Influence of Interplanetary Coronal Mass Ejec5ons on Terrestrial Par5cle Fluxes Through Magnetosphere Disturbances

TL;DR

This paper explores how interplanetary magnetic fields from coronal mass ejections influence Earth's particle fluxes, revealing the roles of magnetic reconnection, field orientation, and energy spectra in space weather effects.

Contribution

It provides new insights into the magnetic configurations of ICMEs affecting ground-level particle fluxes and extends understanding of energy spectra during geomagnetic disturbances.

Findings

IMF Bz component enhances geomagnetic activity via magnetic reconnection.

Magnetic field strength B influences Forbush decreases more than Bz orientation.

Particle energy spectra during magnetic effects are limited to 10 MeV, while FD particles can reach 100 MeV.

Abstract

This study investigates the modulation of particle fluxes at the Earths surface influenced by the intensity and orientation of the Interplanetary magnetic field (IMF) carried by the Coronal Mass Ejecta (ICME). We examine how IMF and its Bz component, opposing the magnetosphere, significantly enhance geomagnetic activity through magnetic reconnection. This reconnection facilitates increased penetration of solar wind particles into the magnetosphere, thus amplifying the fluxes registered by terrestrial particle detectors and enhancing particle fluxes through reduced cutoff rigidity (magnetospheric effect, ME). Conversely, the orientation of the Bz component is less crucial for a Forbush decrease (FD); instead, the strength of the ejecta's scalar magnetic field (B) predominates, potentially triggering a significant FD. The study explores how magnetic field variations influence the flux of neutrons and muons, effectively modifying the observed rates of cosmic ray influx. Comprehensive data from the WIND magnetometer and Aragats spectrometers underline the direct relationship between ICME magnetic configurations and variations in ground-level particle fluxes. Moreover, we discover that the energy spectra of additional particles during ME are limited to 10 MeV due to the low energy of solar protons entering the terrestrial atmosphere. In contrast, the energy spectra of the missing FD particles can extend up to 100 MeV, demonstrating that magnetic traps and cradles formed by interactions between ejecta and Earth's magnetic fields can also deflect medium-energy solar protons. These insights advance our understanding of geomagnetic modulation of particle fluxes and bolster predictive models of space weather impacts on particle detection technologies.