Aerosols, cloud microphysics, and fractional cloudiness.

Abstract: . Possible aerosol-cloud-precipitation effects over Germany are investigated using the COSMO model in a convection-permitting configuration close to the operational COSMO-DE. Aerosol effects on clouds and precipitation are modeled by using an advanced two-moment microphysical parameterization taking into account aerosol assumptions for cloud condensation nuclei (CCN) as well as ice nuclei (IN). Simulations of three summer seasons have been performed with various aerosol assumptions, and are analysed regarding surface precipitation, cloud properties, and the indirect aerosol effect on near-surface temperature. We find that the CCN and IN assumptions have a strong effect on cloud properties, like condensate amounts of cloud water, snow and rain as well as on the glaciation of the clouds, but the effects on surface precipitation are – when averaged over space and time – small. This robustness can only be understood by the combined action of microphysical and dynamical processes. On one hand, this shows that clouds can be interpreted as a buffered system where significant changes to environmental parameters, like aerosols, have little effect on the resulting surface precipitation. On the other hand, this buffering is not active for the radiative effects of clouds, and the changes in cloud properties due to aerosol perturbations may have a significant effect on radiation and near-surface temperature.

TL;DR: In this article, the authors investigate the impact of cloud tuning in the CMIP5 GFDL CM3 coupled climate model by constructing two alternate configurations, and they achieve the desired radiation balance using different, but plausible, combinations of parameters.

TL;DR: In this paper, the authors examined the diurnal cycle of liquid water path (LWP) over the subtropical and tropical oceans using two complete years of TMI (Tropical Rainfall Measuring Mission Microwave Imager) satellite microwave radiometer data.

TL;DR: In this article, the authors used satellite observations from NASA's A-Train constellation of satellites to determine what controls the precipitation susceptibility of warm clouds to aerosol perturbations, and three susceptibility regimes were identified: (i) clouds with low liquid water path (LWP) generate very little rain and are least susceptible to pollution aerosol; (ii), clouds with intermediate LWP where aerosol most effectively suppress precipitation; and (iii, clouds with high LWP, where the susceptibility begins to decrease because the precipitation process is efficient owing to abundant liquid water.

TL;DR: In this paper, the authors studied the effect of pollution on global climate and found that the climate effect is comparable to that of increased carbon dioxide, and acts in the opposite direction, in that increasing absorption also attends increasing pollution.

TL;DR: In this article, the growth of condensate droplets rising above cloud base within small cumuli which are entraining undersaturated environmental air is investigated. But the authors assume that the mixing process is inhomogeneous.

TL;DR: The first International Satellite Cloud Cover Project Regional Experiment (FIRE) as mentioned in this paper was proposed to develop physical models and parameterizations of fractional cloud cover over the Pacific Basin in order to determine fractional Cloud cover parameters, satellite observations by radar and lidar instruments combined with in situ measurements of the cloud-capped marine boundary layer.

TL;DR: The first International Satellite Cloud Climatology Project Regional Experiment (FIRE) as discussed by the authors was used to study extensive fields of stratocumulus clouds off the coast of California, where measurements on the regional and detailed local scales were taken, allowing for a wide interpretation of the mean, turbulent, microphysical, radiative, and chemical characteristics of stratocalumulus.