Disturbance storm time index coupling with solar wind/IMF parameters

Understanding the complex coupling between the interplanetary magnetic field (IMF), solar wind dynamics and geomagnetic activity remains a cornerstone of space weather research. While the broader relationships are well-acknowledged, quantifying the precise, time-dependent impacts of specific heliospheric drivers on the Disturbance Storm Time (Dst) index requires deeper investigation. This study systematically analyzes the interactions between the Dst index and a comprehensive suite of solar wind and IMF parameters-including velocity (v sw ), density (n sw ), dynamic pressure (P sw ), convective electric field (E sw ) and magnetic field components (B x , B y , B z , B total ), alongside the ap and AE indices-using high-resolution data from 2010 to 2018. Employing a robust framework of Time-Shifted Cross-Correlation (TSCC), Cross Wavelet Transform (XWT) and Wavelet Transform Coherence (WTC), we map both the transient lags and localized periodicities of these interactions. TSCC analysis reveals a distinct zero-day lag response, characterized by strong negative correlations for vsw, ap, AE, E sw , B total and P sw against the Dst index, contrasted by positive correlations with B z , n sw and the v sw B z coupling term. Furthermore, XWT and WTC analyses identify high common-power regions and phase-locked coherence dominated by a ∼28-day solar rotation periodicity across the driving parameters. These findings refine our understanding of solar-terrestrial energy transfer mechanisms and offer critical constraints for empirical geomagnetic storm forecasting models.