Geometric Triangulation of Imaging Observations to Track Coronal Mass Ejections Continuously Out to 1 AU

TL;DR

This paper introduces a geometric triangulation method using stereoscopic imaging to track and predict the trajectory of coronal mass ejections from the Sun to Earth, improving space weather forecasting.

Contribution

The paper presents a novel triangulation technique that determines CME propagation and velocity continuously out to 1 AU using stereoscopic imaging data.

Findings

Accurately predicted CME arrival time and velocity at Earth.

Revealed non-radial CME motions and velocity changes.

Linked in situ flux-rope structures with imaging observations.

Abstract

We describe a geometric triangulation technique, based on time-elongation maps constructed from imaging observations, to track coronal mass ejections (CMEs) continuously in the heliosphere and predict their impact on the Earth. Taking advantage of stereoscopic imaging observations from STEREO, this technique can determine the propagation direction and radial distance of CMEs from their birth in the corona all the way to 1 AU. The efficacy of the method is demonstrated by its application to the 2008 December 12 CME, which manifests as a magnetic cloud (MC) from in situ measurements at the Earth. The predicted arrival time and radial velocity at the Earth are well confirmed by the in situ observations around the MC. Our method reveals non-radial motions and velocity changes of the CME over large distances in the heliosphere. It also associates the flux-rope structure measured in situ with the dark cavity of the CME in imaging observations. Implementation of the technique, which is expected to be a routine possibility in the future, may indicate a substantial advance in CME studies as well as space weather forecasting.