Transfer Entropy Approach To Discovering The Rank Of Solar Wind Drivers To Geomagnetic Storm

Geomagnetic storm is an important space weather event,which will threaten the safety of satellites in orbit and the navigation and communication on the ground,etc.Therefore,the study of geomagnetic storm is not only of academic value,but also has strong practical application needs.The response of geomagnetic system to solar wind variation is mainly nonlinear and complex.The research on the origin,development of geomagnetic storms and relationship between geomagnetic storms and solar wind is one of the hot topics of space science.At present,research related with the solar wind-geomagnetic system mainly focus on the linear correlation coefficient analysis.However,transfer entropy based on information theory can provide powerful model-free directed statistics,which can be used to analyze non-linear relationships that cannot be detected by linear correlation analysis and model hypothesis.The main work of this paper is as follows:1.The algorithm principle of correlation coefficient is systematically discussed.The research methods and status of the relationship between solar wind and magnetosphere based on correlation coefficient are also discussed.2.In this paper,the theoretical basis and calculation principle of the transfer entropy are described.Both the KSG algorithm and the nearest neighbor algorithm are used to calculate the transfer entropy,where the permutation test algorithm is used to validate the calculated results.3.The effects of sunspot number and F10.7 on the solar wind-magnetosphere interaction during high and low solar activity years are analyzed by using the correlation coefficient and transfer entropy.4.The importance coefficient and its calculation method based on transfer entropy are proposed for specific events,and calculated between the interplanetary electric field(E,,the south component of the interplanetary magnetic field(IMF B_Z,,solar wind speed(V_SW,,solar wind temperature(T_SW,,solar wind Density(D_SW,,interplanetary magnetic field(B,,solar wind dynamic pressure(P_SW,and the geomagnetic SYMH index,finally obtain the rank of importance of solar wind parameters that cause geomagnetic storm.In this study,we use the transfer entropy to study the nonlinear relationshipbetween the solar wind parameters and the geomagnetic index,and apply the transfer entropy to quantify the correlation between the solar wind parameters and the geomagnetic index during the geomagnetic storm.The validity of the transfer entropy is verified by the simulation data and the real measured data of the solar wind and magnetosphere,and the importance sequence of the solar wind parameters to the geomagnetic index during the geomagnetic storm is further obtained,which provides the criterion for parameter selection for the model research.