Quantifying the Propagation of Fast Coronal Mass Ejections from the Sun to Interplanetary Space by

Combining Remote Sensing and Multi-point In Situ Observations

The Astrophysical Journal, Volume 882, Number 2
In order to have a comprehensive view of the propagation and evolution of coronal mass ejections (CMEs) from the Sun to deep interplanetary space beyond 1 au, we carry out a kinematic analysis of seven CMEs in solar cycle 23. The events are required to have coordinated coronagraph observations, interplanetary type II radio bursts, and multi-point in situ measurements at the Earth and Ulysses. A graduated cylindrical shell model, an analytical model without free parameters, and a magnetohydrodynamic model are used to derive CME kinematics near the Sun, to quantify the CME/shock propagation in the Sun–Earth space, and to connect in situ signatures at the Earth and Ulysses, respectively. We find that each of the seven CME-driven shocks experienced a major deceleration before reaching 1 au and thereafter propagated with a gradual deceleration from the Earth to larger distances. The resulting CME/shock propagation profile for each case is roughly consistent with all the data, which verifies the usefulness of the simple analytical model for CME/shock propagation in the heliosphere. The statistical analysis of CME kinematics indicates a tendency that the faster the CME, the larger the deceleration, and the shorter the deceleration time period within 1 au. For several of these events, the associated geomagnetic storms were mainly caused by the southward magnetic fields in the sheath region. In particular, the interaction between a CME-driven shock and a preceding ejecta significantly enhanced the pre-existing southward magnetic fields and gave rise to a severe complex geomagnetic storm.