R. T. Gushchina

The Solar Polar Field in the Cosmic-Ray Intensity Modulation

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%.

Estimation of long-term stability of detectors of the world neutron monitor network for the whole monitoring period

Worldwide neutron monitor network today consists of more than 50 neutron monitors. To provide long time observation of solar activity revealed in cosmic rays the first importance has a stable operating of the neutron monitor network. The method of this long time stability estimation is considered in presented work. The quantitative ratios of stable operation and causes of the long time drifts in the neutron monitor data are presented for each station. Now days the new scientific and applying problem stand before the network, so, this network is essentially modernized at present. The main task now is to provide the network operating and operating as a single multidirectional device with sufficiently stable long time accuracy.

The secular variations of cosmic ray cutoff rigidities, caused by century variations in geomagnetic field, and cosmic ray variations

Vertical rigidities of geomagnetic cutoff are obtained for world neutron monitor network with annual resolution for the period of 1950-2020 by the method of trajectory calculations with the model International Geomagnetic Reference Field. Results of the computations show the total decrease of the cut off rigidities in the majority points which is caused by a decrease of the total geomagnetic field during this period. The prognosis of planetary distribution of the cut off rigidities is made up to 2050.