The paper summarizes the state of the art in simulating aerosols and their processes within global atmospheric models. Forty co-authors contributed to these results and we all promote our paper.

The paper is the outcome of a community effort within the AeroCom initiative¹. AEROCOM is an open international initiative of scientists interested in the advancement of the understanding of global aerosol and its impact on climate.

“In this paper we have identified the processes and parameters, which deserve a high priority in order to reduce the uncertainty of the climatic impact attributed to aerosols and their effects on human health.”

The AeroCom initiative has enhanced interactions within the aerosol scientific community. The publication on the Internet of the simulation results has led to the identification of weak components and has provoked the improvement of specific process parameterizations. This paper is one of the papers describing the AeroCom results (see further references on the AeroCom website).

We analyze the life cycles of aerosol particles as simulated by 16 global atmospheric models. The differences of the model simulations have been established for sources and sinks, particle sizes, water uptakes, and concentrations and transport.

In this paper we have identified the processes and parameters, which deserve a high priority in order to reduce the uncertainty of the climatic impact attributed to aerosols and their effects on human health.

I had the chance to work at the Laboratoire des Sciences de l’Environnement et du Climat, in Gif Sur Yvette, France, where the AeroCom project is co-coordinated. I greatly enjoyed the close cooperation with many colleagues.

Since the end of my two-year contract I have continued to be strongly involved in AeroCom, but have not been funded to continue this research.

Through the AeroCom project I realized the worth (and fun) of doing synergistic work and I took great pleasure in coordinating a community effort in order to advance scientific understanding. My current position allows me to combine project coordination and research in the European FP6 project GEOMON².

Generally, I would like to understand the most important processes that cause the established model differences, and to constrain model ensembles with observations. New model intercomparison activities in which I am involved (HTAP and AC&C) concern both aerosols and chemical tracers in a consistent framework. They offer the possibility to jointly investigate these tracers.

At the same time, access to a multitude of observational data is facilitated through the projects like GEOMON, which is embedded in the GEO process. In particular, I am fortunate to be working with the CALIPSO data, a new space-borne LIDAR that delivers vertical aerosol profiles that can be used to better constrain simulated transport patterns.

Aerosols have important impacts both on air quality and on global climate. Reducing the uncertainty of monitoring and predicting their fate in the atmosphere is of relevance for our society.