{
  "abstract": "Accurately quantifying regional anthropogenic CO₂ fluxes is fundamental to improving our understanding of the carbon cycle and for creating effective carbon mitigation policies, and the radiocarbon to total carbon ratio in atmospheric CO₂(Δ¹⁴CO₂) is a robust tracer of fossil fuel CO₂ that can discriminate between biogenic and fossil fuel CO₂ sources. NASA's Atmospheric Carbon and Transport-America (ACT-America) airborne mission between 2016 and 2019 aimed to improve the accuracy of regional greenhouse gas flux estimates, through refining our understanding and characterization of fluxes and flux uncertainties in models. Δ¹⁴CO₂ observations from 26 flights are presented for examining seasonal CO₂ source partitioning in the Mid-Atlantic USA. Observed variability in boundary layer CO₂ at timescales ranging from intra-day to seasonal was largely driven by biogenic CO₂ (CO2bio) variability that ranged from −19.7 ppm in summer to 16.2 ppm in fall, while fossil fuel CO₂ (CO2ff) variability remained at 3.3±2.0 ppm. Carbonyl sulfide uptake was well-correlated with CO2bio uptake, and examining this relationship, as well as that between CO₂ and CO2bio variability reinforces the seasonal extent of gross primary productivity response throughout ACT-America. We use airborne Δ¹⁴CO₂ flask sampling alongside in situ carbon monoxide measurements to calculate high-frequency CO2ff and evaluate the magnitude and diurnal variability of modeled CO2ff, deducing likely transport errors in an example flight. Although ACT-America CO2ff signals were attenuated due to the broad source regions sampled, results illustrate the value of Δ¹⁴CO₂ sampling and observation-based methodologies for regional CO₂ flux attribution, evaluation and improvement of modeled CO₂.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 10,
  "authors": [
    {
      "name": "Bianca C Baier"
    },
    {
      "name": "John B Miller"
    },
    {
      "name": "Colm Sweeney"
    },
    {
      "name": "Scott J Lehman"
    },
    {
      "name": "Chad Wolak"
    },
    {
      "name": "Joshua P Digangi"
    },
    {
      "name": "Yonghoon Choi"
    },
    {
      "name": "Kenneth Davis"
    },
    {
      "name": "Sha Feng"
    },
    {
      "name": "Thomas Lauvaux"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1xfyn1r6qn7cg.bib",
  "cited_by": 1,
  "doi": "10.5194/acp-25-10479-2025",
  "fulltext_url": null,
  "id": "1xfyn1r6qn7cg",
  "issns": [
    "1680-7316",
    "1680-7324"
  ],
  "landing_url": "https://hal.science/hal-05807002v1",
  "language": "en",
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "hal",
      "0.phys"
    ],
    [
      "hal",
      "1.phys.phys"
    ],
    [
      "hal",
      "2.phys.phys.phys-ao-ph"
    ],
    [
      "openalex",
      "2306|Atmospheric and Environmental Gas Dynamics"
    ]
  ],
  "openalex": "W4414182650",
  "pdf_url": "https://hal.science/hal-05807002/document",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-19",
  "publisher": "European Geosciences Union",
  "ris": "https://research.draconitic.com/paper/1xfyn1r6qn7cg.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:59Z",
      "native_id": "hal-05807002",
      "source": "hal",
      "url": "https://hal.science/hal-05807002v1"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "hal:2.phys.phys.phys-ao-ph",
      "subfield": "atmospheric"
    },
    {
      "field": "physics",
      "origin": "hal:0.phys",
      "subfield": "general"
    }
  ],
  "title": "Mid-Atlantic US observations of radiocarbon in CO 2 : fossil and biogenic source partitioning and model evaluation",
  "title_text": "Mid-Atlantic US observations of radiocarbon in CO 2 : fossil and biogenic source partitioning and model evaluation",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:17:59Z",
  "url": "https://research.draconitic.com/paper/1xfyn1r6qn7cg",
  "venue": "Atmospheric Chemistry and Physics",
  "versions": []
}