative to observations. The effect is driven by
ENSO-related anomalies in radiative forcing by Australian dust over
the south-west Pacific Ocean; these anomalies increase (decrease)
surface evaporation in La Niña (El Niño) years. Some of this
moisture is advected towards eastern Australia, where increased
(decreased) moisture convergence in La Niña (El Niño) years
increases the amplitude of ENSO-related rainfall variability. The
modulation of surface evaporation by dust over the south-west Pacific
occurs via surface radiative forcing and dust-induced stabilisation of
the boundary layer. The results suggest that (1) a realistic treatment
of Australian dust may be necessary for accurate simulation of the
ENSO-rainfall relationship over Australia, and (2) radiative feedbacks
involving dust may be important for understanding natural rainfall
variability over Australia. |
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