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Structure of the Power Spectral Density of Galactic Cosmic Ray Variation during 1953-2016

Published online by Cambridge University Press:  24 July 2018

Pauli Väisänen
Affiliation:
Space Climate Research Unit, University of Oulu, Finland email: [email protected]
Ilya Usoskin
Affiliation:
Space Climate Research Unit, University of Oulu, Finland email: [email protected]
Kalevi Mursula
Affiliation:
Space Climate Research Unit, University of Oulu, Finland email: [email protected]
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Abstract

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Fluxes of galactic cosmic rays (GCR) observed at 1 AU are modulated inside the heliosphere at different time scales. Here we study the properties of the power spectral density (PSD) of galactic cosmic ray variability using hourly data from 31 neutron monitors (NM) from 1953 to 2016. We pay particular attention to the reliability of the used datasets and methods. We present the overall PSD and discuss different parts of the spectrum and the related periodicities. We find significant spectral peaks at the periods of 11 years, 1.75 years, 155 days, 27 days and 24 hours and the harmonics of the latter two peaks. We calculate a power law slope of −1.79 ± 0.13 for the period range between 50 and 130 hours and a slope of −1.34 ± 0.17 for the period range between 40 days and 3.4 years (1000 − 30000 h).

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2018 

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