On the features of great Forbush effect during May 2024 extreme geomagnetic storm

TL;DR

This study analyzes the extreme Forbush effect during May 2024's intense geomagnetic storm, revealing significant cosmic ray variations linked to solar activity and geomagnetic disturbances using global neutron monitor data.

Contribution

It introduces a detailed analysis of the Forbush effect during a major geomagnetic storm using unique global neutron monitor methods and data from May 2024.

Findings

Forbush effect magnitude was 15.7% at 10 GV rigidity.

Significant magnetospheric effects (~4%) observed during the storm.

Correlation between solar activity, interplanetary disturbances, and cosmic ray variations.

Abstract

The work investigates the features of galactic cosmic ray density and anisotropy behavior and their relation to solar sources, interplanetary and geomagnetic disturbances from May 8 to May 13, 2024. During this time, powerful solar flares and fast CMEs were recorded, leading to registration of an extreme geomagnetic storm along with one of the most significant Forbush effects for the entire observation period. All the calculations of cosmic ray characteristics are made using the data of global neutron monitor network and unique methods maintained at IZMIRAN: the Global Survey Method and the Ring of Stations Method. It is determined that the magnitude of Forbush effect under study was 15.7% (for particles with 10 GV rigidity) and as an extreme geomagnetic storm was recorded there was a significant magnetospheric effect observed in the data of neutron monitors (~4%).