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Research Paper | Physics | Nigeria | Volume 12 Issue 6, June 2023
Analysis of Galactic Cosmic Ray Forbush Decrease: Case Study of Five (5) Forbush Decrease Events
G. Adagba  | B. A. Oshido
Abstract: The short - term variation of galactic cosmic ray (GCR) flux caused by interplanetary coronal mass ejections (ICMEs) and their associated shocks or magnetic flux ropes is known as Forbush decrease. This temporary decrease in the flux of galactic cosmic rays (GCRs) is observed at earth by NMs at locations that were possibly passed by the ICME depending on the station?s viewing direction. This research investigates five specific occurrences of Forbush Decrease (FD) events and their impact on Galactic Cosmic Ray (GCR) flux. This entails scrutinizing the magnitude and length of the decreases and also taking into account the corresponding solar activity indicators. In order to quantify the temporal profiles of GCR flux throughout each occurrence, we analysed data from worldwide network of Neutron Monitors (NMs) and modelled the magnitude of decrease for each event selected. Interestingly, we found that the magnitudes of Forbush decrease D (t) can be used to detect the arrival of an ICME and to explain the characteristics of Forbush decreases. Secondly, we observed that Forbush decrease caused by shock and or ejecta due to the arrival of an ICME are detected by all polar NMs at the same time and also show similar characteristics excepts for the distinct differences in recovery times. The time of arrival at earth and magnitude of decrease may vary depending on viewing direction of the station. our results have provided valuable guidance for future investigations of Forbush Decrease.
Keywords: Cosmic Rays, Forbush decrease, ICME, Neutron Monitors
Edition: Volume 12 Issue 6, June 2023,
Pages: 7 - 12