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

Abstract

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 1 year of asynchronous particle number size distributions from 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 (JSDS) varied by more than 2 orders of magnitude (0.001–0.6 cm−3 s−1) and the growth rate between the smallest detectable size and 25 nm (GRSDS-25 nm) by about 3 orders of magnitude (0.2–17.2 nm h−1). We found that JSDS was higher by nearly 1 order of magnitude during NPF events in urban areas than mountain sites. GRSDS 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 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, respectively). We emphasize that the physical and chemical pathways responsible for NPF and factors that control its contribution to CCN production require in situ field observations using recent advances in aerosol and its precursor gaseous measurement techniques.

Measurement report: Contribution of atmospheric new particle formation to ultrafine particle concentration, cloud condensation nuclei and radiative forcing: Results from five-year observations in Central Europe

“…However, the site-to-site comparison of Jnuc implied that stronger anthropogenic influences could lead to a higher Jnuc, which was consistent with previous studies (e.g. Bousiotis et al, 2021b;Sebastian et al, 2022). Due to relatively fewer anthropogenic emissions, the Jnuc at BOS was notably lower than those observed in LTR and LWE.…”

Numerical simulation and evaluation of global ultrafine particle concentrations at the Earth's surface

“…We derived UFP concentrations from PSDs measured by groups involved in the present study in India, China and the Amazon rainforest. In India PSDs were measured in Delhi (Thamban et al, 2021), Mahabaleshwar and Hyderabad (both Sebastian et al, 2022). Measurements in China were taken in Shanghai (unpublished), Beijing (Liu et al, 2020), Lin'an (Shen et al, 2022) and Gucheng (Li et al, 2021).…”

“…Annual average UFP O concentrations in Delhi (Thamban et al, 2021), Mahabaleshwar and Hyderabad (both from Sebastian et al, 2022) were obtained from a collaboration with groups performing field measurements. Additionally, we adopted daily measurements of PSDs from Gani et al (2020) for the Indian Institute of Technology Delhi (IITD), which we converted to UFP concentrations and combined with the measurements of Thamban et al (2021).…”

Elucidating the mechanisms of atmospheric new particle formation in the highly polluted Po Valley, Italy

“…In theoretical calculations, it is generally assumed that NPF events are more favorable to occur in clean conditions due to lower concentrations of preexisting aerosols, which act as condensational sink (CS), capable of scavenging the gaseous precursors (Kulmala et al, 2017). However, frequent NPF events have also been observed in heavily polluted urban environments (Kulmala et al, 2017;Du et al, 2022), including megacities in China (Chu et al, 2019;Yao et al, 2018) and India (Sebastian et al, 2022). This phenomenon might be associated with the overestimations of CS (Du et al, 2022) and the involvement of multiple precursors in the complex polluted environment (Cai et al, 2023b).…”