Laboratory and Field Studies of Cloud Formation
EMSL Project ID
39926
Abstract
The relationship between aerosol particles and the formation of clouds is among the most uncertain aspects in our current understanding of climate change. Warm clouds have been the most extensively studied, in large part because they are normally close to the Earth's surface and only contain large concentrations of liquid droplets. Ice and mixed-phase clouds have been less studied even though they have extensive global coverage and dominate precipitation formation. Because they require low temperatures to form, both cloud types are infrequently found at ground level resulting in more difficult field studies. Mixed phase and ice clouds, which are normally at much lower concentrations than the droplets found in warm clouds, require precise separation techniques and accurate identification of phase have proven difficult to study. As a result, the climatic impact of ice-containing clouds remains unresolved. We propose combined field and laboratory studies using single particle mass spectrometry and electron microscopy to elucidate the characteristics of particles that render them good or bad droplet and ice nuclei. Field studies of ice and droplet formation will be conducted at the Desert Research Institute's Storm Peak Laboratory located in north-central Colorado. Storm Peak is located at an elevation of over 3000 meters above sea level and is therefore within 'free tropospheric' airmasses (i.e., not subject to local emissions or the planetary boundary layer) . Two three-week studies are planned to take place during winter and spring 2011 in conjunction with DOE's deployment of the AMF2 for StormVEx. We will perform inertial and phase separation of ice crystals and liquid droplets from unactivated aerosol and initiate nucleation of ice crystals and liquid droplets using cloud chambers. We propose to characterize the aerosol particles within crystals and droplets on-line using single particle mass spectrometry and collect particles for off-line analysis using electron microscopy to determine the size and composition of the precursors to cloud formation. In collaboration with the StormVEx scientists our goal is to relate these findings to the cloud characteristics and the effect of anthropogenic activities. Based upon the field studies findings (i.e., what particles nucleate which phase) we propose to conduct a comprehensive set of laboratory experiments to determine: (1) The effect of particle composition on drop and ice formation; (2) The role of coatings on the activation of ice nuclei; (3) the effectiveness of anthropogenic particles as ice nuclei and; (4) the effect of surface morphology on heterogeneous ice formation.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2010-10-01
End Date
2013-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members