CME-Earth Interaction Dynamics: Magnetic Field Strength and Arrival Time as Key Determinants of Geoeffectiveness

While significant progress has been made in space weather forecasting, the exact relationship between coronal mass ejection (CME) magnetic properties and geomagnetic storm intensity remains a critical unsolved problem with important implications for both theoretical understanding and operational forecasting. Our study investigates this relationship through analysis of CME propagation and magnetic field evolution. Using the EUHFORIA model, we examine CME propagation from initiation to Earth arrival. Our analysis of a representative fast CME event reveals an approximately ۴۰-hour Sun to Earth transit time, confirming its classification as a rapid event. Crucially, we observe that when the interplanetary magnetic field (IMF) magnitude at L۱ increases to the ۱۰-۲۵ nT range, this indicates the presence of a turbulent sheath region capable of significantly amplifying magnetic field strength compared to background solar wind values. These enhanced fields, when coupled with sustained southward components, are particularly effective at driving geomagnetic activity.

کلیدواژه ها:

CME ، EUHFORIA- heliosphere- geomagnetic storm-space weather forecasting