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Understanding atmospheric aerosols is important to understanding the effects of aerosol on climate, atmospheric composition, air quality, and human health. There are high uncertainties in the current global climate predictions largely because of our limited understanding of aerosols and clouds.
Nucleation is a gas to particle conversion process in which solid or liquid aerosol particles form directly from gas phase species and thus is an important step in the chain reactions that lead to cloud formation, but the mechanisms are poorly understood. Current nucleation theories are also hampered by high uncertainties because of the lack of laboratory and atmospheric measurements. Our research is designed to overcome some of these shortcomings in the field to yield a better understanding of aerosol formation processes in the atmosphere.
Kent State University Atmospheric Chemistry Group is equipped with a series of world-class, state of art chemical and aerosol instruments, including two Chemical Ionization Mass Spectrometers (CIMS) that measure low concentrations of sulfuric acid with negative ion chemistry and measure ammonia and organic compounds with proton transfer (PTR-MS) chemical ionization, and three Scanning Mobility Particle Spectrometers (SMPS).
These projects are currently supported by several major research grants from NSF, NOAA, and Ohio Board Regents (OBR).
1. Kinetics Studies of Aerosol Nucleation: Laboratory Studies
We study chemical processes of nucleation under atmospherically relevant conditions, with two high-sensitivity CIMS to directly measure low concentrations of aerosol precursors (sulfuric acid, ammonia and organic compounds). Our objectives are to investigate the role of ammonia and organic compounds that play in aerosol nucleation and growth. These results will provide information of immediate use to modelers who are trying to predict aerosol and cloud condensation nuclei concentrations.
2. Atmospheric Observations of New Particle Formation
2.1. Long-term observations of new particle formation: In the relatively less polluted atmosphere (Kent, Ohio)
We have been conducting long-term, ground-based observations of new particle formation at Kent, OH, by directly measuring sulfuric acid and ammonia with CIMS (starting from January 2006). Using this unique and rich datasets of aerosol sizes and aerosol precursors, we investigate aerosol nucleation processes in the lower troposphere.
As a part of the PROPHET 2009 CABINEX field campaign conducted in the University of Michigan Biological Station during June - August 2009, we study new particle formation processes in the remote northern American forest environment.
In the collaboration with the University of Denver
and the National Center for Atmospheric Research (NCAR),
we performed aerosol size measurements on a new NSF / NCAR High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) GV aircraft using DU aerosol instruments in NCAR.
This is the first science mission that took place on the GV aircraft.
There are hundreds of organic compounds in the atmosphere and some condensable organics can contribute to aerosol formation. We develop CIMS techniques to detect those low-volatility organic compounds with proton transfer (PTR-MS) chemical ionization.
4. Measurements of Henry’s law constants of volatile organic compounds relevant to atmospheric chemistry
Henry’s law constant (solubility) is an important chemical property to understand the roles that organic compounds may play in aerosol and cloud formation. We use a gas chromatography-flame ionization detector (GC-FID) to detect solubility of volatile organic compounds (VOCs) in water and model organic solutions.
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