Forbush decrease on June 1-10, 2025: A comprehensive analysis based on neutron monitor and space observations

Abstract

The study presents an analysis of the event recorded on 1–10 June 2025 by the AATB neutron monitor (Almaty, Kazakhstan, 3340 m a. s. l., geomagnetic cutoff rigidity R = 5.9 GV). The amplitude of the cosmic ray intensity decrease registered by the neutron monitor was about 12%, which classifies the event as a major Forbush decrease. The source of the disturbances was active region AR 14100, where a series of M3.4 and M8.1 flares (30–31 May 2025) occurred, accompanied by fast halo-type coronal mass ejections (CMEs) with velocities reaching up to 1700 km/s. A comparison of neutron monitor data with interplanetary parameters revealed the classical structure of an interplanetary CME, including an interplanetary shock observed on 1 June at 05:45 UT, a disturbed sheath region, and the CME ejecta extending until 2 June at 01:10 UT. The event was accompanied by the development of a strong geomagnetic storm, peaking on 2 June. The results demonstrate a close relationship between solar activity, the dynamics of interplanetary CMEs, and the modulation of galactic cosmic ray (GCR) fluxes, which points out the importance of an integrated approach to space weather diagnostics and forecasting.