ACPC Science Approach

The current phase of the ACPC initiative pursues the idea laid out by Rosenfeld et al. (Rev. Geophys. 2014; doi 10.1002/2013RG000441) that comprehensive field experiments for different cloud regimes in different world regions are considered the most promising avenue to advance our understanding of aerosol-cloud-precipitation interactions.

On the basis of the discussions in the Scientific Steering Committee and at the 2015 New York workshop, ACPC works with a new generation of high resolution atmospheric models, allowing us to realistically represent cloud and precipitation processes, but at the same time enabling coupled interactions between cloud-active aerosol, clouds, and precipitation, to simulate domains large enough and periods long enough to allow for a full development of interaction, adjustment, and feedback processes for a given cloud regime.

Since then, “roadmaps” for two cloud regimes have been defined and pursued, one targeting shallow clouds (marine stratocumulus clouds in the VOCALS region and period) and one targeting deep convective clouds (in the Houston, USA, region for a case in June 2013 where observations are available).

Model simulations from various international groups are defined, analysed and compared following approaches pioneered by the Global Atmospheric Systems Studies (GASS) and International WMO Cloud Modelling Workshop initiatives, and with regular advice from colleagues involved in both activities.

The next workshop, planned for 2-6 April 2017 in Bad Honnef, Germany, will investigate on the basis of the model simulations which observations are most promising to identify signatures of aerosol effects on clouds and precipitation despite the large natural variability. This research benefits from experience with “observations systems simulation experiments” (OSSE). In all discussions, ACPC modelers and observationalists interact closely to address the individual components of aerosols, clouds, precipitation, and radiation, as well as their interactions.