Time evolution of cosmic-ray intensity and solar flare index at the maximum phase of cycles 21 and 22 |
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| Affiliation: | 1. Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimiopolis Zografos, 15783 Athens, Greece;2. Section of Astrophysics, Astronomy and Mechanics, Physics Department, University of Athens, Panepistimiopolis Zografos, 15783 Athens, Greece;3. Research Center for Astronomy and Applied Mathematics, Academy of Athens, 14 Anagnostopoulou str., 10673 Athens, Greece;1. National Research Base of Intelligent Manufacturing Service, Chongqing Technology and Business University, Chongqing 400067, China;2. Institute of Groundwater and Earth Sciences, Jinan University, Guangzhou 510632, China;1. CRESST/University of Maryland at Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, United States;2. Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, United States;3. Department of Physics, University of Maryland, College Park, MD 20742, United States;4. Institute for Space Research, Moscow, Russia;5. Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, United States;6. Computer Sciences Corporation, Lanham-Seabrook, MD 20706, United States;7. Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, United States;8. Department of Physics, Catholic University of America, Washington, DC 20064, United States;1. ARPA Lombardia, Via Juvara 22, 20129, Milano, Italy;2. European Commission, Joint Research Centre (JRC), Retieseweg 111, 2440, Geel, Belgium;3. Jožef Stefan Institute, Ljubljana, Slovenia;1. Dept. of Mechanical Engineering, Jadavpur University, Kolkata-700032, India;2. Dept. of Applied Electronics & Instrumentation Engineering, Haldia Institute of Technology, Haldia-721657, India;3. Dept.of Computer Science & Electronics, Ramakrishna Mission Vidyamandira, Belur Math, Howrah-711202, India;4. Dept.of Instrumentation & Electronics Engineering, Jadavpur University, Kolkata-700106, India |
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| Abstract: | Analysis of the time series into trigonometric series allows the investigation of cosmic-ray (CR) intensity variations in a range of periodicities from a few days to 1 year. By this technique the amplitude and the phase of all observed fluctuations can be given. For this purpose, daily CR intensity values recorded at Climax Neutron Monitor station for the time intervals 1979–1982 and 1989–1991, which correspond to the epochs of maximum activity for solar cycles 21 and 22, respectively, have been studied. The data analysis revealed the occurrence of new periodicities, common or not, in the two solar maxima. A search of our results was done by a power spectral analysis determining independently possible systematic periodic or quasi-periodic variations. Based on the fact that during these maxima the CR intensity tracks the solar flare index better than the sunspot number, the same analysis was performed on these data, which are equivalent to the total energy emitted by the solar flares. Both analyses result in periodicities with different probability of occurrence in different epochs. Occurrence at peaks of 70, 56, 35, 27, 21 and 14- days were observed in all time series, while the periods of 140–154 and 105 days are reported only in the 21st solar maximum and are of particular importance. All of the short-term periods except of those at 27 and 154-days are recorded for first time in CR data, but they had already been observed in the solar activity parameters. Moreover, each parameter studied here has a very different power spectrum distribution in periods larger than 154 days. The possible origin of the observed variations in terms of the CR interaction in the upper atmosphere and the solar cavity dynamics is also discussed here. |
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