SSNPF

Seasonal/spatial vertical NPF variation study

1 March 2025 - 30 November 2025

Lead Scientist: Jie Zhang

Observatory: AMF (ARM Mobile Facility 1) - CRG

New Particle Formation (NPF) is one of the largest sources of atmospheric particles (in terms of number concentrations) and significantly contributes to the formation of cloud condensation nuclei in the troposphere. Presently, the limited scope of vertical measurements, coupled with spatial diversity constraints, limits a more precise and detailed comprehension of NPF and its atmospheric behaviors. Thus, there is an urgent need for concurrent observations and studies of NPF events at higher altitudes across a range of atmospheric conditions from rural to urban environments. Such extensive research is essential to fully grasp NPF's role in climate dynamics and more confidently project future climate change.

The overlapping deployments of the first ARM Mobile Facility (AMF1) and the third ARM Mobile Facility (AMF3) in 2025, with focusing on the aerosol-cloud interaction under different atmospheric conditions, present a unique and valuable opportunity to address this scientific gap, after combining the proposed ARM tethered ballon system (TBS) deployments from this campaign. Specifically, AMF1 is set to be stationed in the Baltimore region for the Coast-Urban-Rural Gradient Atmospheric Experiment (CoURAGE) with atmospheric conditions heavily influenced by urban emissions. In contrast, the AMF3 deployment in Bankhead National Forest (BNF) is under warmer, more humid conditions with notable biogenic emissions. Here, we propose this “Seasonal/Spatial Vertical NPF Variation Study” campaign with TBS deployments for vertical NPF measurement, to explore the mechanisms behind the vertical NPF and their spatial diversity, as well as the subsequent effects on CCN in varied atmospheric environments, after integrating the surface AMF1 and AMF3 NPF measurements, and the 3- dimensional model simulations.

We aim to address several fundamental scientific questions: (a) What are the mechanisms for the aloft NPF and its interaction with the surface NPF and/or aerosol concentration? (b) What is the seasonal/spatial variation of these mechanisms and interactions? (c) What is the contribution of these surface and aloft NPF events to the regional CCN concentrations as well as their related indirect radiative effect? (d) What is the seasonal/spatial variation for the contributions and the related indirect radiative effect?