Atmospheric Visibility and PM10 as Indicators of New Particle Formation in an Urban Environment.
It is well-known that new particle formation (NPF) in the atmosphere is inhibited by pre-existing particles in the air that act as condensation sinks to decrease the concentration and, thus, the supersaturation of precursor gases. In this study, we investigate the effects of two parameters-atmospheric visibility, expressed as the particle backscatter coefficient (BSP), and PM10 particulate mass concentration-on the occurrences of NPF events in an urban environment where the majority of precursor gases originate from motor vehicle and industrial sources. This is the first attempt to derive direct relationships between these two parameters and the occurrence of NPF. NPF events were identified from data obtained with a neutral cluster and air ion spectrometer over 245 days within a calendar year. Bayesian logistic regression was used to determine the probability of observing NPF as functions of BSP and PM10. We show that the BSP at 08 h on a given day is a reliable indicator of an NPF event later that day. The posterior median probability of observing an NPF event was greater than 0.5 (95%) when the BSP at 08 h was less than 6.8 Mm(-1).
International Laboratory for Air Quality and Health, Queensland University of Technology , GPO Box 2434, Brisbane, QLD 4001, Australia.
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Jayaratne
International Laboratory for Air Quality and Health, Queensland University of Technology , GPO Box 2434, Brisbane, QLD 4001, Australia.
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Clifford
International Laboratory for Air Quality and Health, Queensland University of Technology , GPO Box 2434, Brisbane, QLD 4001, Australia.
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Morawska
D000393:Air Pollutants / Q000032:analysis; D001272:Atmosphere / Q000737:chemistry*; D001499:Bayes Theorem; D002947:Cities; D016015:Logistic Models; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D011336:Probability; D013997:Time Factors
D000393:Air Pollutants; D052638:Particulate Matter