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Chosson et al (J. Atmos. Sci., 2007; p. 2670-2682), Grabowski (J. Climate, 2006; p. 4664-4682), and Slawinska et al (J. Climate, 2008; 1639-1647) all showed that assumptions concerning microphysical transformations during entrainment and mixing (i.e., the homogeneous versus inhomogeneous mixing) have a dramatic impact on the albedo of a field of convective clouds. This is because of a significant dilution of these clouds due to entrainment of dry environmental air and the complexity of the small-scale mixing and homogenization. This aspect is especially relevant for the first indirect aerosol effect, that is, the change of the mean albedo as a result of the change of cloud condensation nuclei. To better simulate the indirect effects on shallow warm (ice-free) clouds, a two-moment bulk warm-rain microphysics scheme has been recently developed by Morrison and Grabowski (J. Atmos. Sci. 2007; p. 2839-2861 and 2008, 792-812). A novel feature of the scheme is that it allows prescribing homogeneity of subgrid-scale mixing, from the homogeneous to extremely inhomogeneous. This poster will present results of the application of the scheme to the nonprecipitating (BOMEX experiment; Siebesma et al., J. Atmos. Sci. 2003; p. 1201-1219) as well as precipitating shallow convection (RICO experiment; http://www.knmi.nl/samenw/rico/). |
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