Prediction of coronal mass ejection geo-effectiveness using Solar Orbiter as a far upstream monitor in real-time

Coronal mass ejections (CMEs) are the main drivers of severe space weather at Earth which can cause significant disruption to both satellite and ground systems, necessitating accurate predictions for timely mitigation. The complicated nature of the processes affecting CMEs as they propagate makes understanding and predicting their physical properties and global structure a challenging task, from both a fundamental and practical space weather perspective. Current challenges lie in forecasting CME arrival time and magnetic structure prior to Earth arrival, closely related to our ability to directly measure their magnetic field configuration between the Sun and 1 AU, which is critical for assessing their geo-effectiveness.

Recent opportunities provided by Solar Orbiter crossing the Sun-Earth line have allowed us to monitor upstream solar wind conditions in real-time. On 23 March 2024, Solar Orbiter observed a fast CME whilst located upstream of Earth at 0.39 AU. It provided observations of the CME magnetic field vector in real time, with a lead time of over one day before Earth impact. We present the analysis performed that led to the first real-time prediction of the geomagnetic magnitude of a severe geomagnetic storm (minimum Dst -130 nT) with sufficient accuracy and lead time. Our results demonstrate the necessity of future real-time upstream solar wind monitors towards providing accurate and timely predictions of space weather effects.