New insights into the size-resolved chemical mixing state of atmospheric dust: Impacts on cloud formation and optical properties
Abstract
With increasing dust storms due to climate change and land use changes in arid regions, the influence of dust on atmospheric processes is increasing. Understanding the impact of dust on cloud formation and optical properties is imperative to predicting future climate change. The chemical composition of different dust source regions globally varies, and thus, the impacts on cloud formation properties and optical properties also vary. In situ measurements of atmospheric dust particles using on-line single particle mass spectrometry provide unique insights into dust sources, size distributions, and both the degree and type of atmospheric processing. Aerosol time-of-flight mass spectrometry (ATOFMS) was first used by our research group to probe the composition of Asian dust particles during ACE-Asia in 2001. In these studies onboard the R/V Ronald H. Brown, a strong effect of dust mineralogy on heterogeneous reaction processes of dust with atmospheric oxidants was clearly observed. These initial studies inspired further lab and field studies aimed at developing a better understanding of the heterogeneous processing of dust, as well as impacts on cloud formation and optical properties. Current lab studies are probing how the effects of dust mineralogy and aging processes affect the ability of dust particles to activate as cloud condensation nuclei (CCN). In addition, further field studies have probed dust particles in a variety of environments including dust suspended in the Asian outflow on Jeju Island (Korea) and most recently aircraft measurements in flights over Wyoming and Colorado. The goal of both lab and field studies involves determining how effectively dust particles activate as cloud and ice nuclei, and provide insights into the differences in chemistry that determine which particles that activate versus those that do not. The general types of dust observed in different regions of the world, as well as the types of reaction processes these particles undergo in the atmosphere, impact the cloud forming and optical properties of dust. New measurements of the optical properties of dust particles as a function of size and chemistry will be presented, directly linking the mixing state of dust with other species, such as black carbon, to optical properties measured with the single-particle mass spectrometer. Results from these field and lab studies will be summarized in this presentation and related to the global impact of dust on climate.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.A42A..04P
- Keywords:
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- 0305 Aerosols and particles (0345;
- 4801;
- 4906);
- 0320 Cloud physics and chemistry;
- 0321 Cloud/radiation interaction;
- 0365 Troposphere: composition and chemistry;
- 0368 Troposphere: constituent transport and chemistry