[P-EM11] Space Weather and Space Climate

[PEM11-17] Causality Relationships Analysis in Magnetospheric Space Weather: The Case of the Dst Index and Its Potential Drivers

*Dr Hua-Liang Wei¹、Michael A Balikhin¹、Richard J Boynton¹、Simon N Walker¹ (1.The University of Sheffield)

キーワード：Space weather, Dst index, System identification, Causality analysis

Understanding, quantifying and modelling the response behaviour of the Earth’s magnetosphere to the solar wind is important for evaluating and monitoring the impacts of space weather on our Earth. The analysis and accurate characterization of the causal relationship from solar wind to magnetosphere is difficult because the evolution and response of the associated dynamics are complex, nonlinear and time-varying. In this work, a nonlinear dynamic system identification approach, called Nonlinear Autoregressive Moving Average with eXogenous inputs (NARMAX) method, together with other methods, is applied to investigate Granger causal relationships from solar wind parameters to the intensity of geomagnetic storms characterized by the Dst index. For illustration purposes, causality test results obtained from data of Dst index three solar wind parameters (solar wind velocity, dynamic pressure and proton density), and two interplanetary magnetic field (IMF) indices (southward IMF and solar wind rectified electric field), are presented to show the performance of the proposed causality analysis methods.