The NPF Effect on CCN Number Concentrations: A Review and Re‐Evaluation of Observations From 35 Sites Worldwide. Issue 19 (4th October 2021)

• Record Type: Journal Article
• Authors: Ren, Jingye; Chen, Lu; Fan, Tianyi; Liu, Jieyao; Jiang, Sihui; Zhang, Fang
• Is Part Of: Geophysical research letters. Volume 48:Issue 19(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-10-04
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL095190
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The new particle formation (NPF) effect on cloud condensation nuclei (CCN) differs from region to region and remains highly uncertain. Here, we re‐evaluate the NPF‐initiated enhancements in CCN number concentrations ( E_N CCN ) by compiling results from 35 field sites worldwide and five global models. We show the E_N CCN at sites close to the anthropogenic sources are more than 2‐fold as large as that at remote sites with supersaturations of 0.1%–1.0%. The enhancements anti‐correlate with the time scales for the new particles to grow to CCN size, which are 5–10 and 20–30 hr at polluted and remote sites, respectively. We further reveal that under polluted environments the condensational growth of new particles may be accelerated, leading to larger E_N CCN . The models fail to simulate the E_N CCN in polluted regions. Our study highlights the importance of parameterizing the time scale of NPF to affect CCN differently for remote and polluted regions in models. Plain Language Summary: New particle formation, which is a large source of cloud condensation nuclei (CCN), can affect regional weather and climate. Here we review and re‐evaluate the new particle formation (NPF) effect on CCN number concentrations ( N CCN ) by integrating and compiling results of multiple field sites and models mostly from previous studies. We reveal that the time scale for new particle growth, which highly depends on the degree of air pollution in different regions, regulate the NPF‐initiated N CCN enhancement at the sites. Therefore, it is important for model to parameterize the time scale of NPF to affect CCN differently for different regions. Key Points: The new particle formation (NPF) effect on N CCN are re‐evaluated by compiling results of 35 field sites worldwide and five global models The sites close to anthropogenic sources have greater NPF‐initiated N CCN enhancements, which are underestimated by the models The NPF‐initiated N CCN enhancements are inversely correlated with time scales of the new particle growth to CCN size