IONOSPHERIC ELECTRODYNAMICS USING MAGNETIC APEX COORDINATES
IONOSPHERIC ELECTRODYNAMICS USING MAGNETIC APEX COORDINATES
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DOI：
10.5636/jgg.47.191
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发表时间：
1995-01-01
期刊：
影响因子：
--
通讯作者：
RICHMOND, AD
中科院分区：
文献类型：
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作者：
RICHMOND, AD
本文推导了一般地磁场的电离层电动力学方程，并将其具体应用于磁顶坐标系。提出了两个相关的坐标系：修正的顶点坐标系，适用于涉及电场和磁场排列电流的计算;准偶极子坐标系，适用于涉及高度积分电离层电流的计算。偶极子引起的地磁场畸变会导致电动力学方程的修正，在某些地理位置畸变系数超过50%。在等势地磁场线的假设下，它示出了如何场线集成电动力学方程可以在磁纬度和经度的二维表示，以及如何高度集成和场向电流密度可以计算。本文导出了与三维电流系统有关的电离层上下磁扰动的简化计算表达式。它示出了如何修改顶点坐标系的基矢量可以应用到地图电场，等离子体漂移速度，磁扰动，坡印亭通量沿着地磁场到其他高度，自动考虑到这些矢量的大小和方向的变化沿着磁力线。同样，它示出了如何准偶极子坐标是有用的表达水平电离层电流，等效电流，和地面磁扰动。一个计算机代码可用于有效计算本文中描述的各种坐标、基向量和相关量。
The equations of ionospheric electrodynamics are developed for a geomagnetic field of general configuration, with specific application to coordinate systems based on Magnetic Apex Coordinates. Two related coordinate systems are proposed: Modified Apex Coordinates, appropriate for calculations involving electric fields and magnetic-field-aligned currents; and Quasi-Dipole Coordinates, appropriate for calculations involving height-integrated ionospheric currents. Distortions of the geomagnetic field from a dipole cause modifications to the equations of electrodynamics, with distortion factors exceeding 50% at some geographical locations. Under the assumption of equipotential geomagnetic-field lines, it is shown how the field-line-integrated electrodynamic equations can be expressed in two dimensions in magnetic latitude and longitude, and how the height-integrated and field-aligned current densities can be calculated. Expressions are derived for the simplified calculation of magnetic perturbations above and below the ionosphere associated with the three-dimensional current system. It is shown how the base vectors for the Modified Apex coordinate system can be applied to map electric fields, plasma-drift velocities, magnetic perturbations, and Poynting fluxes along the geomagnetic field to other altitudes, automatically taking into account changes in magnitude and direction of these vector quantities along the field line. Similarly, it is shown how Quasi-Dipole coordinates are useful for expressing horizontal ionospheric currents, equivalent currents, and ground-level magnetic perturbations. A computer code is made available for efficient calculation of the various coordinates, base vectors, and related quantities described in this article.