Abstract View
Exploring Sources of Ultrafine and Nucleation Mode Particles
Alyssa Zimmerman, Markus Petters, NICHOLAS MESKHIDZE, North Carolina State University
Abstract Number: 373
Working Group: Urban Aerosols
Abstract
Ultrafine particles with diameters less than 100 nm suspended in the air are a topic of interest in air quality and climate sciences. Sub-10 nm particles are of additional interest due to their health effects and contribution to particle growth processes. Ambient measurements were carried out at North Carolina State University in Raleigh, NC between April to June 2019 and November 2019 to May 2020 to investigate the temporal variability of size distribution and number concentration of ultrafine particles. A mobile lab was deployed between March and May 2020 to characterize the spatial distribution of sub-10 nm particle number concentration.
The three key findings, that may be important for the near ground‐level particle number concentration and size distribution for a typical SE US city, will be discussed in this presentation:
1. New particle formation (NPF) and growth events, both Class A and Class B, were observed regularly (about 5 per month). Particles exhibited prolonged modal growth over 8 hr, which may indicate a regional scale nucleation event. The NPF events happen under relatively clean as well as polluted conditions (particularly Class B events).
2. The spatial patterns observed during both stationary and mobile deployments suggest that multiple temporally stable and spatially confined anthropogenic point sources are responsible for direct emissions of nucleation mode particles. These sub-10 nm sized particles dominated number concentration during periods of low planetary boundary layer height and low solar radiation. These particles were present during both the regular and the NPF days.
3. The slight reduction in ultrafine particle number concentration was observed during reduced economic activity caused by the COVID-19 pandemic. However, this reduction was within interseasonal variability and significantly smaller than a ~75% reduction in the average daily traffic.