The formation and growth of ultrafine particles in two contrasting environments: a case study

Kompalli, Sobhan Kumar ; Babu, Suresh S. ; Moorthy, Krishna K. ; Gogoi, Mukunda M ; Nair, Vijayakumar S. ; Chaubey, Jai Prakash (2014) The formation and growth of ultrafine particles in two contrasting environments: a case study Annales Geophysicae, 32 . pp. 817-830. ISSN 0992-7689

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Formation of ultrafine particles and their subsequent growth have been examined during new particle formation (NPF) events in two contrasting environments under varying ambient conditions, one for a tropical semi-urban coastal station, Trivandrum, and the other for a high-altitude free-tropospheric Himalayan location, Hanle. At Trivandrum, NPF bursts took place in the late evening/night hours, whereas at Hanle the burst was a daytime event. During the nucleation period, the total number concentration reached levels as high as ~ 15 900 cm−3 at Trivandrum, whereas at Hanle, the total number concentration was ~ 2700 cm−3, indicating the abundant availability of precursors at Trivandrum and the pristine nature of Hanle. A sharp decrease was associated with NPF for the geometric mean diameter of the size distribution, and a large increase in the concentration of the particles in the nucleation regime (Dp 25 nm). Once formed, these (secondary) aerosols grew from nucleation (diameter Dp 25 nm) to Aitken (25 ≤ Dp ≤ 100 nm) regime and beyond, to the accumulation size regimes (100 ≤ Dp ≤ 1000 nm), with varying growth rates (GR) for the different size regimes at both the locations. A more rapid growth ~ 50 nm h−1 was observed at Trivandrum, in contrast to Hanle where the growth rate ranged from 0.1 to 20 nm h−1 for the transformation from the nucleation to accumulation – a size regime that can potentially act as cloud condensation nuclei (CCN). The faster coagulation led to lifetimes of 1 h for nucleation mode particles.

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Source:Copyright of this article belongs to European Geosciences Union.
ID Code:98714
Deposited On:02 Apr 2015 07:41
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