Cloud chamber and single-particle mass spectrometry studies of aerosol-cloud interactions
Authors
Mikhail S. Pekour — Pacific Northwest National Laboratory
Daniel James Cziczo — Massachusetts Institute of Technology
Gourihar Kulkarni — Pacific Northwest National Laboratory
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Category
Aerosol-Cloud-Radiation Interactions
Description
Mass spectra of ice crystal residual particles. (a) Spectrum obtained at the Storm Peak Laboratory in the Colorado Rocky Mountains when ambient aerosol was exposed to cirrus cloud conditions within an ice chamber. (b) Spectrum obtained at the Jungfraujoch Research Station of an ice crystal from a mixed-phase cloud. (c) Spectrum obtained when Arizona Test Dust was exposed to cirrus cloud conditions within a large cloud chamber. Reproduced from D. J. Cziczo, et al. 2009. "Inadvertent Climate Modification Due to Anthropogenic Lead." <i>Nature Geosciences</i>, doi:10.1038/ngeo499.
It is now highly certain that anthropogenic activities have caused a warming of the Earth’s atmosphere. The addition of small aerosol particles has offset, to some extent, the warming attributed to greenhouse gases via the so-called "direct effect." Aerosol particles can also act as sites of condensation and lead to the formation of clouds, and this is termed an "indirect effect." Particles that form droplets are known as cloud condensation nuclei (CCN), and those that form ice are known as ice nuclei (IN). Our group has undertaken studies using commercial and custom "cloud chambers," which mimic cloud formation conditions in the laboratory and at remote field sites. Droplets or ice crystals that are formed are then separated and analyzed with single-particle mass spectrometry to determine the initial aerosol size and composition and the role played by anthropogenic components. The effect of anthropogenic coatings is considered. Lead, an anthropogenic component that can have a significant impact on both precipitation and the Earth’s radiative balance through perturbations to ice formation, will also be discussed.
