Dynamics of Cosmic-Ray Cutoff Rigidity and Magnetospheric Parameters during Different Phases of the Storm of November 20, 2003

Geomagnetism and Aeronomy - The correlations between variations in the geomagnetic cutoff rigidity of cosmic rays and the Dst and Kp geomagnetic indices and solar-wind and IMF parameters are...     

Correction of data from the neutron monitor worldwide network

The method for correcting data from individual neutron monitors at the worldwide network of cosmic ray stations, characterized by the instrument drift and sporadic variations, has been proposed. The correction is performed using the method of spectrographic global survey. The proposed method makes it possible to correct data from the global network of stations immediately during processing and can be used in studies of cosmic-ray intensity long-term variations and in the real-time operation mode.     

Variations in the geomagnetic cutoff rigidity of cosmic rays at individual points of the Asian region during the extreme events of 2003

The variations in the geomagnetic cutoff rigidity in Irkutsk, Alma-Ata, and Beijing in October–November 2003 were calculated using ground-based measurements of cosmic ray intensity from the worldwide network of stations and GOES spacecraft. The calculated variations in geomagnetic cutoff rigidity are presented together with D _st variations of the geomagnetic field. The obtained results are compared to calculations performed using the Tsyganenko model of the magnetosphere.     

Variations of Geomagnetic Cosmic Ray Thresholds and Their Latitudinal Behavior in the Period of Solar Disturbance in September 2005

The period of interplanetary, geomagnetic and solar disturbances of September 7–15, 2005, is characterized by two sharp increases of solar wind velocity to 1000 km/s and great Dst variation of the geomagnetic field (~140 nT). The time variations of theoretical and experimental geomagnetic thresholds observed during this strong geomagnetic storm, their connection with solar wind parameters and the Dst index, and the features of latitudinal behavior of geomagnetic thresholds at particular times of the storm were studied. The theoretical geomagnetic thresholds were calculated with cosmic ray particle tracing in the magnetic field of the disturbed magnetosphere described by Ts01 model. The experimental geomagnetic thresholds were specified by spectrographic global survey according to the data of cosmic ray registration by the global station network.     

Spatial-Energy Characteristics of Cosmic Rays and Parameters of Magnetospheric Current Systems in March and June 2015

The data from terrestrial observations of cosmic rays at the global network of stations by the method of spectrographic global survey were used to analyze two Forbush decreases during the geomagnetic storms in March and June 2015. The spectra of cosmic ray variations, pitch angle anisotropy of cosmic rays at different phases of Forbush decrease development, and the changes in the planetary system of geomagnetic cutoff rigidities are presented. It is shown that, during the approximation of the spectra of variations by the power function of particle rigidity in the interval of 10–50 GV, the spectrum index is softer at the maximum modulation phase than during the phases of cosmic ray intensity decline and recovery. In the axisymmetric model of the bounded magnetosphere of the Earth, which takes into account the currents at the magnetopause and the ring current, the distance to the subsolar point and the radius of the ring current, as well as the contribution of the ring current to the changes in geomagnetic cutoff rigidity and to the Dst index during the studied events, are determined.     

Cosmic Rays during Forbush Effects in March 1989 and March 1991: Spectra of Variation,Anisotropy, and Variations of Geomagnetic Cutoff Rigidity

Geomagnetism and Aeronomy - Two Forbush effects that occurred during geomagnetic storms in March 1989 and March 1991 are analyzed based on ground-based measurements of cosmic rays at a global...