The Solar Polar Field in the Cosmic-Ray Intensity Modulation

24th European Cosmic Ray Symposium

Paouris, E.^1 ; Mavromichalaki, H.^1 ; Belov, A.^2 ; Eroshenko, E.^2 ; Gushchina, R.^2

Faculty of Physics, National and Kapodistrian University of Athens, Athens, Greece^1

Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences (IZMIRAN), Moscow, Russia^2

关键词: Cosmic ray intensity;    Cosmic ray modulation;    Heliospheric current sheet;    Interplanetary magnetic fields;    Root mean square deviations;    Solar magnetic cycle;    Solar magnetic fields;    Wavelet analysis method;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/632/1/012074/pdf
DOI  :  10.1088/1742-6596/632/1/012074

来源: IOP

【 摘 要 】

In this work the modulation of galactic cosmic-ray intensity based on solar and heliospheric indices for the solar cycle 23 (1996-2008), is studied. In previous works a number of different indices such as the sunspot number, the CME-index, the interplanetary magnetic field and the heliospheric current sheet tilt were selected to be the most appropriate ones in order to describe the cosmic ray intensity of 10 GV observed by the network of neutron monitors. The new approach is an extension of this study to the influence of the solar magnetic field parameters, such as the mean magnetic field and the polar magnetic field, on the cosmic ray (CR) modulations. Using the wavelet analysis method a major periodicity of about 20-21 years was confirmed in the solar magnetic field data, indicating the existence of the solar magnetic cycle in CR variations. The best empirical relation of the cosmic ray modulation taking into account the sunspot number, the CME-index, the mean solar magnetic field and the solar polar field was improved significantly: a relative root mean square deviation (RMSD) between the observed and the calculated cosmic ray intensity values is found to be 8.7% instead to the previous one of about 10%.