3-D Modeling of Subionospheric VLF Propagation in the Presence of Localized D-Region Perturbations Associated with Lightning
Abstract
A theoretical model of multiple-mode, subionospheric VLF wave propagation in the presence of localized perturbations of the nighttime D-region has been developed. Such perturbations could be produced, for example, by lightning-induced electron precipitation associated with a characteristic type of phase or amplitude perturbation in VLF signals known as Trimpi events. Our model assumes that the ionospheric perturbation is slowly varying in the horizontal plane and that mode-coupling within the region of the perturbation is therefore negligible. However, the model does assume mode-coupling along the paths between the transmitter and receiver, the transmitter and the perturbation, and the perturbation and receiver. The model accounts for (1) effects of perturbations with finite extent in the dimension transverse to the great circle (GC) path between transmitter and receiver, and (2) effects of perturbations which lie off the GC path as well as on it. The formulation used for the numerical calculations depends significantly on the mode refractive index of the ambient earth-ionosphere waveguide and the mode refractive index in the region of the perturbation. In the calculations, values for the mode refractive index are determined from the electron-density-versus-altitude profiles of both the ambient and perturbed ionospheres.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 03, 1990
- Accession Number
- ADP006320
Entities
People
- T. F. Bell
- U. S. Inan
- W. L. Poulsen
Organizations
- Stanford University