日冕物质抛射与大尺度电流螺度的关联研究

。Magnetic helicity is a physical quantity that indicates the topological complexity of a magnetic field configuration (in the corona)..CME is proposed to be an unavoidable burst of the magnetic helicity accumulation in the corona. Theoretical study and numerical simulation indicate that an upper bound on the magnetic helicity may exist for force-free fields like the fields state in corona. It is noted that the accumulation of magnetic helicity in excess of this upper bound would initiate a non-equilibrium state,resulting in a natural and unavoidable CME burst in the corona.In this study, the inversion technique of deriving the vector magnetic field from full-disk longitudinal magnetograms is first dicussed based on SOHO/MDI observations.This technique will be aplied to extract vector fields from full-disk longitudinal magnetograms from which the current helicity can be diredctly derived. These derived current helicity maps can used to get the average current helicity of north and south hemispheres in visible solar disk, and to investigae the correlation between the current helicities and the CME erupting frequency so as to grasp the obtainable parameters for forecasting the CMEs.

磁螺度是描述磁场拓扑复杂性的物理量。日冕物质抛射是磁螺度在日冕中不断积累的一种必然。日冕中磁螺度的积累超过某一上限时,将不存在无力场平衡态,产生爆发。本文从观测角度，利用全日面纵向磁图反演大尺度矢量磁场的综合磁图，利用此方法获得矢量磁场综合磁图计算太阳表面全球的综合电流螺度分布，从综合电流螺度图上取每天南北半球的大尺度磁场的平均电流螺度，研究其与每日CME发生次数的关系，来了解CME的发生与磁螺度之间的联系。为进一步利用可观测量预报CME打下基础。

我们研究了23太阳活动周月日冕物质抛射（CME）的发生率与光球表面全球大尺度电流螺度的相关性。我们运用了Pevtsov和Latushko使用过的一种技术方法来从全日面纵向磁场获得全球的矢量磁场，但我们使用了与他们不同的计算电流螺度的方法，并且我们关注于电流螺度在整个太阳周的演化规律。我们发现月日冕物质抛射（CME.）的发生率与光球表面全球大尺度电流螺度变化之间有很强的相关性。这进一步增添了电流螺度在太阳爆发中扮演重要角色的证据。