Comparison of observed and theoretically calculated amplitudes of Forbush effects for events associated with the arrival of a shock wave
This paper examines the role of plasma compression regions ahead of interplanetary coronal mass ejections in the formation of Forbush effects decreases in cosmic ray intensity during the first phase. The aim of this study is to identify and quantify the relationship between the structure of the CME (specifically, the parameters of the compression region behind the shock front) and the nature of the observed Forbush effect. To this end, events with intensity decrease amplitudes greater than 5 percent were selected, and a theoretical model of cosmic ray behavior at the shock front was tested using modern analytical methods and mathematical models. Analysis of the results for two dozen events revealed satisfactory agreement between the theory and observations. The key reason for some discrepancies is the need to integrate the magnetic field over the particle gyro radius. The obtained data provide insight into the mechanisms of cosmic ray modulation in such environments.