Ice nucleation particles (INPs) are responsible for freezing supercooled liquid water droplets above homogeneous freezing in the atmosphere. However, heterogenous ice nucleation is a rare process, yet has important implication for precipitation and for the lifetime of a cloud. Previous work in our group suggests that field-collected dissolved organic matter (DOM) is an efficient ice nucleating particle (INP) in the immersion freezing mode. Indeed, we observed that the 50% frozen fraction of DOM (at 20 mg of C/L, relevant to cloud water concentrations) nucleates water as high as -8 °C compared to pure water (18.2 MΩ·cm) which nucleates at -25 °C in our home-built drop freezing experimental setup.
Speaking of our home-built drop freezing technique, we are currently characterizing our new drop Freezing Ice Nuclei Counter (FINC) and looking forward to sharing our inter comparison data with other drop freezing instruments.
Current project leaders: Master students Killian Brennan and Anna Miller
We are interested in understanding which subcomponents of field-collected DOM are responsible for nucleation at higher temperatures, with the goal of identifying new INPs and new parameters to predict INPs.
Current project leader: Master student Anna Miller
As a subcomponent of DOM, lignin can also act as an ice nucleating macromolecule. We are investigating its IN activity as well as how different lab treatments and atmospheric processes are impacting this activity.
Current project leader: Internship student Sophie Bogler