AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Physical Characterization and Modeling of Particle Nucleation and Particle Growth in the Central U.S.
CHARLES STANIER, Robert Bullard, Can Dong, Ashish Singh, University of Iowa
Abstract Number: 508 Working Group: Remote and Regional Atmospheric Aerosols
Abstract New particle formation (NPF) and growth control the concentration of aerosols and cloud droplets, which in turn play an important role in both global climate and human health. While atmospheric nucleation has been examined world-wide in many urban as well as remote forested locations, it has not been studied extensively in the non-forested Midwestern United States, where SO2 from coal-fired power plants as well as ammonia from agricultural activity are prevalent. Furthermore, the annual average particles counts, seasonal pattern of particle counts and nucleation activity, and ratio of sulfur to ammonia is changing as SO2 emissions in the region decrease and agricultural patterns change. Ten months of aerosol size distributions measured from 3 nm to 5 microns at Bondville, IL, a station with a long-term record of many radiation, meteorology, and aerosol variables, are reported and related to the long-term record at the site. Enhanced particle numbers in the nuclei size range (3-10 nm) followed by particle growth to larger sizes occurred during approximately 41% of the study days during summer and fall months. Average diurnal patterns of size-resolved particles at this site have 3-10 nm particles peaking at 10 AM local standard time, and total particle concentrations peaking at 11 AM local standard time. Monthly particle growth rates are reported. Finally, the strengths and weaknesses of the nucleation explicit version of the WRF-Chem regional coupled meteorology / atmospheric chemistry model to reproduce the absolute number, timing, frequency and size of the nuclei and ultrafine particles are discussed.