Solar Cyclic Modulation of Diurnal Variation in Cosmic Ray Intensity
Cosmic rays are ions that move at relativistic speeds. They generate secondary cosmic rays by successive collisions with atmospheric particles, and then, the secondary particles reach the ground. The secondary particles are mainly neutrons and muons, and the neutrons are observed by the ground neu...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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The Korean Space Science Society
2018-12-01
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| Series: | Journal of Astronomy and Space Sciences |
| Subjects: | |
| Online Access: | http://janss.kr/journal/article.php?code=64508 |
| _version_ | 1797369589023113216 |
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| author | Eun Ho Park Jongil Jung Suyeon Oh Paul Evenson |
| author_facet | Eun Ho Park Jongil Jung Suyeon Oh Paul Evenson |
| author_sort | Eun Ho Park |
| collection | DOAJ |
| description | Cosmic rays are ions that move at relativistic speeds. They generate secondary cosmic rays by successive collisions with
atmospheric particles, and then, the secondary particles reach the ground. The secondary particles are mainly neutrons and
muons, and the neutrons are observed by the ground neutron monitor. This study compared the diurnal variation in cosmic
ray intensity obtained via harmonic analysis and that obtained through the pile-up method, which was examined in a previous
study. In addition, we analyzed the maximum phase of the diurnal variation using four neutron monitors with a cutoff rigidity
below approximately 6 GV, located at similar longitudes to the Oulu and Rome neutron monitors. Expanding the data of
solar cycles 20–24, we examined the time of the maximum cosmic ray intensity, that is, the maximum phase regarding the
solar cyclic modulation. During solar cycles 20–24, the maximum phase derived by harmonic analysis showed no significant
difference with that derived by the pile-up method. Thus, the pile-up method, a relatively straightforward process to analyze
diurnal variation, could replace the complex harmonic analysis. In addition, the maximum phase at six neutron monitors
shows the 22-year cyclic variation very clearly. The maximum phase tends to appear earlier and increase the width of the
variation in solar cycles as the cutoff rigidity increases. |
| first_indexed | 2024-03-08T17:49:03Z |
| format | Article |
| id | doaj.art-5a77c29a67d54c4ead64d5a63c15011d |
| institution | Directory Open Access Journal |
| issn | 2093-5587 2093-1409 |
| language | English |
| last_indexed | 2024-03-08T17:49:03Z |
| publishDate | 2018-12-01 |
| publisher | The Korean Space Science Society |
| record_format | Article |
| series | Journal of Astronomy and Space Sciences |
| spelling | doaj.art-5a77c29a67d54c4ead64d5a63c15011d2024-01-02T09:12:28ZengThe Korean Space Science SocietyJournal of Astronomy and Space Sciences2093-55872093-14092018-12-01354219225https://doi.org/10.5140/JASS.2018.35.4.219Solar Cyclic Modulation of Diurnal Variation in Cosmic Ray IntensityEun Ho Park0Jongil Jung1Suyeon Oh2Paul Evenson3Chonnam National UniversitySpace Science and Geology, Chungnam National UniversityChonnam National UniversityUniversity of DelawareCosmic rays are ions that move at relativistic speeds. They generate secondary cosmic rays by successive collisions with atmospheric particles, and then, the secondary particles reach the ground. The secondary particles are mainly neutrons and muons, and the neutrons are observed by the ground neutron monitor. This study compared the diurnal variation in cosmic ray intensity obtained via harmonic analysis and that obtained through the pile-up method, which was examined in a previous study. In addition, we analyzed the maximum phase of the diurnal variation using four neutron monitors with a cutoff rigidity below approximately 6 GV, located at similar longitudes to the Oulu and Rome neutron monitors. Expanding the data of solar cycles 20–24, we examined the time of the maximum cosmic ray intensity, that is, the maximum phase regarding the solar cyclic modulation. During solar cycles 20–24, the maximum phase derived by harmonic analysis showed no significant difference with that derived by the pile-up method. Thus, the pile-up method, a relatively straightforward process to analyze diurnal variation, could replace the complex harmonic analysis. In addition, the maximum phase at six neutron monitors shows the 22-year cyclic variation very clearly. The maximum phase tends to appear earlier and increase the width of the variation in solar cycles as the cutoff rigidity increases.http://janss.kr/journal/article.php?code=64508cosmic raydiurnal variationsolar cycle |
| spellingShingle | Eun Ho Park Jongil Jung Suyeon Oh Paul Evenson Solar Cyclic Modulation of Diurnal Variation in Cosmic Ray Intensity Journal of Astronomy and Space Sciences cosmic ray diurnal variation solar cycle |
| title | Solar Cyclic Modulation of Diurnal Variation in Cosmic Ray Intensity |
| title_full | Solar Cyclic Modulation of Diurnal Variation in Cosmic Ray Intensity |
| title_fullStr | Solar Cyclic Modulation of Diurnal Variation in Cosmic Ray Intensity |
| title_full_unstemmed | Solar Cyclic Modulation of Diurnal Variation in Cosmic Ray Intensity |
| title_short | Solar Cyclic Modulation of Diurnal Variation in Cosmic Ray Intensity |
| title_sort | solar cyclic modulation of diurnal variation in cosmic ray intensity |
| topic | cosmic ray diurnal variation solar cycle |
| url | http://janss.kr/journal/article.php?code=64508 |
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