Public Abstract

DE-SC0025873: New particle formation, subsequent particle growth, and their contribution to cloud condensation nuclei population in southeast U.S.

Award Status: Active

Institution: Washington University, St Louis, MO
UEI: L6NFUM28LQM5
DUNS: 068552207

Most Recent Award Date: 04/22/2025
Number of Support Periods: 1
PM: Stehr, Jeffrey

Current Budget Period: 04/15/2025 - 10/14/2026
Current Project Period: 04/15/2025 - 04/14/2028
PI: Wang, Jian

Supplement Budget Period: N/A

Public Abstract

New particle formation, subsequent particle growth, and their contribution to cloud condensation nuclei population in southeast U.S. Jian Wang, Washington University in St. Louis (Principal Investigator) Lu Xu, Washington University in St. Louis (Co-Principal Investigator) New particle formation (NPF) and particle growth represent a major source of cloud condensation nuclei (CCN), contributing to about half of CCN globally by model estimation. Despite recent advances, our understanding of NPF and particle growth in the Southeast United States (U.S.) remains inadequate. The Southeast is characterized by distinct landscapes and vegetation types differing from boreal forests and urban cities where NPF has been extensively studied. This contrast raises questions on the transferability of conclusions from other regions to the Southeast. Currently, there are significant knowledge gaps in nucleation mechanisms, the species and processes that drive the particle growth, and the contribution of NPF to CCN in the Southeast U.S. These knowledge gaps are largely due to a lack of both long-term observations and comprehensive measurements of precursors as well as nucleation and condensing species. The overarching goal of this project is to quantify and achieve a molecular-level understanding of NPF, particle growth, and the contribution of NPF to CCN population in the Southeast. Our proposed research will leverage long-term Atmospheric Radiation Measurement (ARM) Mobile Facility #3 (AMF3) observations and comprehensive measurements during two Intensive Operation Periods (IOPs) at the Bankhead National Forest (BNF) site in Alabama. We will analyze the long-term AMF3 observations to (1) quantify NPF frequency, particle formation rate, and particle further growth rate, and (2) conduct statistical analyses regarding the dependence of these quantities on air mass type, meteorological and synoptic conditions. To elucidate the NPF processes and particle growth at a molecular level, we will deploy state-of-the-art instruments during the two IOPs. Measurements during the two IOPs will allow us to quantify the nucleation rate, characterize nucleating species, and identify nucleation mechanisms. Subsequently, we will investigate the species and processes driving the initial growth from stable clusters to ~3 nm particles and the further particle growth from ~3 nm towards CCN size. Building upon the findings from the above analyses, we will probe the underlying mechanisms behind the low NPF frequency in the Southeast U.S. during summer. Finally, we will examine the particle hygroscopicities during NPF events and quantify the contribution of NPF to CCN population in this region using long-term AMF3 measurements. Overall, our proposed activities entail a comprehensive analysis of the entire process, from the nucleation of gas molecules to the growth of new particles into CCN sizes. The project outcomes will advance the molecular-level understanding of NPF, particle growth, and their contribution to CCN population in the Southeast. These processes are crucial in controlling the CCN population and aerosol-cloud interactions. The results from this project are also anticipated to aid in the development of physically based parameterizations for accurately representing the aforementioned processes and assessing aerosol indirect effects in global models. Furthermore, our proposed activities in the Southeast., a region different from boreal forests and urban cities where NPF has been extensively studied, have the potential to uncover unique phenomena and open new research avenues.

New particle formation, subsequent particle growth, and their contribution to cloud condensation nuclei population in southeast U.S.

Jian Wang, Washington University in St. Louis (Principal Investigator)

Lu Xu, Washington University in St. Louis (Co-Principal Investigator)

New particle formation (NPF) and particle growth represent a major source of cloud condensation nuclei (CCN), contributing to about half of CCN globally by model estimation. Despite recent advances, our understanding of NPF and particle growth in the Southeast United States (U.S.) remains inadequate. The Southeast is characterized by distinct landscapes and vegetation types differing from boreal forests and urban cities where NPF has been extensively studied. This contrast raises questions on the transferability of conclusions from other regions to the Southeast. Currently, there are significant knowledge gaps in nucleation mechanisms, the species and processes that drive the particle growth, and the contribution of NPF to CCN in the Southeast U.S. These knowledge gaps are largely due to a lack of both long-term observations and comprehensive measurements of precursors as well as nucleation and condensing species.

The overarching goal of this project is to quantify and achieve a molecular-level understanding of NPF, particle growth, and the contribution of NPF to CCN population in the Southeast. Our proposed research will leverage long-term Atmospheric Radiation Measurement (ARM) Mobile Facility #3 (AMF3) observations and comprehensive measurements during two Intensive Operation Periods (IOPs) at the Bankhead National Forest (BNF) site in Alabama. We will analyze the long-term AMF3 observations to (1) quantify NPF frequency, particle formation rate, and particle further growth rate, and (2) conduct statistical analyses regarding the dependence of these quantities on air mass type, meteorological and synoptic conditions. To elucidate the NPF processes and particle growth at a molecular level, we will deploy state-of-the-art instruments during the two IOPs. Measurements during the two IOPs will allow us to quantify the nucleation rate, characterize nucleating species, and identify nucleation mechanisms. Subsequently, we will investigate the species and processes driving the initial growth from stable clusters to ~3 nm particles and the further particle growth from ~3 nm towards CCN size. Building upon the findings from the above analyses, we will probe the underlying mechanisms behind the low NPF frequency in the Southeast U.S. during summer. Finally, we will examine the particle hygroscopicities during NPF events and quantify the contribution of NPF to CCN population in this region using long-term AMF3 measurements. Overall, our proposed activities entail a comprehensive analysis of the entire process, from the nucleation of gas molecules to the growth of new particles into CCN sizes.

The project outcomes will advance the molecular-level understanding of NPF, particle growth, and their contribution to CCN population in the Southeast. These processes are crucial in controlling the CCN population and aerosol-cloud interactions. The results from this project are also anticipated to aid in the development of physically based parameterizations for accurately representing the aforementioned processes and assessing aerosol indirect effects in global models. Furthermore, our proposed activities in the Southeast., a region different from boreal forests and urban cities where NPF has been extensively studied, have the potential to uncover unique phenomena and open new research avenues.