What fuels banana-type particle growth events?

Kangming Xu

Most particles in the atmosphere are produced by so-called new particle formation (NPF) events that occur in many different environments throughout the atmosphere. These events largely control the abundance of the particles that influence the radiative balance of the Earth system through the indirect aerosol effect. The evolution of particle size with time in NPF events often shows a characteristic banana-like shape. There is increasing evidence that semi-volatile organic compounds (SVOCs) play a significant role in fuelling particle growth during these events. However, the physical and chemical mechanisms behind NPF are still poorly understood.
In this project we propose to identify the nature (molecular weight, elemental composition) of those SVOCs that contribute most to NPF in different environments. Taking advantage of new technological tools, we could be able to measure hundreds – at this point largely unknown – SVOCs simultaneously in the particle and the gas phase, and thus identify those SVOCs that trigger NPF events. This research aims at elucidating the processes leading to enhanced concentrations of cloud condensation nuclei, which represents a strong, yet poorly understood feedback in the climate system.