Aggregation of ice-nucleating macromolecules from Betula pendula pollen determines ice nucleation efficiency

• DOI: 10.5194/egusphere-2024-752
• Publication Date: 2024-04-29T06:27:45Z
• Authors: Florian Wieland; Nadine Bothen; Ralph Schwidetzky; Teresa M. Seifried; Paul Bieber; Ulrich Pöschl; Konrad Meister; Mischa Bonn; Janine Fröhlich-N...; Hinrich Grothe
• Keywords: Ice nucleus; Frost (temperature); Supercooling; Betula pendula

Abstract. Various aerosols, including mineral dust, soot, and biological particles, can act as ice nuclei, initiating the freezing of supercooled cloud droplets. Cloud droplet significantly impacts properties and, consequently, weather climate. Some nuclei exhibit exceptionally high nucleation temperatures close to 0 °C. Ice Nucleating Macromolecules (INMs) found on pollen are typically not considered among most active nuclei. Still, they be highly abundant, especially for species such Betula pendula, a widespread birch tree in boreal forest. Recent studies have shown that certain tree-derived INMs activity above -10 °C, suggesting could play more significant role atmospheric processes than previously understood. Our study reveals three distinct INM classes at -8.7 -15.7 -17.4 °C present B. pendula. Freeze-drying freeze-thaw cycles noticeably alter their capability, results heat treatment, size, chemical analysis indicate correspond size-varying aggregates, with larger aggregates nucleating higher agreement previous fungal bacterial nucleators. findings suggest pendula potentially important because prevalence temperatures.