Estimating arrival time of Earth-directed CMEs at \textit{in-situ} spacecraft using COR & HI observations from STEREO

TL;DR

This study improves CME arrival time predictions at Earth by combining stereoscopic and heliospheric imaging techniques with the Drag Based Model, addressing uncertainties caused by CME interactions and solar wind effects.

Contribution

It introduces a combined method using 3D triangulation and geometric triangulation with heliospheric images to enhance CME arrival time forecasting accuracy.

Findings

Heliospheric imaging significantly improves CME propagation predictions.

The combined approach reduces errors in CME arrival time estimates.

Comparison with in-situ data validates the method's effectiveness.

Abstract

The prediction of the arrival time and transit speed of CMEs near the Earth is one of the key problems in understanding the solar terrestrial relationship. Although, STEREO observations now provide a multiple view of CMEs in the heliosphere, the true speeds derived from stereoscopic reconstruction of SECCHI coronagraph data are not quite sufficient in accurate forecasting of arrival time of a majority of CMEs at the Earth. This is due to many factors which change the CME kinematics, like interaction of two or more CMEs or the interaction of CMEs with the pervading solar wind. In order to understand the propagation of CMEs, we have used the 3D triangulation method on SECCHI coronagraph (COR2) images, and geometric triangulation on the J-maps constructed from Heliospheric Imagers HI1 and HI2 images for eight Earth-directed CMEs observed during 2008-2010. Based on the reconstruction, and implementing the Drag Based Model for the distance where the CMEs could not be tracked unambiguously in the interplanetary medium, the arrival time of these CMEs have been estimated. These arrival times have also been compared with the actual arrival time as observed by \textit{in-situ} instruments. The analysis reveals the importance of heliospheric imaging for improved forecasting of the arrival time and direction of propagation of CMEs in the interplanetary medium.