# 3D Reconstruction and Interplanetary Expansion of the 2010 April 3rd CME

## TL;DR

This paper presents a comprehensive 3D analysis of the 2010 April 3rd CME, combining spacecraft imaging, empirical modeling, and cosmic ray data to understand its expansion, magnetic properties, and impact on cosmic rays.

## Contribution

It introduces a detailed 3D reconstruction of the CME using the GCS model and links its expansion and magnetic properties to cosmic ray decreases, providing new insights into CME behavior.

## Key findings

- CME expands linearly towards Earth
- Magnetic field power law index is approximately 1.6
- Estimated initial magnetic field is around 0.01 G

## Abstract

We analyse the 2010 April 3rd CME using spacecraft coronagraphic images at different vantage points (SOHO, STEREO-A and STEREO-B). We perform a 3D reconstruction of both the flux rope and shock using the Graduated Cylindrical Shell (GCS) model to calculate CME kinematic and morphologic parameters (e.g. velocity, acceleration, radius). The obtained results are fitted with empirical models describing the expansion of the CME radius in the heliosphere and compared with in situ measurements from Wind spacecraft: the CME is found to expand linearly towards Earth. Finally, we relate the event with decreases in the Galactic Cosmic Ray (GCR) Flux, known as Forbush decreases (FD), detected by EPHIN instrument onboard SOHO spacecraft. We use the analytical diffusion-expansion model (ForbMod) to calculate the magnetic field power law index, obtaining a value of approximately 1.6, thus estimating a starting magnetic field of around 0.01 G and an axial magnetic flux of around 5x1E20 Mx at 15.6 Rsun.