Solar energetic particle (SEP) events, driven by solar flares and coronal mass ejections (CMEs), are occasionally accompanied by ground level enhancements (GLEs), detected by neutron monitors. While GLEs represent only a subset of SEP events, their occurrence may provide insight into the acceleration and propagation mechanisms of SEPs. In this study, we conducted a statistical analysis of 122 SEP events from 1997 to 2023, including 16 events associated with GLE and 106 without, using elemental composition data from the ACE/SIS instrument and X-ray fluence data from GOES/XRS. The results show that SEP events with GLE exhibit significantly higher fluences of SIS elements (He, C, N, O, Ne, Mg, Si) than those without, particularly at high energy channels. Notably, the fluences of carbon and oxygen were particularly enhanced in SEP events associated with GLE, suggesting a potential role for these elements in the generation of GLEs. A strong correlation (average r ≈ 0.75) was observed between the X-ray fluence of associated solar flares and the elemental fluences in SEP events with GLE, whereas a weaker correlation (average r ≈ 0.32–0.40) was found for SEP events without GLE. These findings imply that the presence of a GLE is linked to distinct acceleration conditions and enhanced ion production, particularly of light ions with large charge-to-mass ratios. This study contributes to a better understanding of SEP composition, GLE-associated mechanisms, and their relevance to space weather forecasting and radiation hazard assessments.

Introduction
Data
Results
    The ACE/SIS Elemental Fluences
    Comparison of the Normalized Fluence of Six Elements Observed by ACE/SIS
    X-ray Fluences of Solar Flares Associated with SEP Events
Summary and Discussions
    Elemental Intensities and Fluences Observed by ACE/SIS
    Comparison of Normalized Fluences of Six Elements
    X-ray Fluences of Solar Flares Associated with SEP Events
    Discussion
Acknowledgments
References

• Jongil Jung(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Young-Sil Kwak(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea, Department of Astronomy and Space Science, University of Science and Technology, Daejeon 34113, Republic of Korea)
• Yu Yi(Department of Earth, Environmental and Space Convergence Science, Chungnam National University, Daejeon 34134, Republic of Korea)
• Suyeon Oh(Department of Earth Science Education, Chonnam National University, Gwangju 61186, Republic of Korea) Corresponding author