BLACARAT · Black Carbon in the Atmosphere: Emissions, Aging and Cloud Interactions

Atmospheric aerosol particles have been shown to impact the earth's climate because they scatter and absorb solar radiation (direct effect) and because they can modify the microphysical properties of clouds by acting as cloud condensation nuclei or ice nuclei (indirect effects). Radiative forcing by anthropogenic aerosols remains poorly quantified, thus leading to considerable uncertainty in our understanding of the earth’s climate response to the radiative forcing by greenhouse gases. Black carbon (BC), mostly emitted by anthropogenic combustion processes and biomass burning, is an important component of atmospheric aerosols. Estimates show that BC may be the second strongest contributor (after CO2) to global warming. Adverse health effects due to particulate air pollution have also been associated with traffic-related BC particles. These climate and health effects brought BC emission reductions into the political focus of possible mitigation strategies with immediate and multiple benefits for human well-being.Laboratory experiments aim at the physical and chemical characterisation of BC emissions from diesel engines and biomass burning under controlled conditions. A mobile laboratory equipped with state-of-the-art aerosol sensors will be used to determine the contribution of different BC sources to atmospheric BC loadings, and to investigate the evolution of the relevant BC properties with atmospheric aging during transport from sources to remote areas. The interactions of BC particles with clouds as a function of BC properties will be investigated with in-situ measurements by operating quantitative single particle instruments behind a novel sampling inlet, which makes selective sampling of interstitial, cloud droplet residual or ice crystal residual particles possible. Above experimental studies aim at improving our understanding of BC’s atmospheric life cycle and will be used in model simulations for quantitatively assessing the atmospheric impacts of BC.