A Time-efficient, Data-driven Modeling Approach for Predicting the Geomagnetic Impact of Coronal Mass Ejections

Abstract

To understand the global-scale physical processes behind coronal mass ejection (CME)–driven geomagnetic storms and predict their intensity as a space weather forecasting measure, we develop an interplanetary CME flux rope–magnetosphere interaction module using 3D magnetohydrodynamics. The simulations adequately describe CME-forced dynamics of the magnetosphere including the imposed magnetotail torsion. These interactions also result in induced currents, which are used to calculate the geomagnetic perturbation. Through a suitable calibration, we estimate a proxy of geoeffectiveness—the Storm Intensity index (STORMI)—that compares well with the Dst/SYM-H index. Simulated impacts of two contrasting CMEs quantified by the STORMI index exhibit a high linear correlation with the corresponding Dst and SYM-H indices. Our approach is relatively simple, has fewer parameters to be fine-tuned, and is time efficient compared to complex fluid-kinetic methods. Furthermore, we demonstrate that flux rope erosion does not significantly affect our results. Thus our method has the potential to significantly extend the time window for predictability—an outstanding challenge in geospace environment forecasting—if early predictions of near-Earth CME flux rope structures based on near-Sun observations are available as inputs. This study paves the way for early warnings based on operational predictions of CME-driven geomagnetic storms.