Atmos. Chem. Phys. Discuss., 10, 763-783, 2010
© Author(s) 2010. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Longwave indirect effect of mineral dusts on ice clouds
Q. Min and R. Li
Atmospheric Sciences Research Center, State University of New York, Albany, NY 12203, USA

Abstract. In addition to microphysical changes in clouds, changes in nucleation processes of ice cloud due to aerosols would result in substantial changes in cloud top distribution as mildly supercooled clouds are glaciated through heterogonous nucleation processes. Measurements from multiple sensors on multiple observing platforms over the Atlantic Ocean show that the cloud effective temperature increases with mineral dust loading with a slope of +3.06 °C per unit AOD. The macrophysical changes in ice cloud top distributions as a consequence of mineral dust-cloud interaction exert a strong cooling effect (up to 16 w m−2) of thermal infrared radiation on cloud systems. Induced changes of ice particle size by mineral dusts influence cloud emissivity and play a minor role in modulating the outgoing longwave radiation for optically thin ice clouds. Such a strong cooling forcing of thermal infrared radiation would have significant impacts on cloud systems and subsequently on climate.

Citation: Min, Q. and Li, R.: Longwave indirect effect of mineral dusts on ice clouds, Atmos. Chem. Phys. Discuss., 10, 763-783, doi:10.5194/acpd-10-763-2010, 2010.
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