Ion and particle size distribution measurements in the Indo-Gangetic Plain: seasonal insights and challenges in new particle formation event characterization
- 1University of Helsinki (Helsinki, Finland)
- 2Indian Institute of Technology Delhi (New Delhi, India)
Abstract
New particle formation (NPF) is a major source of atmospheric aerosols and cloud condensation nuclei, influencing climate and air quality. In highly polluted regions such as the Indo-Gangetic Plain (IGP), where precursor concentrations and condensation sinks are among the highest globally, NPF remains poorly constrained due to limited observations of particles and ions in the sub–10 nm size range. Here, we investigated the occurrence and growth of NPF at a suburban IGP site (CAS-AO, Sonipat, Haryana), during May–December 2023 using ion (0.8–42 nm) and particle (2.5–42 nm) measurements together with meteorological data. NPF events were frequent during summer, occurring on 30 of 35 valid days in May–June (86 %), and were much less frequent during the winter/post-monsoon period, with 20 out of 73 valid days (28 %). The weak seasonal variability of ion concentrations relative to nucleation-mode particles suggests that particle survival and growth were strongly modulated by condensation sink, meteorology, and air-mass heterogeneity. The median daily condensation sink during 06:00–12:00 LT was lower on event days than on non-event days (0.0095 vs. 0.0292 s ⁻¹ ). Particle growth rates increased with size, from 14.7 nm h ⁻¹ in the 3–7 nm range to 19.0 nm h ⁻¹ in the 7–20 nm range, indicating size-dependent growth. In this high-background setting, pollution plumes and meteorological variability intermittently mask or distort NPF signals, limiting the direct applicability of both visual and automated classification methods and growth rate estimation methods. Our observations highlight that careful application and improvement of data analysis methods, along with precursor gas measurements, are required to better constrain nucleation processes by avoiding methodological sensitivity due to the complexity of aerosol dynamic processes in multi-source, high-condensation-sink environments, such as IGP.
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BibTeX
@article{srivastav2026particle,
title = {{Ion and particle size distribution measurements in the Indo-Gangetic Plain: seasonal insights and challenges in new particle formation event characterization}},
author = {Gaurav Kumar Srivastav and Aasif Ahmad Wagay and Janne Lampilahti and Jaswant Rathore and Ravi Kumar Kunchala and Dilip Ganguly and Markku Kulmala and Tuukka Petäjä and Pauli Paasonen and Roseline C. Thakur and Shahzad Gani},
journal = {Atmospheric Chemistry and Physics},
year = {2026},
month = oct,
doi = {10.5194/acp-26-14917-2026},
url = {https://acp.copernicus.org/articles/26/14917/2026/},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Ion and particle size distribution measurements in the Indo-Gangetic Plain: seasonal insights and challenges in new particle formation event characterization
AU - Gaurav Kumar Srivastav
AU - Aasif Ahmad Wagay
AU - Janne Lampilahti
AU - Jaswant Rathore
AU - Ravi Kumar Kunchala
AU - Dilip Ganguly
AU - Markku Kulmala
AU - Tuukka Petäjä
AU - Pauli Paasonen
AU - Roseline C. Thakur
AU - Shahzad Gani
PY - 2026
DA - 2026/10/23
JO - Atmospheric Chemistry and Physics
DO - 10.5194/acp-26-14917-2026
UR - https://acp.copernicus.org/articles/26/14917/2026/
AB - New particle formation (NPF) is a major source of atmospheric aerosols and cloud condensation nuclei, influencing climate and air quality. In highly polluted regions such as the Indo-Gangetic Plain (IGP), where precursor concentrations and condensation sinks are among the highest globally, NPF remains poorly constrained due to limited observations of particles and ions in the sub–10 nm size range. Here, we investigated the occurrence and growth of NPF at a suburban IGP site (CAS-AO, Sonipat, Haryana), during May–December 2023 using ion (0.8–42 nm) and particle (2.5–42 nm) measurements together with meteorological data. NPF events were frequent during summer, occurring on 30 of 35 valid days in May–June (86 %), and were much less frequent during the winter/post-monsoon period, with 20 out of 73 valid days (28 %). The weak seasonal variability of ion concentrations relative to nucleation-mode particles suggests that particle survival and growth were strongly modulated by condensation sink, meteorology, and air-mass heterogeneity. The median daily condensation sink during 06:00–12:00 LT was lower on event days than on non-event days (0.0095 vs. 0.0292 s ⁻¹ ). Particle growth rates increased with size, from 14.7 nm h ⁻¹ in the 3–7 nm range to 19.0 nm h ⁻¹ in the 7–20 nm range, indicating size-dependent growth. In this high-background setting, pollution plumes and meteorological variability intermittently mask or distort NPF signals, limiting the direct applicability of both visual and automated classification methods and growth rate estimation methods. Our observations highlight that careful application and improvement of data analysis methods, along with precursor gas measurements, are required to better constrain nucleation processes by avoiding methodological sensitivity due to the complexity of aerosol dynamic processes in multi-source, high-condensation-sink environments, such as IGP.
SN - 1680-7324
SN - 1680-7316
ER -