Southern Ocean Ice Nucleating Particles: Sources, Composition, and Model Parameterizations

Kathryn Moore, Colorado State University
EVS Seminar Graphic

Supercooled liquid clouds are ubiquitous over the Southern Ocean (SO), even to temperatures below -20 °C, and comprise a large fraction of marine boundary layer clouds. Earth system models and reanalysis products have struggled to reproduce the observed cloud phase distribution and occurrence of cloud ice in the region. Recent simulations determined the microphysical representation of ice nucleation and growth has a large impact on these properties, however, measurements of SO ice nucleating particles (INPs) to validate simulations are sparse. In this talk, I will present measurements of aerosols and INPs from simultaneous aircraft and ship campaigns conducted in austral summer 2018, which include the first in situ INP observations in and above cloud in the region. I will evaluate existing INP parameterizations and methods to estimate required aerosol inputs, discuss the variation in INP and aerosol composition with altitude, and present recent work assessing long-range versus local sources.