AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Physical and Model-based Characterization of Ultrafine Particle Size Distributions, Nucleation, and Particle Growth in the Central US
CAN DONG, Robert Bullard, Ashish Singh, Yuyan Cui, Alma Hodzic, Charles Stanier, University of Iowa
Abstract Number: 517 Working Group: Aerosol Physics
Abstract New particle formation (NPF) is a frequently observed phenomenon worldwide. Ten months (July 2013 to June 2014) of continuous measurements of particle number size distribution were performed at a rural Midwestern location of Bondville, IL. A twenty-year record of particle number observations is also available at the site. The site is characterized by a large decrease in regional sulfur dioxide (SO2) emissions over the twenty-year period. Observation data show that NPF occurred during each month of the field campaign, with different frequency and intensities. NPF events were more frequently observed in spring (65.3% of classifiable days) and summer (58.8% of classifiable days). Observed growth rates were highest in summer with a median value of 3.49 nm/h. The minimum growth rate occurred in winter. These measurements are combined with the NPF-explicit WRF-Chem model to investigate the model’s skill at reproducing the influence of SO2 on NPF, as well as diel patterns, nucleation intensity, growth rates, and seasonal patterns in these features. Results from sensitivity model simulations on the growth rates of newly formed particles from condensable oxidation products of biogenic gases are discussed.