INTERPRETING THE STRUCTURE OF OBLIQUE IONOGRAMS.
STANFORD UNIV CA STANFORD ELECTRONICS LABS
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Oblique ionograms are records of sweep-frequency ionospheric sounders with transmitter-receiver separation of hundreds or thousands of kilometers. These ionograms cannot be inverted to give ionospheric electron density profiles without making unrealistically drastic assumptions concerning the nature of the ionosphere. However, oblique ionograms can be calculated from a known ionospheric electron density distribution. This report describes a method for performing the calculation by using a digital computer and gives 135 examples of the resulting ionograms. The technique takes full account of earth and ionosphere curvatures and allows arbitrary choice of electron density variation with height and longitudinal distance but not with lateral distance. The geomagnetic field is neglected in the interest of economy, but it could be included. Examples of synthetic ionograms are given for 24 different ionospheres. Of particular interest are the computed results which show the effect of lower ionospheric layers and of the nature of the electron density distribution between the various layers in the ionosphere. The synthetic ionograms include raypath takeoff angles and also the absolute group-time delay these quantities are particularly useful since they are not available on experimental ionograms. Author
- Atmospheric Physics