Aerosols effects on convective clouds and climate (ACCLAIM)

Research Project, 2012 – 2015

Clouds play a key role in the climate system. Small anthropogenic perturbations of the cloud system potentially have large radiative effects. Aerosols perturb the global radiation budget directly, by scattering and absorption, as well as indirectly, by the modification of cloud properties and occurrence. The applicability of traditional conceptual models of indirect aerosol effects to convective clouds is disputed as cloud dynamics complicates the picture.

Strong evidence for numerous aerosol effects on convection has been established in individual disciplines: through remote sensing and in-situ observations as well as by cloud resolving and global modelling. However, a coherent scientific view of the effects of aerosols on convection has yet to be established.

The primary objective of ACCLAIM is to recast the effects of aerosols on convective clouds as basis for improved global estimates of anthropogenic climate effects. Specific objectives include: i) to unravel the governing principles of aerosol effects on convective clouds; ii) provide quantitative constraints on satellite-retrieved relationships between convective clouds and aerosols; and ultimately iii) to enable global climate models to represent the full range of anthropogenic climate perturbations and quantify the climate response to aerosol effects on convective clouds.