Our main research interests revolve around the physicochemical properties of atmospheric aerosol (relative stable suspensions of liquid or solid particles in a gas with diameters of 2 nm – 100 µm) and its sources with subsequent impacts for air quality and climate.

Figure above displays typical chemically complex aerosol particles collected on substrates for microscopic imaging. (A) Particles from the free troposphere collected in the eastern North Atlantic (China et al., 2017). (B) Urban aerosol collected in Los Angeles (Wang et al., 2012). (C) Ambient particles collected in the Sacramento, California area (Knopf et al., 2014). (D) Aerosol collected close to a waster incinerator in Mexico City (Knopf et al., 2014).

The composition of aerosol particles defines their roles in a multitude of atmospheric processes such as the global radiative budget (climate), cloud formation, the hydrological cycle, and air quality, the latter also impacting health-related issues. In fact, the effect of aerosol particles on the global radiative budget and thus climate has been identified as the largest unknown to predict future climate changes.

To advance our understanding of these processes our group is currently addressing the following research topics:

• Examination of the aerosol composition by means of micro-spectroscopic and chemical imaging analyses.
• Determination of the governing parameters that allow ice-nucleating particles to initiate heterogeneous ice nucleation.
• Assessing the multiphase chemical reaction kinetics between gaseous oxidants and particulate matter to determine the chemical transformation of particles during atmospheric transport.
• Understanding the biological processes in ocean water that lead to the physicochemical characteristics of sea spray aerosol.
• Development of novel analytical instruments for aerosol research including an unmanned aerial vehicle for assessing atmospheric conditions and for collection of aerosol particles.
• Current laboratory instrumentation.

Please click on these themes to learn more about our projects.