Ice nucleation in aerosols containing biomolecules

生物气溶胶对大气中冰成核粒子的数量虽小，但贡献很大。由此形成的冰对云微物理至关重要，并在云的辐射特性和降水中发挥作用。然而，由于缺乏对非均相冰成核过程和有效成核剂性质的了解，目前在气候模式中的应用受到限制。此外，颗粒间不同的成核能力阻碍了冻结时间依赖性的测定。本研究的目的是利用模型生物分子制备具有均匀成核能力的冰成核粒子样品，并研究成核效率作为表面几何和化学的函数。成核速率将通过液滴冷冻试验和适应悬浮单液滴冷冻的电动平衡来测量。这将有助于理解大气条件下冰的成核机制。

Biological aerosols represent a small but efficient contribution to populations of ice nucleating particles in the atmosphere. The resultant ice formation is crucial to cloud microphysics and plays a role in cloud radiative properties and precipitation. However, applications to climate models are currently limited by a lack of understanding of the heterogeneous ice nucleation process and the properties of effective nucleating agents. Furthermore, differing nucleating abilities between particles hinder the determination of the time dependence of freezing. The aim of this research is to use model biomolecules to produce samples of ice nucleating particles with uniform nucleating ability and to study nucleating efficiency as a function of surface geometry and chemistry. Nucleation rates will be measured by droplet freezing assays and by adaptation of an electrodynamic balance for levitated single droplet freezing. This will aid understanding of the ice nucleation mechanism in atmospheric conditions.