I am YESP scientist in the modeling department at the Institute of Climate and Energy Systems - Troposphere (ICE-3). My expertise is in modeling atmospheric multiphase chemistry on local, regional, and global scales. To accomplish my research, I develop and apply atmospheric chemistry models of varying complexity to study how natural and anthropogenic emissions influence the composition of the atmosphere, air quality and related health implications for our current and future society. I specialize in modeling the atmospheric impact of extreme emission events, such as particularly intense wildfires.
The ongoing climate crisis leads to severe social and economic stresses. The greatest uncertainty in our understanding of climate change originates from the interaction between clouds and aerosols. Aerosols can directly be emitted into the atmosphere by natural phenomena and human activities. Similarly, these activities emit organic compounds that, through chemical processing, can lead to the formation of so-called secondary organic aerosols. In the atmosphere, aerosols can scatter light and act as cloud nuclei. This means they can alter cloud properties like the size of cloud droplets, influencing the cloud's reflectivity and lifetime. These aspects perturb the Earth’s radiative budget and influence its climate. Furthermore, chronic and acute exposure to elevated concentrations of ambient aerosols poses significant health risks.
Chemical compounds emitted into the atmosphere contain elements in relatively low oxidation states. Their oxidation is crucial to determining their impact on atmospheric composition and can occur in the gas and aqueous phases. I am an expert in representing multiphase chemical kinetics in and across these phases, which is essential to advancing our understanding of atmospheric oxidants and aerosol precursors.
To this end, I developed the Jülich Aqueous-phase Mechanism of Organic Chemistry. My study demonstrated, for the first time, that detailed aqueous-phase chemistry can be represented in cloud droplets in global model applications. Subsequently, I expanded the capabilities of our in-house atmospheric chemistry model, MESSy, to explicitly represent aqueous-phase chemistry in deliquescent aerosols. Compared to other atmospheric chemistry models, this feature makes our model unique.
Wildfires are a growing concern regarding climate change and air quality. They are known for their significant impact on the composition of the atmosphere. In regions with ample fuel sources and hot, dry, or windy conditions, surface fires can lead to high-intensity crown fires and frequent downwind spotting. In addition to significant carbon dioxide and aerosol emissions, biomass burning events are characterized by substantial non-carbon dioxide emissions, which encompass a wide range of species. These emissions significantly influence atmospheric chemistry on a regional to global scale.
My research focuses on modeling the impact of extreme wildfires on atmospheric composition and air quality in the lower and upper troposphere/lower stratosphere. Specifically, I examined the effects of the 2015 Indonesian peatland fires. I demonstrated that these surface fires significantly impacted the regional oxidation capacity and that short-lived compounds were quickly transported to higher altitudes due to the ongoing Asian monsoon. Currently, I am investigating the impact of the 2019 Williams Flats Fires in Washington, USA.
Globally, chronic and acute exposures to elevated concentrations of ambient fine particulate matter represent a significant risk factor for non-communicable diseases and increased premature mortality. Typical morbidities include chronic rhinosinusitis, respiratory diseases, and worsening cardiovascular health due to oxidative stress and systematic inflammation. In my research I focus on modelling air quality and its consequences for human health. In a recent study published in the Nature Partner Journal Clean Air, I investigate the great success of the U.S. Clean Air Act, which the US passed in 1970 to reduce air pollution. We find that its implementation avoids about 300,000 annual premature death related to air pollution. We further find that the adherence to the 2016 Paris Agreement would reduce the premature death related to air pollution by one third. A related interview to this study can be found here.
