Validation of electron density profiles derived from oblique ionograms over the United Kingdom

Inversion algorithms are available to derive the vertical electron density profile at the midpoint of an oblique sounder path. The techniques open up the possibility of monitoring the ionosphere at otherwise inaccessible loca tions, such as over sea or inhospitable terrain. A new method of monitoring the ionosphere based on radio tomography can be used to create two-dimensi onal images of electron density. The results in this paper compare midpoint profiles derived from oblique ionograms with corresponding profiles obtain ed from tomographic images of electron density and from a vertical ionosphe ric sounder. The comparisons illustrate the oblique sounder inversion techn ique and its inherent limitations. The results provide useful information o n the complementary nature of the separate ionospheric measurement techniqu es and have implications for the use of these measurements as inputs to rea l-time ionospheric models.