Abstract:
A small fraction of enigmatic atmospheric aerosol particles is capable of catalysing the formation of ice in the atmosphere. These particles therefore limit the extent to which a cloud can supercool, leading to cloud glaciation and precipitation. These special particles, known as ice nucleating particles, have a disproportionate impact on the properties of of cloud types ranging from deep convective systems in the tropics through to persistent stratus cloud at the poles. In this talk I will focus on one particular cloud system type: shallow cold clouds across the worlds oceanic mid- to high-latitudes. These clouds cover vast areas and exert a substantial cloud radiative effect, yet their representation in models is extremely poor. In fact, the specific cloud types associated with model biases have been identified to be the shallow stratus and cumulus clouds in the cold sector of cyclone systems. We have shown that the concentration of ice nucleating particles is a first order driver for the properties of these clouds and their role in climate feedbacks. However, the concentration, temperature spectra and sources of ice nucleating particles relevant for these specific clouds types is poorly defined. I will discuss our recent laboratory, field and modelling research on INP sources in the mid- to high-latitudes relevant for these specific cloud systems. Finally, I will summarise what the key remaining questions are and speculate on how changes in future ice nucleating particle emissions might lead to a positive climate feedback.
What is the Joint Oslo Seminar (JOS):
Atmospheric and climate sciences have a stronghold in Oslo among the four institutions University of Oslo, the Meteorological Institute, CICERO and NILU. This joint seminar invites renowned international experts to contribute to an informal series of lectures, meant to create interaction with the Oslo atmospheric and climate science community on recent highlights and analysis in the field. All seminars will be held on Thursdays (Noon -1pm) and lunch (sandwiches) will be served on a “first-come-first-served”-basis.