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| Titel |
Impact of the Desert dust on the summer monsoon system over Southwestern North America |
| VerfasserIn |
C. Zhao, X. Liu, L. R. Leung |
| 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 ; 12, no. 8 ; Nr. 12, no. 8 (2012-04-24), S.3717-3731 |
| Datensatznummer |
250011072
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| Publikation (Nr.) |
 copernicus.org/acp-12-3717-2012.pdf |
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| Zusammenfassung |
| The radiative forcing of dust emitted from the
Southwest United States (US) deserts and its impact on monsoon circulation
and precipitation over the North America monsoon (NAM) region are simulated
using a coupled meteorology and aerosol/chemistry model (WRF-Chem) for 15
years (1995–2009). During the monsoon season, dust has a cooling effect
(−0.90 W m−2) at the surface, a warming effect (0.40 W m−2) in the
atmosphere, and a negative top-of-the-atmosphere (TOA) forcing (−0.50 W m−2)
over the deserts on 24-h average. Most of the dust emitted from
the deserts concentrates below 800 hPa and accumulates over the western
slope of the Rocky Mountains and Mexican Plateau. The absorption of
shortwave radiation by dust heats the lower atmosphere by up to 0.5 K day−1
over the western slope of the Mountains. Model sensitivity simulations with
and without dust for 15 summers (June-July-August) show that dust heating of
the lower atmosphere over the deserts strengthens the low-level southerly
moisture fluxes on both sides of the Sierra Madre Occidental. It also
results in an eastward migration of NAM-driven moisture convergence over the
western slope of the Mountains. These monsoonal circulation changes lead to
a statistically significant increase of precipitation by up to ~40 %
over the eastern slope of the Mountains (Arizona-New~Mexico-Texas regions).
This study highlights the interaction between dust and the NAM system and
motivates further investigation of possible dust feedback on monsoon
precipitation under climate change and the mega-drought conditions projected
for the future. |
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