时变三维电离层层析成像重建公式

基于GPS信标观测数据重建电离层电子密度的时变三维电离层层析问题的数学基础，在简化电离层电子密度随时间变化的条件下，导出了三维平行束层析重建公式. 在二维情况下，本文导出的三维平行束层析重建公式与Yeh等给出的二维电离层层析重建公式相同. 文中还讨论了有限视角和有限接收机孔径对重建图像的影响. 根据文中给出的三维平行束层析重建公式，在这些非理想条件下，对一个脉冲源函数进行CT重建的结果表明，基于GPS信标观测数据重建电离层电子密度的时变三维电离层层析是可行的.

RECONSTRUCTION FORMULA OF TIME-DEPENDENT 3-D COMPUTERIZED IONOSPHERIC TOMOGRAPHY

This paper illuminates the mathematical foundation of time-dependent three-dimensional computerized ionospheric tomography (CIT) for reconstructing ionospheric electron density (Ne) from ground-based GPS beacon measurements. After simplifying the relation between Ne and time, the formula of 3-D parallel-beam tomography is theoretically deduced and proved to be the same as the 2-D CIT inversion formula derived by K.C. Yeh when it is applied to 2-D cases. Furthermore, this paper investigates the effects of limited view angle and finite receiver aperture on recovered images. Specifically, the response to an impulse source function with the established 3-D parallel-beam reconstruction formula under these non-idealized conditions is numerically computed. The results indicate the feasibility of time-dependent three-dimensional CIT to reconstruct (Ne) from ground-based GPS beacon measurements.