Aerosol Composition and Ice Nucleation Potential Across Altitudes in a Forested Mountain Environment: Observations from Crested Butte

NURUN NAHAR LATA, Jessie Creamean, Thomas Hill, Paul DeMott, Russell Perkins, Sonia Kreidenweis, Zezhen Cheng, Darielle Dexheimer, Julia Laskin, Daniel Feldman, Swarup China, Pacific Northwest National Laboratory

     Abstract Number: 615
     Working Group: Aerosol Chemistry

Abstract
Understanding the vertical variability of aerosol particles and their ice nucleation potential (INP) is critical for improving our knowledge of cloud and precipitation processes. This study examines the composition and mixing state of aerosol particles collected in July 2022 at the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) site in Crested Butte Mountain (elevation: 2886 meters). Aerosol sampling was conducted using the Size and Time-resolved Aerosol Collector (STAC) and the “IcePuck” filter sampler deployed with a tethered balloon system (TBS), enabling offline chemical and ice nucleation analyses. The CSU Ice Spectrometer was used to determine the immersion freezing properties of collected particles over a temperature range of 0 to –30 °C. Multimodal micro-spectroscopy techniques—including computer-controlled scanning electron microscopy (CC-SEM) with energy-dispersive X-ray spectroscopy and scanning transmission X-ray microscopy with near-edge X-ray absorption fine structure (STXM/NEXAFS)—were applied to characterize particle size, chemical composition, and mixing state. Analyses revealed variations in size-resolved composition and mixing state across altitudes, particularly during pre-convection and light precipitation periods. Dominant particle classes included carbonaceous material, sulfate, potassium-rich particles, and minor dust. These findings provide valuable insight into the chemical and morphological complexity of aerosols in mountainous environments and their potential role in ice formation.