Large-amplitude Bidirectional Anisotropy of Cosmic-Ray Intensity Observed with Worldwide Networks of Ground-based Neutron Monitors and Muon Detectors in 2021 November
Issued Date
2022-10-01
Resource Type
ISSN
0004637X
eISSN
15384357
Scopus ID
2-s2.0-85150309598
Journal Title
Astrophysical Journal
Volume
938
Issue
1
Rights Holder(s)
SCOPUS
Bibliographic Citation
Astrophysical Journal Vol.938 No.1 (2022)
Suggested Citation
Munakata K., Kozai M., Kato C., Hayashi Y., Kataoka R., Kadokura A., Tokumaru M., Mendonça R.R.S., Echer E., Lago A.D., Rockenbach M., Schuch N.J., Bageston J.V., Braga C.R., Jassar H.K.A., Sharma M.M., Duldig M.L., Humble J.E., Sabbah I., Evenson P., Mangeard P.S., Kuwabara T., Ruffolo D., Sáiz A., Mitthumsiri W., Nuntiyakul W., Kóta J. Large-amplitude Bidirectional Anisotropy of Cosmic-Ray Intensity Observed with Worldwide Networks of Ground-based Neutron Monitors and Muon Detectors in 2021 November. Astrophysical Journal Vol.938 No.1 (2022). doi:10.3847/1538-4357/ac91c5 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/84494
Title
Large-amplitude Bidirectional Anisotropy of Cosmic-Ray Intensity Observed with Worldwide Networks of Ground-based Neutron Monitors and Muon Detectors in 2021 November
Author(s)
Munakata K.
Kozai M.
Kato C.
Hayashi Y.
Kataoka R.
Kadokura A.
Tokumaru M.
Mendonça R.R.S.
Echer E.
Lago A.D.
Rockenbach M.
Schuch N.J.
Bageston J.V.
Braga C.R.
Jassar H.K.A.
Sharma M.M.
Duldig M.L.
Humble J.E.
Sabbah I.
Evenson P.
Mangeard P.S.
Kuwabara T.
Ruffolo D.
Sáiz A.
Mitthumsiri W.
Nuntiyakul W.
Kóta J.
Kozai M.
Kato C.
Hayashi Y.
Kataoka R.
Kadokura A.
Tokumaru M.
Mendonça R.R.S.
Echer E.
Lago A.D.
Rockenbach M.
Schuch N.J.
Bageston J.V.
Braga C.R.
Jassar H.K.A.
Sharma M.M.
Duldig M.L.
Humble J.E.
Sabbah I.
Evenson P.
Mangeard P.S.
Kuwabara T.
Ruffolo D.
Sáiz A.
Mitthumsiri W.
Nuntiyakul W.
Kóta J.
Author's Affiliation
Joint Support-Center for Data Science Research
The Public Authority of Applied Education and Training
Kuwait University
Shinshu University
The Graduate University for Advanced Studies
George Mason University
University of Tasmania
Instituto Nacional de Pesquisas Espaciais
Mahidol University
The University of Arizona
National Institute of Polar Research
Chiang Mai University
The Bartol Research Institute
Nagoya University
The Public Authority of Applied Education and Training
Kuwait University
Shinshu University
The Graduate University for Advanced Studies
George Mason University
University of Tasmania
Instituto Nacional de Pesquisas Espaciais
Mahidol University
The University of Arizona
National Institute of Polar Research
Chiang Mai University
The Bartol Research Institute
Nagoya University
Other Contributor(s)
Abstract
We analyze the cosmic-ray variations during a significant Forbush decrease observed with worldwide networks of ground-based neutron monitors and muon detectors during 2021 November 3-5. Utilizing the difference between primary cosmic-ray rigidities monitored by neutron monitors and muon detectors, we deduce the rigidity spectra of the cosmic-ray density (or omnidirectional intensity) and the first- and second-order anisotropies separately for each hour of data. A clear two-step decrease is seen in the cosmic-ray density with the first ∼2% decrease after the interplanetary shock arrival followed by the second ∼5% decrease inside the magnetic flux rope (MFR) at 15 GV. Most strikingly, a large bidirectional streaming along the magnetic field is observed in the MFR with a peak amplitude of ∼5% at 15 GV, which is comparable to the total density decrease inside the MFR. The bidirectional streaming could be explained by adiabatic deceleration and/or focusing in the expanding MFR, which have stronger effects for pitch angles near 90°, or by selective entry of GCRs along a leg of the MFR. The peak anisotropy and density depression in the flux rope both decrease with increasing rigidity. The spectra vary dynamically, indicating that the temporal variations of density and anisotropy appear different in neutron monitor and muon detector data.