A Double-Adaptive Adjustment Algorithm for Ionospheric Tomography

A double-adaptive adjustment algorithm (DAAA) is proposed to reconstruct three-dimensional ionospheric electron density (IED) distribution. In the DAAA method, relaxation factor of multiplicative algebraic reconstruction technique (MART) first adaptively adjusted by introducing adaptive MART (AMART). To avoid voxels without any rays traversing them becoming dependent on initial IED values, smoothing constraints are generally imposed general, elements matrices invariant in iterative process. They affect accuracy and efficiency inversion. overcome above limitation, adjustments constrained matrix subsequently carried out. Both numerical simulation actual global navigation satellite system (GNSS) experimental results validate that tomography have been improved method. Finally, new applied structure ionosphere during different geomagnetic activities. The comparisons show vertical profiles method agreement with those recorded from ionosonde, inverted total content (VTEC) also agrees products center for orbit determination Europe (CODE) quiet storms. confirm reliability superiority