EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2026-4905 Measurement Report: Tethered Balloon Observations of Vertically Resolved Aerosol Size Distributions during the U.S. DOE ARM CoURAGE and BNF Campaigns Guo Yuhang 1 Kuang Chongai 2 Dexheimer Darielle 3 Shrivastava Manish https://orcid.org/0000-0002-9053-2400 4 Enekwizu Ogochukwu 2 Wang Yang https://orcid.org/0000-0002-0543-0443 5 Mao Jingbo 1 Luo Gan https://orcid.org/0000-0002-9588-7008 1 Yu Fangqun https://orcid.org/0000-0001-8862-4835 1 Zhang Jie https://orcid.org/0000-0003-2935-9220 1 Atmospheric Sciences Research Center, University at Albany, State University of New York, Albany, NY 12203, USA Environmental Science and Technologies Department, Brookhaven National Laboratory, Upton, New York Environmental Science Division, Sandia National Laboratories, Albuquerque, New Mexico, USA Pacific Northwest National Laboratory, Richland, Washington, USA Department of Chemical, Environmental and Materials Engineering, University of Miami, Coral Gables, Florida, 33146, United States 14 09 2026 2026 1 21 Copyright: © 2026 Yuhang Guo et al. 2026 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-4905/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-4905/egusphere-2026-4905.pdf

The vertical distribution of aerosol particle size is important for aerosol transport, atmospheric mixing, and surface air quality, yet vertically resolved aerosol size-distribution observations remain limited. Here, a miniature scanning electrical mobility spectrometer (mSEMS) was deployed aboard the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Tethered Balloon System (TBS) during the 2025 CoURAGE and Bankhead National Forest (BNF) campaigns. Aerosol particle number size distributions were measured from the surface to approximately 1200 m AGL over a diameter range of 10–300 nm. A total of 63 aerosol profiles were obtained, providing one of the most comprehensive vertically resolved aerosol size-distribution datasets collected using a tethered balloon platform. Within the planetary boundary layer (PBL), observations revealed vertically homogeneous profiles associated with efficient turbulent mixing and heterogeneous profiles reflecting incomplete mixing, surface influences, or elevated particle layers. Profiles extending above the PBL further resolved distinct aerosol transitions into the lower free troposphere and nocturnal residual layer. A representative case on 27 March 2025 at BNF documented the evolution of particles associated with a regional new particle formation and growth event: particles formed during the previous day were preserved overnight within the residual layer, vertically reorganized during early-morning boundary-layer development, and subsequently remixed throughout the daytime mixed layer. These observations demonstrate strong coupling between boundary-layer evolution and aerosol vertical structure and establish an observational framework linking aerosol size distributions, residual-layer storage, and atmospheric mixing. The dataset provides valuable constraints for understanding lower-tropospheric aerosol life cycles and evaluating atmospheric chemistry and transport models.