Although many studies focused on the CCN effect,

Although tremendous efforts and enormous progress has been made in the last decades to improve our knowledge about the role of aerosols in the climate system. However, aerosols and clouds still introduced the largest uncertainty to estimates Earth’s energy budget (IPCC, 2013). As one of the four major terrestrial sources of atmospheric aerosols (biomass burning, desert dust, and biogenic and anthropogenic air pollution), wind-blown dust aerosols are of key importance because they contribute to about half of the global annual particle emissions by mass (Huneeus et al., 2011). Dust plays a crucial role in modifying the feature of the hydrological cycle and other characteristics of the climate system by virtue of their interactions with radiation and cloud. Dust significantly impact the Earth’s radiation budget by scattering and absorption of solar and terrestrial radiation (Balkanski et al., 2007; Tegen and Schepanski, 2009) which is known as the direct radiative effect. Dust also act as cloud condensation nuclei (CCN) or effective ice nuclei (IN; Hoose and Möhler, 2012)) and altering cloud microphysical properties, known as the indirect radiative effect (Albrecht, 1989; Ellis and Palmer, 2016). Evaporation of cloud droplets and associated reduction in cloud cover due to excess heating of the atmosphere caused by dust is termed as the semi-direct effect (Hansen et al., 1997; Allen and Sherwood, 2010). While many studies focused on the CCN effect, the IN effect has obtained less attention. Mineral dust is the most common atmospheric IN that may have an important climatological effect due to their role in cloud microstructure and radiative properties (Carrió et al., 2007). The most of the mineral dust particles transported from continental areas to oceanic region have a wide size distribution from 0.5 ?m to 75 ?m diameters (Maring, 2003). DeMott (2003) and Sassen et al. (2003) reported the extremely large numbers of heterogeneous IN in high clouds associated with Saharan dust using the observations from the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE). Microphysical effects of dust alter vertical distribution of precipitation and shift the precipitation size spectrum from heavy to light precipitation (Min et al., 2009; Li and Min, 2010). The dust indirect effect on warm clouds strongly depends on the cloud top height and the precipitation regimes (Li et al., 2010b). Dust induced change in ice clouds due to homogenous and heterogeneous nucleation processes would result in substantial changes in cloud top distribution and such changes would have a strong cooling effect of LW radiation on cloud systems (Min and Li, 2010).


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