ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-7-3203-2007 Long-range transport of mineral aerosols and its absorbing and heating effects on cloud and precipitation: a numerical study Yin Y. 1 Chen L. 1 Nanjing University of Information Science and Technology, Nanjing 210044, China 27 02 2007 7 1 3203 3228 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys-discuss.net/7/3203/2007/acpd-7-3203-2007.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/7/3203/2007/acpd-7-3203-2007.pdf

There have been numerous recent publications showing that mineral dust might be a good absorber for solar radiation in addition to its capability as cloud condensation nuclei (CCN) and ice forming nuclei (IFN), and could lead to reduced cloud cover and precipitation in the region it presents. This effect is investigated using a cloud model with detailed microphysics of both warm and ice phase processes. The model is initialized using measured distributions and concentration of mineral dust particles. Our results show that when the dust layer with peak concentration appears at the cloud-base height and below 3 km, where the temperature is warmer than –5°C, inhibits the development of cloud particles and precipitation, and together with early activation of larger cloud droplets on giant cloud condensation nuclei, which accelerates drizzle formation through collision coalescence process, reduces the cloud optical depth and albedo. It is also found that only when the dust layer locates at altitudes with temperature colder than –5°C, mineral aerosols can act as effective ice nuclei and intensify the ice-forming processes. Under this condition, the existence of dust layer can either increase or decrease cloud optical depth and albedo, depending on the concentration and chemical composition of the absorbing components, or the time the mineral aerosols suspended in the atmosphere.

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