How are Forbush decreases related with IP magnetic field enhancements ?

TL;DR

This study investigates the relationship between cosmic ray Forbush decreases and interplanetary magnetic field enhancements caused by CMEs, revealing a strong correlation in their profile shapes at high rigidities.

Contribution

It demonstrates a clear similarity between FD profiles and magnetic field compressions, providing new insights into the physical connection between cosmic ray decreases and magnetic field variations.

Findings

FD profiles closely match magnetic field compression shapes

The correlation is observed at rigidities between 12 and 42 GV

Results suggest magnetic field enhancements influence FDs

Abstract

Cosmic ray Forbush decreases (FDs) are usually thought to be due to Earth-directed coronal mass ejections (CMEs) from the Sun and their associated shocks. When CMEs and their shocks reach the Earth, they cause magnetic field compressions. We seek to understand the relation between these magnetic field compressions and FDs at rigidities between 12 and 42 GV using data from the GRAPES-3 instrument at Ooty. We find that the shapes of the Forbush decrease profiles show a startling similarity to that of the magnetic field compression in the near-Earth IP medium. We seek to understand the implications of this interesting result.