# A STEREO Survey of Magnetic Cloud Coronal Mass Ejections Observed at Earth in 2008--2012

## TL;DR

This study uses STEREO and SOHO imaging to analyze 31 magnetic cloud-associated CMEs from 2008-2012, reconstructing their 3D structure and kinematics to improve understanding and prediction of CME impacts at Earth.

## Contribution

It provides the first comprehensive 3D reconstructions of CME flux ropes from Sun to Earth, linking imaging data with in-situ measurements and offering predictive formulas for CME arrival times.

## Key findings

- Flux rope orientations from imaging do not match in-situ measurements.
- Velocities within CMEs are well-reproduced by imaging-based reconstructions.
- Different surface phenomena are associated with distinct CME morphologies.

## Abstract

We identify coronal mass ejections (CMEs) associated with magnetic clouds (MCs) observed near Earth by the Wind spacecraft from 2008 to mid-2012, a time period when the two STEREO spacecraft were well positioned to study Earth-directed CMEs. We find 31 out of 48 Wind MCs during this period can be clearly connected with a CME that is trackable in STEREO imagery all the way from the Sun to near 1 AU. For these events, we perform full 3-D reconstructions of the CME structure and kinematics, assuming a flux rope morphology for the CME shape, considering the full complement of STEREO and SOHO imaging constraints. We find that the flux rope orientations and sizes inferred from imaging are not well correlated with MC orientations and sizes inferred from the Wind data. However, velocities within the MC region are reproduced reasonably well by the image-based reconstruction. Our kinematic measurements are used to provide simple prescriptions for predicting CME arrival times at Earth, provided for a range of distances from the Sun where CME velocity measurements might be made. Finally, we discuss the differences in the morphology and kinematics of CME flux ropes associated with different surface phenomena (flares, filament eruptions, or no surface activity).