A model-independent algorithm for ionospheric tomography 1 : theory and tests

This paper presents a model-independent algorithm for tomography of the ionosphere. The prior knowledge consists of the following pieces of information: electron density cannot be negative, the ionosphere is basically smooth and stratified and electron density is low at high (more than aproximately 700 km) and low (less than approximately 100 km) altitude.Tests based on simulated measurements show that the method recovers the latitudinal structure well, whereas the vertical structure is recovered with moderate success: the estimated height of the layer of maximum electron density may be as much as 90 km in error. Because of the imposed smoothness, the method tends to underestimate the peak in electron density, by as much as one third in unfavorable cases.