Measurement instruments for the detection and collection of biological aerosol particles at the TROPOS research station in Melpitz (Poleno on the left and the Hirst pollen trap in green) in front of the background of a raining cumulus congestus cloud.
The Bioaerosol team (led by Dr. Susan Hartmann) aims to achieve a better understanding of the interactions between the biosphere and the atmosphere within the Earth system. To this end, the team detects, characterizes, and investigates aerosol particles of biological origin. The focus is on particles such as pollen, spores, bacteria, algae, and their components, which, despite their small contribution to the total aerosol mass, play important climate-relevant roles.
A key focus of the work is bioaerosol detection. Here, we investigate biological particles such as pollen and spores and their spatial and temporal distribution. Our goal is clear: we aim to better understand their role in cloud formation and their impact on air quality.
Another central aspect is the investigation of the functionality of biological ice-nucleating particles (INP). Biological INP catalyze the freezing of water droplets particularly efficiently at temperatures just below 0 °C, alter the properties of mixed-phase clouds, and thus contribute to precipitation formation [1]. Ice-nucleating macromolecules such as specific proteins or polysaccharides [2] play a key role in this process. Our team applies classical nucleation theory to parameterize the freezing behavior of bioaerosols for use in cloud-resolving models.
A third focus of the Bioaerosol team is worldwide field measurements of biological INP in the atmosphere. Several studies have been conducted in the climate hotspot region of the Arctic and in the southern part of South America. In the Arctic, a pronounced seasonal cycle of biological INP was identified, with the biological fraction being highest in summer [3]. In contrast, no seasonal cycle of biological INP was observed in South America, and at −10 °C the biological fraction accounted for 90% of the total INP population [4].