Ground-based Observations of Temporal Variation of the Cosmic-Ray Spectrum during Forbush Decreases
Observations of temporary Forbush decreases (FDs) in the Galactic cosmic-ray (GCR) flux due to the passage of solar storms are useful for space-weather studies and alerts. Here, we introduce techniques that use global networks of ground-based neutron monitors and muon detectors to measure variations...
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2025-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/add7d1 |
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| author | W. Mitthumsiri D. Ruffolo K. Munakata M. Kozai Y. Hayashi C. Kato P. Muangha A. Sáiz P. Evenson P.-S. Mangeard J. Clem S. Seunarine W. Nuntiyakul N. Miyashita R. Kataoka A. Kadokura S. Miyake K. Iwai H. Menjo E. Echer A. Dal Lago M. Rockenbach N. J. Schuch J. V. Bageston C. R. Braga H. K. Al Jassar M. M. Sharma N. Burahmah F. Zaman M. L. Duldig I. Sabbah T. Kuwabara |
| author_facet | W. Mitthumsiri D. Ruffolo K. Munakata M. Kozai Y. Hayashi C. Kato P. Muangha A. Sáiz P. Evenson P.-S. Mangeard J. Clem S. Seunarine W. Nuntiyakul N. Miyashita R. Kataoka A. Kadokura S. Miyake K. Iwai H. Menjo E. Echer A. Dal Lago M. Rockenbach N. J. Schuch J. V. Bageston C. R. Braga H. K. Al Jassar M. M. Sharma N. Burahmah F. Zaman M. L. Duldig I. Sabbah T. Kuwabara |
| author_sort | W. Mitthumsiri |
| collection | DOAJ |
| description | Observations of temporary Forbush decreases (FDs) in the Galactic cosmic-ray (GCR) flux due to the passage of solar storms are useful for space-weather studies and alerts. Here, we introduce techniques that use global networks of ground-based neutron monitors and muon detectors to measure variations of GCR rigidity spectra in space during FDs by (1) fitting count rate decreases for power-law rigidity spectra in space with anisotropy up to second order and (2) using the “leader fraction” derived from a single neutron monitor. We demonstrate that both provide consistent results for hourly spectral index variations for five major FDs, and they agree with daily space-based data when available from the Alpha Magnetic Spectrometer. We have also made the neutron monitor leader fraction publicly available in real time. This work verifies that ground-based observations can be used to precisely monitor GCR spectral variation over a wide range of rigidities during space-weather events, with results in real time or from short-term postanalysis. |
| format | Article |
| id | doaj-art-28cdd32bb1204bfa87fff61ef9285105 |
| institution | OA Journals |
| issn | 2041-8205 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj-art-28cdd32bb1204bfa87fff61ef92851052025-08-20T02:32:08ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019861L710.3847/2041-8213/add7d1Ground-based Observations of Temporal Variation of the Cosmic-Ray Spectrum during Forbush DecreasesW. Mitthumsiri0https://orcid.org/0000-0002-3776-072XD. Ruffolo1https://orcid.org/0000-0003-3414-9666K. Munakata2https://orcid.org/0000-0002-2131-4100M. Kozai3https://orcid.org/0000-0002-3948-3666Y. Hayashi4https://orcid.org/0000-0002-0890-0607C. Kato5https://orcid.org/0000-0002-4913-8225P. Muangha6A. Sáiz7https://orcid.org/0000-0001-7771-4341P. Evenson8https://orcid.org/0000-0001-7929-810XP.-S. Mangeard9https://orcid.org/0000-0003-4865-6968J. Clem10https://orcid.org/0000-0001-5681-6883S. Seunarine11https://orcid.org/0000-0003-3272-6896W. Nuntiyakul12https://orcid.org/0000-0002-1664-5845N. Miyashita13https://orcid.org/0009-0006-3569-7380R. Kataoka14https://orcid.org/0000-0001-9400-1765A. Kadokura15https://orcid.org/0000-0002-6105-9562S. Miyake16https://orcid.org/0000-0002-3067-655XK. Iwai17https://orcid.org/0000-0002-2464-5212H. Menjo18https://orcid.org/0000-0001-8466-1938E. Echer19https://orcid.org/0000-0002-8351-6779A. Dal Lago20https://orcid.org/0000-0002-4361-6492M. Rockenbach21https://orcid.org/0000-0002-9737-9429N. J. Schuch22https://orcid.org/0000-0002-7720-6491J. V. Bageston23https://orcid.org/0000-0003-2931-8488C. R. Braga24https://orcid.org/0000-0003-1485-9564H. K. Al Jassar25https://orcid.org/0000-0002-4486-237XM. M. Sharma26https://orcid.org/0000-0002-2090-351XN. Burahmah27https://orcid.org/0000-0003-3691-6806F. Zaman28https://orcid.org/0000-0002-4807-4258M. L. Duldig29https://orcid.org/0000-0001-7463-8267I. Sabbah30https://orcid.org/0000-0002-7037-322XT. Kuwabara31https://orcid.org/0000-0001-6584-9054Department of Physics, Faculty of Science, Mahidol University , Bangkok 10400, Thailand ; david.ruf@mahidol.ac.thDepartment of Physics, Faculty of Science, Mahidol University , Bangkok 10400, Thailand ; david.ruf@mahidol.ac.thDepartment of Physics, Shinshu University , Matsumoto, Nagano 390-8621, Japan ; kmuna00@shinshu-u.ac.jpPolar Environment Data Science Center , Joint Support-Center for Data Science Research, Research Organization of Information and Systems, Tachikawa, JapanDepartment of Physics, Shinshu University , Matsumoto, Nagano 390-8621, Japan ; kmuna00@shinshu-u.ac.jpDepartment of Physics, Shinshu University , Matsumoto, Nagano 390-8621, Japan ; kmuna00@shinshu-u.ac.jpDepartment of Physics, Faculty of Science, Mahidol University , Bangkok 10400, Thailand ; david.ruf@mahidol.ac.thDepartment of Physics, Faculty of Science, Mahidol University , Bangkok 10400, Thailand ; david.ruf@mahidol.ac.thBartol Research Institute, Department of Physics and Astronomy, University of Delaware , Newark, DE, USABartol Research Institute, Department of Physics and Astronomy, University of Delaware , Newark, DE, USABartol Research Institute, Department of Physics and Astronomy, University of Delaware , Newark, DE, USADepartment of Physics, University of Wisconsin River Falls , River Falls, WI 54022, USADepartment of Physics and Materials Science, Faculty of Science, Chiang Mai University , Chiang Mai 50200, ThailandDepartment of Physics, Shinshu University , Matsumoto, Nagano 390-8621, Japan ; kmuna00@shinshu-u.ac.jpScience and Technology Group, Okinawa Institute of Science and Technology , Okinawa, JapanPolar Environment Data Science Center , Joint Support-Center for Data Science Research, Research Organization of Information and Systems, Tachikawa, Japan; National Institute of Polar Research , Tachikawa, JapanNational Institute of Technology (KOSEN) , Gifu College, Gifu, JapanInstitute for Space-Earth Environmental Research, Nagoya University , Nagoya, JapanInstitute for Space-Earth Environmental Research, Nagoya University , Nagoya, JapanNational Institute for Space Research , São José dos Campos, BrazilNational Institute for Space Research , São José dos Campos, BrazilNational Institute for Space Research , São José dos Campos, BrazilSouthern Space Coordination, National Institute for Space Research , Santa Maria-RS, BrazilSouthern Space Coordination, National Institute for Space Research , Santa Maria-RS, BrazilThe Johns Hopkins University Applied Physics Laboratory , Laurel, MD, USAPhysics Department, Kuwait University , Kuwait City, KuwaitPhysics Department, Kuwait University , Kuwait City, KuwaitDepartment of Physics, College of Science, Kuwait University , Sabah AlSalem University City, KuwaitDepartment of Physics, College of Science, Kuwait University , Sabah AlSalem University City, KuwaitSchool of Natural Sciences, University of Tasmania , Hobart, AustraliaDepartment of Applied Sciences, College of Technological Studies , Public Authority for Applied Education and Training, Shuwaikh, KuwaitBartol Research Institute, Department of Physics and Astronomy, University of Delaware , Newark, DE, USAObservations of temporary Forbush decreases (FDs) in the Galactic cosmic-ray (GCR) flux due to the passage of solar storms are useful for space-weather studies and alerts. Here, we introduce techniques that use global networks of ground-based neutron monitors and muon detectors to measure variations of GCR rigidity spectra in space during FDs by (1) fitting count rate decreases for power-law rigidity spectra in space with anisotropy up to second order and (2) using the “leader fraction” derived from a single neutron monitor. We demonstrate that both provide consistent results for hourly spectral index variations for five major FDs, and they agree with daily space-based data when available from the Alpha Magnetic Spectrometer. We have also made the neutron monitor leader fraction publicly available in real time. This work verifies that ground-based observations can be used to precisely monitor GCR spectral variation over a wide range of rigidities during space-weather events, with results in real time or from short-term postanalysis.https://doi.org/10.3847/2041-8213/add7d1Forbush effectCosmic raysSpace weatherCosmic ray detectorsSolar-terrestrial interactions |
| spellingShingle | W. Mitthumsiri D. Ruffolo K. Munakata M. Kozai Y. Hayashi C. Kato P. Muangha A. Sáiz P. Evenson P.-S. Mangeard J. Clem S. Seunarine W. Nuntiyakul N. Miyashita R. Kataoka A. Kadokura S. Miyake K. Iwai H. Menjo E. Echer A. Dal Lago M. Rockenbach N. J. Schuch J. V. Bageston C. R. Braga H. K. Al Jassar M. M. Sharma N. Burahmah F. Zaman M. L. Duldig I. Sabbah T. Kuwabara Ground-based Observations of Temporal Variation of the Cosmic-Ray Spectrum during Forbush Decreases The Astrophysical Journal Letters Forbush effect Cosmic rays Space weather Cosmic ray detectors Solar-terrestrial interactions |
| title | Ground-based Observations of Temporal Variation of the Cosmic-Ray Spectrum during Forbush Decreases |
| title_full | Ground-based Observations of Temporal Variation of the Cosmic-Ray Spectrum during Forbush Decreases |
| title_fullStr | Ground-based Observations of Temporal Variation of the Cosmic-Ray Spectrum during Forbush Decreases |
| title_full_unstemmed | Ground-based Observations of Temporal Variation of the Cosmic-Ray Spectrum during Forbush Decreases |
| title_short | Ground-based Observations of Temporal Variation of the Cosmic-Ray Spectrum during Forbush Decreases |
| title_sort | ground based observations of temporal variation of the cosmic ray spectrum during forbush decreases |
| topic | Forbush effect Cosmic rays Space weather Cosmic ray detectors Solar-terrestrial interactions |
| url | https://doi.org/10.3847/2041-8213/add7d1 |
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