利用转移熵研究引起磁暴扰动的太阳风参数重要性排序

磁暴是重要空间天气灾害性事件，能够影响卫星的安全在轨运行和地面电网系统等。目前，对于太阳风–磁层相互作用的研究多集中在分析相关系数的线性关系，而基于信息论的转移熵可以提供强大的无模型有向统计量，可用来分析传统相关性分析和模型假设检测不到的非线性关系。本文利用转移熵的方法，研究了磁暴期间的太阳风驱动参数。利用第23和24太阳活动周的小时精度数据进行长时间尺度分析，发现太阳风向地磁的信息传递呈双峰分布，表现出与太阳活动水平的一致性。利用2010－2018年93个地磁暴期间的分钟精度数据进行短时间尺度分析，结果表明：行星际电场（E）和行星际磁场南向分量（$ {B}_{z} $）对地磁指数Sym-H在时间延迟为60 min时信息传递较强，而太阳风速度 $ {v}_{mathrm{s}mathrm{w}} $、温度 $ {T}_{mathrm{s}mathrm{w}} $、数密度$ {D}_{mathrm{s}mathrm{w}} $、磁场B和动压$ {P}_{mathrm{s}mathrm{w}} $对Sym-H指数的信息传递较弱。上述研究结果能够为太阳风–磁层相互作用的建模提供参数选择及确定预测范围的依据。

Transfer Entropy Approach to Discovering the Ranking of Solar Wind Drivers to Geomagnetic Storm

Geomagnetic storm is an important disaster event in space weather, which can affect satellite orbit and ground power system. At present, in the solar wind-magnetosphere system, most studies focus on the linear relationships analyzed by the correlation coefficient. However, transfer entropy can provide powerful model-free directed statistics, which can be used to analyze non-linear relationships that cannot be detected by traditional correlation analysis and model hypothesis. The hourly resolution data of solar activity cycle 23 and 24 were used to analyze the large time scale. The information transmission of solar wind and geomagnetic has a bimodal distribution, which is consistent with the solar activity level. Using the minute resolution data of 93 geomagnetic storms from 2010 to 2018 for small time scale analysis, the results show that E, ${{rm{IMF}}B}_{z}$ have strong information transmission to the geomagnetic Sym-H parameter when the time delay is 60 minutes, while $ {v}_{mathrm{s}mathrm{w}} $, $ {T}_{mathrm{s}mathrm{w}} $, $ {D}_{mathrm{s}mathrm{w}} $, B, $ {P}_{mathrm{s}mathrm{w}} $ are lower. It provides the basis for parameter selection and prediction range determination for solar wind-geomagnetic model construction.