Creamean et al. (2025) Long-term measurements of ice nucleating particles at Atmospheric Radiation Measurement (ARM) sites worldwide

Identification

• Journal: Earth system science data
• Year: 2025
• Date: 2025-12-09
• Authors: Jessie M. Creamean, Carson C. Hume, M. Vázquez, Adam Theisen
• DOI: 10.5194/essd-17-6943-2025

Research Groups

• Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
• Argonne National Laboratory, Lemont, Illinois, USA

Short Summary

This paper presents one of the most comprehensive publicly available datasets of immersion-mode ice nucleating particle (INP) concentrations, generated using a single analytical method through the U.S. Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM) user facility. Collected across diverse global environments over long periods, this dataset reveals distinct seasonal and site-specific differences in INP concentrations and types, providing critical constraints for aerosol-cloud interaction models.

Objective

• To present and describe a comprehensive, long-term, and spatially extensive dataset of immersion-mode ice nucleating particle (INP) concentrations and types, collected using a standardized method across various Atmospheric Radiation Measurement (ARM) sites.
• To facilitate broader scientific utilization of this dataset by experimentalists and modelers to improve understanding of aerosol-cloud interactions and their impacts on cloud microphysics and precipitation formation.

Study Configuration

• Spatial Scale: Global network of ARM sites, including fixed observatories, mobile facility deployments (AMFs), and vertically-resolved tethered balloon system (TBS) operations. Locations span agricultural plains (Southern Great Plains, SGP C1, 36.607° N, 97.488° W, 314 m a.m.s.l.), Arctic coastlines (North Slope of Alaska, NSA C1, 71.323° N, 156.615° W, 8 m a.m.s.l.; Oliktok Point, OLI M1, 70.495° N, 149.886° W, 2 m a.m.s.l.), high-elevation mountain sites (Surface Atmosphere Integrated Field Laboratory, SAIL, GUC M1, 38.956° N, 106.988° W, 2886 m a.m.s.l.; GUC S2, 38.898° N, 106.94° W, 3137 m a.m.s.l.), marine regions (Eastern Pacific Cloud Aerosol Precipitation Experiment, EPCAPE, EPC M1, 32.867° N, 117.257° W, 7 m a.m.s.l.; Cloud And Precipitation Experiment at kennaook, CAPE-k, KCG S3, 40.683° S, 144.690° E, 67 m a.m.s.l.), urban areas (TRacking Aerosol Convection interactions ExpeRiment, TRACER, HOU M1, 29.670° N, 95.059° W, 8 m a.m.s.l.; HOU S3, 29.328° N, 95.741° W, 20 m a.m.s.l.; Coast-Urban-Rural Atmospheric Gradient Experiment, CoURAGE, CRG M1, 39.317° N, 76.586° W, 45 m a.m.s.l.; CRG S2, 39.422° N, 77.21° W, 158 m a.m.s.l.), and forested regions (Bankhead National Forest, BNF M1, 34.342° N, 87.338° W, 293 m a.m.s.l.). TBS deployments provide vertical profiles up to approximately 1500 m a.m.s.l.
• Temporal Scale: Long-term continuous measurements, with the most extensive record being nearly 5 years at SGP C1 (October 2020 – ongoing). Mobile facility deployments typically span 6–18 months, with some up to 5–8 years. Intensive Observational Periods (IOPs) involve daily sampling for shorter durations (e.g., AGINSGP, TRACER, CAPE-K-AEROSOLS). Filter collection frequency varies from daily to approximately every 6 days.

Methodology and Data

• Models used: None explicitly used for generating the data presented in this paper. The dataset is intended to support model development and evaluation efforts.
• Data sources:
  • Sampling: Filter samples collected from ambient air at fixed observatories, mobile facilities, and via miniaturized samplers on tethered balloon systems.
  • Instrumentation: Ice Nucleation Spectrometer (INS, also known as the Colorado State University Ice Spectrometer) for quantifying immersion-mode INP number concentrations. The INS measures freezing temperature spectra between 0 °C and approximately -27 to -30 °C.
  • Sample Processing: Filters are re-suspended in 0.1 µm-filtered deionized water (7–10 mL). Dilution series are prepared and dispensed into 96-well PCR trays (50 µL aliquots).
  • INP Composition Analysis: Thermal treatment (heating to 95 °C for 20 minutes) and hydrogen peroxide (H2O2) digestion (10 % H2O2, 95 °C for 20 minutes under UVB illumination, followed by catalase neutralization) are applied to subsets of samples to classify heat-labile (biological), bio-organic, and inorganic (mineral) INP types.
  • Data Processing and Quality Control: Automated data processing using the Open-source Library for Automating Freezing Data acQuisition from Ice Nucleation Spectrometer (OLAF DaQ INS) software. Comprehensive quality assurance/quality control (QA/QC) protocols are implemented for field sampling, laboratory procedures, and instrument calibration. INP concentrations are calculated following Vali (1971), with 95 % binomial confidence intervals.
  • Archiving: Final data products are archived on the ARM Data Discovery portal in NetCDF and/or ASCII-CSV formats.

Main Results

• A comprehensive, publicly available dataset of immersion-mode INP concentrations is presented, collected using a single, standardized analytical method (INS) across diverse environments.
• The dataset includes total INP concentrations and selectively treated samples, allowing for the classification of biological, organic, and inorganic INP types.
• A continuous 5-year record from the SGP C1 site reveals a pronounced seasonal pattern, with INP concentrations peaking during fall/winter months (October–January) at warmer freezing temperatures (> -10 °C).
• At SGP C1, biological INPs are dominant at -15 °C, with inorganic components increasing in summer, likely due to agricultural dust. At -25 °C, organic and inorganic INPs contribute more, but biological INPs remain overall dominant.
• Intercomparisons across diverse sites (EPC, GUC, HOU, OLI, SGP) demonstrate distinct seasonal and site-specific differences in INP concentrations at -10 °C and -20 °C.
  • At -10 °C, SGP shows winter/fall peaks, GUC shows summer peaks (vegetation), and OLI (Arctic) shows summer peaks (biological productivity). EPC (marine) exhibits the lowest concentrations, while urban and rural HOU sites show similar concentrations.
  • At -20 °C, OLI shows significantly lower INP levels than SGP, suggesting a more prominent source of mineral dust or cold-temperature-active organic INPs at SGP compared to the Arctic coastal OLI site, with OLI concentrations becoming comparable to EPC.

Contributions

• Provides the most comprehensive publicly available dataset of immersion-mode INP concentrations using a single, standardized analytical method, ensuring consistency and comparability across diverse global sites.
• Offers extensive long-term (up to 5 years continuous) and spatially resolved INP measurements, including vertically-resolved data, which are crucial for understanding aerosol-cloud interactions and constraining Earth system models.
• Includes data on INP composition (biological, organic, inorganic) through standardized chemical treatments, enabling detailed source attribution studies.
• Establishes a robust, transparent, and quality-controlled data processing pipeline (OLAF DaQ INS) and makes the data readily accessible to the broader scientific community, encouraging wider utilization for observational studies, mechanistic research, and model development.
• Highlights distinct seasonal and regional INP variability, offering valuable insights into atmospheric drivers and sources across different climatic regimes.

Funding

• Office of Biological and Environmental Research within the U.S. Department of Energy (DOE) through the Atmospheric Radiation Measurement (ARM) user facility (contract no. 0F-60173).

Citation

@article{Creamean2025Longterm,
  author = {Creamean, Jessie M. and Hume, Carson C. and Vázquez, M. and Theisen, Adam},
  title = {Long-term measurements of ice nucleating particles at Atmospheric Radiation Measurement (ARM) sites worldwide},
  journal = {Earth system science data},
  year = {2025},
  doi = {10.5194/essd-17-6943-2025},
  url = {https://doi.org/10.5194/essd-17-6943-2025}
}