地磁场长期变化的自洽正态统计模型

从地磁场时间变化尺度可分的理论考虑和观测事实出发，建立地磁场Reynolds分解，强调地磁场时均部分和长期变化部分均包含所有的多极子分量；重新解释Constabe和Paker关于规一化Gduss系数的统计结果，从而将地磁场长期变化自洽正态模型自洽化．在这一结构最简单的统计模型中，地磁角度要素和总强度的统计分布均为非正态．地磁场方向及其等价表示虚偶极磁矩方向服从广义Fisher分布，可以解释地磁场方向和虚磁偶极矩方向的椭圆分布长轴大致正交的观测事实．模型的VGP角散布不能解释古地磁观测，意味着时均场中显著存在非轴向偶极子分量．解析结果加强了Egbert关于VGP路径优势经度为不均匀采样所致的推论．

A SELF-CONSISTENT NORMAL STAT ISTICAL MODEL OF GEOMAGNETIC FIELD AND ITS SECULAR VARIATION

Considering the observed facts and the theoretical argument that the temporal scale of the secular variation can be divided, the geomagnetic Reynolds decomposition was suggested, in which all multipole components are contained in both the averaged part and the secular varying part of the field. In addition, Constable-Paker's statistical result on reduced Gaussian coefficient is understood anew. A self-coonsistent normal model of the geomagnetic secular variation was established. It was shown that the statistical distributions of angle elements and intensity are non-normal, especially during the polarity reverse transition. The direction of magnetic field and the direction of the virtual geomagnetic moment obey the generalized Fisher distribution, this may be reason why the major axes of data ellipses of the field direction and the VGP position are approximately orthogonal. The angular dispersion of VGP of the model could not explain lava-flows data base, which implies that the obvious non-axial-dipole component was contained in the averaged pars of the field in the past 5 Ma.Analytical results on marginal distribution of VGP longitude strengthen Egbert's corollary that nonuniform sample results in dominant longitude of VGP path during the transition of polarity reversal.