My research interests circle around small-scale atmospheric processes and how these act to form integrative properties of the climate system. I co-lead the Climate Dynamics working group with Jürgen Bader.

Special focus areas of my research are:

• Arctic climate with a focus on Arctic amplification of climate change. How come the Arctic changes faster than the global mean? Why is the Arctic climate so variable? Which are the key processes responsible, and how does the Arctic climate link to the global climate system? 
• Climate sensitivity to an external perturbation is determined by a series of  climate change feedback mechanisms, for example involving changes in atmospheric water vapor, clouds and surface albedo by altering the planetary albedo and emissivity. We study how these processes act to form the climate system response.
• Atmospheric turbulence and convection are central processes in forming the general circulation of the atmosphere as a response to solar heating. Here we study their roles in the climate system and how to best represent them as parameterizations in climate models.
• Cloud-aerosol-climate processes. Clouds need aerosol particles suitable to form cloud droplets on. Yet, cloud processes and precipitation are also the major sink of these aerosol particles. During an expedition into the pristine central Arctic Ocean, we found that there is frequently a lack of aerosol for clouds to form on, and that adding aerosol to the thin, but persistent, Arctic clouds would have a significant warming effect on surface climate (pdf). 
• Climate model development. I actively contribute to the development of our ECHAM climate model, which is our main research tool.

My interest in meteorology evolved from my passion which is sailplane gliding.