Preprints
https://doi.org/10.5194/acp-2021-804
https://doi.org/10.5194/acp-2021-804

  25 Oct 2021

25 Oct 2021

Review status: this preprint is currently under review for the journal ACP.

Observations of particle number size distributions and new particle formation in six Indian locations

Mathew Sebastian1, Sobhan Kumar Kompalli2, Anil V. Kumar3, Sandhya Jose4,5, S. Suresh Babu2, ‪Govindan Pandithurai3, Sachidanand Singh4,5, Rakesh K. Hooda6, Vijay K. Soni7, Jeffrey R. Pierce8, Ville Vakkari6,9, Eija Asmi6, Daniel M. Westervelt10,11, Antti-Pekka Hyvärinen6, and Vijay Punjaji Kanawade1 Mathew Sebastian et al.
  • 1Centre for Earth, Ocean and Atmospheric Sciences, University of Hyderabad, Hyderabad, India
  • 2Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram, India
  • 3Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune, India
  • 4CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi, India
  • 5Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
  • 6Finnish Meteorological Institute, Erik Palmenin Aukio 1, Helsinki, Finland
  • 7India Meteorological Department, Ministry of Earth Sciences, New Delhi, India
  • 8Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA
  • 9Atmospheric Chemistry Research Group, Chemical Resource Beneficiation, North-West University, Potchefstroom, South Africa
  • 10Lamont-Doherty Earth Observatory of Columbia University, New York, USA
  • 11NASA Goddard Institute for Space Studies, New York, NY, USA

Abstract. Atmospheric new particle formation (NPF) is a crucial process driving aerosol number concentrations in the atmosphere; it can significantly impact the evolution of atmospheric aerosol and cloud processes. This study analyses at least one year of asynchronous particle number size distributions at six different locations in India. We also analyze the frequency of NPF and its contribution to cloud condensation nuclei (CCN) concentrations. We found that the NPF frequency has a considerable seasonal variability. At the measurement sites analyzed in this study, NPF frequently occurs in March–May (pre-monsoon, about 21 % of the days) and is the least common in October–November (post-monsoon, about 7 % of the days). Considering the NPF events in all locations, the particle formation rate (JNUC) varied by more than an order of magnitude (0.01–0.6 cm−3 s−1) and the growth rate (GRNUC) by about three orders of magnitude (0.2–17.2 nm h−1). We found that JNUC was higher by nearly an order of magnitude during NPF events in urban areas than mountain sites. GRNUC did not show a systematic difference. Our results showed that NPF events could significantly modulate the shape of particle number size distributions and CCN concentrations in India. The contribution of a given NPF event to CCN concentrations was the highest in urban locations (4.3 × 103 cm−3 per event and 1.2 × 103 cm−3 per event for 50 nm and 100 nm, respectively) as compared to mountain-background sites (2.7 × 103 cm−3 per event and 1.0 × 103 cm−3 per event). To better understand atmospheric NPF and its contribution to CCN concentrations, we would need long-term observational data from various diverse environments in India, aided with regional model simulations to help interpret field observations.

Mathew Sebastian et al.

Status: open (until 15 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-804', Anonymous Referee #1, 12 Nov 2021 reply

Mathew Sebastian et al.

Mathew Sebastian et al.

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Short summary
Characteristics of particle number size distributions and new particle formation at six sites in India were analyzed. We found that particle size distributions show strong seasonal variation. We report a high frequency of new particle formation in pre-monsoon (spring). We found that the cloud condensation nuclei concentration increase from new particle formation events was ~3 times higher in urban locations than in mountain background locations.
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