October 1970 | NTIA Technical Memo OT ITSTM 3
A time-varying electron density model for LF/VLF propagation calculations,
Leslie A. Berry; R. Michael Jones
Abstract: Published measured profiles of the lower ionosphere are used as the basis of an analytic model of the D-region electron density which varies with the sun’s zenith angle. The model is the sum of an exponential layer and a daytime Chapman-like C-layer. The parameters of the model are adjusted by comparing its calculated full wave reflection coefficients with various published experimental propagation data. The model reproduces the measured diurnal variation of amplitude and phase height of VLF and LF signals for summer, mid-latitude conditions, including the sunrise dip in amplitude. The model does not vary enough with season, nor does it compare closely with observations at night. Correspondence with equatorial and polar conditions in not investigated. Further research on seasonal and latitudinal variations is recommended.
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